Iron Pumpkin ... SE and Balanced preamps, 2025 presentation
As title sez - one name, two preamps. Major thingie is AVC Volume attenuation and, sheer luck involved, some free (magnetic) voltage gain.
Reason for 2025 presentation - to show present state (hopefully no further changes
), while there are two preceding threads where you can refresh memory.
Threads:
There is also Papa's tongue-in-cheak thread, I'll say no more, nudgenudge, say no more
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Iron Pumpkin SE, logically, being for single ended signal arrangement, so 5 RCA inputs, and one RCA output; I'm usually mounting doubled RCA outputs, wired simply in parallel.
Iron Pumpkin (no suffix), balanced signal configuration, any number of 5 inputs can be arranged as (permanently) SE/RCA, balanced output can be wired to one or two (parallel) XLRs, or one XLR and (parallel) RCA
2025 iteration, besides major physical change to Big Motherboard, is also having altered arrangement of Iron Turtle (AVC) module,e with (new) 28 steps arrangement.
Step 24 is 0db,
step 23 down to step 1 are each -2db,
step 25 to step 28 are each +2db.
So, ranging from -46db to +8db. Previous arrangement, with 24 steps and jumpers for (permanent) gain set stays as solution for kit/finished preamp with physical/rotary switches controls.
And, yes, now there is a choice between Metglas and Finemet cores; what's the difference between two - pretty much the same as between Cinemag normal nickel and CInemag high nickel - normal isn't much worse than high nor high is much better than normal........ but when you shoot, you usually shoot for better sleep
Dazzling, Shiny and Overwhelming characteristics speech: Fully dual mono (custom made 20VA Donut for audio circuitry is having separate secondaries for channels; custom made 10VA Donut feeding all things Logic and switching), ultragigamega shunt regs, OhYeah! Toshiba For Audio JFets serving in buffers, precious Fujitsu relays for everything what's switched, volume attenuation as explained above, yadayada.......
Button on front, fiddle left-right to set volume, push for incremental cycle through inputs 1 to 5.
Fancyschmanzy remote having same functions, plus mute/unmute buttons.
3.5'' TFT as Eye Candy, Tesla writing for ZML Greetings, then Led Zepp font for functional screen.
Reason for 2025 presentation - to show present state (hopefully no further changes
), while there are two preceding threads where you can refresh memory.Threads:
There is also Papa's tongue-in-cheak thread, I'll say no more, nudgenudge, say no more
Login to view embedded media
Iron Pumpkin SE, logically, being for single ended signal arrangement, so 5 RCA inputs, and one RCA output; I'm usually mounting doubled RCA outputs, wired simply in parallel.
Iron Pumpkin (no suffix), balanced signal configuration, any number of 5 inputs can be arranged as (permanently) SE/RCA, balanced output can be wired to one or two (parallel) XLRs, or one XLR and (parallel) RCA
2025 iteration, besides major physical change to Big Motherboard, is also having altered arrangement of Iron Turtle (AVC) module,e with (new) 28 steps arrangement.
Step 24 is 0db,
step 23 down to step 1 are each -2db,
step 25 to step 28 are each +2db.
So, ranging from -46db to +8db. Previous arrangement, with 24 steps and jumpers for (permanent) gain set stays as solution for kit/finished preamp with physical/rotary switches controls.
And, yes, now there is a choice between Metglas and Finemet cores; what's the difference between two - pretty much the same as between Cinemag normal nickel and CInemag high nickel - normal isn't much worse than high nor high is much better than normal........ but when you shoot, you usually shoot for better sleep
Dazzling, Shiny and Overwhelming characteristics speech: Fully dual mono (custom made 20VA Donut for audio circuitry is having separate secondaries for channels; custom made 10VA Donut feeding all things Logic and switching), ultragigamega shunt regs, OhYeah! Toshiba For Audio JFets serving in buffers, precious Fujitsu relays for everything what's switched, volume attenuation as explained above, yadayada.......
Button on front, fiddle left-right to set volume, push for incremental cycle through inputs 1 to 5.
Fancyschmanzy remote having same functions, plus mute/unmute buttons.
3.5'' TFT as Eye Candy, Tesla writing for ZML Greetings, then Led Zepp font for functional screen.
Coaxial Compression Driver DIY (CCDIY) discussion
- Multi-Way
- 69 Replies
Dear Community,
I recently watched a video about the B&C coaxial compression drivers. After looking them up i was shocked how pricey they are. Then i thought: can't we make our own coaxial compression driver with conventional cheap drivers/parts?
When thinking about the concept i became more and more excited to try.
Directivity control provided by a horn + point source behaviour like a full range/coaxial driver = why not?
Let's discuss the possibilities and try to succeed!
I recently watched a video about the B&C coaxial compression drivers. After looking them up i was shocked how pricey they are. Then i thought: can't we make our own coaxial compression driver with conventional cheap drivers/parts?
When thinking about the concept i became more and more excited to try.
Directivity control provided by a horn + point source behaviour like a full range/coaxial driver = why not?
Let's discuss the possibilities and try to succeed!
Name of these footprint - Jack - Relais
- By franziscko
- Parts
- 6 Replies
Hi, need to know correct name of these footprints....
on Easyeda there are tons and in Eagle tons*tons*tons....
In cases like this, how should I behave?
Thanks!
on Easyeda there are tons and in Eagle tons*tons*tons....
In cases like this, how should I behave?
Thanks!
A Hafler inspired solution for the phantom center image problem
For years I've been pursuing a way of getting better stereo sound like you get when you use a divider wall between stereo speakers to eliminate crosstalk and interference patterns. One way to do this is to add more channels using a matrix. A simple and well known matrix is to turn L and R signals into L-R, L+R, and R-L. What no one has ever told me is that this simple array will do amazing things if you space the speakers apart properly and listen at an appropriate distance. Center panned sounds only play through the center speaker, so there are no interference patterns so that solves the phantom center problem. But what happens when a sound is panned hard to the right or left? For a right panned signal you end up with the array playing a -R in the left channel, a R in the center and another R in the right channel. This of course creates interference patterns, but good ones! They work to create the proper stereo separation and never cause a null to cross our ears! This is because there is a null in the center of the sound field instead of a lobe. So each ear gets an appropriate stereo lobe! Each ear gets a lobe - so punny!
Here's a picture of my current array using basic little Sony SSCS-5 speakers
You can see I'm actually using 5 speakers here. The center channel plays full range down to 100Hz. The inside left and right play down to 600Hz. The outsides play 600Hz and down. This just helps to boost the stereo effect as the wavelengths start to get long compared to the width of the array. 3 speakers works great. 5 just gives it a little something extra and I happen to have lots of speakers and amp channels available.
Watch this video to see how the interference patterns produce excellent stereo throughout a huge range of frequencies. I used Falstadt's great ripple tank simulator to demonstrate how the effect works over a huge range of frequencies. http://www.falstad.com/ripple/Ripple.html. The three dots at the top of the screen represent an appropriately spaced array of 3 speakers playing a hard right panned signal. The circle down below represents the listener's head with strong signal reaching the right ear and weaker signal that is phase delayed reaching the left ear - as it should be. As I play a wide variety of frequencies you can see that strong stereo separation is maintained and no null from interference patterns ever crosses the right ear. You do get some weakening of the signal as the frequency goes down due to the center null widening so you can boost up the side channels in the lower frequencies or add a wider spaced set of speakers for the lower frequencies. I actually do both.
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So what happens with slightly panned signals? The same thing except the lobes are not as different, so no matter the panning there are no unwanted nulls from the interference patterns at the listener's ears.
Also notice what's happening off to the sides - not a lot of energy to light up early side wall reflections.
So how does it sound? I'm elated! It's great! It's not phase-y or weird. The sound stage is natural and oh so clear and smooth with beautiful separation and clarity. It's a revelation. On recordings with wild stereo effects they get really wild like they should. I don't see myself ever going back to a two speaker setup for high quality stereo playback. I tried having the outside speakers playing regular stereo from 600Hz down and it's just a downgrade. This is MUCH better IMHO even in lower frequencies where it looks like it's falling apart and just turning into mono. It's blowing my mind.
As a general starting guideline I recommend spacing the speakers at about 1 foot apart center to center for the 3 center speakers and put the listening position about 8 feet back. You'll hear some good stuff with just 3 speakers but you may need to put a low frequency boost on the side speakers to correct the tone for side panned sounds. You can do this by playing correlated pink noise and panning it left to right. Adjust the lower frequencies on the side speakers until the pink noise sounds similar in tone and volume across left, center, and right of the sound field. Experiment with spacing and listening distance. It's surprisingly flexible.
One difficulty is how to setup the matrix array. I use my Mac mini running Audio Hijack to do it in the digital domain. This allows matrix mixing and access to all 8 channels of my Denon receiver over HDMI. You can do a basic 3 speaker array using a 2 channel playback system by creating a L+R signal for the center speaker and a L-R signal for the side speakers. I run the L+R signal into the right channel, and the L-R into the left channel of the amp. The left channel runs both side speakers in series or parallel. Just wire up the right speaker opposite of the left speaker and it works!
I don't recommend mixing line level signals in the analog domain unless you have appropriate signal mixing hardware that that properly buffers everything. YMMV but my results were lackluster just using Y-connectors. I also don't recommend hooking multiple amp channels up to the same speaker unless you really know what you are doing. If you are using low pass and high pass crossovers on the outboard speakers like I am, watch out for phase reversals. Suddenly your soundstage is backwards!
12/30/2022 Update. After trying a lot of things I'm back to just 3 speakers. With proper spacing and the voids filled in between the speakers to minimize edge diffraction this really produces the purest sound and best imaging. I think I was tricked by the increased overall volume of adding more speakers. So there's something to that. If you have a lot of the same kind of speakers lying around and they can't play very loud, 7 of them playing at once makes a noticeably higher playback level possible than just 2 or 3 of them, and you can get some really great imaging. Turning up the volume a little to make up for the fewer speakers and I'm actually hearing better sound overall. This is great news because it's easier to set up as there are no time delays required and so a simple 2 channel amp and 2 channel dac can be used to power all 3 speakers. You just have to get the stereo signal matrixed into L+R and L-R signals. I heard one person say that the electric summing and differencing causes irretrievable loss of information. It does if you just take the L+R signal by itself, or the L-R signal by itself. But if you mix all the signals, including the inverted L-R, which gives R-L, everything that should reach the ears does. And, much less of what shouldn't.
Here's a picture of my current array using basic little Sony SSCS-5 speakers
You can see I'm actually using 5 speakers here. The center channel plays full range down to 100Hz. The inside left and right play down to 600Hz. The outsides play 600Hz and down. This just helps to boost the stereo effect as the wavelengths start to get long compared to the width of the array. 3 speakers works great. 5 just gives it a little something extra and I happen to have lots of speakers and amp channels available.
Watch this video to see how the interference patterns produce excellent stereo throughout a huge range of frequencies. I used Falstadt's great ripple tank simulator to demonstrate how the effect works over a huge range of frequencies. http://www.falstad.com/ripple/Ripple.html. The three dots at the top of the screen represent an appropriately spaced array of 3 speakers playing a hard right panned signal. The circle down below represents the listener's head with strong signal reaching the right ear and weaker signal that is phase delayed reaching the left ear - as it should be. As I play a wide variety of frequencies you can see that strong stereo separation is maintained and no null from interference patterns ever crosses the right ear. You do get some weakening of the signal as the frequency goes down due to the center null widening so you can boost up the side channels in the lower frequencies or add a wider spaced set of speakers for the lower frequencies. I actually do both.
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So what happens with slightly panned signals? The same thing except the lobes are not as different, so no matter the panning there are no unwanted nulls from the interference patterns at the listener's ears.
Also notice what's happening off to the sides - not a lot of energy to light up early side wall reflections.
So how does it sound? I'm elated! It's great! It's not phase-y or weird. The sound stage is natural and oh so clear and smooth with beautiful separation and clarity. It's a revelation. On recordings with wild stereo effects they get really wild like they should. I don't see myself ever going back to a two speaker setup for high quality stereo playback. I tried having the outside speakers playing regular stereo from 600Hz down and it's just a downgrade. This is MUCH better IMHO even in lower frequencies where it looks like it's falling apart and just turning into mono. It's blowing my mind.
As a general starting guideline I recommend spacing the speakers at about 1 foot apart center to center for the 3 center speakers and put the listening position about 8 feet back. You'll hear some good stuff with just 3 speakers but you may need to put a low frequency boost on the side speakers to correct the tone for side panned sounds. You can do this by playing correlated pink noise and panning it left to right. Adjust the lower frequencies on the side speakers until the pink noise sounds similar in tone and volume across left, center, and right of the sound field. Experiment with spacing and listening distance. It's surprisingly flexible.
One difficulty is how to setup the matrix array. I use my Mac mini running Audio Hijack to do it in the digital domain. This allows matrix mixing and access to all 8 channels of my Denon receiver over HDMI. You can do a basic 3 speaker array using a 2 channel playback system by creating a L+R signal for the center speaker and a L-R signal for the side speakers. I run the L+R signal into the right channel, and the L-R into the left channel of the amp. The left channel runs both side speakers in series or parallel. Just wire up the right speaker opposite of the left speaker and it works!
I don't recommend mixing line level signals in the analog domain unless you have appropriate signal mixing hardware that that properly buffers everything. YMMV but my results were lackluster just using Y-connectors. I also don't recommend hooking multiple amp channels up to the same speaker unless you really know what you are doing. If you are using low pass and high pass crossovers on the outboard speakers like I am, watch out for phase reversals. Suddenly your soundstage is backwards!
12/30/2022 Update. After trying a lot of things I'm back to just 3 speakers. With proper spacing and the voids filled in between the speakers to minimize edge diffraction this really produces the purest sound and best imaging. I think I was tricked by the increased overall volume of adding more speakers. So there's something to that. If you have a lot of the same kind of speakers lying around and they can't play very loud, 7 of them playing at once makes a noticeably higher playback level possible than just 2 or 3 of them, and you can get some really great imaging. Turning up the volume a little to make up for the fewer speakers and I'm actually hearing better sound overall. This is great news because it's easier to set up as there are no time delays required and so a simple 2 channel amp and 2 channel dac can be used to power all 3 speakers. You just have to get the stereo signal matrixed into L+R and L-R signals. I heard one person say that the electric summing and differencing causes irretrievable loss of information. It does if you just take the L+R signal by itself, or the L-R signal by itself. But if you mix all the signals, including the inverted L-R, which gives R-L, everything that should reach the ears does. And, much less of what shouldn't.
Post a Picture that Makes You Laugh
- The Lounge
- 5863 Replies
I’ll go first. Which one of you guys did this?
Quad 44 Preamp - Is it worth keeping and upgrading
- By eldarvanyar
- Solid State
- 17 Replies
Hi,
I have a Quad 44 which I bought a couple of years ago. It's all standard and a mark II version according to the Dada Electronics website.
I have been doing some reading regarding the Quad 44 and I am unsure about the real potential of this preamp and whether I should invest some money in it before using it, or just sell it and put the money into something else.
I am also thinking about having a passive preamp made by BTE Designs as well, so have to decide on which to do first.
Either amp would feed into a Quad 606 MK1 power amp, which I bought earlier this year and immediately sent to Quad for a service, and they also upgraded the PSU to 909 spec.
I am aware that there is the DIY route with DADA Electronics
Quad 44 MKII DIY Upgrade and Revision kit Deluxe
Quad 44 MKII DIY Upgrade and Revision kit Deluxe
I would have to get someone to do the soldering and upgrading for me due to being post stroke and my eyesight not being very good close up
Redhill Audio
QUAD 44 PREAMP UPGRADE - STAGE 1
Elna Cerafine audio-grade electrolytic capacitors
Additional, high-quality Panasonic PPS film capacitor decoupling added to remove noise from critical areas
Solid Film MKS signal path capacitors
Unnecessary signal path capacitors bypassed for reduced grain and a cleaner sound
A well chosen blend ofLME49710NA/LM4562NA National Semi & Texas Instruments Op amps for better refinement and improved detail
Quad 44 Preamp Upgrade - Stage 1
QUAD 44 PREAMP UPGRADE - STAGE 2
Increased capacity Low-ESR Power Supply Capacitors
Output signal path capacitors upgraded to solid film types
Elna Cerafine Decoupling capacitors
LME49710 & TI/National Semi Opamps
Panasonic PPS Bypass Capacitors
2 x Red Hill Audio Mini-Shunt Voltage Regulators +/-15v
Signal Path Improved with Audio Wire "Silver Signal"
http://redhillaudio.co.uk/hifi-upgr...reamp-upgrades/quad-44-preamp-upgrade-stage-2
Amplabs who do upgrades as well.
http://www.amp-labs.co.uk/q44fs-a.htm
Rob from Amplabs serviced and upgraded a Quad 303 that I bought a couple of years ago
http://www.amp-labs.co.uk/servicing.htm
He originally serviced a Yamaha CR1000 for me which I stupidly sold a couple of years ago but he only works on Quad now I think.
I have read online that the Quad 44 suffers from the 4066 CMOS Chip which was originally designed for and used in the Plessey System X Telephone exchanges, and is naturally bandwidth limited.
Other issues include the use of the Op-Amp TL071 as was used in the 405 power amp.
With the modular design and ability to have different boards the Quad 44 could be quite an asset if it sounds any good. Are the MM and MC cards any good or able to be upgraded to anything worthwhile?
Any advice, thoughts or experience much appreciated
Thanks
Lee
I have a Quad 44 which I bought a couple of years ago. It's all standard and a mark II version according to the Dada Electronics website.
I have been doing some reading regarding the Quad 44 and I am unsure about the real potential of this preamp and whether I should invest some money in it before using it, or just sell it and put the money into something else.
I am also thinking about having a passive preamp made by BTE Designs as well, so have to decide on which to do first.
Either amp would feed into a Quad 606 MK1 power amp, which I bought earlier this year and immediately sent to Quad for a service, and they also upgraded the PSU to 909 spec.
I am aware that there is the DIY route with DADA Electronics
Quad 44 MKII DIY Upgrade and Revision kit Deluxe
Quad 44 MKII DIY Upgrade and Revision kit Deluxe
I would have to get someone to do the soldering and upgrading for me due to being post stroke and my eyesight not being very good close up
Redhill Audio
QUAD 44 PREAMP UPGRADE - STAGE 1
Elna Cerafine audio-grade electrolytic capacitors
Additional, high-quality Panasonic PPS film capacitor decoupling added to remove noise from critical areas
Solid Film MKS signal path capacitors
Unnecessary signal path capacitors bypassed for reduced grain and a cleaner sound
A well chosen blend ofLME49710NA/LM4562NA National Semi & Texas Instruments Op amps for better refinement and improved detail
Quad 44 Preamp Upgrade - Stage 1
QUAD 44 PREAMP UPGRADE - STAGE 2
Increased capacity Low-ESR Power Supply Capacitors
Output signal path capacitors upgraded to solid film types
Elna Cerafine Decoupling capacitors
LME49710 & TI/National Semi Opamps
Panasonic PPS Bypass Capacitors
2 x Red Hill Audio Mini-Shunt Voltage Regulators +/-15v
Signal Path Improved with Audio Wire "Silver Signal"
http://redhillaudio.co.uk/hifi-upgr...reamp-upgrades/quad-44-preamp-upgrade-stage-2
Amplabs who do upgrades as well.
http://www.amp-labs.co.uk/q44fs-a.htm
Rob from Amplabs serviced and upgraded a Quad 303 that I bought a couple of years ago
http://www.amp-labs.co.uk/servicing.htm
He originally serviced a Yamaha CR1000 for me which I stupidly sold a couple of years ago but he only works on Quad now I think.
I have read online that the Quad 44 suffers from the 4066 CMOS Chip which was originally designed for and used in the Plessey System X Telephone exchanges, and is naturally bandwidth limited.
Other issues include the use of the Op-Amp TL071 as was used in the 405 power amp.
With the modular design and ability to have different boards the Quad 44 could be quite an asset if it sounds any good. Are the MM and MC cards any good or able to be upgraded to anything worthwhile?
Any advice, thoughts or experience much appreciated
Thanks
Lee
The VeraFi Audio A40 Amp
I have been talking a little bit about this amp on the What’s On the Bench Tonight thread, but thought it’s time to give it its own proper thread. It started as a 25W Class A amp, and now has progressed to 40W - mandatory Class A operation since the topology is SE Class A with a an active push-pull CCS based on the Aksa Lender P-Chan Complementary Aleph (ALPHA Nirvana) output stage developed by Hugh Dean and used here under license to Aspen Amplifiers PLC, Melbourne. The layout is by JPS64 which means this is a state of the art amp in terms of layout symmetry, low impedance traces, thousands of sticking vias, and careful attention to minimizing ground loops and noise immunity.
Some of the notable features that this amp will have includes:
We are exploring anodizing color options for the handles and heatsinks. All black is still a major contender.
The internals will be laid out like this with the amp and its PSU mounted together on each heatsink. The floor of the amp will house the dual toroidal power trafos and also a main board let’s the SSR’s for the soft start, the main IEC soft On/Standby, and speaker SSR’s.
Here is a closeup of one channel of the amp and on-board CRC PSU on one PCB assembly. You can see the temperature sensor on the heatsink. Keantoken helped with the construction and assembly of the amp PCBA.
Initial testing of this amp indicates it sounds superb and the latest work is expand the chassis an extra 50mm deep to reduce heatsink temperatures and permit full 50W operation.
You can listen to it here:
Vanguard speakers
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XSD speakers
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Some of the notable features that this amp will have includes:
- Dual Monoblock design with independent power transformers and amp boards
- Solid State Relays (SSR) for speaker DC protection similar to the RTR SSR designed by jhofland
- SSR Soft Start with soft mains On/Standby button in front panel similar to the SFP designed by jhofland
- Custom All-CNC milled and satin bead blasted hard anodized aluminum chassis with thick 5mm walls and massive 40mm heatsink plates. The chassis is a massive amount of aluminum on the order of 25 to 27lbs. Chassis look, shape, HMI and layout is all my own design and the 3D modeling and CAD is by Darko M.
- Dual analog meters for output power with backlight
- Premium Viborg copper binding posts
- Premium gold plated RCA jacks
- Front panel Mute switch via SSR enable
- Automatic over temperature safety shutdown with dual thermostatic switches that activate the SSR
- Maximum output power of 40W into 8ohms and the wonderful ALPHA Nirvana 2nd harmonic dominant distortion profile with relatively low THD of circa 0.005% THD at 2.83Vrms into 8ohms
- Beautiful classic lines for an enduring timeless visual look
We are exploring anodizing color options for the handles and heatsinks. All black is still a major contender.
The internals will be laid out like this with the amp and its PSU mounted together on each heatsink. The floor of the amp will house the dual toroidal power trafos and also a main board let’s the SSR’s for the soft start, the main IEC soft On/Standby, and speaker SSR’s.
Here is a closeup of one channel of the amp and on-board CRC PSU on one PCB assembly. You can see the temperature sensor on the heatsink. Keantoken helped with the construction and assembly of the amp PCBA.
Initial testing of this amp indicates it sounds superb and the latest work is expand the chassis an extra 50mm deep to reduce heatsink temperatures and permit full 50W operation.
You can listen to it here:
Vanguard speakers
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XSD speakers
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Seeking input from members Review of enhanced print thread functionality
- By Jason
- Forum Problems & Feedback
- 23 Replies
Heavy duty aluminum cutting recommendations please
- By e_fortier
- Construction Tips
- 59 Replies
Hello,
Since the Pass forum uses massive heatsinks and folks don’t mind miscellaneous questions, here’s mine.
I was recently given a few massive heatsinks and looking for recommendations on how to cut them (it’s DIY isn’t it 😀) since a few are too tall. They are similar to the Heatsink USA stuff but slightly more robust.
Heatsink USA :
Mine are also about 10” wide but the rest is different;
Heatsink USA plate is 0.375” (9.5mm) thick , mine are 15mm thick. Heavy like hell 😀
Heatsink USA total thickness with fins is 2.875” (73mm), mine are 83mm.
Based on hands on experience, how would you cut such an aluminum piece so it’s usable, imperfections isn’t an issue, ugly side would be at the bottom, no problem.
Picture below;
Thanks for your help 👍
P.s. I also received some more that are insanely massive but I will keep it for a future thread.
Since the Pass forum uses massive heatsinks and folks don’t mind miscellaneous questions, here’s mine.
I was recently given a few massive heatsinks and looking for recommendations on how to cut them (it’s DIY isn’t it 😀) since a few are too tall. They are similar to the Heatsink USA stuff but slightly more robust.
Heatsink USA :
Mine are also about 10” wide but the rest is different;
Heatsink USA plate is 0.375” (9.5mm) thick , mine are 15mm thick. Heavy like hell 😀
Heatsink USA total thickness with fins is 2.875” (73mm), mine are 83mm.
Based on hands on experience, how would you cut such an aluminum piece so it’s usable, imperfections isn’t an issue, ugly side would be at the bottom, no problem.
Picture below;
Thanks for your help 👍
P.s. I also received some more that are insanely massive but I will keep it for a future thread.
Bogen Challenger RC412 line choke replacement
- By bamavette
- Tubes / Valves
- 5 Replies
I am working on this Bogen Challenger RC412 (tube receiver from about 1960) that has a few problems, one of which is a blown line choke at the AC in. According to the schematic it is 1.9uH, I have not been able to find a replacement.
Any ideas?
See attached pics.
Any ideas?
See attached pics.
Volcano Soundsystem - my flight ready mini Disco/DJ rig build
- PA Systems
- 2 Replies
Hello all. I have been trying to get a small soundsystem together for a while, without being able to make much traction on the project. Mainly due to time constraints and a lot of muddle over the config of such a system. I made many plans and acquired a bunch of parts and equipment for the new system, but it has been difficult to find an optimum due to the following requirements
Extremely portable, to flight ready
Weather resistance, some marine environment ability required
A bit of independence ability from fixed power points
Bass heavy sound
Wireless where able
Multizone compatibility
Live mics and instruments ability
Karaoke
The music is classic and modern Bollywood and West Indian
It took a while for me to note that where I needed environmental protection, the gig was smaller and with a much smaller range of inputs. I have decided to make it a pool of gear that I can mix and match for my needs. I have also had to consider some ready rolled gear instead of all DIY to neatly meet the requirements
Speakers
This is where I am trying something different. The JBL BB3 has sufficient output for the smallest gigs that I do. I acquired a Zealot S89, which appears to be similarly built as the BB3 and contains the same Racer8 driver that I have been messing with. The internal speaker setup is 2.1 with the mains section containing tweeter and midbass two-ways. I have been trying this one out over the last few days and the output is tremendous for something this small. The sound is clean and bass is forward and powerful. Battery life is impressive too. From full charge, the unit lasted a night, day and a night before turning itself off. This was at my regular indoor listening levels. Charge time seems good. My laptop USB-C charger works very well. I timed 6hrs charging time with a regular 5v2A charger and the laptop charger was lot faster, but I wasn't home to get the exact number this time
As is, the S89 will be ample for the porch, garage, deck and boat deck parties. No wires to tape up, trip up on, or pack and unpack. This connects to one of the BT TX fobs. This unit will face me as monitors while supplying the bass for the rest of the BT system. For the mains, I have bought two Zealot S97 units. These will face the floor and connect to the second BT TX fob and operate in TWS with each other. The S89 will be either used on the DJ desk or on the floor in the floor play area if I am mixing a baithak crew. This is a stop gap until I have a better solution here. Anyone who followed my Club Sandwich attempt will be familiar with this issue
I have picked up a further Zealot S51 pair to use as desk monitors for when I have the S89 on the floor. I have to get one more BT TX fob to add the console's headphone out to connect to these in TWS. One end of these speakers is designed as a base to stand the speaker up. It also contains a downward firing PR as well as an upward firing PR on the other end. Btw, the other models also contain dual PR units. I have some red stretchy nylon fabric and sew up some drawstring rucksacks for these speakers. They fit will in my booked of 4x 23kg and 4x 7kg luggage allocations. These are 100L heavy-duty duffels except for a couple of hard shells for the electronics in 7kg carry on allocations. The gear doesn't take up all of those bags
In an earlier attempt, I picked up a pair of DS18 Pro-zt69 coaxes. These are quite efficient, and I am considering tapping the tweeter and woofer wires from the S89 to drive the coaxes as active two-ways. I am reasoning that the powerful lil amp and battery inside the S89 will drive the coaxes a lot louder. To this end, I have been preparing a pair of cabs for the coaxes. I have a pair of SBA racer type PR units that may suit these cabs and coaxes too for a 60-70hz tune. At the moment the cabs are sealed types and 11L internal volume each
For external subs, I am considering a PA 18 with 4R+4R DVC and neodymium mag to reduce weight in a custom composite cab. The subwoofer amp inside the S89 sees a 2R load from a very inefficient driver. I hope that I am correct in reasoning that I can get much louder output with an 18 with coils in parallel. Tuned to the same 40Hz or so as the S89, so as not to upset any DSP filters already in use in that
If I am careful with the tapping, I should be able to retain most of the weather resistance of the unit for when it is used as is and with external speakers, I am hoping for much greater output
For local use with mains power supply, the external speakers will run off proper class d power amps. These are already acquired too
Experimental stuff
The 18" external sub thing will happen later on. Along with the coaxes, I am also building a cab for my DS18 ZR12.4D driver. This is not quite as huge as the ZXI 12" but still substantial. Will fit in my baggage allocations too for the trip coming up. For this trip, I will AB the Zealots vs the coaxes+ZR12.4D. Won't tamper with the Zealots just yet, so will run the external speakers with class d modules
The sources
A Dynabook Protégé for laptop. A Roland DJ-202 as controller and Serato DJ pro with full plugins and expansions bundle. A two into one wireless mic pair for the mic input on the DJ-202. This is my basic source setup for DJ, remix and karaoke
A Yamaha MG12XU console for accommodating more mics and instruments. A further one to one wireless mic pair for vocals from the console. This lot of flight ready sources are topped off with an Akai MPK Mini Mk3 Plus for some keys to complement the Roland TR drums built into the DJ-202
For local use, a Roland JDXI synth and a Roland MX-1 mixer completes the set
I have added two Bluetooth transmitter units to this lot. They are placed on the main and monitor outs of whichever mixer is feeding the PA
Party gear
A fog machine/disco light combo. UV black lights. LED party lights and rope lights. UV reflective backdrops. Projector and screen. Stand for mounting projector and lights
Support gear
Two powerbanks with fold out solar panels. Another pair of smaller powerbanks for the LEDs. USB hub with multiple monitor support. Laptop USB-C charger for the car to top all the things up as backup
I am sure there are some things that I am forgetting to list or missed entirely
Extremely portable, to flight ready
Weather resistance, some marine environment ability required
A bit of independence ability from fixed power points
Bass heavy sound
Wireless where able
Multizone compatibility
Live mics and instruments ability
Karaoke
The music is classic and modern Bollywood and West Indian
It took a while for me to note that where I needed environmental protection, the gig was smaller and with a much smaller range of inputs. I have decided to make it a pool of gear that I can mix and match for my needs. I have also had to consider some ready rolled gear instead of all DIY to neatly meet the requirements
Speakers
This is where I am trying something different. The JBL BB3 has sufficient output for the smallest gigs that I do. I acquired a Zealot S89, which appears to be similarly built as the BB3 and contains the same Racer8 driver that I have been messing with. The internal speaker setup is 2.1 with the mains section containing tweeter and midbass two-ways. I have been trying this one out over the last few days and the output is tremendous for something this small. The sound is clean and bass is forward and powerful. Battery life is impressive too. From full charge, the unit lasted a night, day and a night before turning itself off. This was at my regular indoor listening levels. Charge time seems good. My laptop USB-C charger works very well. I timed 6hrs charging time with a regular 5v2A charger and the laptop charger was lot faster, but I wasn't home to get the exact number this time
As is, the S89 will be ample for the porch, garage, deck and boat deck parties. No wires to tape up, trip up on, or pack and unpack. This connects to one of the BT TX fobs. This unit will face me as monitors while supplying the bass for the rest of the BT system. For the mains, I have bought two Zealot S97 units. These will face the floor and connect to the second BT TX fob and operate in TWS with each other. The S89 will be either used on the DJ desk or on the floor in the floor play area if I am mixing a baithak crew. This is a stop gap until I have a better solution here. Anyone who followed my Club Sandwich attempt will be familiar with this issue
I have picked up a further Zealot S51 pair to use as desk monitors for when I have the S89 on the floor. I have to get one more BT TX fob to add the console's headphone out to connect to these in TWS. One end of these speakers is designed as a base to stand the speaker up. It also contains a downward firing PR as well as an upward firing PR on the other end. Btw, the other models also contain dual PR units. I have some red stretchy nylon fabric and sew up some drawstring rucksacks for these speakers. They fit will in my booked of 4x 23kg and 4x 7kg luggage allocations. These are 100L heavy-duty duffels except for a couple of hard shells for the electronics in 7kg carry on allocations. The gear doesn't take up all of those bags
In an earlier attempt, I picked up a pair of DS18 Pro-zt69 coaxes. These are quite efficient, and I am considering tapping the tweeter and woofer wires from the S89 to drive the coaxes as active two-ways. I am reasoning that the powerful lil amp and battery inside the S89 will drive the coaxes a lot louder. To this end, I have been preparing a pair of cabs for the coaxes. I have a pair of SBA racer type PR units that may suit these cabs and coaxes too for a 60-70hz tune. At the moment the cabs are sealed types and 11L internal volume each
For external subs, I am considering a PA 18 with 4R+4R DVC and neodymium mag to reduce weight in a custom composite cab. The subwoofer amp inside the S89 sees a 2R load from a very inefficient driver. I hope that I am correct in reasoning that I can get much louder output with an 18 with coils in parallel. Tuned to the same 40Hz or so as the S89, so as not to upset any DSP filters already in use in that
If I am careful with the tapping, I should be able to retain most of the weather resistance of the unit for when it is used as is and with external speakers, I am hoping for much greater output
For local use with mains power supply, the external speakers will run off proper class d power amps. These are already acquired too
Experimental stuff
The 18" external sub thing will happen later on. Along with the coaxes, I am also building a cab for my DS18 ZR12.4D driver. This is not quite as huge as the ZXI 12" but still substantial. Will fit in my baggage allocations too for the trip coming up. For this trip, I will AB the Zealots vs the coaxes+ZR12.4D. Won't tamper with the Zealots just yet, so will run the external speakers with class d modules
The sources
A Dynabook Protégé for laptop. A Roland DJ-202 as controller and Serato DJ pro with full plugins and expansions bundle. A two into one wireless mic pair for the mic input on the DJ-202. This is my basic source setup for DJ, remix and karaoke
A Yamaha MG12XU console for accommodating more mics and instruments. A further one to one wireless mic pair for vocals from the console. This lot of flight ready sources are topped off with an Akai MPK Mini Mk3 Plus for some keys to complement the Roland TR drums built into the DJ-202
For local use, a Roland JDXI synth and a Roland MX-1 mixer completes the set
I have added two Bluetooth transmitter units to this lot. They are placed on the main and monitor outs of whichever mixer is feeding the PA
Party gear
A fog machine/disco light combo. UV black lights. LED party lights and rope lights. UV reflective backdrops. Projector and screen. Stand for mounting projector and lights
Support gear
Two powerbanks with fold out solar panels. Another pair of smaller powerbanks for the LEDs. USB hub with multiple monitor support. Laptop USB-C charger for the car to top all the things up as backup
I am sure there are some things that I am forgetting to list or missed entirely
4P1L Headphone amp
- By VT-52
- Tubes / Valves
- 27 Replies
Hiya,
Been posting some pictures here and there of a new project I have started on, might as well share the whole thing. The idea started in 2018 for a regular amp (speakers), but life happened and I lost track of audio once more. The good thing is that I already have some parts that I can re-use, so in today's thinking "they are free".
Goal:
Tubes:
As I want to tinker with the driver tube a bit, the power supplies will be setup to be universal for a 250V output tube and a 200V driver, current for each tube can be up to 50mA with headroom left.
4P1L will run at 225V/30mA/-19V initially (245V/30mA B+)
6E6P will run at 200V/30mA/-3.4V, 2P29L will be 6mA/-20V, so we have 30mA/-20V as worst cases for the PSU (225V/30mA B+)
As I am betting on the 2P29L, the rest of the info will focus on this combination so as not to have two projects in one.
Supply Chassis:
Signal Chassis:
Iron:
signal path
eTracer loadline on one of the 4P1L I have tested. 1.2W max with 10K.
Step 1: Concept
Step 2: Design PCBs for test setup
Step 3: Test
Step 4: Build chassis and integrated PCBs
Been posting some pictures here and there of a new project I have started on, might as well share the whole thing. The idea started in 2018 for a regular amp (speakers), but life happened and I lost track of audio once more. The good thing is that I already have some parts that I can re-use, so in today's thinking "they are free".
Goal:
- Headphone amplifier, 35 ohms
- Tube, single-ended,1000-1500mW of raw power power
- Daily beater, so no rare tubes, nothing end-game, just good music and a cool looking piece of kit
- Must fit on desk and desk must not collapse
Tubes:
- 4P1L
- 2P29L or 6E6P, might also look at other wee tubes like 6Z49, 6C4S, 5842 etc
As I want to tinker with the driver tube a bit, the power supplies will be setup to be universal for a 250V output tube and a 200V driver, current for each tube can be up to 50mA with headroom left.
4P1L will run at 225V/30mA/-19V initially (245V/30mA B+)
6E6P will run at 200V/30mA/-3.4V, 2P29L will be 6mA/-20V, so we have 30mA/-20V as worst cases for the PSU (225V/30mA B+)
As I am betting on the 2P29L, the rest of the info will focus on this combination so as not to have two projects in one.
Supply Chassis:
- Separate chassis for raw DC supplies to conform to the "must fit on desk" rule
- PCBs
- B+ will be SiC diodes, eChoke and MKP caps
- Filaments with SiC diodes and FW/KW caps
Signal Chassis:
- Filter for DH filaments, then Coleman regulator (current source) for DHTs
- LDO voltage regulator for IHT
- Passive B+ filter with RCRC to tune for both stages
Iron:
- 2x SE OPT 10K/50mA
- 2x Lundahl LL2763AM-40mA interstage
- 2x Toroid 250-210-0-210-250V/330mA, 12V/4A, 12V/4A
signal path
eTracer loadline on one of the 4P1L I have tested. 1.2W max with 10K.
Step 2: Design PCBs for test setup
Step 3: Test
Step 4: Build chassis and integrated PCBs
Attachments
Force cancellation bass + OB top system
This is a new project for my friend Mark who has an enormous "great room"
30x52' with vaulted peak ceiling >20' high. The goal is not to fill the entire space with sound but the LR portion, which is about a quarter of the total floor space. Mark seeks a game-ending system, with some financial limits. He also happens to be a master metals fabricator with a lot of skills & tools, which will be brought to play.
I post this as a reality-check / peer-review of my plans.
This pic shows a fraction of the big room.
Initially, Mark wanted scaled-up versions of my LX521 clones with dual 15" SBA Nero-15SW800 in a W-frame force cancellation setup. But after examining the room again, I persuaded him that OB might be too expensive & difficult to achieve 20Hz bass at >100 dB even in just his LR space. I've heard his EV Sentry II & JBL L212 speakers in the space & there's little question the sheer size of the room is a challenge. Amending the acoustics with floating absorbers/diffusers in the ceiling (and elsewhere) is not an option due to WAF. A large rug in the LR is in the works; currently the entire space is reflective.
The current plan is a pair of 12" woofers firing sideways in opposition to each other in a sealed enclosure, topped by an OB lower mid, mid & tweeter. This would be an active system with miniDSP Flex 8 & a mix of amplifiers for the various bands, a turntable, and a Wiim Ultimate streamer/preamp.
The physical design will draw from the iconic Acoustic Research AR9 (1978-82), the modified sealed-bass LX521 I recently made for my son, and the Linkwitz Orion. Mark likes the look of my Orions, which also garner better WA. I believe I can replicate that with side-firing 12" woofers in a sealed box + a WG tweeter to reduce diffraction & control vertical directivity.
The drivers:
Woofer: SBA SB34SWPL76-4 Low sensitivity of 85 dB/2.83V, but 19Hz Fs, a low 79 liters Vas & 0.31 Qts allows 0.7 Q in a 40 liter (or smaller) box, with a slow roll-off easily amended by DSP. Two woofers in a box double that size could easily provide >100 dB to below 30Hz with force cancellation minimizing vibrations to the OB above. 15mm Xmax is excellent, as is the FR claimed in the spec sheet.
Lower Mid: Satori WO24TX -- Since it will be OB & needs to move a lot of air in this big space, I paid attention to Xmax as well as effective piston area. A 12" driver might work better in the lower frequencies (as it will get quite a lot of EQ boost to compensate for the dipole cancellation effects), but this Textreme driver is flat out to 2.5kHz on axis, with little beaming to ~1.5kHz. 8.75mm Xmax is pretty good for a driver like this, and it's an opportunity to find out first hand what a Textreme driver can do. If it can be made to cross well at 2kHz or lower to a WG dome, we might be able to keep it 3-way instead of the usual 4.
High Mid: The Satori MW13TX is a natural choice, given the WO24TX lower mid choice. It will not be necessary if we go 3-way.
Tweeter: My favorite dipole tweeter Aurum Cantus AST2650 will get a shallow waveguide on both sides. The waveguide has yet to be made, but I've seen enough iterations of such that it should not be a big challenge, executed in 3D printing or CNC cut directly in the baffle board.
------------
Tweeter, if 3-way: Satori TW29TXNWG Textreme is a natural. The reviews of the Beryllium WG guide version in both Audioxpress & Hificompass state they are good as low as 1kHz, and there's no reason to believe the Textreme version would be much different. The back tweeter would be the non-waveguide version -- Satori TW29TXN, which is shallow enough not to require cosmetic adjustments for the hole which might end up having to go through the baffle board with the deeper WG tweeter.
One feature that will likely be adopted from the Orion is the mounting of the lower-mid 9.5" driver by its magnet to the top of the bass bin. This config positions the driver on the baffle without touching it, preventing mechanical conduction of the driver's vibrations into the baffle. There's a foam gasket to prevent spurious vibration between the baffle hole and the driver rim. The force cancellation of the bass drivers should keep most of the larger vibrations out of both the box & baffle. This method of mounting the low mid driver will complete the primary anti-vibration scheme.
-
EDIT: Forgot to mention that we'll consider adding one or 2 custom made subs, either like the one I just built with a Nero-15SW800 15" Pro driver, or the SB12" in the main speakers. The main speakers would be treated as subs (because they will be subs) and another 1 or 2 subs added to the sides of the listening area. A challenge is power outlets on one side only.
30x52' with vaulted peak ceiling >20' high. The goal is not to fill the entire space with sound but the LR portion, which is about a quarter of the total floor space. Mark seeks a game-ending system, with some financial limits. He also happens to be a master metals fabricator with a lot of skills & tools, which will be brought to play.
I post this as a reality-check / peer-review of my plans.
This pic shows a fraction of the big room.
Initially, Mark wanted scaled-up versions of my LX521 clones with dual 15" SBA Nero-15SW800 in a W-frame force cancellation setup. But after examining the room again, I persuaded him that OB might be too expensive & difficult to achieve 20Hz bass at >100 dB even in just his LR space. I've heard his EV Sentry II & JBL L212 speakers in the space & there's little question the sheer size of the room is a challenge. Amending the acoustics with floating absorbers/diffusers in the ceiling (and elsewhere) is not an option due to WAF. A large rug in the LR is in the works; currently the entire space is reflective.
The current plan is a pair of 12" woofers firing sideways in opposition to each other in a sealed enclosure, topped by an OB lower mid, mid & tweeter. This would be an active system with miniDSP Flex 8 & a mix of amplifiers for the various bands, a turntable, and a Wiim Ultimate streamer/preamp.
The physical design will draw from the iconic Acoustic Research AR9 (1978-82), the modified sealed-bass LX521 I recently made for my son, and the Linkwitz Orion. Mark likes the look of my Orions, which also garner better WA. I believe I can replicate that with side-firing 12" woofers in a sealed box + a WG tweeter to reduce diffraction & control vertical directivity.
The drivers:
Woofer: SBA SB34SWPL76-4 Low sensitivity of 85 dB/2.83V, but 19Hz Fs, a low 79 liters Vas & 0.31 Qts allows 0.7 Q in a 40 liter (or smaller) box, with a slow roll-off easily amended by DSP. Two woofers in a box double that size could easily provide >100 dB to below 30Hz with force cancellation minimizing vibrations to the OB above. 15mm Xmax is excellent, as is the FR claimed in the spec sheet.
Lower Mid: Satori WO24TX -- Since it will be OB & needs to move a lot of air in this big space, I paid attention to Xmax as well as effective piston area. A 12" driver might work better in the lower frequencies (as it will get quite a lot of EQ boost to compensate for the dipole cancellation effects), but this Textreme driver is flat out to 2.5kHz on axis, with little beaming to ~1.5kHz. 8.75mm Xmax is pretty good for a driver like this, and it's an opportunity to find out first hand what a Textreme driver can do. If it can be made to cross well at 2kHz or lower to a WG dome, we might be able to keep it 3-way instead of the usual 4.
High Mid: The Satori MW13TX is a natural choice, given the WO24TX lower mid choice. It will not be necessary if we go 3-way.
Tweeter: My favorite dipole tweeter Aurum Cantus AST2650 will get a shallow waveguide on both sides. The waveguide has yet to be made, but I've seen enough iterations of such that it should not be a big challenge, executed in 3D printing or CNC cut directly in the baffle board.
------------
Tweeter, if 3-way: Satori TW29TXNWG Textreme is a natural. The reviews of the Beryllium WG guide version in both Audioxpress & Hificompass state they are good as low as 1kHz, and there's no reason to believe the Textreme version would be much different. The back tweeter would be the non-waveguide version -- Satori TW29TXN, which is shallow enough not to require cosmetic adjustments for the hole which might end up having to go through the baffle board with the deeper WG tweeter.
One feature that will likely be adopted from the Orion is the mounting of the lower-mid 9.5" driver by its magnet to the top of the bass bin. This config positions the driver on the baffle without touching it, preventing mechanical conduction of the driver's vibrations into the baffle. There's a foam gasket to prevent spurious vibration between the baffle hole and the driver rim. The force cancellation of the bass drivers should keep most of the larger vibrations out of both the box & baffle. This method of mounting the low mid driver will complete the primary anti-vibration scheme.
EDIT: Forgot to mention that we'll consider adding one or 2 custom made subs, either like the one I just built with a Nero-15SW800 15" Pro driver, or the SB12" in the main speakers. The main speakers would be treated as subs (because they will be subs) and another 1 or 2 subs added to the sides of the listening area. A challenge is power outlets on one side only.
Towards a wideband non switching Auto Bias power amp
- By IanHegglun
- Solid State
- 319 Replies
Syn08 (Ovidiu) said this about implementing an Auto Bias loop here:
Well, there's the challenge. A wideband non switching Auto Bias amplifier circuit that works, doesn't oscillate and blow up, and is not too complex.
To start this thread I'll post some of my findings from simulations of the LT1166 Auto Bias IC, as well as Class-i and Edmond's AutoBias2.
Feel free to post any of your ideas and simulations.
And if anyone has built a successful amplifier using an auto bias circuit then we'd love to hear how you did it, etc.
Cheers, Ian
-------------
Edit: Post summary (Edit: most recent first):
Post 303 Shows 3D views of a PCB for Post 302 circuit (now called Topology 4).
Post 302 The LT1223 again but now driving MOSFETs to demonstrate the autobias loop allows plug-in interchange of BJT's and MOSFETs. Interestingly, the MOSFET's achieve similar high BW with less drive current so 2 pair instead of 5 pair TO-92's can be used.
Post 301 The previous LT1223 CFB opamp with a CFP autobias loop is OK for 16MHz(tbc) without the CFP output stage, instead the discrete HV booster is paralleled for 50mA drive to the power transistors with a +/-9V auxiliary supply.
Post 300 The previous CFP BJT autobias loop is OK for 4MHz(tbc) with a LV LT1223 100MHz CFA with a discrete voltage booster giving low distortion.
Post 295 Bridge and current drive is easy with a HV opamp, where one load terminal is tied to input common (grounded bridge) with a floating PS.
Post 291 Current drive with a HV opamp is very easy using a resistor in series with the loads cold-side for feedback to the opamps inverting input node.
Post 287 CFP BJT autobias loop is OK for 100kHz with a 33 Ohm base pull-up to 9V. Allows a low input current (1mA) drive using a HV opamp (OPA455) with a split rail standard power supply.
Post 282 Only THT with current drive for 4 ohms suggested by Pawel.
Post 281 Current drive version for 200W into 4 ohm, Rout 500 ohms and 0.02% at 1W. Uses 2x OPA1656 LV 100mA opamp drivers.
Post 277 Class-G bridge 800W 4R using 4 slices per side for 20A peaks. Idle dissipation is reduced using Class-G plus McPherson's dissipation diverter.
Post 274 Bridge version for 400W 8R is DC input and DC output. Usescapacitance multiplier with McPherson's dissipation diverter.
Post 271 Mark Johnson query: What if the output capacitor divider capsare not exactly the same? Answer: the voltages equalise quickly due to the amps low output resistance.
Post 269 Power supply circuit to check startup with no dc blocking capacitor. Simulation shows no startup or shutdown transient to the loudspeaker.
Post 267 Input stage level shift with no dc blocking input capacitor.Uses an opamp with a -5V rail and a mirror input stage level shifterwith no signal.
Post 266 simulation using ZXT757 and ZXT857 300V complimentary pair for input stage level shift. Bias trimming calculation for output centering.
Post 257 simulation using a level shift input stage rather than a isolation transformer, allowing a standard non-floating power supply.
Post 256 mr_jj pointed out that Kenpeter back in 2010 had placed a resistor across the sensing diodes between the emitters of the power transistors to make it non-switching Class-AB! My hat is off to Kenpeter. I mention my independent finding in Post 202. The Dadson's circuit found in Post 44 here from his AES Oct 1980 article shows the same autobias sensing diode topology using a Rush spreader arrangement but with Darlington power transistors, but no resistor across the sensing diodes.
Post 254 Bench test using thean OPA1656 100mA opamp to drive power transistors with autobias without discrete driver transistors.
Post 244 Bench tests of a single channel amplifier shows -60dB THD using MUR1615 diodes and biased at 250mA. F-3dB is slightly over 100kHz.
Post 243 Shinichi Kamijo "simple TL bias" circuit is similar topology to my autobias but with a follower output stage and a non-floating power supply.
Post 235 Bridge version bench test. Two floating power supply amps on one supply, where one amp uses a small transformer to isolate the input signal.
Post 222 Tutorial on the floating power supply transconductance autobias output stage. More in Post 245 and Post 251.
Post 220 Using MUR1615 TO-220 power diodes instead of Schottky diodes gives excellent linearity. Bias can be trimmed by two resistors to 9V rail instead of two CCS's (simpler and less error prone).
Post 215 Using MJE3055 TO-220 as diodes instead of Schottky diodes.
Post 210 thru Post 214, Post 217-219. Option of using many (8-10) 1A silicon diodes in parallel per side instead of Schottky diodes so no need for a bias trim pot.
Post 205 FDC6321 CMOS stage allows high current drive without a CFP output stage.
Post 203 A prototype PCB allows stacking of up to slices (3 pair of output transistors).
Post 202 Using a HCU04 CMOS input stage with a CFP output transistors so only 1mA is needed to drive the autobias transistors. The CMOS input stage provides some gain and soft clipping and the option of thermal-SOA protection by dynamically limiting the clip level (more in Post 204). Introduced R13 across the power diodes to provides the keep-on current of 18mA in Q1 and Q2 - even when clipping. Eureka!!
-------------------------
Edit Feb 2025. Overview of development: Toward a Wideband Non-Switching Auto Bias amplifier
The challenge! “A wideband non switching auto bias amplifier circuitthat works, doesn't oscillate and blow up, and is not too complex”.Post1 aim 29 July 2021 by IanHegglun.
Well, there's the challenge. A wideband non switching Auto Bias amplifier circuit that works, doesn't oscillate and blow up, and is not too complex.
To start this thread I'll post some of my findings from simulations of the LT1166 Auto Bias IC, as well as Class-i and Edmond's AutoBias2.
Feel free to post any of your ideas and simulations.
And if anyone has built a successful amplifier using an auto bias circuit then we'd love to hear how you did it, etc.
Cheers, Ian
-------------
Edit: Post summary (Edit: most recent first):
Post 303 Shows 3D views of a PCB for Post 302 circuit (now called Topology 4).
Post 302 The LT1223 again but now driving MOSFETs to demonstrate the autobias loop allows plug-in interchange of BJT's and MOSFETs. Interestingly, the MOSFET's achieve similar high BW with less drive current so 2 pair instead of 5 pair TO-92's can be used.
Post 301 The previous LT1223 CFB opamp with a CFP autobias loop is OK for 16MHz(tbc) without the CFP output stage, instead the discrete HV booster is paralleled for 50mA drive to the power transistors with a +/-9V auxiliary supply.
Post 300 The previous CFP BJT autobias loop is OK for 4MHz(tbc) with a LV LT1223 100MHz CFA with a discrete voltage booster giving low distortion.
Post 295 Bridge and current drive is easy with a HV opamp, where one load terminal is tied to input common (grounded bridge) with a floating PS.
Post 291 Current drive with a HV opamp is very easy using a resistor in series with the loads cold-side for feedback to the opamps inverting input node.
Post 287 CFP BJT autobias loop is OK for 100kHz with a 33 Ohm base pull-up to 9V. Allows a low input current (1mA) drive using a HV opamp (OPA455) with a split rail standard power supply.
Post 282 Only THT with current drive for 4 ohms suggested by Pawel.
Post 281 Current drive version for 200W into 4 ohm, Rout 500 ohms and 0.02% at 1W. Uses 2x OPA1656 LV 100mA opamp drivers.
Post 277 Class-G bridge 800W 4R using 4 slices per side for 20A peaks. Idle dissipation is reduced using Class-G plus McPherson's dissipation diverter.
Post 274 Bridge version for 400W 8R is DC input and DC output. Usescapacitance multiplier with McPherson's dissipation diverter.
Post 271 Mark Johnson query: What if the output capacitor divider capsare not exactly the same? Answer: the voltages equalise quickly due to the amps low output resistance.
Post 269 Power supply circuit to check startup with no dc blocking capacitor. Simulation shows no startup or shutdown transient to the loudspeaker.
Post 267 Input stage level shift with no dc blocking input capacitor.Uses an opamp with a -5V rail and a mirror input stage level shifterwith no signal.
Post 266 simulation using ZXT757 and ZXT857 300V complimentary pair for input stage level shift. Bias trimming calculation for output centering.
Post 257 simulation using a level shift input stage rather than a isolation transformer, allowing a standard non-floating power supply.
Post 256 mr_jj pointed out that Kenpeter back in 2010 had placed a resistor across the sensing diodes between the emitters of the power transistors to make it non-switching Class-AB! My hat is off to Kenpeter. I mention my independent finding in Post 202. The Dadson's circuit found in Post 44 here from his AES Oct 1980 article shows the same autobias sensing diode topology using a Rush spreader arrangement but with Darlington power transistors, but no resistor across the sensing diodes.
Post 254 Bench test using thean OPA1656 100mA opamp to drive power transistors with autobias without discrete driver transistors.
Post 244 Bench tests of a single channel amplifier shows -60dB THD using MUR1615 diodes and biased at 250mA. F-3dB is slightly over 100kHz.
Post 243 Shinichi Kamijo "simple TL bias" circuit is similar topology to my autobias but with a follower output stage and a non-floating power supply.
Post 235 Bridge version bench test. Two floating power supply amps on one supply, where one amp uses a small transformer to isolate the input signal.
Post 222 Tutorial on the floating power supply transconductance autobias output stage. More in Post 245 and Post 251.
Post 220 Using MUR1615 TO-220 power diodes instead of Schottky diodes gives excellent linearity. Bias can be trimmed by two resistors to 9V rail instead of two CCS's (simpler and less error prone).
Post 215 Using MJE3055 TO-220 as diodes instead of Schottky diodes.
Post 210 thru Post 214, Post 217-219. Option of using many (8-10) 1A silicon diodes in parallel per side instead of Schottky diodes so no need for a bias trim pot.
Post 205 FDC6321 CMOS stage allows high current drive without a CFP output stage.
Post 203 A prototype PCB allows stacking of up to slices (3 pair of output transistors).
Post 202 Using a HCU04 CMOS input stage with a CFP output transistors so only 1mA is needed to drive the autobias transistors. The CMOS input stage provides some gain and soft clipping and the option of thermal-SOA protection by dynamically limiting the clip level (more in Post 204). Introduced R13 across the power diodes to provides the keep-on current of 18mA in Q1 and Q2 - even when clipping. Eureka!!
-------------------------
Edit Feb 2025. Overview of development: Toward a Wideband Non-Switching Auto Bias amplifier
The challenge! “A wideband non switching auto bias amplifier circuitthat works, doesn't oscillate and blow up, and is not too complex”.Post1 aim 29 July 2021 by IanHegglun.
- I have exceeded my expectations. A non-switching autobias topology – simple, stable, scaleable.
- Two related topologies: 1) The floating supply version, and 2) The non-floating supply version.
- Several diyAudio members have suggested that I provide a non-floating supply version.
- Topology1. The floating supply version is the simplest, eg, Fig.1 below,100W into 8R, only 2 power transistors & 2 bias transistors, 2x3A diodes, a dual opamp, and a +/-9V 2W supply. Notice no Darlington driver transistors, instead two 100mA opamps operating in parallel. THD 0.1% 1W.
- Topology 1: Completed Wideband Non-Switching Auto Bias amplifier with opamp driver.
- Can be paralleled eg Post254 and bridged eg Posts274 .
- Uses two output capacitors in series. They are forced to half the rail voltage by the feedback loop referenced to half the rail voltage by a voltage divider (R3,R19). They prevent DC damaging the loudspeaker. It's is simple, effective and reliable, with negligible effect on sound quality.
- Topology2. The non-floating supply version. It is a modified floating supply version with an addition input stage where the input is now referenced to the negative rail. The input stage lowers distortion to 0.02% at 1W and a low output resistance of 50 milli-Ohm.
- Topology 2: Wideband Non-Switching Auto Bias amplifier with DC input and non-floating Power Supply.
- An alternative bias circuit, see above Topology 2 dotted area, it eliminates the input capacitor which eliminates the long settling time at turn on.
- The alternative bias circuit avoids a 3rd input stage which avoids a 3rd pole which requires careful frequency compensation. Both Topology 1 and Topology 2 do not use frequency compensation!
- The loudspeaker is protected from DC damage by the two output capacitors in series.
- Topology 2 can be paralleled eg Post257, and bridged eg Posts274 and Class-G bridge Post277.
- Topology 2 has been simulated and a PCB is underway for bench test and listening tests.
- Topology 1 has been bench tested eg Post244 & Post254 and a listening test Post157. The Topology 1 PCB needs updating for an opamp.
- Topology 3. See Post287 and Post291.
- CFP BJT autobias loop is OK for100kHz with a 33 Ohm base pull-up to 9V. Allows a low input current(1mA) HV opamp (LT6090-5 or OPA455) to be used with a split railstandard power supply.
- . . . . Topology 3. Wideband Non-Switching Auto Bias amplifier with DC input and non-floating Power Supply and no auxiliary ±9V supplies.
- Topology 4. See Post301 and Post302
- Using a LV LT1223 CFB opamp with a CFP autobias loop is OK for 16MHz(tbc) without the CFP output stage.The opamps discrete HV booster is paralleled for 50mA drive to the power transistors. The trade off is the ±9V auxiliary supply.
- Topology4. Wideband Non-Switching Auto Bias amplifier with DC input and non-floating power supply and no CFP power stage, instead the auxiliary ±9V supply and higher current opamp booster stage.
Ported cabinet for guitar amp
- By Mikante
- Construction Tips
- 12 Replies
Hello,
I am trying to build a cabinet for my guitar amp. I have build other cabinets but this time is different and i need some help. I need to build a ported cabinet, like the tl806 but the speaker i have is not the famous electrovoice el12.
I m going to use a jensen tornado classic 100 8 ohm istead.
I have used an online calculator to get me in the ballpark, here the results
Now, my doubts, the cabinet volume suggested is huge, 126 liters it is going to be oversized for guitar amp 1x12.
Do you think these results can be trusted or should i use a better source?
I know the tl806 cab design has slots and not pipes for the bass reflex but i don t care, i m not trying to clone the design, just the concept.
I am trying to build a cabinet for my guitar amp. I have build other cabinets but this time is different and i need some help. I need to build a ported cabinet, like the tl806 but the speaker i have is not the famous electrovoice el12.
I m going to use a jensen tornado classic 100 8 ohm istead.
I have used an online calculator to get me in the ballpark, here the results
Now, my doubts, the cabinet volume suggested is huge, 126 liters it is going to be oversized for guitar amp 1x12.
Do you think these results can be trusted or should i use a better source?
I know the tl806 cab design has slots and not pipes for the bass reflex but i don t care, i m not trying to clone the design, just the concept.
Introducing "KRONOS" a vintage inspired 2-Way.
- By zeltergiest
- Multi-Way
- 3 Replies
Hello everyone!
I've recently finished my vintage inspired 2-way design and figured I'd share the journey here for any fellow members who may be interested in the concept or even building it for their self.
Soooo. Let's see it! What is it? Kronos is a sealed 2-way design utilizing the SEAS A26RE4 10inch Woofer and the Visaton FRS 5x-8 2inch in a WG.
Wait, isn't that Visaton driver a full range? Isn't this more of a "WAW" design? Yes, the Visaton is in fact a full range driver but it's actually being utilized as a tweeter in this design. It's mounted in the Visaton WG and integrates perfectly here with the SEAS woofer.
Isn't there already a similar design for this woofer? The A26? Yes, there is. However the tweeter for that design is rather pricey at $350+ each, while the cost here is $14 for each driver and around $19 for each WG currently on Parts Express. (Other options available as well, see below)
Okay okay, enough with the Q&A, let's get into how this came about and details of the design.
Introduction:
The Kronos speaker build was born from a sense of nostalgia—rooted in childhood memories of sitting in front of my dad’s hi-fi system, mesmerized by the towering loudspeakers that filled the room with sound. Those classic designs, with their large woofers and cone tweeters, left a lasting impression. They had a presence—both visually and sonically—that felt larger than life. With Kronos, I set out to pay homage to that era and those experiences, blending the soul of vintage loudspeakers with the clarity and control of modern design. It’s a tribute to the sound that sparked a lifelong passion.
Driver Selection:
To bring the Kronos concept to life, I carefully selected a driver lineup that reflects both the spirit of vintage design and the performance of modern components. For the low end, I chose the SEAS A26RE4, a 10" paper-cone woofer known for its rich tone, effortless bass, and smooth upper response. It’s a direct nod to the classic wideband woofers of the past—capable of anchoring the system with warmth and authority.
For the top end, I went with a more unconventional approach: the Visaton FRS5X, a small full-range cone driver, paired with the Visaton WG 148 R round waveguide. This combination offers a controlled dispersion and a pleasantly natural tone that echoes the voicing of vintage paper cone tweeters, but with improved focus and clarity. To mount the FRS5X, I simply centered it on the waveguide and drilled my own holes—an easy but effective way to create a tweeter solution that stays true to the DIY spirit and captures the character of old-school designs.
Worth noting: With the rise of 3D printing and modern fabrication techniques, custom waveguides for drivers like the Visaton FRS5X are now readily available. For those looking for a more refined or drop-in solution, Heissmann Acoustics offers a purpose-built 3D-printed waveguide specifically designed for the FRS5X. It's a great option for builders who want to simplify the mounting process while maintaining the same compact format and controlled directivity.
Enclosure Details:
The SEAS A26RE4 woofer is housed in an approximately 85-liter (about 3.0 ft³) sealed enclosure, giving it ample volume to breathe and deliver deep, full-bodied bass with natural roll-off—true to the character of classic hi-fi systems. This generous internal volume helps the woofer operate efficiently without excessive low-end boom, maintaining a balanced and effortless presentation.
The Visaton FRS5X is isolated in its own 1-liter (0.035 ft³) sealed chamber. This small compartment ensures that the mid/tweeter remains unaffected by pressure changes from the woofer, allowing it to perform cleanly and consistently.
Throughout the cabinet, adequate internal bracing was incorporated to minimize panel resonance and structural flexing. The result is a rigid and acoustically inert enclosure that supports clean, undistorted output even at higher playback levels.
Crossover Details:
The Kronos crossover began as a theoretical layout, designed with target values based on driver behavior and desired voicing. From there, it was refined entirely by ear, with countless hours of listening and adjustment until the final values locked into place. This process allowed the system to reach a balance that felt natural, dynamic, and emotionally engaging—true to the character I set out to achieve.
The SEAS A26RE4 woofer, a modern version of the W26 used in classic designs like the Dynaco A25, has a naturally smooth roll-off that doesn’t strictly require filtering. That said, I chose to add a small 0.33 mH series inductor to gently tame the upper midrange, making the speaker more forgiving and enjoyable at higher volumes—reducing the risk of harshness or “shouting” without robbing it of presence.
For the FRS5X tweeter, mounted in a waveguide, no series resistor was needed. The waveguide not only improves sensitivity and dispersion control but also helps the FRS5X blend naturally with the woofer. Without the waveguide, I would have added around 1 ohm of series resistance to balance its output. The high-pass network is essentially first-order, using a capacitor for the main roll-off. A parallel inductor was added to keep the tweeter’s upper resonance from bleeding through—simple, but effective.
While a textbook solution might call for an RCL (resistor-capacitor-inductor) network for perfect impedance correction, I found that in practice, a single coil did the job just fine. An optional overall impedance compensation network was included for the sake of completeness, but it's more a nice-to-have than a necessity in this build.
In the end, the crossover reflects the spirit of the whole project—minimalist, purposeful, and guided by listening above all else.
CROSSOVER PCB:
To make this project more accessible for others—especially those new to DIY loudspeakers—I went a step further and designed a dedicated PCB for the crossover network. Rather than relying on point-to-point wiring or a perfboard layout, this custom PCB ensures clean, repeatable assembly and proper part spacing, helping reduce the chance of wiring errors and making the build experience more enjoyable.
The board is laid out with component footprints matched to the actual values used in the final design, and it includes clear labeling for easy reference. Whether you're a first-time builder or a seasoned DIYer, this PCB simplifies the process and makes it easier to achieve consistent results.
I’ll be including a download link at the end of this presentation with everything needed to build your own pair of Kronos speakers—including crossover schematics, PCB files, enclosure plans, and additional notes gathered throughout the build.
Finished Speaker:
Here’s a look at the finished Kronos speaker. Aesthetically, I realize this look might not be for everyone—but that was never the goal. I wanted the finish to reflect the spirit of the project: cheap, fun, and bold. The result is something unique, eye-catching, and artistic.
I’ve had a few people ask how I achieved the finish, so here’s a quick breakdown:
It’s not a high-end veneer or mirror-gloss lacquer—but for a fun, rugged speaker with personality, it gets the job done. Cheap, effective, and satisfying to see come together.
Final Measurements:
Below you can see the final measured response of the Kronos design. The results highlight just how well the Visaton FRS5X in a waveguide and the SEAS A26RE4 woofer integrate—especially considering the simplicity of the crossover network.
The response is impressively smooth, with excellent tonal balance and a natural transition between drivers. The waveguide not only improves the FRS5X’s efficiency and dispersion but also allows it to blend seamlessly with the larger woofer, avoiding the typical disconnect you might expect from such different-sized drivers. The minimal crossover does just enough to shape the response where needed, while preserving the raw, engaging character of the drivers.
This measurement validates the listening impressions—a coherent, dynamic speaker that stays true to its vintage inspiration while performing with modern finesse.
Listening Impressions:
The final implementation of the Kronos exceeded my expectations. While I didn’t build these to be the ultimate reference monitor or the “end-all-be-all” speaker, the result is something that sounds exceptionally good—better than I had originally imagined.
The bass performance is particularly impressive, with deep, full extension that's further enhanced by room gain and proper placement. The SEAS woofer really shines here, delivering weight and authority without muddiness.
Tonally, the speaker holds up well across a wide variety of genres. So far, I've enjoyed everything from Rock, Jazz, Pop, Hip-Hop, EDM, to Classical, and the system has handled them all with confidence. The highs are clean without being harsh, mids are clear and natural, and the overall balance feels cohesive and engaging.
Even at very high listening levels, the speaker maintains its composure, with no sense of strain or collapse—perfect for those nights when you just want to crank things up and let loose.
I’ve also had a few friends over to hear them, and the reactions have been consistently surprised and impressed. There’s something satisfying about watching someone sit down with no expectations, and then light up the moment the music starts.
In Conclusion:
The Kronos has accomplished everything it was designed to do—and then some. It’s a speaker that brings together nostalgic inspiration, modern performance, and hands-on DIY fun in one cohesive package. I’m genuinely proud of how it turned out, and I know I’ll be enjoying these speakers for many years to come.
For those interested in diving deeper into the design—or even building a pair yourself—I’ve put together a comprehensive resource link below. This presentation has only scratched the surface, and the download includes detailed plans, crossover files, PCB layout, measurements, and more.
If you have any questions or run into issues, don’t hesitate to reach out. I’m always happy to help fellow builders in any way I can.
Thanks for taking the time to check out my project—I hope it inspires you to build something of your own.
LINK TO KRONOS BUILD PLANS: https://drive.google.com/drive/folders/1Kpa-w3JEGQmEdG6RKKRCQnM0pMenjgjl?usp=sharing
I've recently finished my vintage inspired 2-way design and figured I'd share the journey here for any fellow members who may be interested in the concept or even building it for their self.
Soooo. Let's see it! What is it? Kronos is a sealed 2-way design utilizing the SEAS A26RE4 10inch Woofer and the Visaton FRS 5x-8 2inch in a WG.
Wait, isn't that Visaton driver a full range? Isn't this more of a "WAW" design? Yes, the Visaton is in fact a full range driver but it's actually being utilized as a tweeter in this design. It's mounted in the Visaton WG and integrates perfectly here with the SEAS woofer.
Isn't there already a similar design for this woofer? The A26? Yes, there is. However the tweeter for that design is rather pricey at $350+ each, while the cost here is $14 for each driver and around $19 for each WG currently on Parts Express. (Other options available as well, see below)
Okay okay, enough with the Q&A, let's get into how this came about and details of the design.
Introduction:
The Kronos speaker build was born from a sense of nostalgia—rooted in childhood memories of sitting in front of my dad’s hi-fi system, mesmerized by the towering loudspeakers that filled the room with sound. Those classic designs, with their large woofers and cone tweeters, left a lasting impression. They had a presence—both visually and sonically—that felt larger than life. With Kronos, I set out to pay homage to that era and those experiences, blending the soul of vintage loudspeakers with the clarity and control of modern design. It’s a tribute to the sound that sparked a lifelong passion.
Driver Selection:
To bring the Kronos concept to life, I carefully selected a driver lineup that reflects both the spirit of vintage design and the performance of modern components. For the low end, I chose the SEAS A26RE4, a 10" paper-cone woofer known for its rich tone, effortless bass, and smooth upper response. It’s a direct nod to the classic wideband woofers of the past—capable of anchoring the system with warmth and authority.
For the top end, I went with a more unconventional approach: the Visaton FRS5X, a small full-range cone driver, paired with the Visaton WG 148 R round waveguide. This combination offers a controlled dispersion and a pleasantly natural tone that echoes the voicing of vintage paper cone tweeters, but with improved focus and clarity. To mount the FRS5X, I simply centered it on the waveguide and drilled my own holes—an easy but effective way to create a tweeter solution that stays true to the DIY spirit and captures the character of old-school designs.
Worth noting: With the rise of 3D printing and modern fabrication techniques, custom waveguides for drivers like the Visaton FRS5X are now readily available. For those looking for a more refined or drop-in solution, Heissmann Acoustics offers a purpose-built 3D-printed waveguide specifically designed for the FRS5X. It's a great option for builders who want to simplify the mounting process while maintaining the same compact format and controlled directivity.
Enclosure Details:
The SEAS A26RE4 woofer is housed in an approximately 85-liter (about 3.0 ft³) sealed enclosure, giving it ample volume to breathe and deliver deep, full-bodied bass with natural roll-off—true to the character of classic hi-fi systems. This generous internal volume helps the woofer operate efficiently without excessive low-end boom, maintaining a balanced and effortless presentation.
The Visaton FRS5X is isolated in its own 1-liter (0.035 ft³) sealed chamber. This small compartment ensures that the mid/tweeter remains unaffected by pressure changes from the woofer, allowing it to perform cleanly and consistently.
Throughout the cabinet, adequate internal bracing was incorporated to minimize panel resonance and structural flexing. The result is a rigid and acoustically inert enclosure that supports clean, undistorted output even at higher playback levels.
Crossover Details:
The Kronos crossover began as a theoretical layout, designed with target values based on driver behavior and desired voicing. From there, it was refined entirely by ear, with countless hours of listening and adjustment until the final values locked into place. This process allowed the system to reach a balance that felt natural, dynamic, and emotionally engaging—true to the character I set out to achieve.
The SEAS A26RE4 woofer, a modern version of the W26 used in classic designs like the Dynaco A25, has a naturally smooth roll-off that doesn’t strictly require filtering. That said, I chose to add a small 0.33 mH series inductor to gently tame the upper midrange, making the speaker more forgiving and enjoyable at higher volumes—reducing the risk of harshness or “shouting” without robbing it of presence.
For the FRS5X tweeter, mounted in a waveguide, no series resistor was needed. The waveguide not only improves sensitivity and dispersion control but also helps the FRS5X blend naturally with the woofer. Without the waveguide, I would have added around 1 ohm of series resistance to balance its output. The high-pass network is essentially first-order, using a capacitor for the main roll-off. A parallel inductor was added to keep the tweeter’s upper resonance from bleeding through—simple, but effective.
While a textbook solution might call for an RCL (resistor-capacitor-inductor) network for perfect impedance correction, I found that in practice, a single coil did the job just fine. An optional overall impedance compensation network was included for the sake of completeness, but it's more a nice-to-have than a necessity in this build.
In the end, the crossover reflects the spirit of the whole project—minimalist, purposeful, and guided by listening above all else.
CROSSOVER PCB:
To make this project more accessible for others—especially those new to DIY loudspeakers—I went a step further and designed a dedicated PCB for the crossover network. Rather than relying on point-to-point wiring or a perfboard layout, this custom PCB ensures clean, repeatable assembly and proper part spacing, helping reduce the chance of wiring errors and making the build experience more enjoyable.
The board is laid out with component footprints matched to the actual values used in the final design, and it includes clear labeling for easy reference. Whether you're a first-time builder or a seasoned DIYer, this PCB simplifies the process and makes it easier to achieve consistent results.
I’ll be including a download link at the end of this presentation with everything needed to build your own pair of Kronos speakers—including crossover schematics, PCB files, enclosure plans, and additional notes gathered throughout the build.
Finished Speaker:
Here’s a look at the finished Kronos speaker. Aesthetically, I realize this look might not be for everyone—but that was never the goal. I wanted the finish to reflect the spirit of the project: cheap, fun, and bold. The result is something unique, eye-catching, and artistic.
I’ve had a few people ask how I achieved the finish, so here’s a quick breakdown:
- I started with a roll-on bedliner called "Total Coat" to create a tough, textured surface.
- After that, I applied a Rust-Oleum yellow paint as the main color.
- For added visual interest, I used Rust-Oleum Black Marbling spray, which creates a random web-like texture and gives the surface a more dynamic, artistic feel.
- Finally, I sealed everything with a Rust-Oleum matte clear coat, which helps protect the finish and reduce glare.
It’s not a high-end veneer or mirror-gloss lacquer—but for a fun, rugged speaker with personality, it gets the job done. Cheap, effective, and satisfying to see come together.
Final Measurements:
Below you can see the final measured response of the Kronos design. The results highlight just how well the Visaton FRS5X in a waveguide and the SEAS A26RE4 woofer integrate—especially considering the simplicity of the crossover network.
The response is impressively smooth, with excellent tonal balance and a natural transition between drivers. The waveguide not only improves the FRS5X’s efficiency and dispersion but also allows it to blend seamlessly with the larger woofer, avoiding the typical disconnect you might expect from such different-sized drivers. The minimal crossover does just enough to shape the response where needed, while preserving the raw, engaging character of the drivers.
This measurement validates the listening impressions—a coherent, dynamic speaker that stays true to its vintage inspiration while performing with modern finesse.
Listening Impressions:
The final implementation of the Kronos exceeded my expectations. While I didn’t build these to be the ultimate reference monitor or the “end-all-be-all” speaker, the result is something that sounds exceptionally good—better than I had originally imagined.
The bass performance is particularly impressive, with deep, full extension that's further enhanced by room gain and proper placement. The SEAS woofer really shines here, delivering weight and authority without muddiness.
Tonally, the speaker holds up well across a wide variety of genres. So far, I've enjoyed everything from Rock, Jazz, Pop, Hip-Hop, EDM, to Classical, and the system has handled them all with confidence. The highs are clean without being harsh, mids are clear and natural, and the overall balance feels cohesive and engaging.
Even at very high listening levels, the speaker maintains its composure, with no sense of strain or collapse—perfect for those nights when you just want to crank things up and let loose.
I’ve also had a few friends over to hear them, and the reactions have been consistently surprised and impressed. There’s something satisfying about watching someone sit down with no expectations, and then light up the moment the music starts.
In Conclusion:
The Kronos has accomplished everything it was designed to do—and then some. It’s a speaker that brings together nostalgic inspiration, modern performance, and hands-on DIY fun in one cohesive package. I’m genuinely proud of how it turned out, and I know I’ll be enjoying these speakers for many years to come.
For those interested in diving deeper into the design—or even building a pair yourself—I’ve put together a comprehensive resource link below. This presentation has only scratched the surface, and the download includes detailed plans, crossover files, PCB layout, measurements, and more.
If you have any questions or run into issues, don’t hesitate to reach out. I’m always happy to help fellow builders in any way I can.
Thanks for taking the time to check out my project—I hope it inspires you to build something of your own.
LINK TO KRONOS BUILD PLANS: https://drive.google.com/drive/folders/1Kpa-w3JEGQmEdG6RKKRCQnM0pMenjgjl?usp=sharing
Post your wildlife pics here
- By chromenuts
- The Lounge
- 170 Replies
In the fall of 2023 my family relocated to North Western Connecticut which is an area that is a bit more rural than we had experienced previously.
One of the daily joys of living in this new area has been the almost daily sitings of wildlife…everything seemingly wanders into our yard when we least expect it…deer, bears, coyotes, hawks, eagles.
One of our favorite almost daily sitings is the Fantastic Mr. Fox who has set up residence on the edge of our property the past two years with Mrs. Fox and produced a brood of 4 pups both years.
The pups usually start venturing out some time in April. Most likely mom is trying to give them some practice at hunting mice for themselves. They are seen playing in and around the pool and rocky bank towards the bottom of our property.
I’m lousy on the draw with my phone camera. I’m sure some of you guys are much better.
Post a pic of some of your furry wild friends that you caught a glimpse of.
One of the daily joys of living in this new area has been the almost daily sitings of wildlife…everything seemingly wanders into our yard when we least expect it…deer, bears, coyotes, hawks, eagles.
One of our favorite almost daily sitings is the Fantastic Mr. Fox who has set up residence on the edge of our property the past two years with Mrs. Fox and produced a brood of 4 pups both years.
The pups usually start venturing out some time in April. Most likely mom is trying to give them some practice at hunting mice for themselves. They are seen playing in and around the pool and rocky bank towards the bottom of our property.
I’m lousy on the draw with my phone camera. I’m sure some of you guys are much better.
Post a pic of some of your furry wild friends that you caught a glimpse of.
MARTS MXD8000w 2ohms bad parts
I would like the part numbers of blown resistors I think they are 4.7ohms but diodes D8 & D10. IC9 & IC14
What's the problem with modern proper loudspeaker cabinets decoupling?
- By silverprout
- Multi-Way
- 162 Replies
Hello,
In a world of engineers i'm a tad shocked to don't see any good decoupling, the mecanical engineers are not all dead since i've recentely be teached by one of them and my last school teacher was also an engenneer (with a PhD in mecanics)... he was young 25 years ago.
People are using CAD and FDM printers here and no one seems able to decouple convenientely a loudspeaker, could you say what i don't understand ?
Aliexpress is full of strange spikes and ridiculous spring systems, are we all idiots ?
Here is a SMR for a microphone :
In a world of engineers i'm a tad shocked to don't see any good decoupling, the mecanical engineers are not all dead since i've recentely be teached by one of them and my last school teacher was also an engenneer (with a PhD in mecanics)... he was young 25 years ago.
People are using CAD and FDM printers here and no one seems able to decouple convenientely a loudspeaker, could you say what i don't understand ?
Aliexpress is full of strange spikes and ridiculous spring systems, are we all idiots ?
Here is a SMR for a microphone :
EL34 Baby Huey Amplifier
- By bandol83
- Tubes / Valves
- 1734 Replies
Hello EL34 Baby Huey builders,
As suggested by SCD in the following thread : http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 I am starting a new thread specially dedicated to the building of Baby Huey amplifier based on my PCB which has been produced in more than 330 pieces and is still requested by many tube amplifier fans in a possible future Group Buy 4 : http://www.diyaudio.com/forums/group-buys/312869-gb-baby-huey-pcb-42.html 🙂
I will put in this thread all the information available about the assembly of the EL34 Baby Huey amplifier and some of the auxiliary board that I have used or designed to add some features to the amplifier. I must tell you that I am not in professional amplifier business, this is just a time consuming hobby for me and, as you will see, English is not my first language and I have sometimes difficulties to explain things correctly, sorry for that but at least you will understand easily schematics, pictures, B.O.M., etc... 😀
History
All that started about two years ago when I read the http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 post from "gingertube" ! As I was interested by the shunt feedback concept that I didn't know I wanted to test it and decided to build the simplest version with two PCL86 tubes. Since I am very bad in point to point wiring, I made a small PCB. This amplifier was so good that I decided to continue my quest and, since the ECL86 or PCL86 were unfortunately no more produced, I made a second PCB for the EL84 version which needed a third tube, a 12AX7 (ECC83) for the input stage and added MOSFET with current source to drive the output tubes. This amplifier was very good and I was very satisfied by the MOSFET driver stage, but I was also a little bit frustrated by the limitation in power, about 12 W, and the fact that I could not use different power tubes...
To solve this problem, I made an identical version but with octal socket to accept many compatible tubes from the 6V6 to the KT88 and the EL34 Baby Huey was born ! Following the presentation of this solution on the diyaudio forum some members asked me if I could sell the PCB, I had never done this before but since the moderator move this discussion to the Group Buy forum I have received several request and started a GB1 with a target of 50 boards but finally closed it with 80 PCB ordered 🙂 I had to send them Worldwide and to learn how to make PayPal invoice... Later others readers asked me for more board and I offered a second and "last" GB2 which finished with 120 boards ordered !!!
Later, since there was still a strong demand, I asked Prasi, to whom I have bought a CRC power supply PCB, if he would accept to manage a third GB and he kindly accepted 🙂 He also suggested to make 2.4 mm boards for better rigidity. Now 120 more boards have been ordered and are in production and there is already 20 PCB's in waiting list for a possible GB4 ?
Documentation
In this first post I will enclose some of the latest documents available for building the EL34 Baby Huey and I will add more in next posts depending of your questions.
You will find the updated BOM in the GB letter, the latest schematics, some building recommendations, how to connect and to adjust the amplifier and several pictures showing the PCB assembled on top side (big components go on bottom side), a 6CA7 board fully assembled in test and finally the EL34 Baby Huey in its enclosure nearly finished (two vu-meters are still missing).
More pictures and data will come from all the people who have built this nice small amplifier. It is a very nice project for those who have never made and listen a tube amplifier, but remember there is some lethal high voltage (up to 500 V) and you should be very careful when you work on it
Have a nice time building the EL34 Baby Huey...
Best regards,
Marc
As suggested by SCD in the following thread : http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 I am starting a new thread specially dedicated to the building of Baby Huey amplifier based on my PCB which has been produced in more than 330 pieces and is still requested by many tube amplifier fans in a possible future Group Buy 4 : http://www.diyaudio.com/forums/group-buys/312869-gb-baby-huey-pcb-42.html 🙂
I will put in this thread all the information available about the assembly of the EL34 Baby Huey amplifier and some of the auxiliary board that I have used or designed to add some features to the amplifier. I must tell you that I am not in professional amplifier business, this is just a time consuming hobby for me and, as you will see, English is not my first language and I have sometimes difficulties to explain things correctly, sorry for that but at least you will understand easily schematics, pictures, B.O.M., etc... 😀
History
All that started about two years ago when I read the http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 post from "gingertube" ! As I was interested by the shunt feedback concept that I didn't know I wanted to test it and decided to build the simplest version with two PCL86 tubes. Since I am very bad in point to point wiring, I made a small PCB. This amplifier was so good that I decided to continue my quest and, since the ECL86 or PCL86 were unfortunately no more produced, I made a second PCB for the EL84 version which needed a third tube, a 12AX7 (ECC83) for the input stage and added MOSFET with current source to drive the output tubes. This amplifier was very good and I was very satisfied by the MOSFET driver stage, but I was also a little bit frustrated by the limitation in power, about 12 W, and the fact that I could not use different power tubes...
To solve this problem, I made an identical version but with octal socket to accept many compatible tubes from the 6V6 to the KT88 and the EL34 Baby Huey was born ! Following the presentation of this solution on the diyaudio forum some members asked me if I could sell the PCB, I had never done this before but since the moderator move this discussion to the Group Buy forum I have received several request and started a GB1 with a target of 50 boards but finally closed it with 80 PCB ordered 🙂 I had to send them Worldwide and to learn how to make PayPal invoice... Later others readers asked me for more board and I offered a second and "last" GB2 which finished with 120 boards ordered !!!
Later, since there was still a strong demand, I asked Prasi, to whom I have bought a CRC power supply PCB, if he would accept to manage a third GB and he kindly accepted 🙂 He also suggested to make 2.4 mm boards for better rigidity. Now 120 more boards have been ordered and are in production and there is already 20 PCB's in waiting list for a possible GB4 ?
Documentation
In this first post I will enclose some of the latest documents available for building the EL34 Baby Huey and I will add more in next posts depending of your questions.
You will find the updated BOM in the GB letter, the latest schematics, some building recommendations, how to connect and to adjust the amplifier and several pictures showing the PCB assembled on top side (big components go on bottom side), a 6CA7 board fully assembled in test and finally the EL34 Baby Huey in its enclosure nearly finished (two vu-meters are still missing).
More pictures and data will come from all the people who have built this nice small amplifier. It is a very nice project for those who have never made and listen a tube amplifier, but remember there is some lethal high voltage (up to 500 V) and you should be very careful when you work on it
Have a nice time building the EL34 Baby Huey...
Best regards,
Marc
Attachments
-
Group Buy letter & BOM Aug 22, 2018.pdf
-
Schema EL34 rev. 3 12 july 2018.pdf
-
Building recommendations EL34 Amplifier 27 jan 2018.pdf
-
Connecting the Amplifier 3 oct 2017.pdf
-
Adjusting the Amplifier 27 jan 2018.pdf
-
Montage ampli EL34 fini dessus.JPG -
Ampli 6CA7 gros plan.JPG -
EL34 Baby Huey nearly finished.jpg
New Purifi Tweeter Data Sheet
- By SBA_SLOB_GUY
- Multi-Way
- 19 Replies
Hi all, here in Europe there is at least one shop where i could pull the spec sheet
https://doc.soundimports.nl/pdf/brands/purifi/PTT1.3T04-HAG-01/PTT13T-HAG-01-Datasheet.pdf
The application information is good, never seen something so good explained from other vendors
So far - so good, Stefano
P.S.: this is the hint that VituixCAD is becoming a quasi standard even in the industry
https://doc.soundimports.nl/pdf/brands/purifi/PTT1.3T04-HAG-01/PTT13T-HAG-01-Datasheet.pdf
The application information is good, never seen something so good explained from other vendors
So far - so good, Stefano
P.S.: this is the hint that VituixCAD is becoming a quasi standard even in the industry
Blew something in a Chinese JLH1969 circuit. How to diagnose problem?
- Solid State
- 20 Replies
Sorry -- another basic question...
I was adjusting a pair of these for 24V/1.2A when I heard a tiny "tick" somewhere. After the "tick" I've now got no voltage at the "1/2 voltage (KT1 adjusted)" transistor.
I assume I blew something. Nothing visually changed anywhere (no scorching or blown caps). Replacing both trimpots on one of the boards didn't solve the problem.
Any ideas of what happened? Can I test items installed in the circuit with a multimeter? If I can, any suggestions what to check?
I was adjusting a pair of these for 24V/1.2A when I heard a tiny "tick" somewhere. After the "tick" I've now got no voltage at the "1/2 voltage (KT1 adjusted)" transistor.
I assume I blew something. Nothing visually changed anywhere (no scorching or blown caps). Replacing both trimpots on one of the boards didn't solve the problem.
Any ideas of what happened? Can I test items installed in the circuit with a multimeter? If I can, any suggestions what to check?
Misplaced PDF or website about open baffle woofers in the corner
- By gupsta
- Full Range
- 4 Replies
I vaguely recall a few years ago reading something that I found on the web that discussed placing the dipole woofers in the corner. I'd like to read it again but can't remember what it was called or where it was. I recall thinking it was a decent paper and had outlined diagrams showing the woofers placed near the corner such that from the listening position you're looking at the side of the woofer.
I tried placing my slob in the corner this evening and the bass seems easier on the ear drums but as expected needs much more gain; digital xo 100Hz.
I tried placing my slob in the corner this evening and the bass seems easier on the ear drums but as expected needs much more gain; digital xo 100Hz.
DIY soundcard intended for measuring amplifiers
- By MagicBus
- Equipment & Tools
- 201 Replies
I've been working on this for about a year and still incomplete but almost done. I couldn't hold myself to post some first pics.
Actually, it has been quite some time I'm fooling around low cost soundcards trying to modify them for improved performance. What strikes me is that although manufacturers don't hesitate to use top class chips, the overall performance is compromised by design. For example the power supply even if it's not the USB Vbus, it will be just a small external wall wart. Another problem is the necessity for a user friendly front panel which leads to a messy PCB layout. And then it comes the copyright war forcing companies to adopt proprietary solutions especially in the software domain, causing even instability issues in some cases. Most of the time I came to think what if app notes were followed to the letter but this would take a complete redesign from scratch. Eventually it happened.🙂
I rush to catch up any queries. This is not meant to be a giant killer. In fact, I deliberately stayed within limited bandwidth and dynamic range to avoid meeting spooky shadows. The target was the low to mid cost commercial soundcards. That said, it costs more than a Focusrite Scarlet to build 😱 and one might think that it doesn't manage any better. But all these products need some kind of input protection and usually adding that will also add THD+N. So, my soundcard is ready to accept an amplifiers output, the loop measurement are taken on these inputs and the total cost is much less than a soundcard-input interface combo.
And it's mine, which is priceless...
About specifications: Two channels -stereo- full balanced I/O. Input impedance 100k. Input sensitivity for 0dBFS 1,5Vrms differential. Input protection for 400VDC. Also it should be OK for 100Vp AC but I haven't tested that. Output can drive most usual loads with a max 2,6Vrms differential. Full duplex up to 192kHz/24bit, but usable only at 48kHz with ARTA, REW and the alike.
Still on the bench, I expect a little more improvement when I put it in the box. I verified that at least for the 50Hz noise. Lock down delays but it shouldn't take long more. I'll share all schematics and gerber files for anyone who needs something like that and can build it.
Actually, it has been quite some time I'm fooling around low cost soundcards trying to modify them for improved performance. What strikes me is that although manufacturers don't hesitate to use top class chips, the overall performance is compromised by design. For example the power supply even if it's not the USB Vbus, it will be just a small external wall wart. Another problem is the necessity for a user friendly front panel which leads to a messy PCB layout. And then it comes the copyright war forcing companies to adopt proprietary solutions especially in the software domain, causing even instability issues in some cases. Most of the time I came to think what if app notes were followed to the letter but this would take a complete redesign from scratch. Eventually it happened.🙂
I rush to catch up any queries. This is not meant to be a giant killer. In fact, I deliberately stayed within limited bandwidth and dynamic range to avoid meeting spooky shadows. The target was the low to mid cost commercial soundcards. That said, it costs more than a Focusrite Scarlet to build 😱 and one might think that it doesn't manage any better. But all these products need some kind of input protection and usually adding that will also add THD+N. So, my soundcard is ready to accept an amplifiers output, the loop measurement are taken on these inputs and the total cost is much less than a soundcard-input interface combo.
And it's mine, which is priceless...About specifications: Two channels -stereo- full balanced I/O. Input impedance 100k. Input sensitivity for 0dBFS 1,5Vrms differential. Input protection for 400VDC. Also it should be OK for 100Vp AC but I haven't tested that. Output can drive most usual loads with a max 2,6Vrms differential. Full duplex up to 192kHz/24bit, but usable only at 48kHz with ARTA, REW and the alike.
Still on the bench, I expect a little more improvement when I put it in the box. I verified that at least for the 50Hz noise. Lock down delays but it shouldn't take long more. I'll share all schematics and gerber files for anyone who needs something like that and can build it.
Attachments
Questions about balanced input and output stages
- By hobby_guy
- Analog Line Level
- 21 Replies
Hi all!
I'm working on a "stomp box" for microphone, not guitar, so the input is a balanced XLR (dynamic mic) and the output should be suitable for a mixer/PA (balanced output).
The circuit is based around a PT2399, so I need to take out a single-ended signal using an INA333. My design relies on op amps (TLV2462) to amplify the signal etc. All these ICs run on 5 V single power supply, so I need to add a 2.5 V DC offset to signal path.
I am currently focusing on the input and output stages, how to hook up to XLR contacts and feed into the INA333. Similarily, on the output, how to connect the balanced signal (which I create using op amps). Please review my design as shown in the images.
Are the coupling caps on the input stage oriented the right way, with cathode towards the mic? Also, I believe I should have a 48K to ground on the output (just before the XLR contacts) but I should not have this ground on the input stage. The 48K to ground on the output is to stabilize the potential at the output, right? On the input, the potential will be stabilized by the "bias" resistors which add the 2.5 V offset to the signal, so I don't need the ground connection (also, it would create an unintended voltage divider) so these should be omitted.
Input stage
Output stage
I guess I also wonder if it makes any difference if the op amps on the output (which create the balanced signal) are in series, or in parallel as in my design?
I'm working on a "stomp box" for microphone, not guitar, so the input is a balanced XLR (dynamic mic) and the output should be suitable for a mixer/PA (balanced output).
The circuit is based around a PT2399, so I need to take out a single-ended signal using an INA333. My design relies on op amps (TLV2462) to amplify the signal etc. All these ICs run on 5 V single power supply, so I need to add a 2.5 V DC offset to signal path.
I am currently focusing on the input and output stages, how to hook up to XLR contacts and feed into the INA333. Similarily, on the output, how to connect the balanced signal (which I create using op amps). Please review my design as shown in the images.
Are the coupling caps on the input stage oriented the right way, with cathode towards the mic? Also, I believe I should have a 48K to ground on the output (just before the XLR contacts) but I should not have this ground on the input stage. The 48K to ground on the output is to stabilize the potential at the output, right? On the input, the potential will be stabilized by the "bias" resistors which add the 2.5 V offset to the signal, so I don't need the ground connection (also, it would create an unintended voltage divider) so these should be omitted.
Input stage
Output stage
I guess I also wonder if it makes any difference if the op amps on the output (which create the balanced signal) are in series, or in parallel as in my design?
My OPA1656 RIAA PreAmp (one more)
- By Ansible
- Analogue Source
- 144 Replies
Hello everyone,
I decided to build my first RIAA phono stage, using OPA1656 and the schematic shown in the datasheet.
Where possible, I tried to use 0805 smd components for resistors and capacitors (exclusively Thin Film and C0G/NPO), except for the two 100nF that decouple the power lines. These are X7R. About the four 100uF capacitors, I chose Nichicon UES Bipolar.
The only change to the circuit concerns the removal of the 150 pF capacitor (for the capacitive load), replaced by three capacitors (22pF, 47pF, and 100pF) selectable or not, through a 3x SPST Dip Switch, for 8 possible combinations of capacity (0, 22, 47, 69, 100, 122, 147, 169 pF).
Considering that an average interconnect cable has a capacity of around 100pF, being able to add values between 0 and 169 pF, allows you to optimize the right input capacity in the most critical range of many cartridges (100 - 250 pF), especially those that prefer low input capacities.
I attach the schematic and some images of the PCB layout, in its current state. I have already made all the connections, but I have not yet added the ground plane on the bottom, so as not to confuse the traced tracks. I used 20 mills traces for all the signal lines, and 30 and 35 mills, only for the power lines.
But before completing the PCB I would like to hear some opinions on the layout and ask some questions:
1 - Is this preliminary rooting good enough, or are there obvious errors? Can it be improved with small changes?
2 - For simplicity I used classic 2.54 mm connectors for inputs and outputs. The input RCA connectors will be the standard through-hole type, fixed to the rear panel.
If placed at a distance of about 35 mm from each other, they will be located almost exactly above the two fixing holes of the PCB, on the input side, with the advantage of being able to use really short input cables (15 - 20 mm or even less). Slightly longer cables for the outputs I think are less of an issue.
From a sonic point of view, would it be better to use different connectors?
3 - About the Output capacitor, the last two lines of page 21 of the datasheet, state:
"... C5 is chosen to be the same value as C4; for simplicity however, the value of C5 must be large enough to avoid attenuating low-frequency information."
In my schematic, C5 corresponds to C13, C14 (100uF).
How do I check or calculate if the value is large enough, to avoid attenuation at low frequencies?
4 - Any other suggestions or criticisms, will be useful. 🙂
Regards,
Marco
I attach the schematic and images of the pcb in its current state.
Schematic From OPA1656 datasheet:
Actual layout without ground plane:
Board preview:
I decided to build my first RIAA phono stage, using OPA1656 and the schematic shown in the datasheet.
Where possible, I tried to use 0805 smd components for resistors and capacitors (exclusively Thin Film and C0G/NPO), except for the two 100nF that decouple the power lines. These are X7R. About the four 100uF capacitors, I chose Nichicon UES Bipolar.
The only change to the circuit concerns the removal of the 150 pF capacitor (for the capacitive load), replaced by three capacitors (22pF, 47pF, and 100pF) selectable or not, through a 3x SPST Dip Switch, for 8 possible combinations of capacity (0, 22, 47, 69, 100, 122, 147, 169 pF).
Considering that an average interconnect cable has a capacity of around 100pF, being able to add values between 0 and 169 pF, allows you to optimize the right input capacity in the most critical range of many cartridges (100 - 250 pF), especially those that prefer low input capacities.
I attach the schematic and some images of the PCB layout, in its current state. I have already made all the connections, but I have not yet added the ground plane on the bottom, so as not to confuse the traced tracks. I used 20 mills traces for all the signal lines, and 30 and 35 mills, only for the power lines.
But before completing the PCB I would like to hear some opinions on the layout and ask some questions:
1 - Is this preliminary rooting good enough, or are there obvious errors? Can it be improved with small changes?
2 - For simplicity I used classic 2.54 mm connectors for inputs and outputs. The input RCA connectors will be the standard through-hole type, fixed to the rear panel.
If placed at a distance of about 35 mm from each other, they will be located almost exactly above the two fixing holes of the PCB, on the input side, with the advantage of being able to use really short input cables (15 - 20 mm or even less). Slightly longer cables for the outputs I think are less of an issue.
From a sonic point of view, would it be better to use different connectors?
3 - About the Output capacitor, the last two lines of page 21 of the datasheet, state:
"... C5 is chosen to be the same value as C4; for simplicity however, the value of C5 must be large enough to avoid attenuating low-frequency information."
In my schematic, C5 corresponds to C13, C14 (100uF).
How do I check or calculate if the value is large enough, to avoid attenuation at low frequencies?
4 - Any other suggestions or criticisms, will be useful. 🙂
Regards,
Marco
I attach the schematic and images of the pcb in its current state.
Schematic From OPA1656 datasheet:
Actual layout without ground plane:
Board preview:
Help with an oscillating amplifier with Exicon mosFET ECF10P20 & ECF10N20
- By carcotado
- Solid State
- 53 Replies
Attachments
TIS/VAS transistores KSA1220AY + KSC2690AY for sale
Hi All,
I have a stock of new transistores for sale bought from Mouser and Farnell some years ago:
108 -> 50 x KSA1220AY (Fairchild/On Semi)
108 -> 50 x KSC2690AY (Fairchild/On Semi)
160 V / 1.2 A / 20 W / TO-126 / (highest grade hFE = 160-360).
Price per pair with a minimum qty of 20 pieces: 1.5 Euros/pair + Shipping.
Matching available. Please PM.
Regards,
VS
I have a stock of new transistores for sale bought from Mouser and Farnell some years ago:
108 -> 50 x KSA1220AY (Fairchild/On Semi)
108 -> 50 x KSC2690AY (Fairchild/On Semi)
160 V / 1.2 A / 20 W / TO-126 / (highest grade hFE = 160-360).
Price per pair with a minimum qty of 20 pieces: 1.5 Euros/pair + Shipping.
Matching available. Please PM.
Regards,
VS
Attachments
The whisky and whiskey thread
- By audiobomber
- The Lounge
- 38 Replies
From a thread I've been following, it appears there may be interest in discussing all things whisky (or whiskey for American and Irish variations). What's your favourite, how do you take it, where and when, why even? Excursions into other liquors are tolerated.
ELEKIT TU-8550 Pre-Amplifier
Another wonderful design from Mr Fujita - TU-8550
You can view and listen TU-8550 PREAMPLIFER in the coming -
Tube Preamp Kit TU-8550
PRICE : $1,175.00
JJ 12AX7 X 4
JJ 12AU7 X 2
[Circuit configurations, stock tubes]
Flat amp (line amp) : 2x 12AX7, 1x 12AU7, SE input/output
Phono equalizer amp : 2x 12AX7, 1x 12AU7, CR type, RIAA equalizer amp
A-power : DC-power (all tubes)
B-power : MOSFET, slow start, constant voltage power
* Line AMP *
Unbalanced output, continuously variable gain
[Max. output voltage] (1kHz)
Over 30V rms (Volume at the max.)
[Max. gain] (Volume at the max.)
Approx. 17dB (approx. 7 times)
[Frequency response] (-3dB, 47kΩ load) 5Hz to 200kHz
[Residual noise] (IHF-A)
15μV (Volume at the max.)
6.5μV (Volume at the middle)
4.3μV (Volume at the min.)
[SN ratio (IHF-A)]
130dB (Volume at the middle)
126dB (Volume at the max.)
* Equalizer amp *
[Max. output voltage] (1kHz) 20V rms (1kHz)
[Gain (1kHz)] 29dB
[SN ratio(IHF-A)] 112dB
[RIAA equalization] Within ±0.5dB (20Hz to 20kHz)
[Input resistance] 47kΩ
* General *
[Input/output terminal / Input and output impedance]
PHONO IN：RCA jack, for MM cartridge, 47kΩ
LINE IN： 4 lines
LINE 1, 2, 3 : RCA jack, over 50kΩ)
LINE 4 : 3.5mm stereo phone jack (front), approx.12kΩ)
PRE OUT：RCA jack, 2 lines (parallel output), approx.1.1kΩ
REC OUT：RCA jack, 1 line, approx.2.4kΩ for PHONO
Output impedance of the sound source + 1kΩfor LINE IN
[Power voltage] AC 100V 50/60Hz
(For overseas, 115V(110 –120V) or 230V(220 –240V), 50/60Hz)
IEC standard, 3P inlet type
[Rated power consumption] 23W
[Dimensions] W352 x H66 x D298 mm (including projections)
[Weight] Approx.4.0kg (Assembled, excluding AC cord)
4X VCAP 0.47 CuTF (option )
2x150W Amp module for sale
- By Erica.C
- Vendor's Bazaar
- 1044 Replies
Hi, All
Announce some SMPS+Class D amplifier integrated modules here:
FFA001V3
Output: 2x150W @ 4 / 8ohm
Input: 85--265Vac, constant power SMPS
Size: 90x150mm
Price: $49.9/Unit, w/o shipping (Inc. I/O buffer and mating cables)
FFA001V3-HB
Note: Configured as a high-bass mode. CH1=300W@4OHM and CH2=120W@8OHM, similar to the Pascal U-PRO2
Price: $54.9/Unit, w/o shipping (Inc. I/O buffer and mating cables)
FFA002V2 (1U height)
Output: 2x300W @ 4 / 8ohm
Input: 85--265Vac, constant power SMPS
Size: 95x200mm
Price: $99.9/Unit, w/o shipping (Inc. I/O buffer and mating cables)
FFA003V1
Output: 1x150W @8Ohm / 1x300W @4ohm
Input: 85--265Vac, constant power SMPS, heavy-duty design
Size: 90x245mm
Price: $64.9/Unit (Inc. AL base plate and Volume IO buffer) w/o shipping
PM me if you need more information.
Thanks~
Pics of FFA001V3
Pics of FFA002V2
Pics of FFA003V1
Misc
--- FFA001_V3 spec sheet & Test data;
--- FFA001_V3 & I/O_V1&I/O_V2 dxf file;
--- FFA001_V3 RearPanel_XLR 3D drawings;
--- FFA001_V3 RearPanel_RCA drawing and PDF;
Announce some SMPS+Class D amplifier integrated modules here:
FFA001V3
Output: 2x150W @ 4 / 8ohm
Input: 85--265Vac, constant power SMPS
Size: 90x150mm
Price: $49.9/Unit, w/o shipping (Inc. I/O buffer and mating cables)
FFA001V3-HB
Note: Configured as a high-bass mode. CH1=300W@4OHM and CH2=120W@8OHM, similar to the Pascal U-PRO2
Price: $54.9/Unit, w/o shipping (Inc. I/O buffer and mating cables)
FFA002V2 (1U height)
Output: 2x300W @ 4 / 8ohm
Input: 85--265Vac, constant power SMPS
Size: 95x200mm
Price: $99.9/Unit, w/o shipping (Inc. I/O buffer and mating cables)
FFA003V1
Output: 1x150W @8Ohm / 1x300W @4ohm
Input: 85--265Vac, constant power SMPS, heavy-duty design
Size: 90x245mm
Price: $64.9/Unit (Inc. AL base plate and Volume IO buffer) w/o shipping
PM me if you need more information.
Thanks~
Pics of FFA001V3
Pics of FFA002V2
Pics of FFA003V1
Misc
--- FFA001_V3 spec sheet & Test data;
--- FFA001_V3 & I/O_V1&I/O_V2 dxf file;
--- FFA001_V3 RearPanel_XLR 3D drawings;
--- FFA001_V3 RearPanel_RCA drawing and PDF;
Attachments
ESP Project 97 preamp scratchy volume pot noise
- By delverboy
- Analog Line Level
- 3 Replies
I was told this design could cause scratchiness in the pot because of loading and after about 4 months of use it seems that may be the case.
I'm seeking advice on two changes I was considering.
Replace the conductive plastic Alps RK27 (from Ebay so probably a knockoff) with this Vishay cermet, and swapping out the LM4562 with a FET input OPA2134 to reduce the pot load. I know an OPA1642 would be a better choice but it's not available in DIP8.
Output stage shown.
VR4 is 50K so R112/212 is 6k8 and R113/213 is 15k, per Rod's instructions.
I'm seeking advice on two changes I was considering.
Replace the conductive plastic Alps RK27 (from Ebay so probably a knockoff) with this Vishay cermet, and swapping out the LM4562 with a FET input OPA2134 to reduce the pot load. I know an OPA1642 would be a better choice but it's not available in DIP8.
Output stage shown.
VR4 is 50K so R112/212 is 6k8 and R113/213 is 15k, per Rod's instructions.
2-Way MEH build
After months of research on Multiple Entry Horns, I’ve decided to build my own. While there are some excellent designs available, I’ve decided to design my own due to size constraints and budget limitations. My goal is to build a complete system for under €2000, including drivers, amplifiers, DSP, materials etc.
I’ll be documenting the journey and sharing the lessons I learn along the way. Since I’m new to this, I’d greatly appreciate any feedback or suggestions for improvement.
For those unfamiliar with Multiple Entry Horns (also known as Synergy or Unity Horns), I’ll include some resources below. In this post, I’ll refer to them as MEHs.
Why Synergy horns?
Synergy Calc V5
Synergy Patent
SynTripP: 2-way 2-part Virtual Single Point Source Horn | diyAudio
Scott Hinson’s MEH
The Design
Designing this project involved plenty of trial and error with drivers, designs, and Hornresp parameters. First I was going to build a 3-way MEH using four 4” drivers and two 10” drivers per horn + big subs using 15” drivers. However, when I discussed this with my better half, she wasn’t happy with the big size. So I changed it to a more compact design: 30x30cm 2-way MEHs paired with subwoofers.
For the 3-way MEH I got ideas and insights from Syn 9/Syn 10 and Cosynes, Scott Hinson’s MEH and SynTripPs. After deciding to go with a smaller horn, I began exploring more compact designs, such as: Two way synergy Horn, Portable Battery Powered MEH Build and others.
Size
Using Synergy Calc , I calculated the size and parameters for Hornresp. According to Bill Waslo: “with horns, bigger is better!”. While I would have preferred larger dimensions, I had to consider WAF, so I settled on a 30x30cm horn with an 80° coverage angle and horizontal pattern control to 850 Hz. After reading this discussion I changed the S1 value to 5.06 to match the CDs opening area to get a more precise Hornresp Simulation..
Drivers
Hornresp is a fantastic tool for modeling speakers, big thanks to David McBean for his contributions! After countless evenings testing various drivers and parameters, I settled on the following components:
Compression Driver - FaitalPRO HF108 (8Ω) I chose it because it works well in short horns and wide dispersion waveguides and people seem to like it a lot. The recommended crossover is 1300 Hz, which is what I’ll go with in my design.
Midrange - 2x FaitalPRO 4FE35 (8Ω) in parallel - they simulated well in Hornresp and have been used in some MEH builds before.
Hornresp parameters
3d printed horn
The inner section of the horn (shown in light grey in the 3D rendering) will be 3D-printed, while the outer flare will be constructed from 2 sheets of 19mm MDF with a dispersion angle of 130 degrees
The HF108 compression driver has a 31-degree exit angle, so the horn starts with a matching 31-degree angle and gradually transitions to an 80-degree angle at the midrange entry point.
To minimize unexpected cancellation notches, the inner corners of the horn are smoothed with 2mm rounded edges.
Mid driver Port location:
From Why Synergy horns?:
I’m crossing between the mid and the compression driver (CD) at 1300 Hz, which means the port holes for the mid drivers should be within 6.596 cm (calculated as 343/1300/4) of the CD’s exit.
I’ve been wondering if the critical distance is measured from the mid ports to the CD’s acoustic diaphragm or its exit. The CD’s exit seems to work well in previous designs posted here, so I decided to go with that. This approach also simplifies placement by allowing the ports to be positioned farther out.
To ensure I stayed within the critical distance, I decided to shorten L12 slightly (the distance between the CD’s exit and the plane of the mid-entry ports). L12 is 4.28 cm, meaning the centre of the mid-entry port is 5.84 cm from the centre of the CD’s exit, so it’s well within the required 6.596 cm for the crossover.
The circumference of the cross-sectional area at the tap-in point is calculated as 6.531*4=26.124, which is close to the wavelength of 1300 Hz.
However, when I model it in Hornresp, the cancellation notch appears well above 1300 Hz, and the mids start to roll off around 2000 Hz. I can increase the distances well above 6.6 cm before I get the cancelation notch near 1300 Hz. I’m not sure if I’ve missed something in my calculations and the measurements may differ when I measure the build speakers.
Mid driver Vrc:
I made the Vrc (closed rear chamber volume) fairly small 2 L in total (1L per driver). I still haven’t figured out how I will limit the chamber volume. Using tubes like those in the Cosynes would be challenging due to the distance between the mids and the compression driver.
Mid driver Vtc:
I didn’t feel like I needed to minimize the Vtc (throat chamber volume) as the mids can play high enough frequency already. Making it smaller using cone plugs seems more beneficial with bigger woofers (like on the SynTripPs) and also the B&C 4NDF34 which have been used in some designs. For now I’ve estimated 50cc per driver, but will measure the volume when I receive them. I might adjust the sizing after doing the final calculations with the correct volume.
Mid driver port size:
There are 2 entry ports per driver, 4 in total. The entry points are frustrumised, 2.76 cm in diameter closest to the driver and 1.95 on the inside of the horn, which translate to Ap1 of 24 cm² and Ap2 of 12 cm².
The ports are relatively small, with port velocity exceeding 17 m/s when played above 105 dB below 200 Hz. These are meant for home hi-fi use, so I don’t plan to play them too loud. I also don’t want to make them too big, so they affect the CD’s output. The ports are placed next to the corners to minimise the effect they have on the CD.
Vertical drivers:
This is something I haven’t seen mentioned often, and it seems to be overlooked in many MEH designs. I will place all the drivers vertically, on the side walls of the horn, to avoid driver sag.
Ported or sealed box:
While I was designing the 3-way MEH with 2x 10” woofers I tried modeling the low drivers in both ported and sealed box. I ended up choosing sealed after reading Arts comment from the SynTripP thread.
Subwoofers:
I haven’t decided on the subwoofers yet.
I’m considering adding two subs within the same enclosure as side-firing woofers in a push-push alignment. For example, two GRS 8SW-4HE drivers in a sealed configuration with a ca 42L volume. Here is a promising recommendation for these woofers.
If I go with this approach, I might decrease the vertical coverage angle of the MEH horn to 60 degrees to make space for the woofers below the horn. I guess it would be good idea to have the woofers close to the horn, within ¼ wavelength of the crossover frequency, but have also read that it doesn’t matter very much for frequencies below 100 Hz.
Adding the subs in the same enclosure would significantly increase the height of the enclosure, which may not pass the WAF. Alternatively, I could build a separate subwoofer placed approximately 1.5 meters away
Is it better to integrate side-firing subwoofers within the same enclosure or should I make a separate enclosure, which would need to be ca 1.5m away? I’d appreciate any feedback or suggestions on driver selection!
Amplifier and DSP:
As I don’t own any of the parts needed I have the opportunity to build the whole system from scratch.
The TPA3255/51 amps seem to offer great value for the money.
I’m looking into: Fosi ZA3, AIYIMA A70, Topping PA5 II and the upcoming 3e audio amps. I haven’t decided yet and would appreciate any recommendations.
Finding a DSP solution that fits the budget has been tricky. High-quality DSPs can be expensive, while the cheaper options often come with limitations.
I’ve decided to go with a Raspberry Pi 5 running CamillaDSP. For the DAC, I’ll start with the cheapest option: the AliExpress cards mentioned in this guide. RPi 5 Quad Stereo Sound with PCM5102A – Simple DIY Electronic Music Projects. User dptucunduva has had good results with it.
The reasons I chose it are:
It’s cheap and has good potential for upgrades. I can switch out the DAC module for a proper sound card like the Motu Ultralite mk5.
It’s a very flexible system, the Raspberry Pi can act as a streamer and allows for lots of add-ons like a remote controller, Those who use CamillaDSP seem very happy with it.
HiFiBerry DAC, which uses the same DAC chip seems to be decent according to the measurements here. I’m not expecting any fantastic results but see it as a cheap solution that has all the active crossover functions needed.
Next steps:
The CD and mid-drivers are on their way, and I plan to begin 3D printing the horn in early January. In the meantime I’ll focus on refining the horn design, adding mounting holes, figure out how to do the right vrc size. I also need to decide which amplifiers to use and start building the Raspberry Pi DSP. Additionally, I’ll work on designing the subwoofers and determining whether side-firing woofers are the best option.
Any suggestions or input would be greatly appreciated!
I’ll be documenting the journey and sharing the lessons I learn along the way. Since I’m new to this, I’d greatly appreciate any feedback or suggestions for improvement.
For those unfamiliar with Multiple Entry Horns (also known as Synergy or Unity Horns), I’ll include some resources below. In this post, I’ll refer to them as MEHs.
Why Synergy horns?
Synergy Calc V5
Synergy Patent
SynTripP: 2-way 2-part Virtual Single Point Source Horn | diyAudio
Scott Hinson’s MEH
The Design
Designing this project involved plenty of trial and error with drivers, designs, and Hornresp parameters. First I was going to build a 3-way MEH using four 4” drivers and two 10” drivers per horn + big subs using 15” drivers. However, when I discussed this with my better half, she wasn’t happy with the big size. So I changed it to a more compact design: 30x30cm 2-way MEHs paired with subwoofers.
For the 3-way MEH I got ideas and insights from Syn 9/Syn 10 and Cosynes, Scott Hinson’s MEH and SynTripPs. After deciding to go with a smaller horn, I began exploring more compact designs, such as: Two way synergy Horn, Portable Battery Powered MEH Build and others.
Size
Using Synergy Calc , I calculated the size and parameters for Hornresp. According to Bill Waslo: “with horns, bigger is better!”. While I would have preferred larger dimensions, I had to consider WAF, so I settled on a 30x30cm horn with an 80° coverage angle and horizontal pattern control to 850 Hz. After reading this discussion I changed the S1 value to 5.06 to match the CDs opening area to get a more precise Hornresp Simulation..
Drivers
Hornresp is a fantastic tool for modeling speakers, big thanks to David McBean for his contributions! After countless evenings testing various drivers and parameters, I settled on the following components:
Compression Driver - FaitalPRO HF108 (8Ω) I chose it because it works well in short horns and wide dispersion waveguides and people seem to like it a lot. The recommended crossover is 1300 Hz, which is what I’ll go with in my design.
Midrange - 2x FaitalPRO 4FE35 (8Ω) in parallel - they simulated well in Hornresp and have been used in some MEH builds before.
Hornresp parameters
3d printed horn
The inner section of the horn (shown in light grey in the 3D rendering) will be 3D-printed, while the outer flare will be constructed from 2 sheets of 19mm MDF with a dispersion angle of 130 degrees
The HF108 compression driver has a 31-degree exit angle, so the horn starts with a matching 31-degree angle and gradually transitions to an 80-degree angle at the midrange entry point.
To minimize unexpected cancellation notches, the inner corners of the horn are smoothed with 2mm rounded edges.
Mid driver Port location:
From Why Synergy horns?:
I’m crossing between the mid and the compression driver (CD) at 1300 Hz, which means the port holes for the mid drivers should be within 6.596 cm (calculated as 343/1300/4) of the CD’s exit.
I’ve been wondering if the critical distance is measured from the mid ports to the CD’s acoustic diaphragm or its exit. The CD’s exit seems to work well in previous designs posted here, so I decided to go with that. This approach also simplifies placement by allowing the ports to be positioned farther out.
To ensure I stayed within the critical distance, I decided to shorten L12 slightly (the distance between the CD’s exit and the plane of the mid-entry ports). L12 is 4.28 cm, meaning the centre of the mid-entry port is 5.84 cm from the centre of the CD’s exit, so it’s well within the required 6.596 cm for the crossover.
The circumference of the cross-sectional area at the tap-in point is calculated as 6.531*4=26.124, which is close to the wavelength of 1300 Hz.
However, when I model it in Hornresp, the cancellation notch appears well above 1300 Hz, and the mids start to roll off around 2000 Hz. I can increase the distances well above 6.6 cm before I get the cancelation notch near 1300 Hz. I’m not sure if I’ve missed something in my calculations and the measurements may differ when I measure the build speakers.
Mid driver Vrc:
I made the Vrc (closed rear chamber volume) fairly small 2 L in total (1L per driver). I still haven’t figured out how I will limit the chamber volume. Using tubes like those in the Cosynes would be challenging due to the distance between the mids and the compression driver.
Mid driver Vtc:
I didn’t feel like I needed to minimize the Vtc (throat chamber volume) as the mids can play high enough frequency already. Making it smaller using cone plugs seems more beneficial with bigger woofers (like on the SynTripPs) and also the B&C 4NDF34 which have been used in some designs. For now I’ve estimated 50cc per driver, but will measure the volume when I receive them. I might adjust the sizing after doing the final calculations with the correct volume.
Mid driver port size:
There are 2 entry ports per driver, 4 in total. The entry points are frustrumised, 2.76 cm in diameter closest to the driver and 1.95 on the inside of the horn, which translate to Ap1 of 24 cm² and Ap2 of 12 cm².
The ports are relatively small, with port velocity exceeding 17 m/s when played above 105 dB below 200 Hz. These are meant for home hi-fi use, so I don’t plan to play them too loud. I also don’t want to make them too big, so they affect the CD’s output. The ports are placed next to the corners to minimise the effect they have on the CD.
Vertical drivers:
This is something I haven’t seen mentioned often, and it seems to be overlooked in many MEH designs. I will place all the drivers vertically, on the side walls of the horn, to avoid driver sag.
Ported or sealed box:
While I was designing the 3-way MEH with 2x 10” woofers I tried modeling the low drivers in both ported and sealed box. I ended up choosing sealed after reading Arts comment from the SynTripP thread.
Subwoofers:
I haven’t decided on the subwoofers yet.
I’m considering adding two subs within the same enclosure as side-firing woofers in a push-push alignment. For example, two GRS 8SW-4HE drivers in a sealed configuration with a ca 42L volume. Here is a promising recommendation for these woofers.
If I go with this approach, I might decrease the vertical coverage angle of the MEH horn to 60 degrees to make space for the woofers below the horn. I guess it would be good idea to have the woofers close to the horn, within ¼ wavelength of the crossover frequency, but have also read that it doesn’t matter very much for frequencies below 100 Hz.
Adding the subs in the same enclosure would significantly increase the height of the enclosure, which may not pass the WAF. Alternatively, I could build a separate subwoofer placed approximately 1.5 meters away
Is it better to integrate side-firing subwoofers within the same enclosure or should I make a separate enclosure, which would need to be ca 1.5m away? I’d appreciate any feedback or suggestions on driver selection!
Amplifier and DSP:
As I don’t own any of the parts needed I have the opportunity to build the whole system from scratch.
The TPA3255/51 amps seem to offer great value for the money.
I’m looking into: Fosi ZA3, AIYIMA A70, Topping PA5 II and the upcoming 3e audio amps. I haven’t decided yet and would appreciate any recommendations.
Finding a DSP solution that fits the budget has been tricky. High-quality DSPs can be expensive, while the cheaper options often come with limitations.
I’ve decided to go with a Raspberry Pi 5 running CamillaDSP. For the DAC, I’ll start with the cheapest option: the AliExpress cards mentioned in this guide. RPi 5 Quad Stereo Sound with PCM5102A – Simple DIY Electronic Music Projects. User dptucunduva has had good results with it.
The reasons I chose it are:
It’s cheap and has good potential for upgrades. I can switch out the DAC module for a proper sound card like the Motu Ultralite mk5.
It’s a very flexible system, the Raspberry Pi can act as a streamer and allows for lots of add-ons like a remote controller, Those who use CamillaDSP seem very happy with it.
HiFiBerry DAC, which uses the same DAC chip seems to be decent according to the measurements here. I’m not expecting any fantastic results but see it as a cheap solution that has all the active crossover functions needed.
Next steps:
The CD and mid-drivers are on their way, and I plan to begin 3D printing the horn in early January. In the meantime I’ll focus on refining the horn design, adding mounting holes, figure out how to do the right vrc size. I also need to decide which amplifiers to use and start building the Raspberry Pi DSP. Additionally, I’ll work on designing the subwoofers and determining whether side-firing woofers are the best option.
Any suggestions or input would be greatly appreciated!