I was wondering if someone has done a 1ET9040 build and could share some details? I only have the Micro audio Cobra S1 SMPS set, the 1ET9040 and a pair of the new Neurochrome buffers. That means I will need to source the cabling, switches and enclosures, anyone seen or has an idea where to look? Will be truly appreciated!

One of my early projects: the Objective 2 (or O2) headphone amplifier, built as a preamp. 4 RCA inputs with rotary selector, one stereo RCA output. Includes 15 volt AC adapter (this is an important detail, don't use a 12v DC adapter!).

Sold

Asking $40 obo, local pickup in San Francisco preferred. Will ship ConUS at cost.

I have spent several hours over the past two days searching for size/shape compatible surrounds. The most likely candidate so far are surrounds from Simply Speakers.

The surrounds attach to the underside of the SBX500 woofer discs which is a shiny metal surface - presumably aluminum.

Two years ago I attempted surround replacement to the undrside of 5" woofers with a poly cone and those surrounds coincidently came from Simply Speakers. That attempt was not successful due to the awkwardess of accessing the underside of the cone and the clear, fast setting adhesive provided by Simply Speakers. I think that clear glue was rubber based. There was not enough time for me to position the surround on the cone before the glue got too stickey to work with. They then sent me some conventional slower setting white glue.

I expect that gluing a surround to the underside of these Technics SBX500 woofer discs will be fiddly and somewhat time consuming. My question is will the conventional white' slower setting glue bond properly with the metal surface of the disc's inderside?

The attached photos are as they are now. The residual old surround material on the disc's underside is still in place. I am debating on attempted removal by blade & scraping or trying some type of solvent.

Hey all,

I have a Tact S2150X Digital Amplifier (Silver Faceplate) with volume remote for sale, It has the Equibit chipset, and has Digital only inputs (no analog inputs)...basically an integrated PowerDAC. Its 150 watts @ 8 ohms and 300 watts @ 4 ohms. Amp also has the ability to do high or low pass crossover outputs.

The amp firmware has the latest version (unfortunately, the latest firmware REMOVED the Room Correction ability that the peramps have - why would they do this?)

Works great - I have two, but will be holding onto one. Also have a Tact RCS 2 Preamp (Black Faceplate) that does the room correction also available...

Asking $725 + ship...

Specs:
Power (RMS. per channel) 8 ohm 2 x 150W Power (RMS. per channel) 4 ohm 2 x 300W
Output current (peak, per channel) >50 A
Signal-to-noise ratio ( A-weighted) >110dB
Dynamic range (20 Hz - 20 kHz) >130dB
THD+N (all power levels 20Hz-20kHz) <0.01%
Digital resolution 16-24 bit Linearity (-120dB) +- 0,2dB
Dimensions (WxHxD) 450x140x420 mm 17.7x5.5x16.5 in.
Weight (shipping) 18 kg / 37 lbs

For Sale: Elliot Sound Products P-101 Amp. One of my favorite amps, and has been used on conventional, planar and Electrostatic speakers...

Powered by a SMPS and housed in an old Hafler Chassis. Looks and sounds great...with +/-60v rails, over 300 watts @4 ohms. Exicon output devices.

$350 + ship, or pick up in West sub of Chicago...

Hello all,

Decided to sell my pair of Hawthorne Audio Silver Iris Speakers... Each Coax driver has a 15" Eminence for LF, and a 1" Compression Driver for HF...

Building an Open-Baffle type speaker doesn't come any easier!!

Pics forthcoming...$200 + Ship...or pickup in West Sub of Chicago

Amp built years ago when TA0103A were popular - with a Hypex SMSP400 SMPS. Turn on and Turn off thump (these Tripaths were notorious for these thumps) have been mitigated with delays.

Sounds great / clean. See attached pics and Application notes.

Ships from West sub of Chicago

How's $450 + ship? CONUS only please....

Hey all, seeing quite a few Yaquins on Swap Meet, so thought to post mine...

Yaquin MS-110B Tube amp. 50 watts/channel. Biased set and ready to go. New-ish tubes that test very good on my tester. Comes with original manual, fancy remote and cage removal tool. Slight scratching on top from cage, but very clean condition.

Output power: 50W + 50W (6Ω)
Harmonic Distortion: ≤ 1.9% (1kHz)
Frequency Response: 10Hz - 65kHz (-2dB)
SNR: ≥ 85dB (A)
Input sensitivity: ≤ 0.3V (1kHz)
Load Impedance: 4Ω-8Ω
Tube: KT88 × 4 12AU7 × 2 12AT7 × 2
Dimensions: (length) 300mmX (W) 420mmX (high) 200mm
Weight: approximately 25 kg

Features: (from ebay ad...quite funny)

• Power tubes use the latest improved KT88-98 and strong output push-pull circuit.
• Preamplifier part is as "SRPP" circuit and excellent "long tail" type inverter circuit. So that a wider frequency response and better sound quality.
• Audio output transformer dedicated silicon steel imported from Japan (0.35mm thick) and oxygen-free copper wire and special high-strength multi-layer winding process grouping production (divided into 15 layers), so that the machine wide frequency response, ensuring high the machine, , the low-frequency sounds good, transparent and powerful.
• The machine adopts well-know brand dedicated audio BC capacitors and also Philipps (MKP) nonpolar capacitor.
• High quality gold-plated resistor, the main channel using a dedicated sound Japan (ALPS) volume motor potentiometer with quiet background music, noise low, no sound pollution and durable.
• High voltage power supply for the automatic delay control, can effectively extend tubes life.
• Switch between ultra-linear (UL) and three poles (TR) connection mode, to meet different user needs.
• Function with remote control and high quality headphone output.

New on ebay around $1200...How about $750?

Pick up in West sub of Chicago...or can ship for $$ (55 pounds)

Big Flower - the logical sequel to Horn Flower.






Initial design concept study outcome - the stands in the top picture is what I will end up with.

I have had a lot of fun and learnt much from HF. Some things with them are really desirable and I wanted to see if they could be improved on... and a reason to get a 3D printer 😉

Positives: Great clarity, resolution and timing.
Negatives: Small(er) stage (but very precise), limited low bass and som midrange anomalies (comb filtering) due to that the 4 woofers plays quite high (1400 Hz)

Also the bild quality of the "box" was pretty sketchy and despite the cool "hair", it probably generated quite a lot of diffraction.

So to keep the positives and remedy the negatives, enter the Big Flower.

Same concept but with improvements (finger crossed):

• 260mm diameter horn -> 520mm
• 4pcs of 4" bass driver -> 6pcs of 5,5
• XO@1400 -> 800 (hopefully, 900/1k still ok)
• Larger volume per driver - > improved lows
• ATH G2 inspired horn at full width should decrease diffraction
• Lower XO should mean less LF drivers c-c distance interference
• Thanks to bass driver placement and stands/mount design, the LF drivers will be much closer to wall and with less c-c despite being larger,

Potential new negatives:

• Only one cavity so now the actual horn is a pressurised surface of the closed/infinite baffle - vibration?
• Using a 1,4" CD instead of a 1" might have impact on top octave
• Increased depth (5cm) gives a longer distance between LF drivers and horn mouth... integration...
• Heavy

The way they where designed and realised was by 3D modelling, molds printed from PETG and casting in concrete. I like concrete - its a varm, nice and strong material 🙂

It was obvious from the beginning that I could not get a printer to make the horns in one cast so it had to be divided and later glued together. I used Sikaflex 291 for this as it had proven very stable and strong when I built my concrete baffle Line Source. All drives were glued to the concrete and still sits there safely.

I did some simulation on speaker level for the Horn FLower which gave some hints that it could work and I think the result mimic'd the simulations quite well. Therefore I didn't do any for the BF because I don't think it is needed - concept works and I feel the new dimensioning can only be better. And then there is CamillaDSP 🙂

Recipe (for a pair):

• Qidi Q1 Pro
• PETG 4-5 rolls (quite some trails, mistakes and re-thinking done - 3rd time a charm...)
• 2x HF SB ROSSO-65CDN-T
• 12x LF SB15nac30-4
• 3,5 x 20kg bags of fibre reinforced floor levelling concrete: Weberflow 120 Reno DR
• 2 tubes of Sikaflex 291
• Div metal parts for the hanger force distribution box
• Rubber mat for horn/basket gasket
• 2x stands out of iron and concrete (of course! 😉)
• 1 pcs of 1977837 ATH A520G2 from Cults3D - even if I wasn't planning to print this exact horn I wanted to contribute to @mabat fantastic project and products. The profile was modified and simulated in ATH/VACS to give a bit wider dispersion.
• Dedicated electronic in one box - 230V in, wifi/eth and 2 pairs / ch of cabling. TBD...

So these will be prototypes and have a number of known "errors" already. They where identified during the path of design, both in modelling, casting and dry assembly but half way in I decided to go ahead with these "less perfect" aspects as I realised that it will take one round before I get them "perfect" (never!) anyways.

So what are these problems:

- It was harder than I could imagine to make a mold for a 60 degres part when it came to rotate a profile, make 6 of them and assemble them to a full circle unit. Sketchup could not do it. I got a plugin that was better but then I made som assumptions about how to get some room for the glue which I overestimated and got 5mm instead of 1. Next time, calculate please! 🙂 But I didn't find out until I had made 5 and then I decided to continue anyways.

- Perhaps I have made the concrete goods a little to thick - they have been called tanker stoppers 🙂 and they will be heavy - 40kg+ - a challenge for me to handle. Better have some help during first trials.

- and several minor improvements...

To date, I have all components ready to be assembled except the stands but they are waiting order confirmation.

I will continue posting about the assembly process, measuring and dialling in.

Tnx for reading - comments welcome.

//

This thread's purpose is to assist builders with their Aleph Jzm kits.

For general discussion, customization, parts substitutions, or anything unrelated to the kits, The Aleph Jzm thread is perfect.

The goal is to have this thread be a quick source for relevant information for kit builders. It will also be used as a source of information to update the Aleph Jzm Build Guide. At this time, comments are not active in the build guide.

For builders specifically needing help with their power supply, please search for a thread supporting your specific power supply, create a separate thread as needed, or post your question in the The Aleph Jzm thread.
For those needing assistance with their amplifier boards or overall assembly and wiring, please post the following:

1) The current step # from the AJzm build guide.
2) Well-lit, in-focus photos of the build in its current state.
3) A description of the issue or question.

Hello everyone. I am helping a friend with a fullrange project. He wanted some Voxativ drivers but, saw the price and just to much money. We stumbled upon a company called Sonido fullrange driver's. Looks really nice. Not to many reviews but the gallery has a lot of customers using these driver's. Also they are not to much money compared to other fullrange driver's. I did e mail the owner very nice and very helpful. I like that. So what are your thoughts and have you heard or know of anyone that has used or heard these fullrange driver's? Thanks jm

For your viewing pleasure.
Speaker fantasy art.

---

What Is An Aleph Jzm?

The Nelson Pass designed First Watt Aleph J is a classic. @Zen Mod created this version of the Aleph J to make the project more approachable to newer builders while maintaining the characteristics of the original. For more advanced DIYers and those that like to experiment, there are options to use a variety of JFETs and customize the circuit to suit personal tastes. For those that don't know Zen Mod, he was gracious enough to post a video to introduce himself and share a few thoughts. It can be found on YouTube.

What’s In The kit?

All the electronics components needed to complete a pair of amplifier PCBs, including 8 matched JFETs.



What Is Needed To Complete The Full Project?

At this time, a complete kit including everything required to complete an amplifier is not available. You’ll need a power supply, chassis, wiring, and a few other parts. Everything you need can be purchased directly from the diyAudio store and well-known retailers world-wide. Suggestions are included in the build guide, and/or you can customize to your heart’s content.

What Skill Level Is Required?

This project is intended for intermediate to advanced DIYers. It may be the perfect project after an Amp Camp Amp. Newer builders willing to do a little studying should have no trouble following the build guide. However, it is critical that builders know how to identify parts from schematics, match those parts to PCB locations based on the silkscreen, and have good soldering skills. Most importantly, all builders are responsible for their own safety and must understand essential safety practices and precautions when dealing with mains powered electronics.

Feel free to review the Aleph Jzm Build Guide in advance if you're trying to determine if this project might be for you. The guide will continue to be updated. The Aleph Jzm Kit Build Support thread is also available if you have questions.

The purpose of this thread is aimed for people who (or recently completed) are currently undergoing construction of the Elektor Preamplifier 2012 that was published in April, May and June 2012.
See these links.
https://www.elektormagazine.com/labs/preamplifier-2012-1-introduction-and-line-intonevolume-board-110650

http://https://www.elektormagazine.com/magazine/elektor-201204/19844

Your constructions, ideas, problems, images etc would be valuable for other constructors to view.

Although, most readers will be familiar with the Elektor project, below i have list some basic details below.
Printed Circuits Boards for this project are available direct from Elektor: -

LLLL BOARD (110650-6V120) £14.95
POWER SUPPLY BOARD (110650-5V110) £16.95
FRONT PANEL BOARD (110650-4V110) £11.95
INPUT BOARD (110650-3) £22.95
Preamplifier 2012 (2) (110650-2) £22.95
LINE-IN/TONE/VOLUME BOARD (110650-1) £22.95

I asked the question some months back: How do our loudspeakers compare to expensive, high end, HIFI brand loudspeakers?"

I have answers.

The Short of it:
For those of you who do not want to read this entire write up I will be kind and put my summary up top in a bullet list. There was 3 of us who went. One musician, one loudspeaker builder, and one wife who only ever listens to the system the former two have and doesn't know how any of it works. We listened to 60 systems in one day. Back to back to back. We then came home and listened to my systems.

The BAD

• Most of them do not sound good
• Most of them have a roughness to the upper mids that just sounds terrible. They use these great drivers but drive them straight into their cone resonances. This was the #1 thing we all found wrong with about 80% of the systems
• I swear they pick their crossover points at random. Their crossover networks are pretty goofy
• A lot of them have phase issues. You stand up and it just sucks. You move to the left and it sucks. You have to sit directly center
• Some of them were amazing. These were generally ones where the loudspeaker designer was right there in the room and you could ask him questions. I will get to these units in a bit
• Anything with DSP had a roughness to it. Every single one of us, by the 3rd floor, could walk into a room blind folded and tell you if it was a DSP system or a passive system. Passive ALWAYS sounded better. We listened to about 60 systems back to back throughout the course of a day. DSP to the 3 of us = no good. Was not really subjective. It was objective.
• A lot of them beam really badly. The ones that don't, have a harsh upper mid range
• Do more expensive drivers sound better? Yes, if you use them properly. Saw some $400 drivers implemented horrendously and some implemented properly. And everything inbetween. But mostly the former.

The good

• A couple of systems were just incredible. All of these except two had the loudspeaker designer in the room.
• The better systems used either bespoke of expensive drivers.
• There were a couple mid tier systems that sounded really good.

You can skip the individual review and go to my comparisons with my own loudspeakers at the very bottom
Lets go through one by one now (I am not going to include most of the bad ones. They sounded so bad I had to just get out of there. If it isn't listed below here and it was at the show, it sounded like crap):


This 4 way was great. It had dynamics and a lightness. Lows were washed out but it was still good



This was ATC. I hear people praise their old mid dome here so I checked them out.

This two way was horrendous. One of the worst speakers at the show. The driver on the table is what they were showing off. Do not buy this thing. It was sticky, like someone covered it in honey. I would guess in your house it'd be covered in dust within a couple weeks. Bad, just all bad.


Morel

These were great. The mid is the one up top and is ported. The woofers down below are also ported. These were REALLY good. I spoke with the engineer about how they don't measure or simulate well. He explained their motor design in detail. It will not simulate right because their design is so different. They have special software they have to use for their motor designs. The price point of morels now looks very attractive to me.



This one wasn't playing. I just thought it was a fun design with the dual AMTs in front of the woofer


MTM Illuminator design. What's not to like? Horrendous upper mid range. So sharp and attacking. Not good. Lows were good, not very dynamic. No idea what they cost but its too much. Feel like the designer dropped the ball here.


I will now never build a line array. This thing just sounded odd. Like a blade of people singing on the left and then a blade of instruments on the right. It was all washed out vertically. Hard to explain. Not a fan. None of us liked this, all of us thought it was just strange sounding. And not strange in a good way.

Full range driver build by Songer. Second best sounding full rang behind a Voight pipe Alpair 11 build. This thing was great. Good dynamics, good upper mid range, very nuetral, good dyanmics. It had it all. It is a giant full range so it beamed like crazy. Move your head left or right and the tone changes. But still very good.


I think these are called frugal horns? Big woofer and a compression driver. Engineer was in the room. Not my cup of tea but the BEST compression driver I have ever heard. He crosses these to the woofer at 700 hz. Pretty impressive and fluid, natural sound out of these. The big woofer lacked dynamics to say the least.




Triangle Art

These were bad. Like just plain bad. Maybe they would sound good if you were 60 feet back in a big room? Crazy directional. Everything sounded muddy. All looks, no beauty.


AudioVideo Artistry

******* AMAZING. What do the Accuton driver's sound like? ******* AWESOME. End game design right here. Nothing topped these except their big brother which will be on this list somwhere. These Accuton drivers are insane. I think he has at least $7k, at LEAST, worth of drivers and crossover components in each of these.

Do expensive drivers sound better? In this case, YES YES YES, they ******* do. I had to shake this man's hand. Can't stop gushing over these.



Alright, we need to chat about these domes. This dome was, BY FAR, the best mid at the entire show. Everything else pales in comparison to these. I asked him if I could buy a set of the mids and he said I could. I just have to call Playback Distribution and ask for a replacement pair. I will be buying a set. Maybe we can get a group buy together? I'm telling you, you haven't heard ANYTHING like this before. These are like sorcery. I will be making a second post where I try to buy these. This is a game changing driver.

As a speaker in totallity these were AWESOME. They are small, but they blow out of the water almost everything else at the show. Another one where the engineer was in the room. I spoke with him 3 times today. Kept coming back.


These were ok. Harsh upper mid. Tweeter were good but they ran them too low. A lot of expensive stuff to sound like garbage. Crazy.


26" dual opposed woofer. It shakes the building. Sounds no different from my coffee table subwoofer in my office. This doesn't hit as low as my coffee table. Impressive...... if you don't have a coffee table that hits to 11 hz.




Tannoy

You like jazz? These are for you. Grainy, poor imaging, you are hyper aware that the sound is coming from the speaker. No low end dynamics. Great for trumpets and a saxophone. Pretty sure they were made for that.


My first taste of open baffle. My buddy liked them. I did not. Sounds all washed out. Someone moved a table and the guy had to jump on the dsp to correct the room again. Not for me. Zero bass


More open baffle. More of the same, washed out and not defined. These had bass because of the horn. That was even a little washed out.



Harsh upper mid. Looks cool, doesn't sound very good.


PS Audio

These are some of the best at the show. If you can tame a mid planar, nothing really compares for silky smooth vocals. Paul did it right. I have half a mind to use a planar mid for every mid I do even though I just gushed over those mid domes.

Each track used 2 to 3 will SA1186 2 SC2837 2.

LAPT power transistors, ultra-high frequency FT, solve the CFP switch distortion.

Tiny hand in the distortion + 0.6 V.

I had fun last night at Bryan Adam’s “So Happy it Hurts” gig in Dublin’s 3Arena.

I found I knew the majority of the songs and a live Rock gig is always fun. He has a prolific back catalogue!

Great performances all round and some fun with videos and the “So Happy it Hurts” flying car!

Bryan comes over very well and really engages with the audience. He was on stage for over 2 hours and it was entertaining throughout.

Since this an audio forum, I should mention the sound! 🙂 it was very good, not short on volume, but not deafeningly loud either. The drum kit packed a hell of a punch as you would hope, and sound was clear without being fatiguing. The screaming guitar solos were clear without melting your eardrums. My inner audio nerd wanted to measure the SPL but I managed to resist!

Overall a thumbs up, no complaints, and well worth the price of admission.

What was your last gig experience?

Jeff.

I wanted to build a DIY amplifier for my speaker. I just assembled it on a perfboard for testing, and when I tried adjusting the bias, nothing happened. When I checked, there was no bias voltage, so I started checking from the long-tailed pair and found weird voltages. I tried replacing the current mirror transistors (Q4 and Q3), and there was no difference, so I tried replacing Q5 and Q1, but nothing. Looking at the board, I don’t really see missing connections. I tried disconnecting the VAS, and nothing really changed. Where should I look?

Hello all 🙂

Just to introduce myself, have been modifying and playing with electronics, mainly audio, for years, in the early days often fixing them after I'd broken them ! Work in IT, networking, virtualisation etc and electronics is a hobby, for fun. Have a number of classic (old, British) transistor amplifiers all modified in some form or another.

Latest is Lehmann Audio BCL which needs fixing after somebody tried upgrading it and just went too far.

Looking to build more and fix less, I'd like to try building a tube amp.

I am not going to get around to using these drivers. This is a good opportunity for those of you that haven't experimented with high end drivers to get some for much cheaper than retail!

Prices listed are before shipping. Buy the whole set for even more discount!

I will ship to continental USA, only.

PM for offers and to request any more details.

Pictures in following posts.

Update:
AT drivers sold.
Millennium tweeters sold.

A bunch of foil coil inductors available. Some are lightly used, some are more used. They all at least have holes drilled in the ends of the leads. The Jantzens are very lightly used. Some were previously mounted. The Alphacores are more used. Some of them have roughed up leads.

Plus a couple big 12G 3.3 mH solid core inductors.

All from very good manufacturers.

Prices listed are prior to shipping, which will be worked out with the buyer. I will only ship to continental USA.

PM for offers and to request any more details.

Pictures in following post.

True Wireless Stereo (TWS) Bluetooth for Speakers

Hi Folks,
I am looking for a way to have two physically separated wirelss Bluetooth speakers play stereo. I do not want a wire connection between the left and the right and I want it to connect like a single BT device. I know that this is possible as I have several earbuds and headphones that do this. They ususally call this TWS (true wireless stereo) and I have searched and searched but have failed to find either a line level TWS receiver pair or a simple Class D amp pair with TWS. I know that if I hacked into the wireless earbuds, I could indeed take the headphone outputs and connect them each to a power amp and make my own TWS amplifier. But that seems silly. Surely, there must be a commercial off the shelf solution for this already?

The idea here is to have a stereo BT speaker set, physically placed in a room. I do not want clutter from a wire running from the left to the right one.

I do not need a lot of power. 5W or 15W woud be enough.

Hello guys 😉

This is my current project. Its a MiniDSP style active crossover heavily inspired by Cyperpits Octavia. Its still a work in progress and most of all a experimentation/test bed for me to learn how to design audio electronics.

It's based on a ADAU1466, similar to what is used in the fusion amps. The goal is to have a stereo analog input, SpDif in and out as toslink and RCA, 8 analog outputs and a trigger out to wake up amps as signal is detected.

For now I have only finished my "DSP core board" The DAC's and ADC are just cheap aliexpress modules for now. I almost finished my own DAC and SPDIF-out board based on the PCM5102A's. The ADC board is also conceptually done but still needs a lot of schematic and pcb work. This is what it looks like on the inside.


When I get my own DAC and ADC board the connections to the DSP board will be done via ribbon cables with every second line being GND to ensure good signal integrety.
I designed it this way with seperate PCB's as it allows me to focus on one thing at a time without making it unnecesarily tight and expensive to iterate. I can then try different DAC's or ADC's at a later time without having to pay for a new DSP chip and vice versa. It needs a fairly big box to allow all the connections on the back anyway.. Each pcb is 99x99 mm so they stay in the cheap range at JLCPCB. Its a 4 layer PCB with SIG on top, GND, POWER and SIG/GND on the bottom. Im currently using a Wondom ICP5 to program the DSP instead of the expensive USBi as I had it on hand. However, I hope to be able to make my own USB programmer based on the freeusbi and integrate it on the board eventually. But the software part of that scares me a bit as I have zero idea how it works with windows drivers and whatever..

It all started because I was playing around with a Wondom Jab5. I really loved Sigma Studio but I really did not like the wondom quality. The noise floor was unacceptable and eventually one of the amplifier chips on the board just died.. Having fallen in love with sigma studio I couldn't just go with a minidsp and my fusion amps also do not allow you to use sigma studio even though it is beeing used behind the scenes in both devices. I couldn't find any other product with less questionable quality than the wondom or the likes...
So I got the brilliant idea of making my own xD
As a Mechanical engineer I knew that I was waaay out of my comfort zone. However, thanks to opensource projects such as FreeDSP, analog devices excellent documentation and engineering support, and youtube channels such as Phil's lab it seems it may actually be possible for me to make something that works 😍

The DSP board is working and the overall unit performs surprisingly well. I belive the limiting factors currently is mostly the ADC and to some extend the power delivery for the ADC's which will be much improved in my own design. However, I have some wierd issues that I am currently trying to trouble shoot:

1. When the ICP5 is connected I get a lot of audible noise in the speakers both white noise, a whine and some kind of periodical ticking. It goes away when the programmer is disconnected again. This was also the case when using wondom dsp's with this programmer. Im not sure if it will be different with a USBi or if its something with my design. I was considdering to add some kind of isolation between the ICP5 and my DSP but was afraid to overcomplicate things in the first go.
   Any ideas how to get rid of this? it is a bit annoying when experimenting in sigma studio.
   
   
2. I get a bit of noise and a periodical clicking noise as soon as I connect my AC/DC adapter. Even though my DSP is turned off (I only break the positive line, the negative is connected directly to the DSP board) and no source is connected. This is the adapter i use: Ac-adapter-100-240v-to-12v-3a-dc
   I also tried a 7v mean well one, while it gets significantly better its still there. Not sure if theese adapters are simply not suited for audio, or if my power interface is to simple. with limited knowledge on this matter i pretty much coppied the Octavia power input with some small changes (added a fuse and a diode to the reverse polarity circuit).
   
   
   
   
   
3. I am having some wierd EEPROM issues. Most of the time it works as intended but sometimes it just refuses to write the program to the EEPROM. The wierd thing is I do not change any settings related to the EEPROM to stop it working or to get it working again. It seems pretty random. Its not related to on time. Can this be a SPI noise thing? related to the ICP5 (guess not because sigma stuido can talk to the DSP just fine)?. Faulty EEPROM?

Please critizie all you want, I want to learn from this 😀

I was not paying close attention, but, a whole range of WIMA caps was knocked out by a lack of film to make them with no hope to replace them

The EOL was sent of Feb 28 2025 and last order was march 12th. Thats pretty dramatic.

🙁

https://www.mouser.com/PCN/Wima_WIMA_Letter_MYLAR_PET_PEN_27_02_2025.pdf

Hi All,

Florent here, Frenchie living in London at the moment.

I had different little handmade but bought sound systems in the past and decided now to build my own little stack..
Plan is for a pair of Keystone, a pair of HD15 and a pair of SyntripP.
Wood is just getting cut and I have a few queries to get through this project !

Best

Florent

Have one. It was bought 12 March 2025. Today it stopped working after a reboot because of a macOS update. Orange LED blinking.... No recovery possible.

Felt wrong when I got it. A smart phone without display that can't make telephone calls. Half of the weight of the previous one, no USB A ports at all (many many devices are USB A), 3.5 mm audio output at the front (WHY?) but worse of all a power switch at the bottom. This stupid design decision made me wanting to skip it but the flesh is weak. I guess my feelings were right, this seems a cheap knockoff of what the Mac Mini used to be and the power button is spitting regular customers in the mouth. Of course I want the thing to shutdown every day, no normal soul leaves stuff powered on for no reason. Why does it otherwise even have a power on/off switch?

It is (was...) fast but so was the previous one. Well does this prove that it is not of the known Apple quality? No it does not but it is the first Mac that dies on me (except the notorious 27" iMac) in such a short time. Less than a month old. Thankfully the M2 still was here.

Here is a new project, virtual for the time being, but I'll certainly give it a try one of these days.

It is a current dumping amplifier, but with an originality: the class A amp is based on a boosted-rails opamp. This means that the signal part of the amplifier is minimal, and that any standard opamp having a maximum supply of 36V (or even less) is suitable.

The pic shows the circuit and its operation, with the supply rails moving in a "telescopic" fashion about the output voltage, and keeping their difference ~constant.

The basic principles of the technique are detailed here: http://joebrown.org.uk/images/DualPSU/BootstrappingOpAmps.pdf

Unlike a conventional opamp amplifier, two resistive dividers are involved in the gain, and the actual gain is determined by the difference in the ratio's of the dividers.
If we call K- the ratio of the divider of the (-) output and K+ that of the (+) input, the gain can be written as (1 - K-)/(K- - K+).

I have some questions (to this always greatly helpfull community!):

1. How do I overcome the nasty impedance peak of the Tang Band W3-881SJF Full range unit? I was hoping to use this as a mid driver from 400Hz to 4000Hz in a 3 way design. But I am worried about the huge impedance peak this driver has.

2. A lot of people are writing or talking online about complex crossovers sucking the life out of the sound.. (am I thinking about impedance correction networks and notch filters here?)

I would like to pair a 10" sealed or 8" ported woofer to this driver, and have a tweeter take over on top where the 3" driver starts loosing on dispersion of energy.
but I am very uncertain how to go about this.. Any thoughts are welcome! (By the way, the speaker is to be used in a domestic situation for stereo music listening in a livingroom. My main goal here is to have as wide a range of frequencies come from a very small point, to obtain fantastic stereo imagery.

Signal transformers made according Deutsche Post specifications via Pflichtheft so very stringent high quality requirements.

I have F&G, Sedlbauer and a few other brands. Pairs are of course both the same brand and year of manufacture (most are made in 1985).

All measure equally well. They are flat from 20 Hz to 20 kHz. They weigh 970 gram a piece. When you are used to Aliexpress stuff these are something else with 0.00xx% distortion at 2 Vrms in the whole audio band. They can be used 2:1, 1:1 and 1:2. They are 80 x 90 x 40 mm. Please note that they have all the mechanical and electrical items one likes to have like shielded casing, static screen and incredibly good performance. Maximum voltage is 60V 😀 Sound quality simply is excellent.

I think 150 Euro a pair ex shipping within mainland Europe is a fair price. They won’t be shipped to any destination outside Europe.

Hello

I have WinISD installed on my MacBook Pro 16, via Bootcamp and Windows 10- when I open it, the screen is zoomed out so far that I can't even read it with readers on. I've tried changing the screen scaling, but that just zooms in on a portion if the window and doesn't allow me to scroll to the fields I need to access. Is there a solution to changing the resolution that I'm missing? System preferences doesn't seem to work, what else can I try? will installing an older version help?
TIA

I am planning a 3 way speaker with: Purifi 10 inch aluminium bass with 2 passive radiators, the Bliesma M142 giant dome tweeter
and a Bliesma T34A/B in the tweeter. Has anyone already realised a similar project and would like to exchange ideas?

I have built some speakers by combining parts of two others, using SEAS and Vifa drivers. First impressions were quite positive, however after a while they can be a but tiring/harsh. I'm interested in thoughts on my approach.

I started with some Interdyn P32's with blown tweeters and melted crossovers. These use a SEAS 25 F-EW 10" woofer. It's a small-ish sealed box which appears similar to Dynaco A25 and has fibreglass insulation. I decided that keeping this box would ensure the right parameters for the driver.

Separately, I had some Sony SSU-280 speakers that were missing the 10" woofer. These are unusual for Sony in that they used scandinavian drivers, a Vifa K10MD-18 mid range and D19TD-05 tweeter. I'm almost certain the original driver is a Peerless 830668 based on the size of the cutout and what was around at the time they were made, but I can't be 100% sure.

In any case, what i did was pulled the tweeter, midrange and crossover from one box, to make sure the cutoff frequencies were right, and put them in the other box that had the woofer matched to the enclosure. Should work ok, right?

Hello, I'm Focus! I am a mobile DJ with a passion for subwoofer construction and audio electronics. I enjoy experimenting with sound, understanding the mechanics, and optimizing equipment for maximum performance.
I'm excited to be part of this forum, where I can find a wealth of valuable information and inspiration for my projects

I have a substantial amount of these lovely transistors. Very low Cob, 1p8-2p5.

Sold in 50 quantities. $5/pair.

R

18Sound 1.4'' drivers NSD1480N 8Ω, Pair and their match Horns XR1464C . All in their boxes.
Only Europe Area. Price for all 1.000 Euros plus shipping.

https://en.toutlehautparleur.com/br...n-compression-driver-8-ohm-1-4-inch-exit.html
https://en.toutlehautparleur.com/18-sound-xr1464c-horn-for-1-4-inch-compression-driver.html

As per thread title, am trying to repair a Classe CA-2300 and any info on this amp would be great to help sort it.
Many thanks

Hey Guys
I am trying to come up with a 1 inch
Compression Driver on a budget here
Trying to stay around $100 per driver.
Is there anything that you would say is on the Warmer Smoother side of the spectrum ?
Trying to stay away from ear fatigue here.
I will be using it with
The B&C me45 horn.
Thanks

I've come up with a possible new topology for the input stage and VAS of an amplifier using opamps well above their normal voltage limits.

Background:

A negative impedance converter (NIC) is an opamp circuit that synthesizes a negative input impedance. In the diagram point A is the where the negative impedance is created.



the input impedance formula is: - R1 * R3 / R2

Here that's - 15k x 10k / 5k = -30k

So I add +30k as R4 to this, creating zero impedance at input - or put another way a current-mode input. With this circuit each milliamp of current at the input gives 40V at the output, and the opamp magically keeps the input at virtual ground.

Note that the opamp inputs are at 30V when the output is hypothetically at 40V - in other words if we can bootstrap or float the opamp supply suitably this circuit only sees a differential of 10V across its terminals for each mA of input current.

Given a real opamp capable of running at +/- 18V, and able to drive to within 3V of each rail, we have 30V of voltage differential available, so this circuit with 3mA input would see point A at 90V and the output at 120V (and similarly for negative swings).

I split R3 into two equal parts to provide a bootstrap voltage that's midpoint between the inputs and output of the opamp, and use zeners and BJTs to bootstrap the supply so it can swing up and down with the signal.




The left hand opamp does the input and loop feedback, the right hand one is the NIC.


Note that the bootstrapping takes a small amount of current from the network, distorting the behaviour slightly. However the first opamp closes a feedback loop around the whole circuit (its the input stage in effect) which re-linearizes this. Driving the current into the negative impedance converter effectively boosts the open loop gain as this integrates the input opamp's voltage signal.

I fiddled around with compensation in an ad-hoc manner, to get the simulation stable and not too horrid on clipping or square waves, but there's lots more fun to be had working on compensation on a breadboarded version I think 🙂

The ratio R1+R2 : R2 sets the voltage swing magnification factor of the circuit. This can be tailored to the voltage rails - here 120V = 4 x 30V (where 30V is my opamp signal swing range), so I've used a ratio of 4, ie R1 = 3 * R2.

I've added rudimentary diode input and output protection to the opamp stages, and the high value of the inter-stage resistor allows this to limit currents to safe levels - again experimentation with a breadboarded circuit as to the robustness of the scheme is needed.

The output stage and biasing arrangements are just lashed up as a demo for simulation - for instance voltage limits and secondary breakdown limits are no doubt completely exceeded and there's no thermal compensation! I'm not so interested in comments about these parts of the circuit 🙂

But comments on the idea are very welcome!

[PS Some of the images from posts below seem to have vanished recently, I'll include them here:

NIC_plot.png:

NIC_wave.png:

NIC_wave_detail.png:

NIC_scope.png:

The schematic I downloaded from the internet differs substantially from the amplifier I have on my bench. It shows MPSA42 devices and a different number of diodes, as well as different capacitors. The unit I'm working on has MPSL01 devices, so I suspect it's an older model than depicted on schematic I have.

Problem in brief>

Right channel clipping positive peaks at 80 watts output (observed on bench). Customer complains it's sometimes making loud static/noise.

This far, I have checked voltage drop across all .33-ohm emitter resistors. Also did an ohmmeter check of same parts. It looks like all the output devices are functioning, based on seeing about 300mV across all resistors. This draws my attention to a possible problem on the driver PCB piggyback. Unfortunately, my schematic is the wrong version.

If someone (Nelson?) has the right one for s/n 770811, I would appreciate a copy, Thank you!

I need something with a lot more glowing tubes on it. My current amp, one big hot 6AS7 isn't enough. I feel the need for a big push-pull, 3 stage, regulator tubes, lots of heat. brrrrrrrr !

This is my bid to earn a 'sticky' thread. My first attempt at a Pre-amp. It's dual-mono throughout. The RIAA is all-BJT based off the famous NAD3020 circuit. There is an all-BJT shunt regulator based off Salas designs. And there is a cathode follower output buffer loaded on an active 'amplified resistor'. Haven't tested it yet, but this thread is for piccies 😀

Hello,
This is a quick GB, I'm going to be ordering from Prufusion in early May, so if you'd like to join in, ...deadline is May 10.

If you want anything answered here in the thread I'll add it to the list in the first post. On May 10, I will be contacting interested parties through a private message.

1, HRDSTL
KTA1837 - 50pcs (1x tube)
KTC4793 - 50pcs (1x tube)
KTC3503 - 60pcs (1x tube)
KTA1381 - 60pcs (1x tube)

2x W26FX002
2x W22NY001
2x W18NX001
2x T29CF002

These came from my Next-4 of which the cabinets and filters were sold. All units are used and in perfect condition.
Price: €1700,- + P&P + PayPal fee

All units come in their original boxes except for the W26FX002.
Prefer pick-up in The Netherlands (Leeuwarden) but shipping is also possible at cost.
Picture shows one of two complete sets, can make more pictures if you are serious interested.

Hi! My name is Vit, I'm from Amsterdam. I am interested in electronics and assembling amplifiers, DACs and other devices. Here I want to find a solution to issues related to the currently available applications for playing music - Moode Audio, Volumio.

I want to run my design's past the forum as this will be my first tube related build.

First the power supply.
The high voltage section:


Low voltage section:


The full power supply PCB:


____________________________________

Now the preamp design:



First the input is buffed to maintain a constant high input impedance and remain unaffected by the feedback divider that can be changed via potentiometer RV2A.
Simulated THD is nice and low and no sign of obvious problems.

However, I am also considering another design that also looks quite good:


Distortion is slightly higher, but now is almost entirely 2nd harmonic. High impedance can also be had (scale R9) and feedback amount can be changed via R14.

What do you think about this circuit? It seems like it might be worth a try. Do I need and additional protection for J1?
Maybe the first amp circuit if better?

Also what is the best way to switch the bootstrap capacitor in and out as this drastically changes distortion and would be nice to compare while listening.
Any feedback is much appreciated.
I can attach ASC files if anyone is interested.

Hello everyone.🙂

This is the first thread I have opened here with the aim to share my experiences with you and to broaden my knowledge about electronics from possible replies.

Over the 2020/2021 winter I have built an amplifier based on A60+ boards from eBay and was quite satisfied with the result: an amplifier sounds great, is relatively easy to build and involves everything what is needed to complete the project: power supply and effective speaker protection.

Below is a photo of one channel of the amplifier.

The amplifier comes in two different versions:
A60, smaller, with 3 output pairs of transistors
A60+, larger, with 8 pairs of output transistors.

There are variety of possible versions: with different output transistors
MJL3281A/MJL1302A
2SA1943/2SC5200

It is also possible to purchase bare boards, partially stuffed boards, complete boards and also amplifiers in chassis.

In addition to this the board incorporates a solid power supply and effective speaker protection. You only have to add your heat sinks large enough, transformers, transistors and capacitors.

I have decided initially for a A60+ version without output transistors and without power supply capacitors.

I also have tested A60+ and it sounds splendid indeed. Someone else on internet said its sound is "golden" and has gone that far to state that it has "euphoric tone". He is right it really sounds extraordinary. Just read this review.

I have also done extensive measurements: it measures great. It is done right across the whole audio spectrum and beyond. I will repeat the measurements and make them soon public.

The sound was great so I have decided to spend a bit more of time and money on this project.

I have purchased two A60+ and three smaller A60. This will be my spring 2021 project.

Finally, some hints for these who decide to build this amplifier:

Only capacitors with diameter 35mm and 10mm lead spacing will fit into this board. Initially I was afraid that just 4X10.000uF per channel wouldn't be enough, but it works indeed very well.

Carefully with biasing – this is a wild beast and can quickly go incredibly hot.

Chose heat sinks large enough to have freedom to set higher bias.

Syn08 (Ovidiu) said this about implementing an Auto Bias loop here:

" I haven't see a solid non switching full solution for the entire audio band, but only partial improvements over the standard solution of an acceleration cap (100nF, in your case), which is not a solution for non switching, but only a bandaid to limit the effect of the crossover mess.

Part of this lack of solutions is of course keeping the complexity within reasonable limits; Edmond's solution mentioned above, in despite of it's stability issues, is already a rather complex circuit, and I don't think anything simpler could be designed and successfully implemented."

Click to expand...

Well, there's the challenge. A wideband non switching Auto Bias amplifier circuit that works, doesn't oscillate and blow up, and is not too complex.

To start this thread I'll post some of my findings from simulations of the LT1166 Auto Bias IC, as well as Class-i and Edmond's AutoBias2.

Feel free to post any of your ideas and simulations.

And if anyone has built a successful amplifier using an auto bias circuit then we'd love to hear how you did it, etc.

Cheers, Ian
-------------
Edit: Post summary (Edit: most recent first):
Post 303 Shows 3D views of a PCB for Post 302 circuit (now called Topology 4).
Post 302 The LT1223 again but now driving MOSFETs to demonstrate the autobias loop allows plug-in interchange of BJT's and MOSFETs. Interestingly, the MOSFET's achieve similar high BW with less drive current so 2 pair instead of 5 pair TO-92's can be used.
Post 301 The previous LT1223 CFB opamp with a CFP autobias loop is OK for 16MHz(tbc) without the CFP output stage, instead the discrete HV booster is paralleled for 50mA drive to the power transistors with a +/-9V auxiliary supply.
Post 300 The previous CFP BJT autobias loop is OK for 4MHz(tbc) with a LV LT1223 100MHz CFA with a discrete voltage booster giving low distortion.
Post 295 Bridge and current drive is easy with a HV opamp, where one load terminal is tied to input common (grounded bridge) with a floating PS.
Post 291 Current drive with a HV opamp is very easy using a resistor in series with the loads cold-side for feedback to the opamps inverting input node.
Post 287 CFP BJT autobias loop is OK for 100kHz with a 33 Ohm base pull-up to 9V. Allows a low input current (1mA) drive using a HV opamp (OPA455) with a split rail standard power supply.
Post 282 Only THT with current drive for 4 ohms suggested by Pawel.
Post 281 Current drive version for 200W into 4 ohm, Rout 500 ohms and 0.02% at 1W. Uses 2x OPA1656 LV 100mA opamp drivers.
Post 277 Class-G bridge 800W 4R using 4 slices per side for 20A peaks. Idle dissipation is reduced using Class-G plus McPherson's dissipation diverter.
Post 274 Bridge version for 400W 8R is DC input and DC output. Usescapacitance multiplier with McPherson's dissipation diverter.
Post 271 Mark Johnson query: What if the output capacitor divider capsare not exactly the same? Answer: the voltages equalise quickly due to the amps low output resistance.
Post 269 Power supply circuit to check startup with no dc blocking capacitor. Simulation shows no startup or shutdown transient to the loudspeaker.
Post 267 Input stage level shift with no dc blocking input capacitor.Uses an opamp with a -5V rail and a mirror input stage level shifterwith no signal.
Post 266 simulation using ZXT757 and ZXT857 300V complimentary pair for input stage level shift. Bias trimming calculation for output centering.
Post 257 simulation using a level shift input stage rather than a isolation transformer, allowing a standard non-floating power supply.
Post 256 mr_jj pointed out that Kenpeter back in 2010 had placed a resistor across the sensing diodes between the emitters of the power transistors to make it non-switching Class-AB! My hat is off to Kenpeter. I mention my independent finding in Post 202. The Dadson's circuit found in Post 44 here from his AES Oct 1980 article shows the same autobias sensing diode topology using a Rush spreader arrangement but with Darlington power transistors, but no resistor across the sensing diodes.
Post 254 Bench test using thean OPA1656 100mA opamp to drive power transistors with autobias without discrete driver transistors.
Post 244 Bench tests of a single channel amplifier shows -60dB THD using MUR1615 diodes and biased at 250mA. F-3dB is slightly over 100kHz.
Post 243 Shinichi Kamijo "simple TL bias" circuit is similar topology to my autobias but with a follower output stage and a non-floating power supply.
Post 235 Bridge version bench test. Two floating power supply amps on one supply, where one amp uses a small transformer to isolate the input signal.
Post 222 Tutorial on the floating power supply transconductance autobias output stage. More in Post 245 and Post 251.
Post 220 Using MUR1615 TO-220 power diodes instead of Schottky diodes gives excellent linearity. Bias can be trimmed by two resistors to 9V rail instead of two CCS's (simpler and less error prone).
Post 215 Using MJE3055 TO-220 as diodes instead of Schottky diodes.
Post 210 thru Post 214, Post 217-219. Option of using many (8-10) 1A silicon diodes in parallel per side instead of Schottky diodes so no need for a bias trim pot.
Post 205 FDC6321 CMOS stage allows high current drive without a CFP output stage.
Post 203 A prototype PCB allows stacking of up to slices (3 pair of output transistors).
Post 202 Using a HCU04 CMOS input stage with a CFP output transistors so only 1mA is needed to drive the autobias transistors. The CMOS input stage provides some gain and soft clipping and the option of thermal-SOA protection by dynamically limiting the clip level (more in Post 204). Introduced R13 across the power diodes to provides the keep-on current of 18mA in Q1 and Q2 - even when clipping. Eureka!!
-------------------------
Edit Feb 2025. Overview of development: Toward a Wideband Non-Switching Auto Bias amplifier
The challenge! “A wideband non switching auto bias amplifier circuitthat works, doesn't oscillate and blow up, and is not too complex”.Post1 aim 29 July 2021 by IanHegglun.

• I have exceeded my expectations. A non-switching autobias topology – simple, stable, scaleable.
• Two related topologies: 1) The floating supply version, and 2) The non-floating supply version.
• Several diyAudio members have suggested that I provide a non-floating supply version.
• Topology1. The floating supply version is the simplest, eg, Fig.1 below,100W into 8R, only 2 power transistors & 2 bias transistors, 2x3A diodes, a dual opamp, and a +/-9V 2W supply. Notice no Darlington driver transistors, instead two 100mA opamps operating in parallel. THD 0.1% 1W.
• 

  Topology 1: Completed Wideband Non-Switching Auto Bias amplifier with opamp driver.​
• Can be paralleled eg Post254 and bridged eg Posts274 .
• Uses two output capacitors in series. They are forced to half the rail voltage by the feedback loop referenced to half the rail voltage by a voltage divider (R3,R19). They prevent DC damaging the loudspeaker. It's is simple, effective and reliable, with negligible effect on sound quality.
• Topology2. The non-floating supply version. It is a modified floating supply version with an addition input stage where the input is now referenced to the negative rail. The input stage lowers distortion to 0.02% at 1W and a low output resistance of 50 milli-Ohm.
• 

  Topology 2: Wideband Non-Switching Auto Bias amplifier with DC input and non-floating Power Supply.​
• An alternative bias circuit, see above Topology 2 dotted area, it eliminates the input capacitor which eliminates the long settling time at turn on.
• The alternative bias circuit avoids a 3rd input stage which avoids a 3rd pole which requires careful frequency compensation. Both Topology 1 and Topology 2 do not use frequency compensation!
• The loudspeaker is protected from DC damage by the two output capacitors in series.
• Topology 2 can be paralleled eg Post257, and bridged eg Posts274 and Class-G bridge Post277.
• Topology 2 has been simulated and a PCB is underway for bench test and listening tests.
• Topology 1 has been bench tested eg Post244 & Post254 and a listening test Post157. The Topology 1 PCB needs updating for an opamp.
• 
  
• Topology 3. See Post287 and Post291.
• CFP BJT autobias loop is OK for100kHz with a 33 Ohm base pull-up to 9V. Allows a low input current(1mA) HV opamp (LT6090-5 or OPA455) to be used with a split railstandard power supply.
• 
• . . . . Topology 3. Wideband Non-Switching Auto Bias amplifier with DC input and non-floating Power Supply and no auxiliary ±9V supplies.
• 
  
• Topology 4. See Post301 and Post302
• Using a LV LT1223 CFB opamp with a CFP autobias loop is OK for 16MHz(tbc) without the CFP output stage.The opamps discrete HV booster is paralleled for 50mA drive to the power transistors. The trade off is the ±9V auxiliary supply.
• 
• Topology4. Wideband Non-Switching Auto Bias amplifier with DC input and non-floating power supply and no CFP power stage, instead the auxiliary ±9V supply and higher current opamp booster stage.

For years, I’ve been looking for an affordable device that can extract multichannel audio from HDMI and output it digitally for further processing, specifically for DSP. Keeping everything in the digital domain ensures the best possible audio quality.

My goal was to create a high-quality multichannel audio system that was also affordable, modular, and user-friendly. However, this proved to be quite challenging. The closest I got to achieving that goal is the setup described below:

Flow Chart:

1. Smart TV (Spotify and video source)
   ↓ (Audio via SPDIF)
2. Raspberry Pi
   • Receives SPDIF output from the TV.
   • Applies DSP (Digital Signal Processing).
     ↓ (4 Audio Channels via USB)
3. Okto DAC8(8 Channel DAC)
   • Receives 4-channel audio via USB from Raspberry Pi.
   • Converts digital audio to analog.
     ↓ (Analog Audio Out)
4. 2 DIY Mono Block Amplifiers + 2 Active Subwoofers
   • Each amplifier receives one analog audio channel.
   • Amplifies audio for output to speakers.

Unfortunately, this setup resulted in stereo audio only, which didn’t meet my expectations. It could have been improved by using something like FFMPEG (thanks to @phofman for suggesting this) on the Raspberry Pi to process Dolby-encrypted audio over SPDIF for surround sound. However, I didn’t have the skills or the motivation to dive into that. Getting Camilla DSP working on the Pi and getting it to process the TOSLINK input was already a tough challenge. Once set up, though, Camilla DSP proved to be a great piece of software. The TOSLINK input had a specific quirk, requiring a special power-on sequence to work, which wasn’t very user-friendly for my household.

I considered the Vanity PRO, which seemed like the best affordable high-quality solution, but for my use case I couldn't justify the cost.

Then, I discovered a post from @yulen (on DIY Audio) promoting his 5AES to HDMI Black Box, which caught my attention, @mdsimon2 expressed an interest in the device as well. The product, a converter from HDMI to 5 AES, also includes optional DSP processing via Sigma Studio. It features 2x HDMI input and 1x HDMI outputs, with up to 4K @ 30Hz output. (Note: I have since edited this post to reflect the correct HDMI connections as I made a mistake in my original post)

While the product was intriguing, I had some concerns as it didn’t support Dolby decryption. However, the built-in DSP was a big plus for me. After several emails back and forth with Yulen (thanks for your patience!), I decided to try the product. Yulen assured me that it would work well with an Apple TV set to LPCM out, which was a perfect source for my needs—Spotify, Apple Music, Netflix, etc.

I made the purchase, it cost me $278 US or ~ £220GBP for the unit with the DSP module, this included tracked shipping to the UK, and within a week or so, the Black Box arrived—well-packaged and complete with the parts as discussed, along with the DSP board. I also ordered an Apple TV to pair with it.

To connect the Black Box to my DAC, I had to find a suitable DB25 to XLR cable. I then had to re-solder the connections to match the pinout of the Black Box (Yulen does sell premade cables if needed). This was my first time soldering a DB25 connector, so managing the soldering iron temperature and ensuring correct pinout was a bit tricky, but I got it done in a few hours.

Without the DSP board, the Black Box is plug-and-play and works flawlessly. It automatically adjusts audio output from stereo to multichannel depending on the content being played (e.g., Apple Music defaults to stereo, while movies play in 5.1). I’ve even seen it handle all 8 channels of audio. Since everything remains in the digital realm, there is no loss in sound quality.

I’m currently running a 3.2 audio system. Since I haven’t set up the DSP yet, I’m only getting stereo sound and 3.1 channels for movies. Once the DSP is configured, I plan to add room correction and blend some of the rear surround channels into the front speakers. I also hope to split the LFE channel between the two subwoofers and add crossovers to the stereo signal to make full use of both subs.

Here’s the current setup, outlined in the flow chart below:

Flow Chart:

1. Apple TV (Spotify and video source)
   ↓ (Audio and Video via HDMI)
2. Black Box
   • Receives LPCM HDMI output from Apple TV.
   • Applies DSP (not yet implemented).
     ↓ (4 Audio Channels via AES/EBU) + (HDMI video signal to TV)
3. Okto DAC8(8 Channel DAC)
   • Receives 4-channel audio via AES/EBU from Black Box.
   • Converts digital audio to analog.
     ↓ (Analog Audio Out)
4. 1 DIY Mono Block Amplifier + 1 DIY Stereo Amplifier + 2 Active Subwoofers
   • Each amplifier receives one analog audio channel.
   • Amplifies audio for output to speakers.

Images of it in my application:







I ordered the required DB25 cable from here:
DB25 Cable

Additionally, I’ve ordered a generic UART USBi module and DB9 connector to communicate with the DSP board.

I support small manufacturers and appreciate the creativity and support from the DIY community, so I highly recommend checking out Yulen’s Black Box if you’re looking for a similar solution. Yulen also makes and sells other innovative products, which you can find on his blog (use a browser translator) and on his TikTok page, @SoundProAudio8.

He also has some upgrades for the black box in the pipeline, one is including HDMI ARC. Personally I would like to see 2x HDMI input with one being HDMI ARC, a boost in the frame rate at 4k to 60hz even though 30hz has proved fine so far and HDCP decryption. Overall I'm very happy with product though and even without any upgrades it's perfect, I'm looking forward to utilising the DSP in the near future. Note the unit already has 2x HDMI input and 1x HDMI output

Yulen is very patient and helpful but please be mindful of the language barrier.

Has anyone else used the Black Box and if so what's your application?

SIT5 review on 6moons: https://6moons.com/audioreview_articles/firstwatt-sit5/

It's only the beginning and to be continued.

Last week TI put a preliminary datasheet online for the OPA1656, a low noise, very low distortion op amp targeting audio applications and fabricated in a CMOS process.

http://www.ti.com/product/OPA1656

I just checked and the sample button for the prototype devices is now active:

http://www.ti.com/product/OPA1656/samplebuy

I started this project in 2017 with the designer of the OPA1622, and although I had a change in my role at TI before the device was released to market, I'm still very proud of what was accomplished. The goals of the project were fairly straightforward:

1. Start with the OPA1688 architecture which gives very good distortion performance, even with low-impedance loads. Beef up the output stage even more.

2. Push the input voltage noise down as much as possible. Ideally below the OPA1652 and OPA1678 levels, which are fabricated in the same process.

3. Don't let power supply current limitations get in the way of performance. OPA2134 and NE5532 both have power supply currents of about 4mA per channel, and have been widely adopted in the market (understatement). That seemed like a reasonable target for the supply current of the OPA1656 as well.

A quick snapshot of the OPA1656 performance specs:

• 2.9nV/rtHz broadband voltage noise
• 6 fa/rtHz broadband current noise
• -131 dB THD+N at 1kHz, 600 ohm load, 3.5Vrms signal, 80-kHz measurement bandwidth
• 53 MHz gain bandwidth product, 24V/us slew rate
• >100mA output current
• 4.0mA typical supply current, 4.5mA max

I'm looking forward to seeing what people think of the device, and hopefully it finds its way into a few projects on here!

Christmas comes a bit early this year! The single channel version of the OPA1656, called the OPA1655, released yesterday and the product page is now live on ti.com: https://www.ti.com/product/OPA1655

It doesn't look like units have been stocked yet for ordering, but they should be in-stock soon.

Hi there,

I'm confused with Surface Mount electrolytic capacitors identification : are those 33µF/10V or 68µF/10V ? Please note I've been unable to measure any of them as they are all dead, their electrolyte leaked all over the PCB, causing a lot of damage.

Thanks !

Hello all
The racer8 driver that I am testing is measuring at 2R impedance using DATS. Looking for recommendations on a good amp module to suit. Around 50-100w would be plenty

Seems the TPA3118D2 is 2R capable, but not sure which boards support this properly and are reliable for long term use

Will be run of a 12v battery via a DC upstepper

Anyone know how these two compare? Obviously the LM3886 is Class AB, and the TPA3255, Class D? But I've read good things about the TPA3255, and I even saw a TI expert in a forum recommending ditching the LM3886 for the TPA3255. Anyone heard both and can comment?

Hello. I have a question about modeling the acoustic design for a low-frequency speaker. I am confused by the different final frequency response with and without the "show effect of inductance" function. Which of these options will be closer to the real response?
Blue line with inductance effect. 2 dB differecnce at 55 Hz 😕

Over the years Ive built many indirectly and directly heated amplifiers, and always if some dht was in the system, it sounded better in a way I cant quite explain. A lot of people build amps with them, they even started to be made again for new amplifiers etc. From the builders standpoint it has only disadvantages - you need separate filament supply for each tube, well filtered, current regulated in the best case, everything that happens on the cathode, every small hum or noise gets amplified. They are more microphonic than indirectly heated tubes. Now I have DAC output stage with the 45 tube used as a preamp tube. (if anyone wants more details, its choke loaded with output capacitors). And the same thing happened.
Like I said I can not even properly describe the sound. It never is boring every track is interesting, I actually enjoy music now. I stopped thinking about how to better the schematic, I just dont know what to play next. The sound is big, like even at lower listening values. Like it comes from nothing in the air. The voices and treble are heavenly. Music is now actually touching me emotionally way more than before. Like the simplest description that Im always saying is magical emotional sound. That just is not quite there with other tubes.

My big question is WHY, what electrical factors are different than from indirectly heated amplifiers? I really want to find out why this happens. I wondered the same thing in electrolytic vs foil caps in the power supply, but the explanation here was quite simple, being way lower losses in the dielectric, vibration not being a problem cause the foil caps are sinked in oil. The tangens delta difference between electrolytic and foil cap is like 0.3 vs 0.001. Plus the foil caps are way better at filtering higher frequency noise etc. But with DHTs I still dont know. Why nobody measured this?
Its the exceptional linearity (the curves are perfectly spaced and also as flat as a ruler).
Or its some microphonic feedback from the speaker vibrations getting to input tubes?
Or its the special care that you must take while building a DHT amp compared to indirectly heated amp?
Or its a different cause? I still dont know, does anybody has any ideas?

I want substantial horns for a home cinema speaker project, from JBL 2384 size as a minimum up to Klipsch K402 size. I won't buy from the US while they slap us with trade war tariffs, so do any Aussies either have, or know of any for sale already in the country? Or can recommend a local equivalent? Or even have a horn to loan that I can pull a mould from? (I expect it's too much to hope to find a ready-made mould)
If not then I may do a mould from scratch perhaps modeled in ATH software.
I would probably try a foam male mould, simple wet layup carbon fibre/Kevlar (well, not actually Kevlar,😉 probably a tariff free Chinese equivalent)
Would there be any interest in such a project? It's practically a patriotic duty🇦🇺😃

David

I salvaged a pair of mini piezos and was thinking of adding them as super-tweeters.
Do they need a cap? They were originally installed behind 2.2uF?
Do they need a resistor? What does the resistor do?

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I know this forum excludes politics, but I don't consider this a political issue, rather a universal existential threat. This is devastating news and I feel it's important to spread awareness over every avenue I can.

ELEKIT TU-8888 Monoblock (available now)​

Another wonderful products from Mr Fujita...
PCB type DIY KIT...


















Here below are the spec of the monoblock amp.
Tube usable : KT series from 88 to 170 (for output tubes) KT170 recommended
EF86 x 1 and ECC82 x 1 (driver tubes)
Max. output : Over 50W/unit (with KT170)
Manual bias adjustment - A meter at the top panel
No headphone feature
SP impedance : 4ohm and 8ohm
Input x 1
Balance adjustment volume (with 41-point click) on the rear side
Coupling capacitors : 3pcs (100n 450V x 1, 470n 630V x 2)
Max size for the coupling cap :
100n 450V ... D22 x L44 mm
470n 630V ... D20xL57 mm
* as of now and could change the spec a bit.
Tubes are not included.
*The amp is designed to use custom made Lundahl LL3733"
PCB for OPT and harnesses are included in the kit.

There are only 30 pairs or 60 pieces for USA/Canada in December​

​

Price after Dec 15, 2024 $1,475.00 (will ship from Vancouver Canada)​

I'm doing some playing around with active filter designs, and I'd like to get swept filter responses, showing the frequency response of the filters. I'm used to using a vector network analyzer for looking at RF filters, and I'd like to do the same at audio frequencies.

I've got a Focusrite Scarlet 2i2 3rd gen that should be able to do this, but I'm having trouble figuring out what software to use. I've spent some time poking at REW, and it doesn't look like it supports measurements like that. Are there other packages that will do that?

bye

I would like some input on this.
I am repairing a build of this amp where it is humming badly as the regulator transistor is blown. The particular device is hard to obtain so I tried something similar npn of 120v rating and it worked for a while but then blew as well, I imagine due to over voltage as the B+ is 350v in operation and about 400v at switch on.
The build had worked ok for six months or so but I wonder if the design is a bit vulnerable and could be improved.

Are there any similar amp designs I should consider for inspiration on improving this?

Many thanks

I've got a couple crates just sitting on the floor that I'm already outgrowing. So I needed something with a bit more capacity, and getting the vinyl up off the floor would be nice too...

I used the design here as inspiration. I don't anticipate needing that much capacity anytime soon, and I didn't want something that bulky sticking out into the room. Stacking single rows left-right simplified the design, omitting the center divider.



Lumber was sourced from Menards. I can give more details if needed.

The width of the lumber I used for the side panels and bottoms allowed for a small ledge out front to display the "on deck" sleeves. I ended up routing out a flute along the top edge to create a lip that keeps the sleeve from sliding onto the floor.



I decided to give the side panels some shape. I made a template/profile board and used a flushing bit on the router to transfer the shape to either side.



Simple dowel pin and pocket screw construction.





To prevent the bottom panels from sagging from the vinyl weight, and stiffen up the structure: I added some screws from underneath the bottom panels up into the front and back boards (not shown). It just wasn't needed for mockup purposes so I drilled the holes later.

The Synopsis:

"My thesis is that music written for the ensemble of two violins, one viola, and one cello constitutes the musical art form that most nearly approaches perfection, both in its past achievements and its present possibilities. The greatest minds and most perceptive dispositions find in the literature and performance of string-quartet music an endlessly self-renewing source of wonder and delight. The string quartet is a most felicitous meeting of potential and realization."

There are several YouTube embeds, and a link to a Qobuz playlist.

The pull quote above is the Subtitle of my Tracking Angle Review of the Philharmonic Audio BMR Monitor. BTW, the ArgentPur GaN-FET monobloc amps are AMAZING. Perhaps they are even "The Poor Man's darTZeel." That is, if Poor Men can afford $5,900/pr. SOTA power amps!!!

John Atkinson's measurements and Robert Schryer's review in Stereophile are required reading.

I have built more than a dozen loudspeakers of my own design (with help from outside experts!), and I can't grok (dating myself to the 1970s) how Philharmonic Audio can sell these for $2000/pair.

I noticed that Amazon UK had some In Phase Car Audio XTC17.2 woven glass fibre coned drivers for £ 21.11p, so I decided to order them and make some omnidirectional speakers with them

The driver is mounted on a small chamber that is connected to another, larger chamber by an aperiodic vent. My initial plan was to support the top chamber on coil springs with a foam seal, however the cast iron weights that became available ( the scrap bin at work ) are to heavy, and the temporary foam spacers that I used for initial testing work quite well

Stumbled upon this interesting board on aliexpress, comparing the prices with other ADSP21489 sharc boards this is peanuts, and already with 2 ADC and 3 PCM1798 DAC boards for a 4in/6out system. Anyone have this?

Lusya ADSP21489 development board ADC PCM1804 Input board+DAC PCM1798 output board 4 in 6 out processor B4 007-in Replacement Parts & Accessories from Consumer Electronics on Aliexpress.com | Alibaba Group

MUSES02 is currently $44 each plus shipping at Mouser. Anybody know where to get genuine MUSES02 instead of fakes at a lower price? 4 x 44 + 8 shipping = $184 for four op amps plus tax so ~$200. Not willing to pay that.

I have a 5v regulator with a 2 wave rectifier.
The secondaries powering it are from 12.6vac heater secondaries. (tube amp)
The heaters have been elevated with DC so now I am trying to connect the reg board.
I have been told that I should float the ground of the regulator and relays but not sure how that is done.
Do I ground the the relays to the ground on the regulator board and nothing ground to the chassis?
Do I make the ground reference the junction point of the two 100ohm resistors from the heaters where they connect to the DC?

Hello there all,
I thought that it might be interesting to 'collect' in one Thread the myriad of amplifier-output Stability Networks.
I would love to see variations of these networks AND a general discussion of the subject 🙂

since i am in a good mood i am starting now also a reggae thread. no matter if roots or dance hall. lets start with dub:
Sly & The Revolutionaries With Jah Thomas - Rizla - YouTube

Hi to everyone,

I'm looking for the service manual of an old DBX 224 mkI (round buttons, none on/off mains switch).

Thx a lot in advance

Hi,
I was searching for a good quality sound card with SPDIF input so that I can source audio from my TV (with SPDIF out) and provide 6 discrete good quality DACs for an active 3 way stereo speaker project. I am expecting quality than minidsp (ADAU1701 based ones).

Is this sound card Creative Sound Blaster Z SE good enough and a step above minidsp?

Thanks and Regards,
WonderfulAudio

Hi All,
I know the question is somewhat dumb, but the search didn't yield any clear answers, so: I'm looking for an MC cartridge in the $1000 price range. I have a light ProJect 9cc Evolution tone arm that weighs 8g, so certain types are out of the question. I looked at the following types more closely, but in the end I was confused: Excalibur Gold Hana ML AT-OC9XSL Sumiko Songbird Low AT-ART9XI But I am open and grateful for further suggestions.

Hello, my name is Jean-Michel and I very pleased to join this forum. I own an AXL amplifier from Elektor that I build more than 30 years ago!
I am not using it for many years but I plan to update it with non inductive 0.22 Ohm / 5W resistors and recap it.