MF A1, Kudos to Tim de Paravicini, Ode to my Youth, Babelfishing
Need to get this out of my system ........
When I was a Kido, just barely moving with my first attempts of building amps and preamps from scratch, desperatelly wandering through any available printed sources ( no www yet) in search of/for Holly Grail .... my good friend just acquired specimen of which is later to be one of my all ever favorite amps - Musical Fidelity A1
(what did I knew that I'll have damn long list of my fave amps, not necesarily good ones or special in any tecnical or performance way, but heck - guy can have feelings, liking things just for liking sake
)
Anyhow - not much time did pass, I had it in pieces, first to figure out schematic, and then maybe to think something clever (hell, yeah
) to make it better
Not much time after that, I had built my own, by wonder it worked right from the bat, by wonder I did guess right what output transistor are (ignore thing that I really knew just 2N3055 and needed to chase its "complementary" ..... so I had proper beginner's luck guessing right ones - 2N3055 and BDX18)
And - no wonder that I made exactly same mishaps as mishaps being implemented in original - I did use 100VA mains Iron for 80W of juiced juice, and mine also had beautiful thermal arrangement as original, resulting in oh boy!!!!!!!!!! temperature of heatsinks
Later, when we did some head to head comparison between friend's original one and my "Clone", awe was that "Clone" sounded better - simply beause I did made just power amp portion, really not being able to include preamp section in said moment, planning that to add in later time
Speak of beginner's luck, again
Conclusion - "Clone" did sound better with line level sources, preceded with just 10K pot, than original one having all bells and whistles
Then we did go wild, trying tube stage in front - finding some "modern" solution - ECC88/6DJ8 fed with humongous voltage of 30V ..... it did help some - fact that it was loaded with current source .....
What we did know that MF will follow same easy commercial pats some later, nicely feeding hordes of us ignorant imbeciles ....... in fact - nothing wrong with nice little pleasing boxes, but I later did found following Myths and Legends somewhat disgusting
Do I need to say that it sounded even better with "tube" stage, however flawed it was?
.......................................... fast rewind to www time, I started chasing Holly Grails in every possible direction, beside other things I did found some few itsybitsies about my (then) still fave amp
If you fancy some reading, see attached pic (schm , few posts down) and visit Mark Hennessy page https://www.markhennessy.co.uk/mf_a1/
M. Hennessy is getting most of facts right ....... and I have impression that he's extremely polite, whenever anything worth commenting he did comment
I'm going to be extremmmmmmely polite, not commenting anything about original commercial MF A1, neither first Gen, nor 2nd (just a gimmick, really, having USBandwhatever) nor present - 3rd or, rather, proper 2nd Gen
In last few decades, I had at least a dozen on my workbench for service and improvement, had at least 4 called "mine" ....... where last one of these 4 is still around (serving one of my friends)........... while my described clone is still somewhere around, supposedly still mine but I really need to stretch my gray cells to decipher where it is exactly .............
huh, tired of typing
When I was a Kido, just barely moving with my first attempts of building amps and preamps from scratch, desperatelly wandering through any available printed sources ( no www yet) in search of/for Holly Grail .... my good friend just acquired specimen of which is later to be one of my all ever favorite amps - Musical Fidelity A1
(what did I knew that I'll have damn long list of my fave amps, not necesarily good ones or special in any tecnical or performance way, but heck - guy can have feelings, liking things just for liking sake
)Anyhow - not much time did pass, I had it in pieces, first to figure out schematic, and then maybe to think something clever (hell, yeah
) to make it betterNot much time after that, I had built my own, by wonder it worked right from the bat, by wonder I did guess right what output transistor are (ignore thing that I really knew just 2N3055 and needed to chase its "complementary" ..... so I had proper beginner's luck guessing right ones - 2N3055 and BDX18)
And - no wonder that I made exactly same mishaps as mishaps being implemented in original - I did use 100VA mains Iron for 80W of juiced juice, and mine also had beautiful thermal arrangement as original, resulting in oh boy!!!!!!!!!! temperature of heatsinks
Later, when we did some head to head comparison between friend's original one and my "Clone", awe was that "Clone" sounded better - simply beause I did made just power amp portion, really not being able to include preamp section in said moment, planning that to add in later time
Speak of beginner's luck, again
Conclusion - "Clone" did sound better with line level sources, preceded with just 10K pot, than original one having all bells and whistles
Then we did go wild, trying tube stage in front - finding some "modern" solution - ECC88/6DJ8 fed with humongous voltage of 30V ..... it did help some - fact that it was loaded with current source .....
What we did know that MF will follow same easy commercial pats some later, nicely feeding hordes of us ignorant imbeciles ....... in fact - nothing wrong with nice little pleasing boxes, but I later did found following Myths and Legends somewhat disgusting
Do I need to say that it sounded even better with "tube" stage, however flawed it was?
.......................................... fast rewind to www time, I started chasing Holly Grails in every possible direction, beside other things I did found some few itsybitsies about my (then) still fave amp
If you fancy some reading, see attached pic (schm , few posts down) and visit Mark Hennessy page https://www.markhennessy.co.uk/mf_a1/
M. Hennessy is getting most of facts right ....... and I have impression that he's extremely polite, whenever anything worth commenting he did comment
I'm going to be extremmmmmmely polite, not commenting anything about original commercial MF A1, neither first Gen, nor 2nd (just a gimmick, really, having USBandwhatever) nor present - 3rd or, rather, proper 2nd Gen
In last few decades, I had at least a dozen on my workbench for service and improvement, had at least 4 called "mine" ....... where last one of these 4 is still around (serving one of my friends)........... while my described clone is still somewhere around, supposedly still mine but I really need to stretch my gray cells to decipher where it is exactly .............
huh, tired of typing
Vera-Link TWS Bluetooth Power Amp
I have been developing a new compact stick-on Bluetooth True Wireless Stereo (TWS) amp for passive speakers. It lets you turn any set of passive speakers into an instant streaming solution to have music anywhere in your home, workshop, garage, pool, picnic, etc.
Each amp just needs a local power outlet from the wall or can be battery powered. The amps connect and are paired to each other wirelessly for stereo left and right with a single Bluetooth connection.
The wireless connection to your smartphone, tablet, computer, etc. works instantly and easily for frustration-free Bluetooth 5.0 quality sound. Successful connections are confirmed with a quick tone (no annoying voice) and LED blink from the light pipe indicator at the “eye” of the letter “i” in the word “Link”.
Internally, the Bluetooth RF modules are capable of Bluetooth 5.0 standard (345 kbps max bit rate) and has terrific range and reliability. The Class D amps (TPA3116 based) driven by the Bluetooth RF modules are capable of 50W into 4ohms and 25W into 8ohms, and are wired in parallel bridge tied load (PBTL) so can actually handle 2ohm loads. The amps come with dual 24v 3A desktop universal voltage SMPS modules. Optional low profile 12v 2A wallwart style SMPS (in white) are also available for minimal visual footprint when used along side of decorator furnishings and significant-other-sensitive interior spaces. Even at 12v, 83dB sensitive speakers play plenty loud and clean for most home uses. The sound quality is excellent and the simplicity of it all is fantastic.
Here the Vera-Link is seen attached to the back of the Vanguard speaker:
Here is a nice clean no mess speaker installation in my upstairs bedroom. The white power cables and wallwart blend in very well. All you need are speakers and some stands. You can drive it from your smartphone (which is how most of us listen to music nowadays in my house):
Here is the 24v 3A desktop power supply (two are provided with set):
This is the 12v 2A wallwart power supply (USA and EU plugs available) in white:
The Vera-Link amp kit will sell for $199 a pair complete with 24v 3A power supplies and high quality gold plated banana plugs. The amps come with hook-loop strips with self adhesive for installation to any speaker. 5 unique Vera-Link amp pair Bluetooth names will be available so that you can have multiple sets in one household without confusion.
An early review by Stereo Times is now online:
https://v2.stereotimes.com/post/vera-link-wireless-amplifiers-by-greg-voth/
Also one on Tone Audio magazine:
https://www.tonepublications.com/audiophile-apartment/vera-link-the-most-fun-you-can-have-for-199/
You can order them here:
https://verafiaudiollc.com/
Each amp just needs a local power outlet from the wall or can be battery powered. The amps connect and are paired to each other wirelessly for stereo left and right with a single Bluetooth connection.
The wireless connection to your smartphone, tablet, computer, etc. works instantly and easily for frustration-free Bluetooth 5.0 quality sound. Successful connections are confirmed with a quick tone (no annoying voice) and LED blink from the light pipe indicator at the “eye” of the letter “i” in the word “Link”.
Internally, the Bluetooth RF modules are capable of Bluetooth 5.0 standard (345 kbps max bit rate) and has terrific range and reliability. The Class D amps (TPA3116 based) driven by the Bluetooth RF modules are capable of 50W into 4ohms and 25W into 8ohms, and are wired in parallel bridge tied load (PBTL) so can actually handle 2ohm loads. The amps come with dual 24v 3A desktop universal voltage SMPS modules. Optional low profile 12v 2A wallwart style SMPS (in white) are also available for minimal visual footprint when used along side of decorator furnishings and significant-other-sensitive interior spaces. Even at 12v, 83dB sensitive speakers play plenty loud and clean for most home uses. The sound quality is excellent and the simplicity of it all is fantastic.
Here the Vera-Link is seen attached to the back of the Vanguard speaker:
Here is a nice clean no mess speaker installation in my upstairs bedroom. The white power cables and wallwart blend in very well. All you need are speakers and some stands. You can drive it from your smartphone (which is how most of us listen to music nowadays in my house):
Here is the 24v 3A desktop power supply (two are provided with set):
This is the 12v 2A wallwart power supply (USA and EU plugs available) in white:
The Vera-Link amp kit will sell for $199 a pair complete with 24v 3A power supplies and high quality gold plated banana plugs. The amps come with hook-loop strips with self adhesive for installation to any speaker. 5 unique Vera-Link amp pair Bluetooth names will be available so that you can have multiple sets in one household without confusion.
An early review by Stereo Times is now online:
https://v2.stereotimes.com/post/vera-link-wireless-amplifiers-by-greg-voth/
Also one on Tone Audio magazine:
https://www.tonepublications.com/audiophile-apartment/vera-link-the-most-fun-you-can-have-for-199/
You can order them here:
https://verafiaudiollc.com/
Interesting design that I dubbed "mirror mania"
- By njswede
- Solid State
- 23 Replies
This schematic came up in a conversation on another forum and it intrigued me so much that I drew it up in LTSpice and took it for a spin. It seems to perform vwell. I'm trying to understand the working principle and I think what look like current mirrors are actually working as common base amplifiers. But why? What's the idea behind a design like this? Anyone familiar with it?
Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
- By iancanada
- Digital Line Level
- 13353 Replies
People keep talking too much about jitter issues, but did less to make some kind of improvement. I decided trying to do something real – a working asynchronous I2S FIFO.
Before I go any further, I need to make something clear in advance:
1. FIFO is widely believed as one of the final methods to deal with jitter problems. But the asynchronous FIFO itself is just a technology which could provide a logic function to isolate the two clock domain. That means, for an I2S stream, digital audio data could pass through without any modification but the input clock was blocked and replaced with the new one. The new clock is totally independent from the old one except they should have the similar frequency. The FIFO logic itself does not influence the sound quality;
2. What really makes it sound better (or even worse) is the low jitter secondary clock. For example, if we have a new clock after the FIFO which comes with one digit ps jitter(RMS), we should get much better sound quality than before (the jitter level of the master clock from DIR chip usually around 50ps(RMS) level above corner frequency). So, we should pay more attention on the secondary clock and related interface. Everything connected to secondary clock has to be very carefully to deal with; otherwise new additive jitter will be introduced;
3. The size of the FIFO memory should big enough to meet overflow or empty time caused by the worst case of i2s input clock, but still has to be carefully selected to get the balance between the delay time caused by the working depth(usually half full) of the FIFO;
4. FIFO with low jitter secondary clock could only reduce the play back jitter for an audio DAC, but has nothing to do with the sampling jitter. I don’t have any idea if a CD was reordered with poor clock of the ADC.
The main logic functions could be achieved by a FPGA/CPLD chip together with a megabit SRAM. But the clock section has to use specialized clock/timing circuit, because the jitter performance of the output of FPGA/CPLD are far from what we want.
Below is the possible block diagram of this I2S FIFO project:
https://github.com/iancanada/DocumentDownload
https://twitter.com/iancanadaTT
FifoPi Q7 Jan.12,2023 update https://github.com/iancanada/DocumentDownload/blob/master/FifoPi/FifoPiQ7/FifoPiQ7Manual.pdf
FifoPiQ7_0 by Ian, on Flickr
Before I go any further, I need to make something clear in advance:
1. FIFO is widely believed as one of the final methods to deal with jitter problems. But the asynchronous FIFO itself is just a technology which could provide a logic function to isolate the two clock domain. That means, for an I2S stream, digital audio data could pass through without any modification but the input clock was blocked and replaced with the new one. The new clock is totally independent from the old one except they should have the similar frequency. The FIFO logic itself does not influence the sound quality;
2. What really makes it sound better (or even worse) is the low jitter secondary clock. For example, if we have a new clock after the FIFO which comes with one digit ps jitter(RMS), we should get much better sound quality than before (the jitter level of the master clock from DIR chip usually around 50ps(RMS) level above corner frequency). So, we should pay more attention on the secondary clock and related interface. Everything connected to secondary clock has to be very carefully to deal with; otherwise new additive jitter will be introduced;
3. The size of the FIFO memory should big enough to meet overflow or empty time caused by the worst case of i2s input clock, but still has to be carefully selected to get the balance between the delay time caused by the working depth(usually half full) of the FIFO;
4. FIFO with low jitter secondary clock could only reduce the play back jitter for an audio DAC, but has nothing to do with the sampling jitter. I don’t have any idea if a CD was reordered with poor clock of the ADC.
The main logic functions could be achieved by a FPGA/CPLD chip together with a megabit SRAM. But the clock section has to use specialized clock/timing circuit, because the jitter performance of the output of FPGA/CPLD are far from what we want.
Below is the possible block diagram of this I2S FIFO project:
https://github.com/iancanada/DocumentDownload
https://twitter.com/iancanadaTT
FifoPi Q7 Jan.12,2023 update https://github.com/iancanada/DocumentDownload/blob/master/FifoPi/FifoPiQ7/FifoPiQ7Manual.pdf
FifoPiQ7_0 by Ian, on FlickrAttachments
Tubes4HiFi SP14 really noisy!
- By perkri
- Tubes / Valves
- 253 Replies
Hi,
I ordered the kit without the chassis, as I wanted to build my own - plus I wanted to try to save some $$$’s
I’m getting a LOT of noise out of this…
All the voltages are as they should be.
B+ is 276vdc
H+/H- is 6.13 and 5.87
Voltage drops from 313 to 276 across D13 (both sides…)
6.43vac on heater from transformer
I have checked, double and triple checked the wires from all RCA inputs/outputs. The ground bus and all the connections to that, the ground to the circuit board from the bus. I’ve gone over the input selector, and all the wires coming and going from that. All the connections from the selector, through to the gain and volume controls. The output from the volume to the board, and ground wire are as outlined in the instructions.
I did not install the tape switch, and ran the wires straight from selector to the gain pots.
There are two things I changed as far as the power supply goes. I used an old school toggle switch in place of the power switch that came with the kit. And I accidentally reversed the red and black primaries to the transformers from a hot/neutral perspective. But I don’t think the transformers care about hot/neutral?
The noise is the same regardless of gain/volume settings. It’s the same in both channels. It gradually comes up in volume as the unit powers up. As soon as it’s powered off, it disappears but music keeps playing until it fades away.
The noise is the same, albeit with different volumes, if I run it into my DIY Hiraga Super 30 Class A SS amp, or my DIYAudio VFet SE SS amp.
Thank you for taking the time to read through this, any help would be greatly appreciated!
P
This is the noise as it presents at the speaker…
I ordered the kit without the chassis, as I wanted to build my own - plus I wanted to try to save some $$$’s
I’m getting a LOT of noise out of this…
All the voltages are as they should be.
B+ is 276vdc
H+/H- is 6.13 and 5.87
Voltage drops from 313 to 276 across D13 (both sides…)
6.43vac on heater from transformer
I have checked, double and triple checked the wires from all RCA inputs/outputs. The ground bus and all the connections to that, the ground to the circuit board from the bus. I’ve gone over the input selector, and all the wires coming and going from that. All the connections from the selector, through to the gain and volume controls. The output from the volume to the board, and ground wire are as outlined in the instructions.
I did not install the tape switch, and ran the wires straight from selector to the gain pots.
There are two things I changed as far as the power supply goes. I used an old school toggle switch in place of the power switch that came with the kit. And I accidentally reversed the red and black primaries to the transformers from a hot/neutral perspective. But I don’t think the transformers care about hot/neutral?
The noise is the same regardless of gain/volume settings. It’s the same in both channels. It gradually comes up in volume as the unit powers up. As soon as it’s powered off, it disappears but music keeps playing until it fades away.
The noise is the same, albeit with different volumes, if I run it into my DIY Hiraga Super 30 Class A SS amp, or my DIYAudio VFet SE SS amp.
Thank you for taking the time to read through this, any help would be greatly appreciated!
P
This is the noise as it presents at the speaker…
H2
- By Nelson Pass
- Pass Labs
- 1208 Replies
For the upcoming Burning Amp Festival I created a nice little 2nd Harmonic
Generator. It's similar to what the Korg Nutube does, but uses a Jfet.
I made up a nice batch of them to give away at BAF, and I'm telling you
about it now so you can book your flights, hire babysitters, etc.
You can read all about it at FIRST WATT WATT'S NEW
Generator. It's similar to what the Korg Nutube does, but uses a Jfet.
I made up a nice batch of them to give away at BAF, and I'm telling you
about it now so you can book your flights, hire babysitters, etc.
You can read all about it at FIRST WATT WATT'S NEW
Simple, no-math transformer snubber using Quasimodo test-jig
- By Mark Johnson
- Power Supplies
- 2653 Replies
Attachments
Miro PCM63P with stackable USB-I2S interface
One set of complete and tested Miro PCM63 DAC.
In my opinion, this is the most direct and best combo implementation of the Miro PCM63 DAC.
Sounds wonderful. It is a full, completed DAC, with a pair of Signetics NE5534 op amp for the IV.
You need +5/-5V and +5/-5V (For DAC VA and VD rails) and +/- 10 ~15V for the IV op amp.
All high quality parts are eg. Nichicon gold caps, Wima film caps etc etc... See the pics.
All parts are BRAND NEW including the PCM63P chips. They are installed for the completion and testing to commission the DAC.
Only the op amp ICs are used parts.
Two types of USB-I2S interface can be stacked via the pin headers on the board.
1. JLSounds i2SoverUSB III FIO or older version
2. York + Reclocker
DAC board alone (what you see in the picture in this first post, without USB-I2S interface) + shipping tracked & registered = Singapore dollars 260
I am only ready to accept Paypal Family and Friends as payment.
More information of this DAC here :
https://electrodac.blogspot.com/p/dac-ad1862-almost-tht-i2s-input-nos-r.html
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-209#post-7049224
In my opinion, this is the most direct and best combo implementation of the Miro PCM63 DAC.
Sounds wonderful. It is a full, completed DAC, with a pair of Signetics NE5534 op amp for the IV.
You need +5/-5V and +5/-5V (For DAC VA and VD rails) and +/- 10 ~15V for the IV op amp.
All high quality parts are eg. Nichicon gold caps, Wima film caps etc etc... See the pics.
All parts are BRAND NEW including the PCM63P chips. They are installed for the completion and testing to commission the DAC.
Only the op amp ICs are used parts.
Two types of USB-I2S interface can be stacked via the pin headers on the board.
1. JLSounds i2SoverUSB III FIO or older version
2. York + Reclocker
DAC board alone (what you see in the picture in this first post, without USB-I2S interface) + shipping tracked & registered = Singapore dollars 260
I am only ready to accept Paypal Family and Friends as payment.
More information of this DAC here :
https://electrodac.blogspot.com/p/dac-ad1862-almost-tht-i2s-input-nos-r.html
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-209#post-7049224
New SB Acoustics 6" - SB17NRX2L35-8
Just saw this advertisement but no data to find online:
When this motor structure is anything like the 12" XL driver ... I want it badly for the 8"! And of course a wide range 10" would also be very useful.
Looking forward to HighEnd drivers for a good price, hope they can keep up with the high expectations.
When this motor structure is anything like the 12" XL driver ... I want it badly for the 8"! And of course a wide range 10" would also be very useful.
Looking forward to HighEnd drivers for a good price, hope they can keep up with the high expectations.
Behringer Has a New Measurement Microphone
- By aslepekis
- Equipment & Tools
- 51 Replies
So I've been on the lookout for an affordable, small diaphragm/body omni mic for room measurements. Something that will be be more omni to a higher frequency than a 1/2" mic body. I've had my eye on the MicW M416 for that purpose for some time, but last month I saw that Behringer sells a new measurement mic that looked like it would fit what I was looking for so I took a chance and ordered one.
It's called the ECM PRO, and it's clearly "inspired" by the DPA 4091, or Neumann MA 1. But as of this writing, it is only about $40. There is a calibration file that you can download for it that is highly suspect. I tested it out against one of my calibrated ECM8000's with a tweeter in a low(ish) diffraction cabinet, IR windowed, and trying to get the diaphragms in close to the same point in space.
Here is on axis ECM PRO uncalibrated and ECM8000 calibrated:
Here is ECM PRO 0 degrees to source and 90 degrees to source:
And for comparison, that ECM8000 also at 0 and 90:
I haven't tested it at low frequency yet, but the ECM PRO is as expected, more omni than a ECM8000. Unexpectedly, however, this particular one needs only minimal calibration.
It's called the ECM PRO, and it's clearly "inspired" by the DPA 4091, or Neumann MA 1. But as of this writing, it is only about $40. There is a calibration file that you can download for it that is highly suspect. I tested it out against one of my calibrated ECM8000's with a tweeter in a low(ish) diffraction cabinet, IR windowed, and trying to get the diaphragms in close to the same point in space.
Here is on axis ECM PRO uncalibrated and ECM8000 calibrated:
Here is ECM PRO 0 degrees to source and 90 degrees to source:
And for comparison, that ECM8000 also at 0 and 90:
I haven't tested it at low frequency yet, but the ECM PRO is as expected, more omni than a ECM8000. Unexpectedly, however, this particular one needs only minimal calibration.
ROKSAN ROK L2/S1 Pre-and Power Amp - Schematic and PCB Images wanted
- Solid State
- 5 Replies
Attachments
Rescuing & Reimagining a Technics SL-100c
- By mcrushing
- Analogue Source
- 89 Replies
Dissected, but far from dead:
Here lies the nerve center of an essentially brand-new Technics SL-100c:
So... Where to begin?
Browsing eBay on a recent evening, I ran across a listing to the effect of, " !!PARTS!! Technics SL-100/1500 Tonearm, Platter, Motherboard, Otherboard. "
Okay, uhhh... [clicks mouse]
As advertised, the seller was parting out a "damaged in shipping" 100c that he'd purchased "as a return." After some back-and-forth, a story emerged: Apparently someone bought this $1k+ turntable on Amazon, stripped off the stock cartridge and then returned it in the original box (minus most of the original engineered packaging). As many likely know, there's sort-of a supply chain purgatory where (literally) billions of returned items languish for long periods before being either bundled and resold or trucked off to a landfill. Never did I imagine those items to include things like brand-new turntables with ultra-accurate coreless motors that hifi mags have been raving about.
According to the seller, the unit was basically loose in the box and took a beating in transit: Dustcover destroyed, tonearm badly damaged, chassis cosmetically irredeemable, and... motor working perfectly. Unable to stop myself, I bought the motor, platter and everything you see here for a few hundred bucks.
Why tho?
Well for one thing, I've since confirmed the performance: Assembled with the motor just sitting on my desk, the RPM iphone app shows the platter running at 33.34 +0.03, w/f 0.15% (and even better at 45). That DUSTS the belt-drive deck I spent a mint on five years ago (which frankly leaves me wanting in other ways as well). More than anything, I just want to get my hands into this. I lust after classic broadcast decks, and have long wanted to join the SP-10 club (yes, I've spent a lot of time on The Incredible Thread). But for a lower price-of-entry, and given the specs above, this seems like a pretty cool alternative challenge.
And before anyone asks: Yes, I'm a bit out of my depth. I know this will cost more than I think. I don't yet have all the tools I'll need. There will be massive research and a lot of trial and error. I know there's a lot I don't know, and I'm prepared for this to take a long time.
So all that said, this thread will serve as the build log.
It's getting late, but at some point over the weekend I'll post my progress so far, my overall plan, anticipated next steps, and a few questions for the forum.
Really hoping a few of Technics Heads (and other experienced folks) will vibe with this project, follow and advise.
Cheers!
Here lies the nerve center of an essentially brand-new Technics SL-100c:
So... Where to begin?
Browsing eBay on a recent evening, I ran across a listing to the effect of, " !!PARTS!! Technics SL-100/1500 Tonearm, Platter, Motherboard, Otherboard. "
Okay, uhhh... [clicks mouse]
As advertised, the seller was parting out a "damaged in shipping" 100c that he'd purchased "as a return." After some back-and-forth, a story emerged: Apparently someone bought this $1k+ turntable on Amazon, stripped off the stock cartridge and then returned it in the original box (minus most of the original engineered packaging). As many likely know, there's sort-of a supply chain purgatory where (literally) billions of returned items languish for long periods before being either bundled and resold or trucked off to a landfill. Never did I imagine those items to include things like brand-new turntables with ultra-accurate coreless motors that hifi mags have been raving about.
According to the seller, the unit was basically loose in the box and took a beating in transit: Dustcover destroyed, tonearm badly damaged, chassis cosmetically irredeemable, and... motor working perfectly. Unable to stop myself, I bought the motor, platter and everything you see here for a few hundred bucks.
Why tho?
Well for one thing, I've since confirmed the performance: Assembled with the motor just sitting on my desk, the RPM iphone app shows the platter running at 33.34 +0.03, w/f 0.15% (and even better at 45). That DUSTS the belt-drive deck I spent a mint on five years ago (which frankly leaves me wanting in other ways as well). More than anything, I just want to get my hands into this. I lust after classic broadcast decks, and have long wanted to join the SP-10 club (yes, I've spent a lot of time on The Incredible Thread). But for a lower price-of-entry, and given the specs above, this seems like a pretty cool alternative challenge.
And before anyone asks: Yes, I'm a bit out of my depth. I know this will cost more than I think. I don't yet have all the tools I'll need. There will be massive research and a lot of trial and error. I know there's a lot I don't know, and I'm prepared for this to take a long time.
So all that said, this thread will serve as the build log.
It's getting late, but at some point over the weekend I'll post my progress so far, my overall plan, anticipated next steps, and a few questions for the forum.
Really hoping a few of Technics Heads (and other experienced folks) will vibe with this project, follow and advise.
Cheers!
Tapered Wave Tube with Damp Duct(TWTD) for Alpair10.3, MAOP10, CHR-90
- By nandappe
- Full Range
- 24 Replies
I have made 5" version of TWTD.
---- Alpair10.3 + TWTD at YouTube ----
Tapered Wave Tube with Damp Duct(TWTD) + Alpair10.3 - YouTube
---- Alpair10.3 + TWTD at YouTube ----
Tapered Wave Tube with Damp Duct(TWTD) + Alpair10.3 - YouTube
Help tweaking crossover
Hello all,
I'm in the midst of tweaking my 3-way crossover and I could use some help. My drivers are an Eminence Alpha 15 woofer, a Mark Audio Alpair 12P midrange and a GRS PT2522 planar tweeter. They are in an open baffle. Here is what I have
I realize having the resistor in series on the woofer is not ideal.
I only had frd and zma files for the GRS but here's the frequency response graph on x-sim
and here's the measured in-room response:
as you can see, there's a dip in the mid-range.
Things I'm thinking of doing:
changing the 68uF cap to the woofer to 33uF to smooth the spike at 250K. Change the 1.1uF cap on the LP filter section on the midrange to 5uF. Increase the values of the resistors on my tweeter L pad.
I tried an L pad on the woofer and it sounded terrible. I didn't have a bunch of values of resistors available for use however. I tried resistors in the 2-3ohm range. What would you recommend to attenuate the bass?
As is, the speakers sound pretty good but I'd love to get them more balanced
thanks!
I'm in the midst of tweaking my 3-way crossover and I could use some help. My drivers are an Eminence Alpha 15 woofer, a Mark Audio Alpair 12P midrange and a GRS PT2522 planar tweeter. They are in an open baffle. Here is what I have
I realize having the resistor in series on the woofer is not ideal.
I only had frd and zma files for the GRS but here's the frequency response graph on x-sim
and here's the measured in-room response:
as you can see, there's a dip in the mid-range.
Things I'm thinking of doing:
changing the 68uF cap to the woofer to 33uF to smooth the spike at 250K. Change the 1.1uF cap on the LP filter section on the midrange to 5uF. Increase the values of the resistors on my tweeter L pad.
I tried an L pad on the woofer and it sounded terrible. I didn't have a bunch of values of resistors available for use however. I tried resistors in the 2-3ohm range. What would you recommend to attenuate the bass?
As is, the speakers sound pretty good but I'd love to get them more balanced
thanks!
Aegis DIY Tube Headphone Amplifier
- By L0rdGwyn
- Tubes / Valves
- 227 Replies
Hello,
I am releasing a DIY tube amplifier project, the first complete DIY project I've released on this forum. The amplifier is called Aegis.
I started my DIY journey on the headphone forum Head-Fi. I have something of a tube DIY blog there where I catalog all of my ongoing projects. For a short period of time, I was building and selling my designs as a hobby business, but quickly realized I didn't have the time for it working a full time job. I thought I'd work on a DIY amplifier that forum members could build for themselves without my involvement. I've been working on it for the past year or so.
This is a headphone enthusiast's tube amplifier. I say that as I'm sure some will balk at the cost of parts, which is roughly $2,000 USD. Given what some people are willing to pay for commercial tube headphone amplifiers, which are creeping toward five figure prices, it's relatively affordable. I tried to come up with a design that 1) is easy to build, even for a novice DIYer, 2) uses easy to acquire vacuum tubes, 3) is simple and robust with low likelihood of parts failure and easy to troubleshoot, 4) uses a circuit that is not readily available on the commercial market, and 5) sounds good! I do not typically build budget-oriented designs for myself, and I did not do so here. I like to build amplifiers that look like professionally made products. Please abstain from telling me that it is too expensive, a waste of money, etc. You do not have to build it.
I've included download links to the BOM, chassis CAD files, and an exhaustive project document that includes an explanation of the circuit, schematics, recommended equipment, information on acquiring parts, step-by-step instructions with photos, testing procedures, and some basic measurements. Please note the instructions are written for a new DIYer, not one with experience, so they are very detailed. The gerber files to order the PCBs are attached to this post.
Measurements are in the last section of the build document.
You can find some subjective impressions of the amplifier here:
Login to view embedded media
https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17224730
https://www.head-fi.org/threads/zmf-caldera-new-planar-magnetic-from-zmf.964836/post-17553801
Please let me know if you come across any typos or anything seems out of place and I will try to address it.
Link to build document PDF: https://drive.google.com/file/d/1C2NSRh8DkC1Blr2GMVC_83XAdM0IUFZA/view?usp=sharing
Link to the Excel BOM: https://docs.google.com/spreadsheet...ouid=113213015624875847507&rtpof=true&sd=true
Link to zipped chassis CAD files: https://drive.google.com/file/d/1GXCq11-S97FtTey2lVpv6CgkBul4Uryb/view?usp=sharing
I am releasing a DIY tube amplifier project, the first complete DIY project I've released on this forum. The amplifier is called Aegis.
I started my DIY journey on the headphone forum Head-Fi. I have something of a tube DIY blog there where I catalog all of my ongoing projects. For a short period of time, I was building and selling my designs as a hobby business, but quickly realized I didn't have the time for it working a full time job. I thought I'd work on a DIY amplifier that forum members could build for themselves without my involvement. I've been working on it for the past year or so.
This is a headphone enthusiast's tube amplifier. I say that as I'm sure some will balk at the cost of parts, which is roughly $2,000 USD. Given what some people are willing to pay for commercial tube headphone amplifiers, which are creeping toward five figure prices, it's relatively affordable. I tried to come up with a design that 1) is easy to build, even for a novice DIYer, 2) uses easy to acquire vacuum tubes, 3) is simple and robust with low likelihood of parts failure and easy to troubleshoot, 4) uses a circuit that is not readily available on the commercial market, and 5) sounds good! I do not typically build budget-oriented designs for myself, and I did not do so here. I like to build amplifiers that look like professionally made products. Please abstain from telling me that it is too expensive, a waste of money, etc. You do not have to build it.
I've included download links to the BOM, chassis CAD files, and an exhaustive project document that includes an explanation of the circuit, schematics, recommended equipment, information on acquiring parts, step-by-step instructions with photos, testing procedures, and some basic measurements. Please note the instructions are written for a new DIYer, not one with experience, so they are very detailed. The gerber files to order the PCBs are attached to this post.
Measurements are in the last section of the build document.
You can find some subjective impressions of the amplifier here:
Login to view embedded media
https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17224730
https://www.head-fi.org/threads/zmf-caldera-new-planar-magnetic-from-zmf.964836/post-17553801
Please let me know if you come across any typos or anything seems out of place and I will try to address it.
Link to build document PDF: https://drive.google.com/file/d/1C2NSRh8DkC1Blr2GMVC_83XAdM0IUFZA/view?usp=sharing
Link to the Excel BOM: https://docs.google.com/spreadsheet...ouid=113213015624875847507&rtpof=true&sd=true
Link to zipped chassis CAD files: https://drive.google.com/file/d/1GXCq11-S97FtTey2lVpv6CgkBul4Uryb/view?usp=sharing
ELEKIT TU-8900 2A3/300B (Stereophile Review Available NOW - July 2023 Edition)
ELEKIT 2A3/300B SET AMP
Price US$1945.00 (Ll2785C amorphous core OPT)
This is our first time to offer Amorphous core OPT. I want to make sure the Lundahl amorphous core is superior than the regular C Core.
This is the sample of Amorphous Core for TU-8900.. Amorphous core requires a longer burn in time..
Is it better??
No Takman for this model - Takman is running out of material to make 2% carbon resistors.
TUBE SET OPTIONS:
COSSOR/Linlai Delux 2A3 + Sylvania 12BH7A $380
COSSOR/Linlai Blackplate 300B +Sylvania 12BH7A $345
COSSOR/Linlai WE300B +Brimar 12AU7 $$695
Western Electric WE300B (5 Years Warranty) + Sylvania 12BH7A
COSSOR/LINLAI Delux metal base 2A3 $285
COSSOR/LINLAI WE2A3 $385
COSSOR/LIMLAI E-2A3 $495
Sylvania 12BH7 $95 (pair)
Brimar 6067/12AU7 $159 (pair)
If you buy TU-8900 with LL2785C and Western Electric 300B, the Cossor/Linlai Delux 2A3 is free
COUPLING CAPS 100nF 450V x 2 (VCAP CuTF $195
Cossor/Linlai WE2A3
46 x Audio Note Tantalum Resistors $5.25 each
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap
LEFT - TU-8600S (Metal Tube Cover and metal knob), RIGHT - TU-8900 (Plastic Tube Cover, plastic knob) https://www.flickr.com/photos/64593884@N08/ https://www.flickr.com/photos/64593884@ https://www.flickr.com/photos/64593884@N08/
Login to view embedded media
https://www.flickr.com/photos/64593884@N08/
Matching headphone impedance/volume levels.
You can change the headphone impedance/volume levels by
simply removing the front panel and change the position of a
short pin.
Directly-heated triode tubes like the 300B and 2A3 enjoy an enduring popularity among audiophiles. The 300B with its rich midrange and extended bass- and 2A3 with its delicate expression and gentle tone offer a very special sonic experience. These 2 tubes are similar in appearance but very different in characteristics and can both be used in TU-8900 without any special changes in amplifier settings. Many manufacturers are producing 300B and 2A3 tubes so users can enjoy trying the various versions available from different vendors. *
*NOTE- TUBES ARE NOT INCLUDED WITH THE TU-8900!
■ Automatic detection of 300B and 2A3 tubes
“300B” and “2A3” tubes look similar but their respective filament voltage and operating parameters are totally different. Their supply voltages need to be adjusted depending on which of these tubes are used in the same amp. In TU-8900, the tubes that are installed are detected automatically and the correct filament voltage and voltage of B-power are automatically set. When 300B tubes are installed- the LEDs on the sides of the volume knob will light up in blue. If 2A3 tubes are installed- the volume knob LEDs will light up in green. Additionally- these LEDs on the right and left side of the volume knob will turn red when there is excessive current due to defective tubes, etc., and the current is shut down to protect the amp. The red LEDs will also diagnose the problematic tube- the right side of the volume knob turns red when excess current occurs in the right channel, and vice versa.
■ Tube-friendly design
Warm-up time for directly-heated tubes and indirectly-heated tubes are different. In most designs, directly-heated tubes warm up faster than indirectly-heated tubes- so often directly heated tubes are often overloaded. With TU-8900, the voltage is gradually raised and reduces the level of overload to the directly-heated tubes.
■ 12BH7A instead of 12AU7
TU-8900 is designed to use 12AU7 as voltage amplifying tubes. However, 12BH7A, with high driving ability, can also be used instead of 12AU7.
■ Ample space for larger coupling capacitors
Coupling capacitors can have a big effect on the sound quality. For the TU-8900, high quality conductive polymer electrolytic caps and polypropylene film caps are provided. However, exchanging for other coupling capacitors is also possible. The maximum size of the caps that can fit in the space is 22mm in diameter x 44mm in length.
■ Matching headphone impedance/volume levels
You can change the headphone impedance/volume levels by simply removing the front panel and change the position of a short pin.
■ Newly designed circuitry
The power transformer has independent windings for the right and left channel to minimize the interference between channels as much as possible. The filament power uses the latest DC-DC converter for extremely low noise and high efficiency. Schottky barrier diodes and fast recovery diodes are used as rectifying diodes that reduces even the most negligible noise spikes. Listeners can enjoy music free from noise even when using a pair of high efficiency headphones. The main circuit of the power unit is unitized per channel as a module.
■Easily change the feedback setting to NON-NFB
Many triode tube amps use negative feedback in their design. The TU-8900 has an option for listeners to hear the triode tube sound without negative feedback. In TU-8900, changing the position of a short plug on the PCB can change the setting to NON-NFB. The gain level increases by approx. 8dB when NON-NFB setting.
■ Updated more reliable tube sockets
After brainstorming with our vendor, we have come up with a more reliable 4-pin sockets for 300B/2A3. Tubes are mounted safely and securely when installed in these sockets.
■ High heat-resistant polycarbonate tube cage
The IEC (International Electrotechnical Commission) sets guidelines on thermal limits on materials and parts, such as a chassis and the tube cage. The TU-8900 tube cage top can heat up to 100 degrees C due to the heat from the output tubes. A robust polycarbonate tube cage with high heat resistance is used to meet the IEC standard.
Specifications of TU-8900
●Stock tubes ： 300B (or 2A3) x 2pcs, 12AU7 (or 12BH7A) x 2pcs *Tubes not included
* specifications below are with the 300B+12AU7, with NFB, 8Ω loaded
●Rated output ： 8W+8W (300B) / 3.5W+3.5W (2A3) <THD 10％>
●Rated input ： 1Vrms (300B) / 650ｍVrms (2A3)
●Residual noise： 15μV (IHF-A)
●Frequency response： 7Hz-90kHz (with NFB) / 12Hz-45kHz (Without NFB)
●Input impedance ： 50kΩ
●Output impedance ： 4-6.3Ω, 8-16Ω (SW on backside)
●Input terminal ： LINE x 1
●Output terminal ： Speaker output terminals (L/R channel)：Gold-plated screw type terminal (Banana plug usable)
Headphone terminal ：6.3mm headphone jack
●Power voltage ： AC110-120V or AC220-240V 50/60Hz (3P inlet)
●Power consumption： 95W (300B) / 65W (2A3)
●Measurement ： W356xH214xD320mm (including projections)
●Weight ： Approx. 11.4kg (excluding a power cable)
●JAN code : 4952682107941
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap
Attach files
Price US$1945.00 (Ll2785C amorphous core OPT)
Stereophile Reveiw : July 2023 Edition
https://www.stereophile.com/category/gramophone-dreams
Stereophile Class A Components
https://www.stereophile.com/content/recommended-components-fall-2023-edition-integrated-amplifiersThis is our first time to offer Amorphous core OPT. I want to make sure the Lundahl amorphous core is superior than the regular C Core.
This is the sample of Amorphous Core for TU-8900.. Amorphous core requires a longer burn in time..
Is it better??
No Takman for this model - Takman is running out of material to make 2% carbon resistors.
TUBE SET OPTIONS:
COSSOR/Linlai Delux 2A3 + Sylvania 12BH7A $380
COSSOR/Linlai Blackplate 300B +Sylvania 12BH7A $345
COSSOR/Linlai WE300B +Brimar 12AU7 $$695
Western Electric WE300B (5 Years Warranty) + Sylvania 12BH7A
COSSOR/LINLAI Delux metal base 2A3 $285
COSSOR/LINLAI WE2A3 $385
COSSOR/LIMLAI E-2A3 $495
Sylvania 12BH7 $95 (pair)
Brimar 6067/12AU7 $159 (pair)
If you buy TU-8900 with LL2785C and Western Electric 300B, the Cossor/Linlai Delux 2A3 is free
COUPLING CAPS 100nF 450V x 2 (VCAP CuTF $195
Cossor/Linlai WE2A3
46 x Audio Note Tantalum Resistors $5.25 each
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap
LEFT - TU-8600S (Metal Tube Cover and metal knob), RIGHT - TU-8900 (Plastic Tube Cover, plastic knob) https://www.flickr.com/photos/64593884@N08/ https://www.flickr.com/photos/64593884@ https://www.flickr.com/photos/64593884@N08/
Login to view embedded media
https://www.flickr.com/photos/64593884@N08/Matching headphone impedance/volume levels.
You can change the headphone impedance/volume levels by
simply removing the front panel and change the position of a
short pin.
Directly-heated triode tubes like the 300B and 2A3 enjoy an enduring popularity among audiophiles. The 300B with its rich midrange and extended bass- and 2A3 with its delicate expression and gentle tone offer a very special sonic experience. These 2 tubes are similar in appearance but very different in characteristics and can both be used in TU-8900 without any special changes in amplifier settings. Many manufacturers are producing 300B and 2A3 tubes so users can enjoy trying the various versions available from different vendors. *
*NOTE- TUBES ARE NOT INCLUDED WITH THE TU-8900!
■ Automatic detection of 300B and 2A3 tubes
“300B” and “2A3” tubes look similar but their respective filament voltage and operating parameters are totally different. Their supply voltages need to be adjusted depending on which of these tubes are used in the same amp. In TU-8900, the tubes that are installed are detected automatically and the correct filament voltage and voltage of B-power are automatically set. When 300B tubes are installed- the LEDs on the sides of the volume knob will light up in blue. If 2A3 tubes are installed- the volume knob LEDs will light up in green. Additionally- these LEDs on the right and left side of the volume knob will turn red when there is excessive current due to defective tubes, etc., and the current is shut down to protect the amp. The red LEDs will also diagnose the problematic tube- the right side of the volume knob turns red when excess current occurs in the right channel, and vice versa.
■ Tube-friendly design
Warm-up time for directly-heated tubes and indirectly-heated tubes are different. In most designs, directly-heated tubes warm up faster than indirectly-heated tubes- so often directly heated tubes are often overloaded. With TU-8900, the voltage is gradually raised and reduces the level of overload to the directly-heated tubes.
■ 12BH7A instead of 12AU7
TU-8900 is designed to use 12AU7 as voltage amplifying tubes. However, 12BH7A, with high driving ability, can also be used instead of 12AU7.
■ Ample space for larger coupling capacitors
Coupling capacitors can have a big effect on the sound quality. For the TU-8900, high quality conductive polymer electrolytic caps and polypropylene film caps are provided. However, exchanging for other coupling capacitors is also possible. The maximum size of the caps that can fit in the space is 22mm in diameter x 44mm in length.
■ Matching headphone impedance/volume levels
You can change the headphone impedance/volume levels by simply removing the front panel and change the position of a short pin.
■ Newly designed circuitry
The power transformer has independent windings for the right and left channel to minimize the interference between channels as much as possible. The filament power uses the latest DC-DC converter for extremely low noise and high efficiency. Schottky barrier diodes and fast recovery diodes are used as rectifying diodes that reduces even the most negligible noise spikes. Listeners can enjoy music free from noise even when using a pair of high efficiency headphones. The main circuit of the power unit is unitized per channel as a module.
■Easily change the feedback setting to NON-NFB
Many triode tube amps use negative feedback in their design. The TU-8900 has an option for listeners to hear the triode tube sound without negative feedback. In TU-8900, changing the position of a short plug on the PCB can change the setting to NON-NFB. The gain level increases by approx. 8dB when NON-NFB setting.
■ Updated more reliable tube sockets
After brainstorming with our vendor, we have come up with a more reliable 4-pin sockets for 300B/2A3. Tubes are mounted safely and securely when installed in these sockets.
■ High heat-resistant polycarbonate tube cage
The IEC (International Electrotechnical Commission) sets guidelines on thermal limits on materials and parts, such as a chassis and the tube cage. The TU-8900 tube cage top can heat up to 100 degrees C due to the heat from the output tubes. A robust polycarbonate tube cage with high heat resistance is used to meet the IEC standard.
Specifications of TU-8900
●Stock tubes ： 300B (or 2A3) x 2pcs, 12AU7 (or 12BH7A) x 2pcs *Tubes not included
* specifications below are with the 300B+12AU7, with NFB, 8Ω loaded
●Rated output ： 8W+8W (300B) / 3.5W+3.5W (2A3) <THD 10％>
●Rated input ： 1Vrms (300B) / 650ｍVrms (2A3)
●Residual noise： 15μV (IHF-A)
●Frequency response： 7Hz-90kHz (with NFB) / 12Hz-45kHz (Without NFB)
●Input impedance ： 50kΩ
●Output impedance ： 4-6.3Ω, 8-16Ω (SW on backside)
●Input terminal ： LINE x 1
●Output terminal ： Speaker output terminals (L/R channel)：Gold-plated screw type terminal (Banana plug usable)
Headphone terminal ：6.3mm headphone jack
●Power voltage ： AC110-120V or AC220-240V 50/60Hz (3P inlet)
●Power consumption： 95W (300B) / 65W (2A3)
●Measurement ： W356xH214xD320mm (including projections)
●Weight ： Approx. 11.4kg (excluding a power cable)
●JAN code : 4952682107941
After 200 hours listening, I am confident to offer the Audio Note upgrade option:
46 x Audio Note Tantalum Resistors $5.25 each4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap
Attach files
- Edit silently
For Sale Edfier MR 4 studio monitor (India)
Hi all,
for sale Edifier MR4 studio monitors. As these measured well with respect to linear frequency response, I bought it to check recording quality of hindi film/classical music. The purpose is served and the same are for sale. Pictures were for Indian website so I had to put name and date.
Price is Indian Rs. 9000/- (significantly lower than original price). Shipping Extra at buyers risk.
Thanks and regards.
for sale Edifier MR4 studio monitors. As these measured well with respect to linear frequency response, I bought it to check recording quality of hindi film/classical music. The purpose is served and the same are for sale. Pictures were for Indian website so I had to put name and date.
- Like new condition. Just 2 months old. And not used much. Just tested 35 to 40 titles of Hindi film/classical music cds songs for ~20/30 seconds.
- Another reason for sale is need funds for a new DIY project.
- Probably has carry in warranty still left for 9/10 months. (Service center India : LINK )
- Original Bill, box, cables and literature etc. available.
- Sound quality is good with just enough bass .
- Tone controls with neutral position.
- Headphone, Aux, TRS and RCA inputs.
- Video of working and sound test available.
- This will probably be for India sale only. Or if anyone is visiting India.
- If any question ask.
Price is Indian Rs. 9000/- (significantly lower than original price). Shipping Extra at buyers risk.
Thanks and regards.
Mauthe mechanical clocks
- By Juhazi
- The Lounge
- 20 Replies
Hello retro fans!
I visited local Red Cross flea market and bought a nice vintage art deco-style Mauthe mantel clock, sold in 1965.
The box's oak veneer coating had some erosion, but Osmo furniture wax fixed them easily. Mechanism is labelled W45 XXVI sno 97199
The mechanism is working and it has three bells but seems to not ring on right hour count. Any ideas before I show it to local watchsmith?
I visited local Red Cross flea market and bought a nice vintage art deco-style Mauthe mantel clock, sold in 1965.
The box's oak veneer coating had some erosion, but Osmo furniture wax fixed them easily. Mechanism is labelled W45 XXVI sno 97199
The mechanism is working and it has three bells but seems to not ring on right hour count. Any ideas before I show it to local watchsmith?
Younger brother of the LM3886 - LM2876 in parallel
Attachments
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thd_n_10khz_4ohm.PNG -
thd_n_10khz_8ohm.PNG
OB + IB = Good?
Next project. What to do with the high quality drivers one already owns. Left overs from projects that changed or never was.
Drivers are:
2 x Beyma TPL-150/B: https://www.beyma.com/speakers/Fichas_Tecnicas/beyma-speakers-data-sheet-amt-TPL150B.pdf
4 x Jantzen JA-8008 HMQ: https://jantzen-audio.com/wp-content/uploads/060-0008-1.pdf
2 x Beyma 18PWB1000Fe/S: https://www.beyma.com/speakers/Fich...data-sheet-low-mid-frequency-18PWB1000FeS.pdf
Since I already have Infinite Baffle subs in both my home theater (2 x 18") and my 2 channel setup (4 x 21") in the living room, why not also have it in the upstairs office?
Also, I've always been curious in finding out more about Open Baffle. All the superlatives I read about OB seem to fit my ideas of how music could sound in a room.
The idea:
Room is W3,1 x D4,6 x H2,4 m (ab. 10 x 15 x 8 ft) with slanted ceilings in the width direction. Wall height below is 1,2 m (4 ft).
Put the 18's in thick panels, one left & one right, and attach them to the studs (cc 0,6 m (2 ft)) on the 1,2 m wall. Wall panels are too flimsy to be used as is.
There's a space behind the wall that is big enough for the IB to work. Use them up to 100 Hz.
Build smallish (?) baffles for the 8" and AMT's in a D'Appolito and hang them from the ceiling about 1,5 m (5 ft) in front of the wall where the 18's are mounted.
Open the AMT's back and play dipole. X-over 1500 - 1800 Hz.
Use a MiniDSP Flex8 to do the crossovers, DSP and Dirac. (Already have this also)
Buy some class D amps to power each channel.
Maybe IcePower: https://www.soundimports.eu/en/icep...OlLo3S6XKRe-XzumApw7YwO4ijBXg34UaAkgAEALw_wcB
With power supply: https://www.soundimports.eu/en/icep...OlLo3S6XKRe-XzumApw7YwO4ijBXg34UaAkgAEALw_wcB
Maybe a Wiim as source to play music from Tidal: https://www.wiimhome.com/wiimultra/overview
Questions:
- Is my small room suitable for this idea?
- What width should the baffle be to be able to get output down towards 100 Hz from the 8's?
- Do I maybe have to buy some bigger drivers also to help the 8's to get down to 100 Hz, in a WMTMW?
- If I raise X-over to 150 hz, maybe that will help? Or is that too high for the IB?
These are my thoughts so far and now I would like to hear from you, the people with much more experience in OB. I'm a noob.
Is this idea at all feasible?
Drivers are:
2 x Beyma TPL-150/B: https://www.beyma.com/speakers/Fichas_Tecnicas/beyma-speakers-data-sheet-amt-TPL150B.pdf
4 x Jantzen JA-8008 HMQ: https://jantzen-audio.com/wp-content/uploads/060-0008-1.pdf
2 x Beyma 18PWB1000Fe/S: https://www.beyma.com/speakers/Fich...data-sheet-low-mid-frequency-18PWB1000FeS.pdf
Since I already have Infinite Baffle subs in both my home theater (2 x 18") and my 2 channel setup (4 x 21") in the living room, why not also have it in the upstairs office?
Also, I've always been curious in finding out more about Open Baffle. All the superlatives I read about OB seem to fit my ideas of how music could sound in a room.
The idea:
Room is W3,1 x D4,6 x H2,4 m (ab. 10 x 15 x 8 ft) with slanted ceilings in the width direction. Wall height below is 1,2 m (4 ft).
Put the 18's in thick panels, one left & one right, and attach them to the studs (cc 0,6 m (2 ft)) on the 1,2 m wall. Wall panels are too flimsy to be used as is.
There's a space behind the wall that is big enough for the IB to work. Use them up to 100 Hz.
Build smallish (?) baffles for the 8" and AMT's in a D'Appolito and hang them from the ceiling about 1,5 m (5 ft) in front of the wall where the 18's are mounted.
Open the AMT's back and play dipole. X-over 1500 - 1800 Hz.
Use a MiniDSP Flex8 to do the crossovers, DSP and Dirac. (Already have this also)
Buy some class D amps to power each channel.
Maybe IcePower: https://www.soundimports.eu/en/icep...OlLo3S6XKRe-XzumApw7YwO4ijBXg34UaAkgAEALw_wcB
With power supply: https://www.soundimports.eu/en/icep...OlLo3S6XKRe-XzumApw7YwO4ijBXg34UaAkgAEALw_wcB
Maybe a Wiim as source to play music from Tidal: https://www.wiimhome.com/wiimultra/overview
Questions:
- Is my small room suitable for this idea?
- What width should the baffle be to be able to get output down towards 100 Hz from the 8's?
- Do I maybe have to buy some bigger drivers also to help the 8's to get down to 100 Hz, in a WMTMW?
- If I raise X-over to 150 hz, maybe that will help? Or is that too high for the IB?
These are my thoughts so far and now I would like to hear from you, the people with much more experience in OB. I'm a noob.
Is this idea at all feasible?
Zenductor 2 Amp Camp '24 version
A visual guide to the Rothacher/Pass Zenductor 2
The Zenductor 2 is a mono block, single-ended, zero-feedback, Class-A audio amplifier. You need two for stereo.
Nelson’s article can be found here - https://www.diyaudio.com/community/threads/burning-amp-2024.414636/post-7820909
All photos in this guide will show one amplifier being built.
Parts for one amplifier.
Let's look a little closer at al the various bits -
The circuit board everything attaches to.
Zenductor 2 is powered by a 16v 4.5A brick-style Power Supply.
Here's the magic... the big device is the choke (inductor) that loads the output stage. The darling little transformer is used for voltage gain.
Please note the little circular notch in the plastic closest to the camera, this denotes pin 1.
L to R, RCA input jack, DC power connector, power switch
Capacitors. there are 2 different values that look quite similar. The physically bigger can is 4700uF 25V, the smaller is 6800uF 10V. Make sure you have the right one when stuffing the PCB.
Electrolytic capacitors are polarized. It matters which way they are installed. The long lead is positive (+). The can has negative (-) marked on the heatshrink.
This photo show the 4700uF 25v
1000uF 25v
10uF 35v SILMIC input capacitor.
This is a small value poly capacitor used in the notch network, it's not polarized and can be inserted any way.
Speaker jacks.
Nifty rectangular LED
The input section uses an array of 8 matched Jfet.
Output section is comprised of these two matched Mosfet.
Mosfet heatsinks.
M3 hardware for heatsinks.
Assembly will look like this.
The Zenductor 2 is a mono block, single-ended, zero-feedback, Class-A audio amplifier. You need two for stereo.
Nelson’s article can be found here - https://www.diyaudio.com/community/threads/burning-amp-2024.414636/post-7820909
All photos in this guide will show one amplifier being built.
Parts for one amplifier.
Let's look a little closer at al the various bits -
The circuit board everything attaches to.
Zenductor 2 is powered by a 16v 4.5A brick-style Power Supply.
Here's the magic... the big device is the choke (inductor) that loads the output stage. The darling little transformer is used for voltage gain.
Please note the little circular notch in the plastic closest to the camera, this denotes pin 1.
L to R, RCA input jack, DC power connector, power switch
Capacitors. there are 2 different values that look quite similar. The physically bigger can is 4700uF 25V, the smaller is 6800uF 10V. Make sure you have the right one when stuffing the PCB.
Electrolytic capacitors are polarized. It matters which way they are installed. The long lead is positive (+). The can has negative (-) marked on the heatshrink.
This photo show the 4700uF 25v
1000uF 25v
10uF 35v SILMIC input capacitor.
This is a small value poly capacitor used in the notch network, it's not polarized and can be inserted any way.
Speaker jacks.
Nifty rectangular LED
The input section uses an array of 8 matched Jfet.
Output section is comprised of these two matched Mosfet.
Mosfet heatsinks.
M3 hardware for heatsinks.
Assembly will look like this.
Thermal measurements for Modushop Galaxy 1GX388 2U chassis
I am planning to use a Modushop Galaxy 1GX388 2U 330 mm by 280 mm by 80 mm chassis for a pair of Zenductor 2 amplifiers. To find out whether the 10 mm thick corrugated sidewall profiles are sufficient as heatsinks for 15 W to 25 W dissipated power per side, I did thermal measurements with a DC power supply, a 100 W 8 Ohm power resistor, and a thermal camera built into my cell phone.
The answer is that the chassis should work as is, i.e. without replacing the side walls with real heatsinks.
I attached the power resistor with a pair of spare M3 screws and nuts (supplied with the chassis) to the center region of the flat middle section of the 2-channel side of the Galaxy sidewall profile, and ran tests at about 18 W and 39 W, both with the wall free standing and as part of the assembled chassis (with the rear panel partially slid in, to leave an opening for the resistor power cables, and the remaining opening mostly blocked against air movement).
Temperatures stabilized after 20-30 minutes, and were lower than expected. From the measured temperature rises, and correcting for the heat loss directly from the resistor body to ambient, I compute a thermal resistance of about 1.4 K/W or °C/W.
Graph of four measurements (two power levels, freestanding and chassis-integrated heatsink):
Ambient temperature (the zero level of the graph above) was about 22°C. Interestingly, the equilibrium temperatures for the heatsink (corrugated 10 mm sidewall) were lower in the chassis than free standing. The increase in effective convection surface, from bolting on the other four panels of the chassis) must outweigh the shielding effect of the case.
Between the second and third measurement series, I installed (slid, with the screws and nuts already in place) the sidewall into the chassis.
Also interesting (to me) is that radiation losses are not negligible. A sidewall (448 cm^2, counting both surfaces, but not the corrugations) at 40°C radiates about 5 W more power into a 22°C room than it absorbs. I chose NOT to correct for radiation, since the effect will be of similar magnitude in the real application of the chassis.
As mentioned, I did correct for the direct convective losses from the power resistor, by measuring the resistor equilibrium temperature of 120 °C (!) at 9.68 W, with convection shielded from the resistor mounting surface (sitting on an insulating surface), giving a thermal resistance of 10.2 K/W.
The thermal resistance from the resistor case to the heatsink computed as about 0.5 K/W, which should be similar to achievable case-to-heatsink resistances for transistors. No thermal compound was used.
Example of a thermal image (equilibrium image for 18 W power, resistor mounted to side wall inside the chassis):
The resistor mounting position 'shines through' to the outside surface; I used the maximum, center temperature as heatsink temperature for my calculations. This choice should give correct results for the estimated case temperature of the device to be cooled. The average heatsink (side wall) temperature will be lower than computed from the effective thermal resistance of 1.4 K/W.
Resistor mounting position:
The answer is that the chassis should work as is, i.e. without replacing the side walls with real heatsinks.
I attached the power resistor with a pair of spare M3 screws and nuts (supplied with the chassis) to the center region of the flat middle section of the 2-channel side of the Galaxy sidewall profile, and ran tests at about 18 W and 39 W, both with the wall free standing and as part of the assembled chassis (with the rear panel partially slid in, to leave an opening for the resistor power cables, and the remaining opening mostly blocked against air movement).
Temperatures stabilized after 20-30 minutes, and were lower than expected. From the measured temperature rises, and correcting for the heat loss directly from the resistor body to ambient, I compute a thermal resistance of about 1.4 K/W or °C/W.
Graph of four measurements (two power levels, freestanding and chassis-integrated heatsink):
Ambient temperature (the zero level of the graph above) was about 22°C. Interestingly, the equilibrium temperatures for the heatsink (corrugated 10 mm sidewall) were lower in the chassis than free standing. The increase in effective convection surface, from bolting on the other four panels of the chassis) must outweigh the shielding effect of the case.
Between the second and third measurement series, I installed (slid, with the screws and nuts already in place) the sidewall into the chassis.
Also interesting (to me) is that radiation losses are not negligible. A sidewall (448 cm^2, counting both surfaces, but not the corrugations) at 40°C radiates about 5 W more power into a 22°C room than it absorbs. I chose NOT to correct for radiation, since the effect will be of similar magnitude in the real application of the chassis.
As mentioned, I did correct for the direct convective losses from the power resistor, by measuring the resistor equilibrium temperature of 120 °C (!) at 9.68 W, with convection shielded from the resistor mounting surface (sitting on an insulating surface), giving a thermal resistance of 10.2 K/W.
The thermal resistance from the resistor case to the heatsink computed as about 0.5 K/W, which should be similar to achievable case-to-heatsink resistances for transistors. No thermal compound was used.
Example of a thermal image (equilibrium image for 18 W power, resistor mounted to side wall inside the chassis):
The resistor mounting position 'shines through' to the outside surface; I used the maximum, center temperature as heatsink temperature for my calculations. This choice should give correct results for the estimated case temperature of the device to be cooled. The average heatsink (side wall) temperature will be lower than computed from the effective thermal resistance of 1.4 K/W.
Resistor mounting position:
Compact, low cost, active 3-way speaker
This is an idea which has been noodling about in my head for some time. A small portable active speaker, of modest cost. Something I can easily build multiple copies of, something I can give as a gift if I choose. I have friends who are decent woodworkers who have inquired about making a copy of one of my existing speakers, but they have balked at the expensive drivers and electronics I use… so this is something I can point to and say “you can copy this…”
I also like the idea of an expandable speaker where a second woofer cabinet can be added to extend the bass response and give higher SPL capability. I got this idea from the Barefoot Sound, where several of their very fine monitor speakers are expandable in this way.
========== =============
Primary Goals
The finished system shall be a compact, active, 3-way with 8” woofer, with a total internal volume of 16-24 liters, with sealed box bass alignment. Update: 10" woofer in a 25 liter volume.
Performance Goals
A single 2x4HD shared between two speakers will not provide the necessary 6 channels of signal required by a pair of 3-way speakers. But a single 2x4HD could be used in an active/passive speaker. This is something that has interested me for some time. A passive crossover from tweeter to mid, then active crossover from mid to woofer. There would be 2 amplifier channels required. I find the challenge of this architecture intriguing.
The interesting thing about this approach is that the passive crossover does not need to perform any EQ of the drivers within their individual pass band, nor does it need to manage the overall EQ or voicing of the speaker. This can all be done by DSP. The DSP can also provide BSC for the woofer channel and the mid/tweeter channel. The DSP can tailor the bass response of the woofer. The passive network will need to provide a high-pass and low-pass function for each driver, and relative level matching between tweeter and mid. The passive network will manage the relative magnitude and phase of the drivers through the crossover, and as a result of this, it will manage the directivity index.
The passive network will also manage any out-of-passband EQ. The most likely need for this would be a notch filter on the woofer or midrange at a frequency above the low-pass filter. For example, if the midrange passively crosses to the tweeter at 3k, but the mid has a + 9 dB breakup peak at 8k, the DSP will not be useful in managing that peak. Any EQ at 8k would affect the tweeter response, which would be quite unfortunate. Thus the passive network will need to handle that.
So at this point, I believe this is how I will proceed. There are a lot of amplifier options which offer low cost and acceptable performance, so this remains an open decision.
j.
================== Update 2/01/2024 =================
Index to important posts or milestones
post numbers are included with links
Decision to use a 10” woofer 119
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7447588
Process of defining cabinet dimensions 132
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7449092
Simulating flat face tweeter vs tweeter with waveguide 124 135 164
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7448383
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7449284
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7450834
Concept sketch 197 236
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7452598
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7455272
Decision to use SB15NBAC 236
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7455272
Electronics block diagram 280
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7457445
Prototype testing of tweeters 289 314
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7457716
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7472903
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7471898
Simulations with prototype data to define mid/tweeter spacing 344 351
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7482295
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7482756
Cabinet construction photos 413 452
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7514053
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7522584
Structural bracing and damping strategy 429 439 442
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7517669
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7518089
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7518208
Cutting tapered bevels 466 467
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7526218
Cabinet assessment – looking for resonances 503
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7539527
Driver polar responses measured in finished cabinet 506
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7539853
Final passive crossover design, and system level polar response and Power&DI 583 605
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7558072
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7567335
Frequency response of Class D amplifiers 613 627 634
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7570120
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7570523
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7575669
Documentation
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7586028
I also like the idea of an expandable speaker where a second woofer cabinet can be added to extend the bass response and give higher SPL capability. I got this idea from the Barefoot Sound, where several of their very fine monitor speakers are expandable in this way.
========== =============
Primary Goals
The finished system shall be a compact, active, 3-way with 8” woofer, with a total internal volume of 16-24 liters, with sealed box bass alignment. Update: 10" woofer in a 25 liter volume.
Performance Goals
- Bass response F3 = 40 Hz.
- On axis within target response +/- 1.5 dB from 100 hz – 16 kHz.
- Directivity Index within target response +/- 1.5 dB from 500 Hz – 10 kHz
- No specific max SPL goal or harmonic distortion goal, other than these performance attributes shall be optimized to the extent possible given the drivers selected and the other requirements.
- Low driver cost and low electronics cost. At this point, “low cost” is not really defined, but low driver costs would be in comparison to Scanspeak Revelator, Satori, Bliesma, Purifi, etc. I was thinking on the order of $250 of drivers per side, but this is flexible. In terms of electronics, “low cost” means significantly less than a Hypex FA-123 ($550 per side).
- Easily replicable. This means easily built with readily available parts. I may want to make multiple copies to give as gifts.
- Simple cabinet finishing that does not require weeks of shaping, sanding, veneering, sanding, varnishing, polishing, etc.
- Easily portable.
- A modular design which would allow me to design/fabricate a second bass driver/cabinet later. This would extend the bass response and expand the SPL capability. Update: Modular design is no longer needed with the change from 8" to 10" woofer.
- An opportunity to try new techniques and learn new skills which can be applied to my future high end projects.
- An opportunity to discover new information which would be of use to other DIY speaker builders and developers.
A single 2x4HD shared between two speakers will not provide the necessary 6 channels of signal required by a pair of 3-way speakers. But a single 2x4HD could be used in an active/passive speaker. This is something that has interested me for some time. A passive crossover from tweeter to mid, then active crossover from mid to woofer. There would be 2 amplifier channels required. I find the challenge of this architecture intriguing.
The interesting thing about this approach is that the passive crossover does not need to perform any EQ of the drivers within their individual pass band, nor does it need to manage the overall EQ or voicing of the speaker. This can all be done by DSP. The DSP can also provide BSC for the woofer channel and the mid/tweeter channel. The DSP can tailor the bass response of the woofer. The passive network will need to provide a high-pass and low-pass function for each driver, and relative level matching between tweeter and mid. The passive network will manage the relative magnitude and phase of the drivers through the crossover, and as a result of this, it will manage the directivity index.
The passive network will also manage any out-of-passband EQ. The most likely need for this would be a notch filter on the woofer or midrange at a frequency above the low-pass filter. For example, if the midrange passively crosses to the tweeter at 3k, but the mid has a + 9 dB breakup peak at 8k, the DSP will not be useful in managing that peak. Any EQ at 8k would affect the tweeter response, which would be quite unfortunate. Thus the passive network will need to handle that.
So at this point, I believe this is how I will proceed. There are a lot of amplifier options which offer low cost and acceptable performance, so this remains an open decision.
j.
================== Update 2/01/2024 =================
Index to important posts or milestones
post numbers are included with links
Decision to use a 10” woofer 119
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7447588
Process of defining cabinet dimensions 132
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7449092
Simulating flat face tweeter vs tweeter with waveguide 124 135 164
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7448383
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7449284
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7450834
Concept sketch 197 236
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7452598
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7455272
Decision to use SB15NBAC 236
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7455272
Electronics block diagram 280
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7457445
Prototype testing of tweeters 289 314
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7457716
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7472903
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7471898
Simulations with prototype data to define mid/tweeter spacing 344 351
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7482295
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7482756
Cabinet construction photos 413 452
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7514053
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7522584
Structural bracing and damping strategy 429 439 442
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7517669
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7518089
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7518208
Cutting tapered bevels 466 467
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7526218
Cabinet assessment – looking for resonances 503
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7539527
Driver polar responses measured in finished cabinet 506
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7539853
Final passive crossover design, and system level polar response and Power&DI 583 605
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7558072
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7567335
Frequency response of Class D amplifiers 613 627 634
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7570120
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7570523
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7575669
Documentation
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7586028
Aikido 6GM8 - headphone stage
- By lordearl
- Headphone Systems
- 5 Replies
I am currently finishing a build of the 24V 6GM8 / ECC86 Broskie Aikido line stage amplifier and the space I have in the chassis is very minimal.
Is there a simple way to modify the standard circuit to allow for headphone use? For example, can we increase the value of the output caps (C3) to ensure the frequency response for headphones is adequate?
Is there a simple way to modify the standard circuit to allow for headphone use? For example, can we increase the value of the output caps (C3) to ensure the frequency response for headphones is adequate?
Troubleshooting excessive port noise in diy Subwoofer
- By hepi34
- Subwoofers
- 37 Replies
Hi everyone.
As I mentioned in my introduction post, I recently built two wireless speakers. Both sound great overall, but there's one major issue: port noise, especially from the subwoofer.
I built the subwoofer using a GRS 8SW-4HE-8 8" driver. I settled on a box volume of 40L, excluding port and woofer displacement. I chose a tuning frequency of 26Hz. The transfer function magnitude and SPL curve for this particular configuration looked quite good:
For the port, I went with a 12 by 5 centimeter rectangular port. At a tuning frequency of 26Hz, this port has to be 60cm long. To accomplish this, I had to bend the port once inside of the enclosure. I also added an angle to turn the 90° bend into two 45° ones. Here's a rough sketch of how it looks like from the side:
I accounted for all wood thicknesses during construction to make sure the port length was accurate. The internal length of the port came out to be exactly 60cm, just as planned.
In WinISD, the simulated peak port velocity looked perfectly acceptable for this size and power level. At 90W input, the velocity peaks at around 18.5 m/s at 24Hz, which is already below the tuning frequency of 26Hz, so I didn’t expect any major issues with port noise.
Despite the promising results in WinISD, there are two major issues in practice:
Now my questions are:
Where did I go wrong?
Do I have to simply flare the port?
Why else is there so much port noise?
As I mentioned in my introduction post, I recently built two wireless speakers. Both sound great overall, but there's one major issue: port noise, especially from the subwoofer.
I built the subwoofer using a GRS 8SW-4HE-8 8" driver. I settled on a box volume of 40L, excluding port and woofer displacement. I chose a tuning frequency of 26Hz. The transfer function magnitude and SPL curve for this particular configuration looked quite good:
For the port, I went with a 12 by 5 centimeter rectangular port. At a tuning frequency of 26Hz, this port has to be 60cm long. To accomplish this, I had to bend the port once inside of the enclosure. I also added an angle to turn the 90° bend into two 45° ones. Here's a rough sketch of how it looks like from the side:
I accounted for all wood thicknesses during construction to make sure the port length was accurate. The internal length of the port came out to be exactly 60cm, just as planned.
In WinISD, the simulated peak port velocity looked perfectly acceptable for this size and power level. At 90W input, the velocity peaks at around 18.5 m/s at 24Hz, which is already below the tuning frequency of 26Hz, so I didn’t expect any major issues with port noise.
Despite the promising results in WinISD, there are two major issues in practice:
- It doesn't seem to produce much sound at 26Hz. Audible output really starts around 32–34Hz when sitting directly in front of it, not the 26Hz I was aiming for.
- Port chuffing is excessive. From ~25Hz to ~40Hz, the port noise becomes very noticeable. At times, it seems louder than the speaker itself.
I’ve attached a video showing the port noise when playing a 28Hz sine wave for reference.
Now my questions are:
Where did I go wrong?
Do I have to simply flare the port?
Why else is there so much port noise?
1000VA Isolation Transformer and Bulb Filament Current Limiter Build
- By drtaylor
- Equipment & Tools
- 2 Replies
Over the years of Tube Amp repairs, and old instrumentation restorations, I have always relied on an incandescent bulb current limiter, in conjunction with a Variac. I finally decided to build a piece of kit to make this cleaner, and add a much needed isolation transformer.
It consists of two circuit boards, a Relay controller (no software, just good old logic), and a Lamp board. It contains a large 1000VA toroidal isolation transformer for isolation. There are three duplex AC receptacles on the rear panel that are not isolated, one being a 20A GFCI. The other two are switched on/off by the front panel. There are two ground isolated duplex AC Receptacles on the front panel. One is directly connected to the Isolation secondary, the other is bulb filament current limited by selectable incandescent bulbs controlled by relays. The bulbs are visible through the front panel making it easy to see if any current limiting is taking place. There is an input and output for connecting a Variac to use in conjunction with the current limiting section. The Variac input and output is also isolated from the mains.
Since the transformer had low voltage windings, I rectified and filtered them to provide fixed DC of around ±24V. I just hate wasting windings. The variac is also connected to a pair of Banana Jacks in case I need an variable AC source.
There is a Chinese made Power meter that monitors the isolated outputs.
The build was fairly flawless. I handplaced the SMD parts using a solderpaste stencil, and reflowed them in a modified toaster oven. Everything soldered fine, but I had a couple of bridges on a TSSOP part that I had to clear. The LEDs are too bright at only 5mA, so I might go back and change all the LED resistors. I used RGB LEDs for all of them, and pinned out all three LEDs. I could make any color based on which resistors I placed. I mixed some colors by using more than 1 resistor on them. The LEDs are Right Angle Light Piped to the front panel.
The Lamp Board uses E17 sockets for the incandescent bulbs. I designed this with 20W and 40W E17 bulbs which will not be discontinued as they are oven light bulbs which are exempt from being discontinued. I did discover that a 40W bulb really only draws 32W bulb at 120V which kind of threw my nomenclature into error. However, I was able to kludge in "Calibration" bulbs to get it closer to the desired levels. You can see the kludged bulbs on the back of the lamp board in the open top picture attached. I added a 40W (really 32W) to the 160W bank which then totaled actually 160W. I added a 15W E17 to the 80W bank (two "40"W bulbs) which then actually totaled 79W. I'm going to live with the 40W setting being 32W. The 20W actually was darn close when I used a 25W bulb there. I should have anticipated that 40W bulbs are 20% low. This is consistant no matter what brand I tried. I think I will make a modification to allow an external lamp to be put in parallel for higher powered applications, but so far, it has plenty of power for what I'm doing.
The final build had a lot of wiring to hook up. Mostly wired with 14AWG Elastomeric Insulated hookup wire. I used ferrules in all the terminal block wiring. I used lever Terminal Blocks from WAGO. The picture showing the open top was before I dressed the wiring up neater. There is a lot of wiring in there!
The enclosure panels were supplied by the excellent SENDCUTSEND company and were laser cut. Front, top, and bottom panels are 100mil Aluminum, and the rear panel is 70mil aluminum (because some of the press-fit connectors I used on the back would not work in 100mils). The Front panel is powder coated, also by SENDCUTSEND. I brushed the other panels. The side panels are heat sinks provided by HeatSinksUSA. They are extrusions that are thick enough at their base to drill and tap all the holes that hold the whole thing together. I didn't really need heat sinks, but they were readily available in the size I needed. The price for doing all the aluminum was surprisingly low, and far more accurate than I could manage with drill press, not to mention I have no good way of cutting thick aluminum panels.
The labeling on the front and rear panels is Vinyl originally designed for transfers to things like cups or fabric. But it allows full color, quite detailed nomenclature. I'm really happy how that turned out and it seems quite durable. The labeling was made by Ninjatransfers with their UV DTF Gang Sheet product. I suppied art from Adobe Illustrator.
I have spare circuit boards. If anyone wants to make one (for private use only), I am willing to share all the files for the enclosures, and I have left over raw PCBs.
It consists of two circuit boards, a Relay controller (no software, just good old logic), and a Lamp board. It contains a large 1000VA toroidal isolation transformer for isolation. There are three duplex AC receptacles on the rear panel that are not isolated, one being a 20A GFCI. The other two are switched on/off by the front panel. There are two ground isolated duplex AC Receptacles on the front panel. One is directly connected to the Isolation secondary, the other is bulb filament current limited by selectable incandescent bulbs controlled by relays. The bulbs are visible through the front panel making it easy to see if any current limiting is taking place. There is an input and output for connecting a Variac to use in conjunction with the current limiting section. The Variac input and output is also isolated from the mains.
Since the transformer had low voltage windings, I rectified and filtered them to provide fixed DC of around ±24V. I just hate wasting windings. The variac is also connected to a pair of Banana Jacks in case I need an variable AC source.
There is a Chinese made Power meter that monitors the isolated outputs.
The build was fairly flawless. I handplaced the SMD parts using a solderpaste stencil, and reflowed them in a modified toaster oven. Everything soldered fine, but I had a couple of bridges on a TSSOP part that I had to clear. The LEDs are too bright at only 5mA, so I might go back and change all the LED resistors. I used RGB LEDs for all of them, and pinned out all three LEDs. I could make any color based on which resistors I placed. I mixed some colors by using more than 1 resistor on them. The LEDs are Right Angle Light Piped to the front panel.
The Lamp Board uses E17 sockets for the incandescent bulbs. I designed this with 20W and 40W E17 bulbs which will not be discontinued as they are oven light bulbs which are exempt from being discontinued. I did discover that a 40W bulb really only draws 32W bulb at 120V which kind of threw my nomenclature into error. However, I was able to kludge in "Calibration" bulbs to get it closer to the desired levels. You can see the kludged bulbs on the back of the lamp board in the open top picture attached. I added a 40W (really 32W) to the 160W bank which then totaled actually 160W. I added a 15W E17 to the 80W bank (two "40"W bulbs) which then actually totaled 79W. I'm going to live with the 40W setting being 32W. The 20W actually was darn close when I used a 25W bulb there. I should have anticipated that 40W bulbs are 20% low. This is consistant no matter what brand I tried. I think I will make a modification to allow an external lamp to be put in parallel for higher powered applications, but so far, it has plenty of power for what I'm doing.
The final build had a lot of wiring to hook up. Mostly wired with 14AWG Elastomeric Insulated hookup wire. I used ferrules in all the terminal block wiring. I used lever Terminal Blocks from WAGO. The picture showing the open top was before I dressed the wiring up neater. There is a lot of wiring in there!
The enclosure panels were supplied by the excellent SENDCUTSEND company and were laser cut. Front, top, and bottom panels are 100mil Aluminum, and the rear panel is 70mil aluminum (because some of the press-fit connectors I used on the back would not work in 100mils). The Front panel is powder coated, also by SENDCUTSEND. I brushed the other panels. The side panels are heat sinks provided by HeatSinksUSA. They are extrusions that are thick enough at their base to drill and tap all the holes that hold the whole thing together. I didn't really need heat sinks, but they were readily available in the size I needed. The price for doing all the aluminum was surprisingly low, and far more accurate than I could manage with drill press, not to mention I have no good way of cutting thick aluminum panels.
The labeling on the front and rear panels is Vinyl originally designed for transfers to things like cups or fabric. But it allows full color, quite detailed nomenclature. I'm really happy how that turned out and it seems quite durable. The labeling was made by Ninjatransfers with their UV DTF Gang Sheet product. I suppied art from Adobe Illustrator.
I have spare circuit boards. If anyone wants to make one (for private use only), I am willing to share all the files for the enclosures, and I have left over raw PCBs.
Thoughts on this schematic/design?
- By nzoomed
- Tubes / Valves
- 31 Replies
Im looking at building this Class AB1 cathode biased amplifier based on this design here.
I have most of the components on hand, including a suitable power transformer and pair of OT's.
I am making a few changes, I am using an EF37A/6J7G instead of an EF86 and using 807 tubes instead of 6L6.
Few questions, is the 750pF capacitor across the CT to anode on the tube to remove oscillations? I find its odd only one half has this, ive never seen this before on such a schematic.
There is also an 820pf cap going across for the NFB loop, how critical are the values for these capacitors?
I have quite a bunch of silver mica caps on hand but nothing quite exact, ive got a few 680pF and 1000pF on hand if they will suffice.
Here is the schematic and a rough layout ive drawn of the turret board.
Another issue im unsure will be a problem is i mirrored the layout, so have to cross some wires over, not too sure if this is a worry, you will see what I mean with the channel on the left of the image.
The phase inverter was not too big of a deal, as i just swapped over each triode section.
Im unsure about the path of the heater wiring, but its just rough, I will probably move the tube sockets around some more and I have not included the power supply yet, but all the transformers will sit behind the 807 tubes at the bottom of the image. The filter choke im hoping will fit under the chassis.
I have most of the components on hand, including a suitable power transformer and pair of OT's.
I am making a few changes, I am using an EF37A/6J7G instead of an EF86 and using 807 tubes instead of 6L6.
Few questions, is the 750pF capacitor across the CT to anode on the tube to remove oscillations? I find its odd only one half has this, ive never seen this before on such a schematic.
There is also an 820pf cap going across for the NFB loop, how critical are the values for these capacitors?
I have quite a bunch of silver mica caps on hand but nothing quite exact, ive got a few 680pF and 1000pF on hand if they will suffice.
Here is the schematic and a rough layout ive drawn of the turret board.
Another issue im unsure will be a problem is i mirrored the layout, so have to cross some wires over, not too sure if this is a worry, you will see what I mean with the channel on the left of the image.
The phase inverter was not too big of a deal, as i just swapped over each triode section.
Im unsure about the path of the heater wiring, but its just rough, I will probably move the tube sockets around some more and I have not included the power supply yet, but all the transformers will sit behind the 807 tubes at the bottom of the image. The filter choke im hoping will fit under the chassis.
Antique gear
- By Matt888
- The Lounge
- 215 Replies
Why is there a perception (particularly on social media) that antique equipment sounds better than modern audio gear?
I see countless posts from self-proclaimed audiophiles showing a stack of separates that were designed and manufactured in the 70s, like that somehow proves their audiophile credentials. Tubes and vinyl? Really? It's almost 2025!
In my view, even the cheapest Chi-Fi equipment from the current era sounds superior by orders of magnitude to dusty, out-of-date gear from the ancient past.
What is this trend that older is better? The test of time? Visual bias? Vintage chic?
I don't get it 😅
I see countless posts from self-proclaimed audiophiles showing a stack of separates that were designed and manufactured in the 70s, like that somehow proves their audiophile credentials. Tubes and vinyl? Really? It's almost 2025!
In my view, even the cheapest Chi-Fi equipment from the current era sounds superior by orders of magnitude to dusty, out-of-date gear from the ancient past.
What is this trend that older is better? The test of time? Visual bias? Vintage chic?
I don't get it 😅
3-Way Studio Monitor System
- Multi-Way
- 1 Replies
Hello,
I would like to show you a project I'm just working on. It started with an idea for bass improvement and eventually turned into a design of an entire system.
The subs are already made but not tested for possible improvements. Firstly I have to build the monitor units which contain the amps (Hypex FA 253).
The monitor driver will be Sica 5.5 C 1.5 CP. The sub driver is Peerless by Tymphany SLS-P830669
The concept aims to improve my current monitoring capabilities in my studio of 5x5 meter in near field range by moderate room level.
Usually I use monitors on stands with a distance of 1m to the front wall. So I will build the speakers into stands. The stand will also contain the amp, which makes a free positioning of the subwoofers more convenient. The subwoofers can also stand within the bottom area of the stand for listening in midfield and to blend into the design of pseudo single speaker.
I would like to show you a project I'm just working on. It started with an idea for bass improvement and eventually turned into a design of an entire system.
The subs are already made but not tested for possible improvements. Firstly I have to build the monitor units which contain the amps (Hypex FA 253).
The monitor driver will be Sica 5.5 C 1.5 CP. The sub driver is Peerless by Tymphany SLS-P830669
The concept aims to improve my current monitoring capabilities in my studio of 5x5 meter in near field range by moderate room level.
Usually I use monitors on stands with a distance of 1m to the front wall. So I will build the speakers into stands. The stand will also contain the amp, which makes a free positioning of the subwoofers more convenient. The subwoofers can also stand within the bottom area of the stand for listening in midfield and to blend into the design of pseudo single speaker.
Attachments
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz
- By soekris
- Vendor's Bazaar
- 11039 Replies
Attachments
My personal interpretation of the Baby Huey with EL34
- By zintolo
- Tubes / Valves
- 12 Replies
Hi, after the request of @OldHector , I post here my own version of the Baby Huey with EL34 (that fits well with KT77 and other tubes).
I will also post some guidelines for other tubes like 6550 (I would avoid KT88 because the original pcbs have the sockets too close for KT88).
Let's start with a bit of hystory: this kind of amps have ultralinear and Schade feedback combined.
Schade original feedback (1938) can be found here:
https://www.dos4ever.com/uTracer3/Schade.pdf
Crowhurst reposted that kind of anote-anode feedback in 1952 here:
http://www.tubebooks.org/Books/Crowhurst - Audio Handbook No2 - Feedback 1952.pdf
Yves Monmagnon posted the PP Schade feedback (and phase inverter supply) in pentode configuration plus conventional gnfb here:
http://www.dissident-audio.com/PP_ECL86/Page.html
The EL84 development has been done in 2006 by @gingertube here using 40%UL and Schade feedback:
The EL34 version has been started by bandol (RIP) in 2018 here with 40% UL and Schade feedback:
Here I posted a similar thread with noted on the EL84 version:
Here I will report my takes on the EL34 version, but before a small introduction on Schade feedback:
Numerous tests have been done during the last 90 years, but just to report real measurements, I link some sources:
One is Broskie in 2001:
https://www.tubecad.com/march2001/
One is Bertola with his plts on Schade feedback only.
in 2013 he has tested on the curve tracer the 807a ( https://frank.pocnet.net/sheets/136/3/307A.pdf ) showing how Schade alone can triodify the curves:
source: https://www.bartola.co.uk/valves/2013/03/16/307a-dht-in-triode-and-schade-feedback/#more-1331
Some italians have done tests on the curve tracers too in 2021:
source: https://www.sb-lab.eu/schadeode-alternativa-ultralineare-triodi-virtuali/
There are many others curve tracer plots, but I will only report the ones above.
I will also post some guidelines for other tubes like 6550 (I would avoid KT88 because the original pcbs have the sockets too close for KT88).
Let's start with a bit of hystory: this kind of amps have ultralinear and Schade feedback combined.
Schade original feedback (1938) can be found here:
https://www.dos4ever.com/uTracer3/Schade.pdf
Crowhurst reposted that kind of anote-anode feedback in 1952 here:
http://www.tubebooks.org/Books/Crowhurst - Audio Handbook No2 - Feedback 1952.pdf
Yves Monmagnon posted the PP Schade feedback (and phase inverter supply) in pentode configuration plus conventional gnfb here:
http://www.dissident-audio.com/PP_ECL86/Page.html
The EL84 development has been done in 2006 by @gingertube here using 40%UL and Schade feedback:
The EL34 version has been started by bandol (RIP) in 2018 here with 40% UL and Schade feedback:
Here I posted a similar thread with noted on the EL84 version:
Here I will report my takes on the EL34 version, but before a small introduction on Schade feedback:
Numerous tests have been done during the last 90 years, but just to report real measurements, I link some sources:
One is Broskie in 2001:
https://www.tubecad.com/march2001/
One is Bertola with his plts on Schade feedback only.
in 2013 he has tested on the curve tracer the 807a ( https://frank.pocnet.net/sheets/136/3/307A.pdf ) showing how Schade alone can triodify the curves:
source: https://www.bartola.co.uk/valves/2013/03/16/307a-dht-in-triode-and-schade-feedback/#more-1331
Some italians have done tests on the curve tracers too in 2021:
source: https://www.sb-lab.eu/schadeode-alternativa-ultralineare-triodi-virtuali/
There are many others curve tracer plots, but I will only report the ones above.
ZOUDIO AIO4CH: 4-channel amplifier with DSP and Bluetooth
- By lutkeveld
- Vendor's Bazaar
- 834 Replies
I want to introduce a new product I have been working on for the past years.
It's now available for pre-ordering, which will be shipped in the end of februari, in order of payment.
ZOUDIO AIO4CH: 4-channel amplifier with DSP and Bluetooth
Features:
-4x45W class D amplifier (can also be configured as 2.1 or 2.0)
-Bluetooth V4.2 APT-X with True Wireless Stereo
-Configurable DSP
-Easy to use Windows configuration tool
-Small format with high efficiency
Screenshot configuration tool:
As can be seen, a lot of the settings can easily be changed, such as:
-Start and maximum volume
-Battery protection voltages
-Input (left/right/mono) and output (4.0/2.1/2.0) configuration
-13 general filters (equalizers) en 5 filters per channel (crossovers)
-2 equalizers which can be enabled with a button (e.g. indoor/outdoor, bass-boost)
-Volume dependant (dynamic) equalizer
-Delay per channel
This thread can be used for questions about specifications and how to use the products. Remarks and suggestions for improvement are also welcome for this and future products.
Productpage (datasheet, configuration tool download, ordering): click here
It's now available for pre-ordering, which will be shipped in the end of februari, in order of payment.
ZOUDIO AIO4CH: 4-channel amplifier with DSP and Bluetooth
Features:
-4x45W class D amplifier (can also be configured as 2.1 or 2.0)
-Bluetooth V4.2 APT-X with True Wireless Stereo
-Configurable DSP
-Easy to use Windows configuration tool
-Small format with high efficiency
Screenshot configuration tool:
As can be seen, a lot of the settings can easily be changed, such as:
-Start and maximum volume
-Battery protection voltages
-Input (left/right/mono) and output (4.0/2.1/2.0) configuration
-13 general filters (equalizers) en 5 filters per channel (crossovers)
-2 equalizers which can be enabled with a button (e.g. indoor/outdoor, bass-boost)
-Volume dependant (dynamic) equalizer
-Delay per channel
This thread can be used for questions about specifications and how to use the products. Remarks and suggestions for improvement are also welcome for this and future products.
Productpage (datasheet, configuration tool download, ordering): click here
Attachments
High impedance mic preamp design
- By Tashi1
- Instruments and Amps
- 36 Replies
Long time builder, inexperienced designer. Attempting to make a simple low noise mic pre, with a high impedance input suited for dynamics & ribbons. Came across this circuit by Bob Cordell, dual jfet LSK489 with presumably an impedance in the many many mega-ohms. Anyone built one of these or something similar?
https://www.cordellaudio.com/JFETs/LSK489appnote.pdf page 11/12
I’m mainly trying to figure out the line driver, be nice to use both halves of the 4562 or I could just whack a THAT1606 on the end. Or use a 1646 instead of the 4562 entirely but it might be too hungry coming straight off the transistors without an opamp buffer? Or of course simply do an impedance matched driver after the existing buffer like so
The other thing is this pre apparently provides 60dB, it’d be nice to bring that up to 70. I’m not sure if that’s better squeezed out of the transistors at the front end or done at the end with an opamp?
Any thoughts? Thanks in advance
https://www.cordellaudio.com/JFETs/LSK489appnote.pdf page 11/12
I’m mainly trying to figure out the line driver, be nice to use both halves of the 4562 or I could just whack a THAT1606 on the end. Or use a 1646 instead of the 4562 entirely but it might be too hungry coming straight off the transistors without an opamp buffer? Or of course simply do an impedance matched driver after the existing buffer like so
The other thing is this pre apparently provides 60dB, it’d be nice to bring that up to 70. I’m not sure if that’s better squeezed out of the transistors at the front end or done at the end with an opamp?
Any thoughts? Thanks in advance
J-Box All in One Measuring Device from Aliexpress
- Equipment & Tools
- 6 Replies
Hey guys,
has nobody some experience with the device mentioned above? It comes in two versions.
has nobody some experience with the device mentioned above? It comes in two versions.