I've been working on a bass 8k (power supply seems identical to MD8000.1 so I've been browsing repair posts for those as well). I've replaced IC9, IC3, and IC1 and any accompanying SMDs that needed replaced. I replaced both power supply, output fets, and gate resistors. With the rectifiers pulled to isolate the power supply I can't get it to build a square wave on powerup. IC1 builds a perfect 40khz square wave, IC3 not so much, it tries to build a very odd signal initially and then goes flat once the amp goes through it's power up cycle. While testing R150 went up in smoke. I'm running out of ideas and looking for some guidance. I will be buying Perrys book as soon as I have the funds as well

Any help is greatly appreciated, I have a lot to learn and am very appreciative of any guidance and tips. Thank you!

I’m about to embark on building the Lampucera DAC, as described by Serbian YouTube star iiWi, You can see the video here:
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He claims this is the best DAC he has ever had in his listening room.

The DAC is a precursor to the Lampizator line developed by Lucasz Fikus. Details, documentation, from iiWi here:
https://drive.google.com/drive/folders/1MvSMdEsZ8DPtGMXrzUgQ7ceyAVS86uxO?usp=sharing

Ebay starting kit from HKaudio1 (Lawrence, who has been very responsive):
https://www.ebay.com/itm/1863217614...zPANM_6Rl2&var=&widget_ver=artemis&media=COPY

I’m probably not going to use Lawrence’s included tube output stage, instead following iiWi’s version with the 6N6P [but maybe experiment with the eBay one first].

My first two question areas, for which I am seeking advice:

1. What do you recommend as a source for metal chassis that is easy to mod, and large enough for transformers and giant capacitors as iiWi had?
2. If you look at the schematic, it is based on 220V transformer on input. I have US 120V input. What transformer changes are needed?

• A. Best to stick with toroidal transformers? Seems like a lot of audio guys prefer laminated. Can you recommend any source that is up to the standard here?
• B. I assume it’s easy to find a 120V to 6.3V transformer for tube heater. Any suggestions?
• C. It looks like the anode supplies start with 120V. Does that mean I don’t need any transformers for them?

If anybody has done this, and/or has advice to offer, I’d be most appreciative.

I'm a 2 year student of Ho Chi Minh university of Technology, Electrical & Electronic Faculty. I have passion on making amplifier so that is the reason why i choose that faculty.
It's nice to meet youuu.

I got this amp with the power supply and output sections both having blown fets. I replaced the fets and now when I power it up the power supply starts fine for the first 3 seconds Drawing .4 amps. But when the output stage kicks on the amp draws current for a tenth of a second and the output side shuts down. And keeps cycling this way

Dear all,
more for experimenting than of any practical value I would like to ask
this nice community for inputs & opinions on two related, highly theoretical projects,
the first one realistic, the second one utopia. I asked ChatGPT a bit for answers, but I'm not sure
how accurate the information gained is.

Project #1 (software):
Task: Retrieve digital audio samples of very high quality.
Split the audio range (20 Hz - 20000 Hz) of these samples into non-overlapping, logarithmically spaced bands of a variable number "n".
"n" variable for experimenting, f.ex. n = 1 up to 1000.
Measure total amplitude of every single band and apply this amplitude to a sinus wave of each
band's center frequency. Add all these new sinus waves together again to receive a summed signal which is a 'reduction'
of the source's audio signal (Fourier etc.).
Base Questions: How many bands "n" at a minimum are necessary to understand voice signals again from this source signal reduction
& resynthesis ? And how many at a minimum for 'rather' uncompromised audio quality ?
(Interestingly modern cochlear implants (of course no HiFi quality) use the very low number of 8 - 22 different frequency bands,
that are overlapping, however, and thus correspond possibly to 6 - 12 different bands only, effectively !)

Which software(s) then could do this job for sample source signals efficiently and accurately, but not necessarily in real time ?
(the problem is of course more complex, because not only amplitudes but also the phases of the signals also are important
across these manipulations).

Project #2 (practical utopia):
To build a loudspeaker with a large multitude of single low cost chassis.
Each chassis emits only one single fixed frequency, and each is triggered by an upstream
(cheap & as small as possible) amplifier that receives modulating input only from single sinus waves
(from Project #1).
Question: What is the minimum number "n" of chassis with logarithmically spaced fixed sinus signals
to recover 'rather' optimum audio quality (20, or 40, or 200, or 1000) ?

thank you kindly for any input & critique,
good night,
FrankieS

I've had them for ages and it's time to move on. $600 plus $20 shipping in US . Probably over $70 abroad. Only transformers are for sale.

i have acquired a dynaco 150, she in a bit of a sorry state due to the previous owners tinkering, it runs but has intermittent noise in one channel, so instead of the usual recap and rebuild i was wondering if anyone had used the chassis and transformer and built something completely different inside, maybe a leach? not really interested in the update my dynaco path. so fire away, who has done what and what are some ideas. cheers.

So I have an unfinished over-the-top preamp project that I never finished using kit that is now un-obtanium. What is needed left to do is mount the Raleigh boards to the Bent chassis and wiring it all up. I am not sure what is a reasonable price to ask for this and would appreciate feedback regarding pricing, hence this post. Not sure if that is onside or not. Of course, I could bust out my soldering iron and wire it all up and sell it complete, but I don't seem to have the time and I am a bit unclear the best way to handle grounds when merging the two kits.


Bent Audio full balanced TAP-X with Slagleformers
This is loaded version of the Bent TAP-X, which has four Dave Slagle autoformers inside, fully balanced input to output. It has 4 balanced/2 single ended inputs, 2 balanced/2 single ended outputs and operates seamlessly switching among them. This one also has the Larger and Deeper Case, which permits a DIYer to add to it**. The TAP-X provides 1db steps and +7db gain, though passive. It comes with the very classy and heavy aluminum remote that switches all front panel functions.
Paid $2500 in 2014

**K&K Audio/Raleigh Audio Extreme Linestage Premium Version Kit with amorphous core iron, 6H30Ps, upgrades caps and resistors.
Kit includes Premium Line Stage assembled and tested by factory. Lundahl LL1674 amorphous core Output transformers, Lundahl LL1676 amorphous core input transformers (assembled on their own board), Lundahl LL1683 power transformer.

My kit does NOT include Analog Input Board and Select Switch, 12V Relay Power Supply, the Stepped Shunt Attenuator, nor the Raleigh Chassis from the Raleigh Kit as these tasks are all provided by the TAP-X above.​

​

Paid $2000-2500 back in 2014.
I still have the instruction manuals for each, if I can locate them. I have the Schematics of the Linestage and PSU as well from Dave Davenport. What is needed left to do is mount the Raleigh boards to the Bent chassis and wiring it all up. Also, the top plate of the bent chassis will need some holes to allow the Raleigh kit to breathe if you want to keep the lid on. I bought this before a major move and then never finished the project before moving permanently into the full active speaker setup (JBL M2s) which doesn’t require a preamp.

http://www.bentaudio.com/index2.html

http://www.kandkaudio.com/line-stage/

I can take photos of all the above, but this is more a pricing thread.

Got this PT below, as you can see it has 2 235v @ 60ma winding. Can I connect terminals 3 and 4 to create a center tap for a 235-0-235v @ 160ma?

Also the input is 115V @ 50Hz how will this be effected by a 60 Hz input.

Wanting to use it for a preamp.

BL

Sigh! Brings back some fond memories of the original L'Amp!

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Dan

As naming suggests its going to be >1kw amp, design will be similar to the McIntosh 1.25kw amps but majority is going to be designed by myself from scratch.

Amplifier part:
It will be bridged monoblock = two separate amps in one chassis which feeds one common autotransformer with floating output. I have already successfully built this concept in my “MC502” and liked it very much.

Each amplifier is going to be fully balanced classic, nothing new or special. Input diff populated with ONsemi 2n5551/5401, Voltage amp stage uses fast KSA1381/KSC3503 with local compensation to tweak square as needed. As pre-drivers I want to try use Toshibas TTA/TTC004. As drivers classic and powerful MJE15032/33. No need to use anything extra fast here as everything is quite slowed down and compensated to match output transformers anyway. Drivers will feed 8 pairs of MJL1302/3281. Power supply voltage is going to be about 2x65Vdc and each amp will drive approx. 2,7R load.

Schematic:


Output stage transistors are split to two separate heatsinks, 4 pairs on each. PCBs are going to be interconnected with locking type IDC ribbon cable which connects main drive as well as temp protection sensor. Bias sensing is only on one PCB done by small to92 transistor sitting flat, directly in the middle of output transistor on top of the package. I plan to stick it there with thermal grease and whole assembly with PCB will force it to sit flat in there. This should provide quite quick and effective thermal sensing and bias tracking.

I have tweaked PCB layout and all the feedback sensing on amps PCBs the best I could to mix all the feedback from both split PCBs + output transformer, well the output terminals - so even the internal wiring is compensated 😉 Power traces are laid on PCB borders around for minimal effect on audio paths, with local low-esr blocking for each output transistor separately. Power and signal grounds are completely separate and going to be connected with separate conduit to main caps, the central ground.
Both PCBs of one amp are mirrored so all NPN/PNP output transistors are going to be on the same side when PCBs are oriented against each-other. This should ease up all the wiring. Below are a few pics of amp pcb:



(its still work in progress and don't have all the parts yet)

Audio inputs
are on small extra PCB which enables the use of balanced or unbalanced signal similar to mac amps. There is small switch for selecting the input used. As invertor I am planning to use OPA1611 as I feel that one is going to be most neutral of all. I want to make it as good as possible so I incorporated PP audio input caps, to fit them somewhere, they are going to be populated on the bottom side of the board. On this small board there is also small relay for audio mute, which shorts the inputs when amp turns on/off. There is also opto-isolated remote possibility to turn on/off the amp remotely.

This board also basically makes the common audio input ground of the amps (10k), the 100k input resistors directly on amp boards are basically just prevention for cable faulty.
Schematic:


PCB:

If you had a preference in a waveguide equipped dome tweeter, which one would it be?

It could be a tweeter that already comes with a WG or a combination of tweeter and WG you came up with.

There are a few which IMO are an afterthought just to be trendy, but tweeters which are engineered with the WG as a complete design are actually not that abundant.

My favorite soft dome in a WG is the Morel CAT378. It just does everything really well and can be crossed sucessfully 1st order with just one 3.3 - 5.6 uf cap. There is enough dampening at Fs to not need an LCR, but I still prefer one.

Mr Ohashi's new book will be available in early August 2025 from Amazon.co.jp

Hi There
I just did a recap job on the Amp a couple of days back. I put it back together last night.
The Amp is going into protect when I turn up either of the volumes. Seperately. The fans speed up aswell.
I'm only turning them up one or two notches.
They come out of protect when I turn them back down. The fans slow down too.
I'll try again tonight and see exactly what its doing. Lights etc.

I'm waiting on some BNC male plug to Banana plugs so I can use my scope leads with my multimeter.
A lot safer for testing. I can use the 10x aswell.

If anyone has the proper CA4 Schematic it might be of help. Ive got most of the other ones.
Cheers

BTW. The Amp was known to be going into protect before the recap. I just didn't test it beforehand.
I was under the impression it was in Protect full stop.

***** 03/03/2024 Update of project scope => move from UAC1 to UAC2 ******

Hello,

I'm putting on the bench someting in my head since a long time, that should not be too difficult to achieve for ones with know how... but could not be as easy for me ;-)

I want to program a "simple" USB to I2S, 8 channel device, UAC2, single sampling rate (48kHz or 44.1kHz), with Asynchronous mode.

Why UAC1: because ST proposes some UAC1 libraries, and no UAC2 ones (at least officially). UAC1 works without drivers on Windows and Linux.

SB Full Speed (FS) allows for 8x 48kHz x 1- bits (or 4x 48kHz x 24 bits). Great Monitor studios like Neumann KH150 have internal single 48kHz sampling rate. Many people consider that CD quality is "sufficient" and don't race for more bits, more Hertz. It is easy to find stm32 boards with USB FS, and more difficult with USB HS.

This would aim at providing the connectivity part to a 8ch DAC like ES9080 or AK4458. Overall target is 100% function and 99.5% performance of top products. for that niche need of multichannel. It could pair with RPi / Linux DSP offers like CamillaDSP for active speakers (or speakers / subwoofers combos...).

Plaform is a STM32F4 dicovery board to start with, then could be a STM32 black pill (seems to fit the purpose), which pave the way to dedicated board if needed. Those platforms unfortunatly have SAI, but if done well, the different I2S peripherals can be synchonized as slaves from a master, or all slaves from an external clock. A blackpill could be the USB "module" of a DAC board.

I would be happy if the the code could rely "as much as possible" on HAL libraries, code generated by STM32CubeIDE, and ST USB middleware. But, why did they made that so complex, with so much abstractions, while still needing to dig in all "layers" to fit/finalize code, and not really robust... I reallydon't like it so much, and it does not looks nice to me. But it should ease future portability (at least try to).

Intention is Open Source for the application part (not an expert about ST "mixed" licence for the USB stack but should be OK for DIY community).

Oh, if it already exists on Github or elsewhere, and I have not found it: let me know. I will be super happy ;-)

Current understanding is that, based on existing stereo code, I only need to:

• find all locations where the number of channels impacts the code
• change the nuber of channels from 2 to 8,
• ensure the consistency of the buffer size,
• on periodic basis, slit the 4x2 channels in sequence from the inputs to 4 distinct buffers that will each drive an I2S (through DMA)

Help of people knolageable about USB UAC and STM32 will accept to help... and I may have stupid questions.

I have an almost working stereo code based on ST examples. I have a first version that declares 6 channels, which is not working. I will come tomorrow with some questions...

Go 🙂

JMF

Below is a schematic of a German phaser instrument effects unit from the late 60s/early 70s called “Rotor Sound” and manufactured by Schaller. “Rotor Sound” alludes to the sound produced by a Leslie speaker cabinet. A demonstration of the effect produced by the unit can be heard here.

Similar to the vibrato units Hammond made for its organs, the Rotor Sound uses a saturable reactor as part of the effects filter (as seen at the top of the schematic). The effects filter itself is comprised of a 18-rung ladder network of low-pass filters, the series elements of which are the DCR and the inductance of each reactor’s “power” winding and a capacitor to ground as the sole shunt element.

Driving the reactor’s control winding is a vactrol-based oscillator (lower middle of schematic).



The saturable reactors in the device are two-winding P14/8 pot core transformers:


Someone else measured these saturable reactors; the power winding (the “in circuit” winding) is 2.2mH with a DCR of 65 ohms. The schematic itself does not denote the inductance; all it states is that the total resistance of the power windings in series is 800 ohms (800/18 =~ 44 ohms each).

What I need help with is understanding how to look at the effects filter. My understanding so far is that when the current through the control winding is low, each rung of the ladder network is a second-order LCR filter. When the current through the control winding is high, the core of the reactors saturate and the inductance in the LCR drops significantly, changing the filters topology into that of a first-order RC filter. However, I feel like this is the wrong way of looking at it as daisy-chaining 18 low pass filters is not going to produce an easily calculated response at a given frequency. Still, I feel like this shifting of topology twice per cycle of the LFO is key to understanding the function of the effect.

I’m asking for insight because I have managed to salvage a couple saturable reactors from some Hammond vibrato units and would like to repurpose them for something closer to the phaser schematic above.

Thank you in advance.

I have a box of 8 NOS 3C24 tubes, along with 7 sets if EIMAC HR-2 heat dissipating top caps (misplaced 1 set) for sale. Left DIY quite some time ago and now going through and slowly selling off my pile of parts.

They are US Army/Navy made by N.A. Philips Co. US made. Boxes have date codes as well.

$500 CAD for the lot.

For sale these amazing speakers based on TB W8-1772 on Bob Brines project.
Speakers easy to drive with detailed sound and a great bass response. Unbelivle.

I am looking for the following PAIR of Dynaudio Midranges & Dayton Audio Woofers:

Dynaudio D54 or D52 (with slight horn loading) Midrange Dome Drivers
Would consider the D54AF / D52AF midrange dome drivers as well.

Also looking for Dayton SIG270 (Signature Series) 10" Aluminum Woofers as well.

Let me know what you have.

I have a US Mailing Address and I will pay via PayPal.

Hi !
I have been following Pete ‘s work, and i was ready to order his DC Filament supply boards on eBay for a 300B project. And suddenly, his shop was empty and no reply on his e-mail.
Does anyone know if he’s out of business?
Have a nice day!

Best regards
Thomas

Witam, jestem z Polski. Lubię zrobić coś samodzielnie. Kupiłem używany dac Ad1862 miro. Szukam porad w dalszej modyfikacji.

Up for sale a perfect combo - MINISHARC - COMPACT 4-IN 8-OUT AUDIO PROCESSOR BOARD WITH FIR CAPABILITY, VOL-FP, AN-FP AND DA-FP, MINIDAC8, Remote.
Everything in perfect working condition. I used it as a crossover with my 4-way open baffles.
Very much the same as miniDSP Flex Eight.
Downsizing and don't need it anymore.
More info - https://www.minidsp.com/images/documents/miniSHARC User Manual.pdf
Asking $375 OBO

This is a thread to make announcements and highlight new products that will be coming out in my shop on Etsy.

Here is the link to the store:
https://www.etsy.com/shop/XRKAudio

Products to highlight as of May 3, 2023 are:

RTR BTSB with Tube Buffer - HypeSET (preorder):
https://www.etsy.com/listing/147415...499&click_sum=cca02e94&ref=shop_home_active_1

RTR BTSB Panel Mount buffer:
https://www.etsy.com/listing/137689...619&click_sum=dd1364a2&ref=shop_home_active_2

RTR SSR Speaker Protection:
https://www.etsy.com/listing/932716...41&click_sum=483bacd9&ref=shop_home_active_15

RTR TPA3255 Class D amplifier:
https://www.etsy.com/listing/755264...34&click_sum=c1251dcf&ref=shop_home_active_24

And I will soon add pre-orders for the HyperSET - a BTSB with a SE triode tube buffer and volume control - please stay tuned.

Hello All,
Due to lifestyle changes and some elderly age conditions, I have come to the realization that I will not be able to complete building my inventory of amps, dacs, preamps, etc. So to start things off I have the following items for sale.

I have built the boards to be a dual mono VH4 with completed Rev1 & Rev2 mods. The module pics are attached below. I am only charging for the big ticket items, so, the price per module is 90 usd. These pcbs have not been powered.

Thanks,
MM

I designed this amplifier. The original page is lost.
There are a lot of people asking for the parameters of my design. I re - update the web page.
To facilitate their acquisition

I got two Carver TX-11 tuners and I got them both to work, but power supplies seem to run hotter than a solid state tuner ought to. I recapped one of them, replaced the 22 ohm 2W power resistor with a new 3W wirewound Vishay PAC series. Still, that resistor heats up to 200-210 deg F (93-100 deg C) in normal use.

The 2SD330 power transistor runs about 140 deg F at the heatsink. All other PS components run at near room temperature.

If anyone out there still owns a Carver TX-11, I would like to know how hot it's supposed to get in normal operation, just so I don't go chasing a fault that does not exist.

Schematics attached, PS is at bottom right, R701 is the hot resistor. Unfortunately I am not skilled enough to calculate the as-designed resistor's power dissipation from looking at the schematics.

All feedback is welcome. Thank you in advance!

Wayne's BA2018 with Audio Academy VCU Muses volume control. Built according to Academy Audio's instructions.
Comes with Eizz selector and Lehle transformers for Balanced output. Not in the picture is a remote control for the VCU.
Needs a +0- 14VDC power supply.

€ 175 + shipping.

I am trying to find out how to help the admin of this site. I am not sure if there is anything other than donations that would be of any assistance but if others like myself could all contribute a little it might mount up enough to make a difference. Any ideas?

It can happen to anyone I guess. Simply, that the phones were not plugged all the way into the HP jack on my Phonitor SE, and I was letting it warm up. By the time that wanted to listen music, one channel was out, and even a burning smell came from the amp. Taking the top cover off allowed me to quickly witness the trouble. Two of the SMD resistors on one channel board were burnt right off. I bought this directly from The Music Room a year ago, but highly doubt that they will be much good in this case.
Having said all of this, my two choices are to find a schematic for analysis, or have it shipped to a qualified repair shop. Oh boy. What say you?

Hello All!
Found this forum through various searches on DML technology, it seems to be the best aggregation of information on the internet in that regard. Got curious enough about what was so unique about the sound that I just had to hear them. Learned enough to build my first pair and I'm hooked! Came to say thanks and perhaps learn enough to contribute down the road.

Unfortunate work circumstances are forcing me to sell off some of my gear including my work office system since I am losing my office.

Here is a list of everything I have for sale. I can provide more pictures so please ask.

- F5m built into a repurposed Ross Mega 800 amp chassis that was powder coated black. I set it at 1.2A since I used an Antek AS-2218 and it’s the size of a 3U chassis. - Asking $500.

- Nelson Pass Front End Preamp built into a repurposed 1U server chassis. Grayhill switches for power on and input, 3 inputs, and one output, SMPS filter, RK27 Alps volume pot and symphony polypropylene film output caps. - Asking $150.

- H2 Harmonic Generator with XRK simple capmx, low noise TPS7A low noise voltage regulator, and upgraded 10uf film caps built into an Amazon purchased black chassis. Set for 9 DB gain but easy to change resistors for unity gain - Asking $125.

- Whammy headphone amp with 2 inputs, output, Opa2134, and Belden wiring built into an Amazon purchased black chassis - Asking $300.

- LM3886 Integrated amp built into repurposed Bogen chassis with 3 inputs, Antek as-2222, soft start, speaker relay, and modified XY boards with added schematic changes recommended by Tom with Neurochrome. RK27 10k volume pot. - Asking $350.

- Amp camp Preamp and Amp Camp mini combo with two SMPS filter for each unit. All built onto stacked ACP grounding boards. - Asking $400

- Fostex P1000E speakers from Madisound. - Asking $200

- Sigma 11 PSU in black Hammond chassis. Triad transformer and set for 24 Volts. Perfect for any of the preamps or headphone amps that take a single rail. - Asking $125

We can discuss shipping costs and for some items I can offer to cover all or half.

I have a number of these high voltage HARRIS MOSFETs. 500V-13A, 150W.

I have them in two varieties.

Open to offers.

R

I have a number of these in TO-3 can. Open to offers.

R

Hi all, I'm seriously considering building the Sabourin Speaker System, has anyone built this? If so how did it go? What did they end up costing you?

I've not found much mention of them here.

Paul

I would like to build this amp and I need the power supply ( about 100v 200ma on the v-fet but a bit higher because the Output transformer primary impedance ) to be particularly silent since it is connected to a compression driver with 113db of sensitivity. I was thinking of using a CLCLC power supply (to have few mV of ripple) and I was wondering if the use of a Saligny power (HVHF in this case) could be useful.
My problem is that at most I can use PSUD II and therefore I have no idea how to model a power supply with a Saligny bridge. Any suggestions?

I've got a Pioneer T-6600 reel to reel with a couple problems.

The belts failed due to age related cracking. Where can I get new belts?

The stock reel brakes don't work so good which leaves the sound a little muffled during playback.

From what I've read online there was a mod for better reel brakes, but mine never got that mod.

How do I fix the brakes?

Also is there anything else I should do to this unit before putting it back into regular service?

I plan on using it to play a tape someone recorded that runs slightly fast by altering the AC input frequency to the reel to reel using a variable frequency AC supply.

I currently do that using my AKAI GX-255 for the playback and supply reel with an AKAI Terecorder being the drive unit and take up reel, but that requires work to set it up right as I have to remove the capstan roller off the GX-255 and I have to start playback on both units at the same time. The Pioneer has an AC motor so I can just lower the frequency to achieve the same thing.

Up for sale is a Pair of Waveguide loaded Peerless DA32TX00-08 1-1/4" Corundum Dome Tweeters.
The waveguide boosts around 7.0dB at 1.5k, super smooth.
Condition - just tested as an waveguide prototype.
Asking $200 for the pair.

If you're here, you're probably searching for info on the Toshiba TA7136 (aka the TA7136P or TA7136AP) op amp. You may be having trouble with a device that uses it. Let me guess: is it picking up FM radio? Does it sound a bit fuzzy? Is the noise floor strangely elevated?

You may be having stability issues. This was the case with the Onkyo A-5 I revamped.

Using the spice model of the TA7136 that I developed for the Onkyo, here's the simulated loopgain plot of the tone control reference circuit suggested by the TA7136 datasheet. It's really bad: simulated phase margin and gain margin are zero, as the loopgain phase crosses through -180 degrees right at the ULGF around 1.6MHz.

It's possible to design a circuit around the TA7136 with generous stability margins, and retain plenty of in-band feedback; Toshiba just didn't bother. It's yet another example of bad datasheet reference circuits informing bad mass-produced applications.

Hi. I'm new here. I was wondering if anyone can help me with a SP-14 6BY5 rectifier mod? Thanks. Ian

Has anyone built a class A amp with SMPS
I thinking of building A LuFo stereo amp with a SMPS
LuFo Amp - 39w SE Class A from 28v Rail
I have a SMPS 30volt(variabel) that can give 10A.
But Im thinkig of the heat it Will generate...

Hello there,

I'm reopening an old thread:

Ruark Equinox Driver Quest

I've replaced both the tweeter and the woofer in my Ruark Equinox.

I'm now using:

Scan-Speak D2905/970000 'Classic'

SEAS E0042-08S (W18NX001) 'Excel'

They were the closest matches to the originals.

However, the W18NX001 drivers suggested in that thread are 8-ohm drivers, while the originals were 6 ohms.
I'd need to redesign the crossover to compensate the difference...
I will share the current design and would appreciate your input.
Also if anyone else has done this change on the equinox please share your experience

Thanks

From time to time I stumbled across really nice OB / Dipole designs. Usually I just put them in my favorites, but it may be really nice if we have an exhaustive list of OB systems out there.

Post your systems too! Pics and short description.

===

Let me start with this really nice implementation by Perfect8. No spouse frowning here 😀






http://www.perfect8.com

Hi!

IFI AUDIO ZEN ONE SIGNATURE DAC new for sale, never used. Box opened just for the pictures.

Price 250€ plus shipping.

Best,
jm

Has anyone gotten a Raspberry Pi 5 to work successfully as a DSP crossover music streamier?

I have a working DSP crossover streamer configuration on my Raspberry Pi 2B using Charlie Laub's ACDf filters. The OS is Bullseye 5.10.103-v7+. The 2-channel (stereo) audio stream from mplayer (using -ao alsa) is successfully split into multiple channels and processed by the filters in /etc/asound.conf and this outputs multi-channel PCM 96khz to my AV receiver via HDMI and the resulting sound quality is excellent in my 2.5 way speaker setup. The tweeters go tweet, the squawkers go squawk and the woofers go woof!.

With my new Raspberry Pi 5 running Bookworm 6.6.20+rpt-rpi-27172 I have not been as successful. With sudo raspi-config I have selected 1 PulseAudio (only other choice is 2 Pipewire) and audio output 0 vc4-hdmi-0. On the GUI desktop, I have the options for Stereo, 5.1 Surround, and 7.1 Surround. I have installed the ACDf filters in the (I believe) correct folders /usr/lib/ladspa and for good measure also /usr/local/lib/ladspa, and I have alsa configuration in /etc/asound.conf.

With 7.1 Surround selected on the Desktop:

In terminal
$ speaker-test -t wav -Dpulse -c 8

speaker-test 1.2.8

Playback device is pulse
Stream parameters are 48000Hz, S16_LE, 8 channels
WAV file(s)
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 24 to 262144
Period size range from 8 to 87382
Using max buffer size 262144
Periods = 4
was set period_size = 65536
was set buffer_size = 262144
0 - Front Left
4 - Center
giving sequential 8 channel audio output Front Left, Front Center, etc. to all 6 drivers in my system. The audio is mismatched with the drivers, but I had the same issue on the Raspberry Pi2 and corrected everything using the t-table in /etc/asound.conf.

In terminal
$ sudo speaker-test -t wav -Dpulse - c 8

speaker-test 1.2.8

Playback device is pulse
Stream parameters are 48000Hz, S16_LE, 1 channels
WAV file(s)
ALSA lib pulse.c:242🙁pulse_connect) PulseAudio: Unable to connect: Connection refused

Playback open error: -111,Connection refused

In terminal
$ sudo speaker-test -t wav -Ddefault -c 8

speaker-test 1.2.8

Playback device is default
Stream parameters are 48000Hz, S16_LE, 8 channels
WAV file(s)
ALSA lib pcm_params.c:2226🙁snd1_pcm_hw_refine_slave) Slave PCM not usable
ALSA lib pcm_params.c:2226🙁snd1_pcm_hw_refine_slave) Slave PCM not usable
Broken configuration for playback: no configurations available: Invalid argument
Setting of hwparams failed: Invalid argument

Using the sudo causes the action to fail.

mplayer (using -ao alsa) now gives audio output to Front Left and Front Right channels only at 44.1khz which is the same 44.1khz as the internet radio stream indicating the resampling of /etc/asound.conf is being ignored.

mplayer (using -ao pulse) gives audio output to all channels at 44.1khz which indicates the resampling of /etc/asound.conf is being ignored. This is confirmed by turning off all the outputs in the t-table.

aplay -l reports the following.
** List of PLAYBACK Hardware Devices **
card 0: vc4hdmi0 [vc4-hdmi-0], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: vc4hdmi1 [vc4-hdmi-1], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0

I know that PulseAudio is looking at the configurationi in /etc/asound.conf because I can comment out a formatting character such as #} and this will throw an error with mplayer. It just appears that the filters are being ignored by PulseAudio. Maybe the Pi5 OS being 64bit and the filters were written for 32bit has something to do with it?

Having recently acquired a Sugden Headmaster and a Quad 909, I fitted new drivers - new supplied by Spendor in 1997 but never fitted. I am absolutely delighted with the way everything performs. However, I am concerned about overdriving the Spendors and want the main drivers to last.

So, I got to thinking about taking some of the power away from them with a supplementary woofer/mid-range unit. This led to reading as much as I could about various projects and one in particular was the modification to the B&W DM601 S3 cross over. I subsequently bought a pair from eBay, plus a few other bits - good quality and cheap.

However, the more I thought about, the more I realised - whilst it may keep me entertained, it is not an area where I am likely to produce successful results. So I came to the conclusion that I should leave the Spendors alone and go for creating/making a L.S. of my own.

I became intrigued with a full range speaker, vis a vis centred around Fostex units, in particular their FE208 E Sigma. This unit is recommended for Horn enclosures, but as an intermediary stage, want to use a conventional Ported Enclosure.

Fortuitously, a pair of CM7 crossovers arrived today, which are a joy - given the quality I got for peanuts.

The question is now however; before I lay out some serious cash on drivers - does anyone have any experience with Fostex units and the particular one I am interested in is FE208E Sigma. This is recommended for horn enclosures. However, this is going to be a two stage project. The intention is to couple this with a Monacor RBT - 95SR. It may well be it ends up with the Fostex T900A.

However, this is a serious project to keep me occupied through till spring so some serious advice is needed before splashing the cash.

Any help - no matter how trivial the contributor may feel it is, would be gratefully appreciated. - Kicking ideas around gets one closer to a solution, so everyone's contribution is valuable.

As a base line, ultimately I would like to go for a horn enclosure, so this limits the type of drivers I need to employ.

Hello, I recently acquired a pair of these in great condition. They have a couple issues, but hopefully not a major problem.

I have the full build and owners manual along with schematics

1. The LED's that turn from red to green on the preamp board are out and will need to be replaced. The part number listed in the manual HZ-MNT LED with a 895000 designation. I am having trouble finding this at mouser with this number, although there is a 895006 that comes up as a led that hey stock.Any help sourcing these would be much appreciated

2. I have a minor hum coming from one of them I have not moved tubes around to see it they are causing it. This leads me to my next question. Does this need to be recapped? It was produced somewhere around 1995.

3. If there tubes in it are original, should I just buy new ones?

4. How can I ensure that there is no residual energy in the amplifer so that I can open them up and look around, I wants to listen to them, not have them take me out haha.

5. Thanks for any help along the way on these

SOLD
Miro USB interface stack PCM1704 DAC board for sale.
A pair of PCM1704 with one white dot => J graded chips on the board, and these are very difficult to source these days. These are recycled chips from a reliable seller, removed with proper care. They are not bought from random sellers in Ali or ebay. They work properly and nicely.

Parts has been carefully selected and high quality ones are used. eg. Wima film, Nichicon FG and KZ, Vishay tantalum resistors for the I/V.

What you need to provide :
1. Chassis, wires, connectors etc
2. You will need to give it PSU with rails +/-5V (Analog) , +/-5V (Digital) and +/-10~12V (IV Op amp supply)
3. Compatible USB-I2S interface board that can be stacked on the DAC board, which are not offered in this sales. The two such devices are :
I2SoverUSB v.III Fully Isolated outputs or
York + Reclocker
4. Two single op amp for I/V stage, which are not offered in this sales. Eg. OPA828 is a good one for this DAC.

Payment by PAYPAL FF only please.
DAC + shipping registered & tracking = 230 USD or preferably 300 SGD (Singapore dollars)

Hallo everybody,
I'm an old man from Italy.
I like music better than hifi, but I often read threads in this forum and I find here good info for my clumsy DIY attempts.
Lately I discovered wtfplay software and I like it a lot.
I wish all the best to every forumer.
Please, forgive my English.

Hi DIY Audio
I am a new Member from germany who is seeking for different Infos about DIY Projects.
Hope i will find them here.
Thank you for help 🙂

Good condition and plays well -$250

Since I haven't found anything in this forum about this "cheap" PA amplifier, which is very common in Europe, I'll dedicate a separate thread to it, including an explanation and modification suggestions.
First of all: this thing is a stunner, it's very simple, sounds excellent - in my opinion better than the vast majority of analog transistor complementary push-pull products, i.e. almost everything that has been marketed as hi-fi or high-end, regardless of price! Those who measure good sound in kilos (> 14kg) and watts (> 100) are also catered for. Some would have measured 2 x 250 watts into 4 ohms - so here's a tip;-)

I would also advise everyone to try out an existing device first in order to get to know the built up and parts and their sonic effects before attempting big diy projects. So here is a device that costs about 100 euros, can be connected immediately and makes music - within the framework that is commonly interpreted as "high end" - and will be shown some steps that lead to (for many) audible changes.

"However, the transformer is fat! I have 3 meters distance, but after 20 minutes of listening to music I'm exhausted. I will probably remove the transformer and place it 6 meters away;-) This is a general recommendation - to ALL: keep the transformers far away, set up toroidal transformers and point the "hole" towards the listening position (lowest EMF). Many "square" ones have their lowest EMF at the top or bottom, so a steel plate is angled and the transformer is screwed to it tilted. This is occupational safety and health protection! Please also pay attention to your neighbors and children and cats and dogs and budgies and fish and dust mites;-) This is NOT taught in standard electrical training courses"
copied here: https://www.diyaudio.com/community/...e-220-volt-version.368883/page-2#post-7773808

So, sometime in January I bought these classic 30 year old Tannoy CPA12’s after MZM identified the hidden treasures within: Dual Concentric 12-inch 3134’s. To top it all off, MZM has a ML box for these fitting my living room perfectly. And the price was unbeatable @ 500 dollars including an extra tweeter.

But, surprises kept coming. These pics show the drivers upon arrival at my house. Notice the baskets have been painted, and this had been spilled onto the surrounds and in some places also onto the cones.

One of the drivers have had a party with a lit candle. So, these are just to share with you my first impressions.

After a quick listening test I determined these drivers needed more attention. MZM has been my teacher all along, and I his padawan.

Later I plan to post pics and descriptions of my work. I can allready say that a cracked magnet and off centred throat/top magnet assembly had to be dealt with 🙂

Sharing to help others and perhaps motivate to buy these robust classic drivers and fix them up properly. All it takes is time. Nearly finished, but at least 40-50 hours have been spent allready.

These sensitive drivers sing well with First Watt power specs, and Papa loves Tannoy’s too. So for that reason this is posted in the PL section, where the greediest of boyz reside.

Hi guys. 90% of my audio background is car audio, but within the last year I'd like to build a high-end grade solid-state amplifier (scared of tube voltages) and i am sure ill get enough knowledge of it here
Great to be here and thanks for having me!

Don't want to wait for 3 weeks delivery from China and my friend doesn't want to pay for anything exotic. US only

So now that Aliexpress is off limits for this stuff in the US, and my last order came in today with two transformers wound custom just like the specs below except they made a mistake and wound the last tap for 05V and not 15. I'm highly annoyed for sure. I'm sure I'll find a use for them but until then...

Does anyone know companies that wind custom transformers in the US that can produce the following?

Custom voltage 30VA Transformer

0-115V Primary

Secondary Voltage

03.0W 08V 0.375A
03.0W 08V 0.375A
18.0W 08V 2.250A
06.0W 15V 0.400A

Hello everybody,


I present you attached the cheapest manufacturing way, for single pcb layer ( home made ) with semi-professional look , starting with 0,0375 Euro / cm2.

Can be also tinned, the copper traces ....or even something like " soldermask " ( can be solder through "soldermask" applied )

You can see also some more projects of mine to bellow address:

https://www.dropbox.com/sh/gz4t8fdnt0ylfu3/Fia1FUt9Yu



If someone ( without technical possibilities and required time ) need to build a prototype board or very small quantity ( up to 10 pcs / pcb ) , please feel free to contact me to : msdesignerpro@gmail.com



I can deliver you all over the world , in cheapest way , through National postal mail services.


Kind Regards,


MSdesigner Pro
E-mail: msdesignerpro@gmail.com

Edit May 17, 2023: price drop to $295 in hopes of getting more interest.

I have had many requests to offer the BTSB with a tube interstage buffer - aka, the HyperSET in my shop. It is basically a BTSB in functionality with a SET tube buffer in between the input balanced line receiver opamps and the output balanced line ldriver opamps with DIP switch selectable gain.



Key features include:

• Main topology is similar to BTSB Panel Mount buffer. Plus SET tube buffer after the input balanced receiver.
• Remote power/standby via low level logic signals suitable for front panel switches or microcontrollers for activation.
• Open collector logic output with delay for graceful amp startup and shutdown without pop. This can be interfaced to amps like IcePower for standby/mute control.
• All solid state relays (SSR) for power on and standby.
• SSRs for anti thump control of signal during power up and instant off.
• Optional connection to a dual gang volume pot via MicroMatch connector and ribbon cable so that it can become a standalone preamp. Helper PCB for Alps RK09 style pot is included.
• Remote switch to activate relay to bypass the SET tube stage for a direct all solid state path (same as BTSB).
• Connector for 6.3vdc output that is switched with remote enable to power accessories like LED lighting for meters or indicators.
• The tube sockets have a built in orange LED to indicate that the filament heaters are active.
• All voltages derive from single 12v input using state of the art custom DCDC converters to provide: 90v B+, 6.3v filament, 5v digital logic, and +/-15v analog opamp rails.
• State of the art SMT construction where practical. Through hole parts where needed such as electrolytic or film caps etc.
• Designed for E88CC/6DJ8 or Russian NOS 6N1P. Comes with matched pair of NOS 6N1P (best sounding IMO).
• Selectable gains via DIP switch: 0/6/14/20dB other values also possible with user mods of resistor loads.
• All connections are Molex KK 2 or 3 pin for easy integration into your project.
• Recommend a 12v minimum 1000mA power supply. Class 2 linear wall wart is ideal. SMPS supplies at 12v can also work but I recommend at least 2A to prevent startup hiccup.

Here is a schematic of the SET interstage buffer:


The HyperSET can form the basis of a very transparent and gorgeous sounding preamp project - or it can be integrated as a front end for any amplifier to allow it to receive balanced or single ended input and it can drive balanced and single ended output (in parallel). This means that it has the ability to drive secondary outputs for a subwoofer amp etc. the balanced output stage is an OPA1637 which permits outputs as high as 52Vpp in balanced mode and the single ended outputs are provided by an OPA1642 - the class leading audio opamp for low noise, powerful drive and beautiful sound.

If one adds a panel mount BTSB Lite PCB to this project, you will have a nice combo XLR/TRS and RCA input jack that is easy to mount to any project panel. It includes an auto switching relay to disconnect the RCA if a plug is detected in the balanced input. Perfect accessory for the HyperSET. These PCBs are available in my shop - you can assemble them yourself as they are easy to make.



The HyperSET will be offered as a ready to run (RTR) fully tested and functional board complete with NOS 6N1P. The boards are professionally assembled with state of the art pick and place machines.

I would like to see if there is enough interest in a Group Buy production run. This is a very complex board with more than 300 components so it’s not really a DIY type project for the novice to be built from scratch. The components are all top quality and sourced from Mouser or other reputable source. Tubes are matched Russian NOS 6N1P.

A big thanks to Jhofland for the wonderful design.

Photos below. Last photo shows PCBA with a small breakaway helper PCB for the volume pot and ribbon connector.




Here is a QuickStart diagram:


Price is $325 ea. includes a complete set of 12 Molex KK (2/3 pin) connectors. Available for immediate delivery in my shop:

https://xrkaudio.etsy.com/listing/1474151499

Name / Qnty / Country

Other threads are talking about this amp, but they refer to older and multiple versions. Confusing.

In my opinion, this amp is so good that it deserves a thread alone.

I bought the DIY version on Aliexpress and replaced all components but the transistors, with good quality ones. I also discovered they are maintaining this 9.2 version, the PCB is updated compared to some other PCBs I saw some years ago.

This amp is based on D.Self publications, and with some super easy mods, it becomes a very good HiFi one.
Good points are the CFPs in the front end, and the triplets in the back end. Both refinements are absent in the newer V10 version.

Here is the schematic with the mods. The small resistors I used are all Vishay MBB/SMA 207 professional 1% 0.6W.

I love its sound, very precise, and never harsh. I'm using it all day long, and I compare its sound with the Circlotron's. Very close!

Cheers!

EDIT Apr 28 and 29 2025.
I posted here the new schematic named "L20 v9.2 with working mods" and deleted the old one.
R251 and C151 must be soldered between the bases of the final pairs, the closest points are referred to with the letter "O", one bottom side (left of the board - red), and the other on the top side (right - cyan), Refer to the new "01 PCB Top.jpg" picture.

Hello EL34 Baby Huey builders,

As suggested by SCD in the following thread : http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 I am starting a new thread specially dedicated to the building of Baby Huey amplifier based on my PCB which has been produced in more than 330 pieces and is still requested by many tube amplifier fans in a possible future Group Buy 4 : http://www.diyaudio.com/forums/group-buys/312869-gb-baby-huey-pcb-42.html 🙂

I will put in this thread all the information available about the assembly of the EL34 Baby Huey amplifier and some of the auxiliary board that I have used or designed to add some features to the amplifier. I must tell you that I am not in professional amplifier business, this is just a time consuming hobby for me and, as you will see, English is not my first language and I have sometimes difficulties to explain things correctly, sorry for that but at least you will understand easily schematics, pictures, B.O.M., etc... 😀

History

All that started about two years ago when I read the http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 post from "gingertube" ! As I was interested by the shunt feedback concept that I didn't know I wanted to test it and decided to build the simplest version with two PCL86 tubes. Since I am very bad in point to point wiring, I made a small PCB. This amplifier was so good that I decided to continue my quest and, since the ECL86 or PCL86 were unfortunately no more produced, I made a second PCB for the EL84 version which needed a third tube, a 12AX7 (ECC83) for the input stage and added MOSFET with current source to drive the output tubes. This amplifier was very good and I was very satisfied by the MOSFET driver stage, but I was also a little bit frustrated by the limitation in power, about 12 W, and the fact that I could not use different power tubes...

To solve this problem, I made an identical version but with octal socket to accept many compatible tubes from the 6V6 to the KT88 and the EL34 Baby Huey was born ! Following the presentation of this solution on the diyaudio forum some members asked me if I could sell the PCB, I had never done this before but since the moderator move this discussion to the Group Buy forum I have received several request and started a GB1 with a target of 50 boards but finally closed it with 80 PCB ordered 🙂 I had to send them Worldwide and to learn how to make PayPal invoice... Later others readers asked me for more board and I offered a second and "last" GB2 which finished with 120 boards ordered !!!

Later, since there was still a strong demand, I asked Prasi, to whom I have bought a CRC power supply PCB, if he would accept to manage a third GB and he kindly accepted 🙂 He also suggested to make 2.4 mm boards for better rigidity. Now 120 more boards have been ordered and are in production and there is already 20 PCB's in waiting list for a possible GB4 ?

Documentation

In this first post I will enclose some of the latest documents available for building the EL34 Baby Huey and I will add more in next posts depending of your questions.

You will find the updated BOM in the GB letter, the latest schematics, some building recommendations, how to connect and to adjust the amplifier and several pictures showing the PCB assembled on top side (big components go on bottom side), a 6CA7 board fully assembled in test and finally the EL34 Baby Huey in its enclosure nearly finished (two vu-meters are still missing).

More pictures and data will come from all the people who have built this nice small amplifier. It is a very nice project for those who have never made and listen a tube amplifier, but remember there is some lethal high voltage (up to 500 V) and you should be very careful when you work on it

Have a nice time building the EL34 Baby Huey...

Best regards,
Marc

The theme of this thread will be adjustments and modifications necessary to take advantage of and optimize the performance of the LM7294 device. The base or starting point will be the following schematic:




Due to a wide range of technical understanding, very basic definitions and descriptions of both primary and supporting components should be posted. Hopefully, this "Paint by the numbers" approach will attract and inform both novices like myself as well as those who wish to share their advanced knowledge and experience.

Hi all, this thread is about a JFET & MOSFET preamp I am cooking for sometime now. Its a two stage single ended Class A circuit.
It was developed on the bench involving much experimentation with topology and a range of active parts. Simulations came second.

Some speakers are insensitive, some amps also, or a source is relatively low output like a phono stage. So a line preamp with gain is good to have.

Its named DCG3 because it has DC servo and three MOSFETS. Its standard gain setting is also times three.

The main schematic is attached* Click for full circuit description & Click for the development story

Some THD plots when driving 1.5kOhm line and various actual headphones are also attached.

*(12 Oct 2016 updated and build guide/bom pdf added)

erratum: C6,C7 should read 4x in the BOM. J3 in preamp's schematic is named Q5 on the actual board.

About J3/Q5 possible IDSS tolerances and a matching R3 value: post#452

V1.03 board has correct J3 designation, split ground between channels (can be bridged) and the relay is reconfigured to rest at ground: post #3207

Sept 2023 extra measurements like multi-tone resolution at same level as here. Also THD vs Freq sweeps for alternative J1,J2 types: post#6941-42

Due to the migration from single ended to fully balanced output topology I have a surplus of these wonderful transistors. Rated at 180V/17A and two hole mounting technique they are real workhorses.

The original glimmer insulation will be added at no cost.

Min number: Five pairs.

Price $20/pair + postage at cost.

Regards
R

I bought this four woofer dipole array, apparently locally manufactured here in Milwaukee, around 40 years ago. I've had the "system",
call an "Enigma", which includes a Hafler 200 sourced amp, and a "controller" that sets the crossover blend point and "impact" ..
whatever that is.

I had two of the drivers re-skirted around 15? years ago. Its time to do all four, and I'd like to use an OEM "style" of material if at all
possible -- this time.

Here's a photo of the "working end" of one 15" driver:
Magnet and Basket

An here's a close-up of the surround surface:
Foam Surround

I cannot find any OEM stamps or marks. Can anyone help identify the source of this woofer? I can provide dimensional data, if that helps.
I'm seeking a pointer into a "suspected OEM catalog" circa 1980 ...

--frankb

I am attempting to determine whether the C7 is an IRS20957S. If it is not, please inform me. If you have this information, I would appreciate your assistance.

Thank you.

Hey all...

Just wanted to check if this rabbit hole I've found myself in has turned me totally crazy, or could there be a glimmer of hope in this temporary moment of insanity.

So I have no past experience with true electronics, never built a speaker in my life, never built a DSP system in SigmaStudio, do have some DIY ability and a logical/analytical mind but for some reason after stumbling onto this forum I do now believe I can build myself a new set of Active Studio Monitors.

After recently admiring the Amphion One25A's, Neumann KH310, EVE Audio SC3070, PDP MUM-10H, Tantrum Angry Box ect, watching videos such as:

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I decided those were out of my price range and I'd have to do some saving and wait a while, or what would it cost to build my own...

The idea is for a 8in 3-Way Nearfield Montior, with an externally attached Class D Amp box, DSP (ADAU1452), IO options of Digital/Analogue inputs, push button Preset Profile selection (Flat, Musical, Mid Focused).

A major stumbling block I've come up against in my week long research is a suitable well priced Class D 3-Way amp, that can power 2x100W + 1x200W @4Ohms with low THD. @uriy-ch has the 3-Way 100W board, but that is Digital In only and probably more Hi-Fi focused than my needs.

Then I stumbled across this video:

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And again decided I can build my own of course. They would be based off of the TPA3251 board, IO board using PCM1802 PCM4201 for ADC, Combo XLR/TRS and Toslink In/Out.

I believe I've narrowed the driver selection down as thus:

Opt 1:

Woofer: SB Acoustics SB23NBAC-45-4
Mid Range: SB Acoustics SB15NBAC-35-4
Tweeter: SB Acoustics SB26ADC-C000-4
Crossovers: 250hz and 2kHz

Opt 2:

Woofer: Scan Speak 22W/8534G00
Mid Range: Dayton Audio RS52AN-8
Tweeter: Fountek RD1.0/MeloDavid Be25-8 (undecided all around on this pick)
Crossovers: 500Hz and 4kHz

So what do you think?? Way too ambitious for a first build, or you can do it!!

I guess I'm look for a concensus to tell me I am indeed nuts!! Or as a community I could get the necessary helping hand to make it possible...

Update Jan 32, 2023: video on how to setup and connect your amp for the first time.

Update Sept 24, 2022: Nice build with linear PSU by member Tommost:


Edit Aug 15, 2022: Workaround to supply chain shortage of N131 DCDC buck converter.

Edit July 24, 2020: Review of the TPA3255 amp by Redjr
TPA3255 Reference Design Class D Amp GB

TPA3255 Reference Design Class D Amp GB

Redjr has provided files to allow us to make professional looking front/rear panels that look like this:



Edit June 22, 2020: silk screen error on R203/C203. They are swapped. Thank you to VladC for catching this. More here.

Edit May 20, 2020: Redjr is the first to test his TPA3255 out and he says it sounds great. He used it with a Connexelectronic SMSP, which I previously found to be unsuitably noisy when tested with the 3e TPA3255 and Chinese-made blue EVM clone TPA3255 boards (ubearable hiss sound). But since Redjr says it is silent when used with the present TPA3255 amp, I had to give it a try. And it is quiet with my amp! It must have to do with the layout, the extra RFI/EMI filtering, or maybe the quality components from a Mouser supplied BOM. But my TPA3255 design is compatible with a 400w and 800w 48v SMPS from Connexelectronic. This opens up another viable PSU option for folks waiting too long for the Aliexpress 800w LED PSU.
TPA3255 Reference Design Class D Amp GB

Edit April 23, 2020: The first production verification amp was tested at the reference condition of 10W into 10ohms at 1khz and achieved 0.0011%THD vs the TI specified 0.0021%THD with PFFB enabled:


The 1W case at 3.16Vrms at 10ohms gives 0.00074%THD:


Here is the fully built amp - made in USA:


Edit Jan. 10. 2020: Pre-Orders for the Ready to Run (RTR) Stereo BTL fully assembled and tested amp can be placed here:
RTR TPA3255 Reference Class D amplifier | Etsy
Pricing is $227 ea, shipping is automatically calculated based on 14oz shipping weight and 8in x 6in x 5in box. Shipping in USA will be USPS Priority Mail by default.

Edit Nov 12, 2019: Updated BOM with corrected R221 and W1xx jumper programming (1210 0R resistors) for Stereo Balanced Input and Stereo BTL Outputs:
TPA3255 Reference Design Class D Amp GB

Final Test w/ correct current limit programming resistor, showing FFT at 20.3W rms into 3.3 ohms showing THD is 0.0021%:


Amp was also successfully tested at 200W rms into 4ohms using a large wirewound heater dummy load:


Edit Nov 5, 2019: Build notes/errata on Schematic and BOM
1. One correction to the schematic and BOM that I caught while building this was the value for R221 which sets the max current before the auto-protect kicks in. 220k is not a valid value. Use 22k for 17A (max value). Unless you want to limit it then use the table in the data sheet to set the appropriate value.

2. One other thing are the resistors R275/276 for the LED status lights. 1k is way too bright. I would go with maybe 4k7.

Edit Oct 31, 2019: THD and all-orders of harmonic distortion up to H9 vs Freq up to 10k for 5.6Vrms into 4 ohm load:


Edit Oct 7, 2019: 20W into 3.3ohms FFT looks very nice. Dominant second order harmonic distortion and dominant even orders. About 0.0024% to 0.0029% THD and noise floor is very low. This is with 12v battery feeding 800w DC-DC step up to 51v:


This is with 120VAC wall plug powering an 800w (48vdc adjusted to 50v) SMPS (Aliexpress $44 LED PSU), also 20w into 3.3ohm load:


Setup with 800w SMPS:


Render of revised v01 layout with corrected silkscreen and 3.3v LDO pinouts:


Bottom side:


Edit Sept 27, 2019: The amp is up and running! Sounds great and measurements are very promising.


Edit Aug 17, 2019: latest 3d render with improvements (listed here) included:


Latest bottomside of PCB (note extensive use of groundplane and large short triangular traces for power input and bulk caps all connected to Vdd pins):


***** ORIGIBNAL THREAD START *****
3D render of TPA3255 Reference Design with components populated (top)


First some history... When I first got started in DIYA projects back in 2012, there were no cheap premade Texas Instruments TPAxxxx Class D amps available. Back then, I had to make my own, and I did it with a 25w TPA3118D2 (closely related to the super popular TPA3116D2 in the Juggernaut thread inspired by my experiments in P2P SMT Class D amps).

My first DIY amp ever, a dead-bug flip-chip
The TPA3118 sounded fantastic and eventually, inexpensive variants started popping up on Aliexpress and eBay, culminating in the ubiquitous $12 TPA3116D2 50w Class D amp. I used the TPA3116 for many years in many speakers, often driven by a miniDSP for 2-way to 4-way active speakers. Somewhere along the way, I switched to Class A amps, and you know the rest of the story - culiminating in the popular Alpha series amps and finally, the ABBB.

So what brings me to go back to my Texas Instruments Class D roots? Well, there has been a lot of development by TI over the past 6-7 years and I need some more power to drive some PA speakers and subwoofers. I have a current subwoofer project that has 4 drivers, each driven by its own amp channel and DSP. So I needed a way to make circa 150w to 200w per channel at 8ohms. The TPA3255 is perhaps the best-in-class Class D amp to do this job. One thing that really piqued my interest is that the TPA3255's datasheet says that it only has 85uVrms of noise with no input signal. That is a super quiet background!

So I have been working with JPS64 and Jhofland to develop a new Class D amp based on the TI Reference design, but with some tweaks to make it even better. The design philosophy is to keep the amp more general to allow the user to select SE, BTL, or PBTL operating modes rather than force the user to the typical BTL-only offerings available on eBay/Aliexpress. The TPA3255 when operated in SE mode provides for 4 channels of output, and the audio quallity is very high as the harmonic distortion vs frequency is flat rather than rising (as is the case for BTL). It is also a good thing to keep the possibility of balanced input for the amp to enable a nice quiet drive for folks with high end DACs or preamps. We also added some nice features to make the amp easier to use and more reliable. Like Molex Minfit Jr connectors for quick and reliable connections rather than screw terminal blocks. An NTC ground lifted chassis ground Faston spade is also provided, as well as a header block to allow master/slave operation and also carrier frequency selection. Basically, all optional features are kept to allow the user the widest latitude of how they want to apply the amp.

We are also mounting the main TPA3255 chip on the bottom side so that its thermal pad faces down towards the mounting surface. In this way, the board just needs to be mounted to a metal chassis with the usual standoffs and a small thermal conductor block (aluminum or copper) can be used to mount this amp inside a sealed (non-ventilated) chassis, yet still permit adequate cooling. It eliminates the need for a separate heatsink element. Of course, the amp uses only the best symmetric star-grounding-centric layout methododologies that you have come to know and love from JPS64. Don't forget the thousands of via-stitched traces for extra low impedance current paths. Finally, the crown-jewel of the design is use of premium high current CoilCraft flat copper wire shielded inductors. Those of you familiar with souped-up TPA3116's will reognize these as the ultimate inductors for Class D amps. They look cool too.

The design ended up at a generous 120mm x 124mm and will be 2.0mm thick with 2oz copper traces and ENIG finish. Typical JPS64 via stitching now covered with solder mask (tented vias) to reduce solder bridges. An on-board DC-DC converter provides the necessary 12v auxilary voltage for operation. Maximum power supply voltages is 51vdc single-rail. Typical 48vdc SMPS are perfect for powering this amp. If you already have a 400VA trafo that can make 48v to 51vdc, it can work very well too.

Schematic is in the PDF file below. Board is 120mm x 120mm with four M3 bolt holes offset 4mm from the corners or 112mm x 112mm CTC.

If you are interested, please add your name, number of boards, and country to ship to below.

A huge thanks to JPS64 for his amazing layout of this amp, and also thanks to jhofland for helpful advice on the schematics.

I expect the pricing to be $32 ea and the usual shipping of $5 for CONUS, $10 for CAN, and $15 for everywhere else for up to 4 boards. Additional shipping charges for larger quantities of boards. I still need to order the verification board and build and test to make sure it works before the production boards can be ordered.

GB Interest List example:

JaneDoe - 2 boards - USA

Edit June 3, 2020: If you have ordered a bare PCB, please use this BOM v002P. It contains all the corrections found during production. PM me for an updated schematic if you purchased a board or a RTR amp.

Edit Jun 21, 2020: There is a typo on line 9 of the BOM, it should be 0.01uF 100v X7R 1206. TPA3255 Reference Design Class D Amp GB

For R1021 to R1024, choose any value from 10R to 220R, 51R is a good value, 1% metal thin film, 0805. It is part of the input RFI filter and I am finding that original 2k2 was not needed and attenuated the input signal. Even 0R (jumper can work).

Edit June 22, 2020: there is a design for thermal spacer here - CAD CNC file.

Edit June 19, 2021: how to install thermal paste and under mounted heatsink.
TPA3255 Reference Design Class D Amp GB

Edit Feb 19, 2023: alternate part for SOT-223 12v LDO is MIC2920A-12WS-TR

Would like to buy a few pairs of matched NOS 6EM7 tubes . Please pm me if you have . Thank you

WTB: Please reply either here or by DM with details, condition, and asking price.



Greg in Mississippi

Here ya go guys, a place to share pictures and a brief explanation of your favorite amp or latest project. For discussion or an in-depth writeup, let's post at the Discussion Thread. Hope this will suffice- Who's gonna start things off? (again)

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.


The present SOTA in VR noise cancellation is this:



From Wenzel finesse regulator: Finesse Voltage Regulator Noise! |

Drawbacks are obvious:
a) Low current
b) Affects static and dynamic operation
c) Limited correction ability

Let us start with the basic regulator (including the additional bypass cap, since we strive for the lowest noise).
An additional source symbolizing the noise is shown explicitly.
The bypass cap is effective down to ~10Hz, but the level does not fall below 0dB.



Now, let us add the D-Noizator piggy-back:



The floor drops by more than 30dB.
The circuit works by changing the output node into an AC virtual ground.
Therefore, benefits do not stop at internal noise reduction: all the performances benefit: PSRR, output impedance.

Ultimately, the performances are limited by the discrete transistor.


What about the reality?

I made a test with ST and ONsemi samples. They behave as perfect clones, both with and without the D-Noizator.



With just the cap, the noise is 16μV, as measured by a Levell TM3B.
With the D-Noizator, it falls to 2.5μV~3μV, which seems to indicate that the circuit doesnt deliver all of the promised improvement... except that the noise floor of the TM3 is also 2.5μV~3μV.
The TM3 is not a bad instrument, but it is very cheap, and very dated.
I would need to add a modern LNA to make meaningful measurements.



It is more than promising, anyway.

Of course you cannot throw a large gain into the regulator's loop without consequences: it is now forced to operate at a gain much lower than unity, and without precautions, it oscillates like mad, which comes as no surprise.
However, compensation seems to be easily achieved, and very tolerant: a capacitor larger than 2nF was sufficient to stop oscillations.

A VLF peaking is visible in the response; it could probably be polished off by increasing the splitting of the poles, or similar measures


Detailed index:
Since the thread contains lots of information about various versions, sub-versions, practical implementations, etc. I have decided to gather here all of the most useful links, to help would-be builders chose the best solution for their application.

• First, the recommended implementations for the basic denoiser and nonoiser, here​
• Diego's original dienoiser, and the table of resistor values for different supply voltages​

Implementions, layouts, Gerbers, etc:

• Jack's PCB for the nonoiser in pdf form
• Sadface's Gerbers
• Hicoco's Gerbers
• Tombo56's Gerbers (tested later in the thread) and their updated versions, + negative one, and a minor correction , and BOM
• Mark's VRDN project
• A complete project, including the AC section from Iamwhoiam
• Knauf1919's Gerbers
• Seeyou's implementation of a VRDN clone

These are the designs recommended by Trileru himself:

• First, the denoiser with add-on CCS boards
• The nonoiser add-on boards
• Full size DC supply for AC-coupled Nonoiser with CCS (and lower performance variants possible)
• And the DC-coupled Denoisator with CCS
• An explanatory text by Trileru, detailing his versions of X-noisers
• Components selection guide for Trileru's designs

Measurement results and comparisons:

• First from Vacuphile, who also compared the denoiser with a LT3042​
• Measurements on a regular nonoiser​
• Some stress-testing by Tombo56​
• Transient response by Tombo56​

Miscellaneous:

• Accurate formula to determine the exact output voltage of the nonoiser,​
• Clarification of the Kelvin connections​
• Dienoiser used with 78xx regulators​
• Another application of a denoiser-like circuit to 78xx​
• A tentative (in sim) to apply the denoiser to a TL431, by Tombo56​

I built a pair of amp camps for my college student brother a few years ago and he was done with them and wanted me to help sell them.

They were a bit beat up so I completely rebuilt them with new walnut faceplates and new top/back panel. Basically all I reused was the boards, internals, switches, connectors, wiring, and heat sinks. They still sound great and need a new home. Asking $350 push ship. So basically two amps for the price of one new one.

I also have a single Amp Camp with TungstenAudio’s upgrades and internal Meanwell psu. Asking $250 plus ship

Finally, I have a small Pass Front End Preamp and an H2 harmonic generator in matching chassis. Both together asking $125 and I’ll ship for free.

Lots of cool custom amps I no longer need and need to turn.

Since I have to solder something and it's not easy, my thoughts fly to the new DAC. I know that I'm embarking on a big project, so I'm starting from scratch, from making a PCB, rectifier, regulator, analog stage, digital inputs. I already have the complete analog stage and power supply solved from previous DACs and that's no problem. The analog stage with tubes is not a problem either.
The problem is which new generation DAC to choose, AKM or ESS, ESS is easier to implement, but I've got my eye on the AKM AK4191 and AK4499EX.
And one more thing bothers me, will this be better than the old school, specifically the eight PCM1702s that I'm playing now?
This question is difficult to answer, I know. To me, the old school sound is somehow more natural and pleasant, closer to analog sources. But I also know that the new generation is often built only according to instructions from DS, I have not seen any sophisticated regulators and analog stages in practice so far.

SpeakerSim - speaker simulation software

Hi.

I have made this speaker simulation software.
It works on Windows, Linux, and Mac OS X (requires Java 8 or newer).
Goal was/is to make simple all in one speaker simulator.

It currently has Bass Reflex, Closed box, Aperiodic, and Open Baffle simulator, baffle diffraction, passive filters, active filters, room simulation, power response, listening window response ...

I hope it is useful. Any suggestions, wishes, or ideas are welcome.

Download

MC phono preamp / shunt feedback with inverting INA head
i just finished the first prototype of my phono stage design 😎

the last years i primaly used MC pickups, so the idea was to build a phono pream dedicated to MC, not the usual MM with head amp. important for me:

• DIY friendly, i.e. through hole parts, easy to source, low parts count
• good compromise between noise and headroom
• proper RIAA acuracy

the overall architecture consists of a THAT 1510 as input stage and a shunt feedback RIAA stage. the gain of the input stage is 40dB, this can happily handled by the CFA INA, noise is pretty low. also the INA corrects the phase reverse introducd by the shunt feedback stage. a 2u2 capaciter eliminates any offset voltage and builds a modest 6dB high pass with 15Hz corner to strip away infrasonic frequencies before applying the bass boost. the feedback network is class C to save capacitor cost. i started the network calculations with the capacitors, because E6 has limited values and i wanted to avoid armadas of parallel capacitors. the ratio between the to capacitors in the class C network ist appr. 2,9, so 2*2.2/1.5, 2*10/6.8 or 2*6.8/4.7 are pretty close.
the opamp is a JFET type. i tested also a LM4562, but it realy didn't sound as good in this position.
power supply is pretty standard, delon voltage doubler, LM317/337.

Thomas

SOLD


Asking $45 $35 including USA shipping.

For sale is a second edition of the Tube Preamp Cookbook. Overall very good shape, it might have a markup or two, but I did not see any with my quick look.

USA shipping only via USPS Padded Envelope. Payment by Zelle or Paypal.

.

Hi everybody,

this is a special request, as the gallery section of the passdiy is no longer available for the moment, if you have build an Nelson Pass amplifier can you post pictures of it. It will help me and others to get inspiration for designing our amplifiers. I develop a kind of interest lately in looking for different amplifier aesthetic design and layout. It don't matter if your design is orthodox or unorthodox, just share your realization. No need for words, only pictures will be enough.

Thanks in advance

So, the kit of the AtiRi has been bought and I am thinking of pumping it up and make a Kawero Classic clone (kind of) out of it.
But I need your help regarding the bass segment.
My plan is simple, take the two way AtiRi (15Liter) and put on a 40Liter bass reflex cabinet. untill now same as Kawero.
The woofer I will use for the 40Liter is the 10inch Faitalpro RS350. it will be driven by Hypex Fa501.

Now, I really really want to nail this bass, clean accurate, powerful.
So the following ideas are:
1. 40liter-bass reflex with one RS350 10inch driver
2. 40liter- closed cabinet with one RS350 10 inch driver -infinite baffle
3. 40liter- Closed cabinet with Two!! RS350 10 inch driver

I know its more about opinions and everything is a compromise but it would be great to hear your preferences.

Thanks!

The content of this thread is my personal opinion and does not represent performance based on objective metrics.


Information about symphonic-mpd, a CRAFTED LINUX for Raspberry Pi4.

It has been developed to target audiophile who want high quality music playback on I2S output.

Official Forum
symphonic-mpd

If you are interested, please ask your questions in this thread.

In order to use the SD images of this distribution, you need to join the official forum.
If you would like to join, please email me below with your handle name.

symphonic.mpd@gmail.com
kubotayo@jcom.home.ne.jp
mark.create@gmail.com