I was just wondering if anyone knows what is going on with HifiEngine?
Since the past month I think, registrations are not possible anymore.
I've read some posts in this forum about HiFi-Engine being very paranoid.

My IP-Address was banned for no reason and I didn't even have a user account. I just tried to make one. (Maybe I tried it too often...)

Besides that, I was wondering if someone could help me with getting some documents from HiFi-Engine, as I cannot register nor can I download anything. I do however manage to view the site by using a VPN.
I just can't register and now registrations are closed.

Thanks in advance.

I was feeling nostalgic about the Snell A/IIIs again, sorry, and one thing that struck me was that even for their time (mid 1980s) the mid and tweeters in those speakers were nothing remarkable. A middle of the road Vifa dome tweeter and 4" (I think) poly midrange, or coated paper. As hobbyists we constantly overspend money (well I do anyway) on drivers trying to outdo cheap commercial variants, but maybe the real trick is in the design and not the money spent on the drivers?

So I ask you fellow enthusiasts, you who have built and heard and bought speakers, are there speakers out there you wax poetically for which did not need to use the most expensive cutting edge technology to show the state of the art experience? What were your reference points? Convince us all that we need to spend less money on drivers. 🙂

Hi all,

this construction is from the ADA MP1 guitar preamp. The schema shows a BF256 but the JFET is originally the obsolete 2SK364. I do not know what the BJT actually is. This stage is probably a bit noisy, and I wonder if anyone can suggest JFET (and perhaps BJT) still in production that has low noise figure. Given that gain is unity and the distortion is very low (second harmonic < -90dB if simulation did not lie too much) i think the only relevant parameter here is noise. But, I might have misunderstood something in the circuit, so all comments are, as usual, most welcome!

Cheers,
Mike

Hello everybody.
After Maximax77 request, I want to share with you, a dual rail PS that I have used in all my class A builds.
The idea had come to me by an elektor negative power supply for printers.
So I designed a dual rail +- power supply using the famous 2N6287 / 2N6286 or 7 darlington transistors and used it after my diyaudio/firstwatt CRC board for all my class A amplifiers. The power supply is adjustable via a 2K5 multiturn trimmer and using a 0R1 / 5w resistor at the output, it can draw up to 10A / 50V. The 2N6284/86 transistors require a large heat sink whether have to draw more than 1A continiously. At the image below, the positive rail is only appeared( I don't have a circuit editor yet ) as the negative rail is identical but the transistors ( 2N6287 / BD140 / BC556 ) and the zener diode that is reversed for negative circuit ( The output cap must be flipped vertically too). The zener diode is used for limiting the lower voltage regulation point. For example, if you want a 28VDC at the output, you will use a 24V zener so that when you adjust the trimmer for the desired DC out, the DC measurement will never go below 24VDC. When there is a good DC filtering at the input, the AC ripple is less than 0,2mV.The circuit is very simple and reliable so I don't think there is nothing else for me to add. Have a look and if somebody is interested tobuild it, the layout 6 gerbers are available.
Have a nice day.
Spiros

Hey

Just a little question
My sansui au 222 is clipping a lot on positive half at powering of amplifier, during a few seconds

I guess it is normal as capacitor charge up, but I just wanted to double check!

My plan is a dual mono PSU in an external housing. The background to this is that I'm penny-pinching 😎 and want to compare several amplifier concepts, and if I have to install the PSU every time, that's really expensive.
I have 2 Toroidy Audio Grade Transformers with 2x18V and 300VA. I would install a COMPACT CRC PSU from Prasi for each channel with the LT4320 bridges. What do I have to pay attention to? Does a capacitor bank also have to be in the amplifier housing?
What about the grounding?

Best regards, Eddy

BURNING AMP 2024

October 19-20. Petaluma Community Center (same place as last year, the space worked great!)

320 N McDowell Blvd, Petaluma, CA 94954


Details to follow. Watch this thread.

Looking forward to seeing you there!!

Hey, tube testing gurus! I'm looking at buying a uTracer 6 kit, and wondered if the AT1000 offered anything superior to that unit, in the technical sense? The usual audio tubes will be done (12a*7, 6s*7, 6v6/6l6) so I don't exactly need v6 but I'm springing for the newer design anyways).

The purpose is to get basic information such as plate current and Gm/rp/mu. Ideally I could define the testing parameters, and get the same results as an Amplitrex. I'll test noise/microphonics and shorts separately.

I have a donor tube tester with sockets and switches. The uTracer seems ideal for a much less expensive DIY alternative. Any opinions and/or experience greatly appreciated 🙂

Edit: there's a good uTracer thread here: https://ampgarage.com/forum/viewtopic.php?f=6&t=21903

While recently revisiting an old notebook, I came across a set of conceptual sketches I developed approximately a year ago for a high-output floorstanding loudspeaker system. The original design intent was to engineer a compact yet powerful three-way speaker capable of delivering clean, high-SPL performance—targeting sustained output levels exceeding 100 dB—with minimal distortion across the audible spectrum.

The central design philosophy was to strike a balance between physical footprint and acoustic authority. I aimed to create a speaker that could serve in both casual hi-fi and more dynamic, “party”-style listening scenarios—capable of high output without compromising composure, tonal integrity, or transient fidelity. In essence, the goal is a speaker that "sounds bigger than it looks."

Preliminary Driver Selection:​

At the time of concept development, I had tentatively selected the following transducers based on a combination of efficiency, bandwidth, and cost-to-performance ratio:

• Woofer: GRS 15SSW-4HE 15" High-Efficiency Subwoofer – Side-mounted for enclosure optimization and to enable extended low-frequency response.
• Midrange: Dayton Audio PM220-8 – A high-sensitivity 8" paper cone driver known for its smooth midband performance.
• Tweeter: ScanSpeak Discovery D2604/833000 – A 1" textile dome tweeter, chosen for its excellent dispersion, refined top-end, and low distortion characteristics.

Enclosure & Design Objectives:​

The cabinet volume is currently modeled at approximately 5 cubic feet (~141 liters), which allows the 15" woofer to achieve substantial low-end extension while minimizing excursion-related distortion at high output. The narrow front baffle is intended to aid imaging and maintain domestic compatibility, while the overall height and internal volume support proper driver alignment and acoustic loading.

Moving Forward:​

I've recently decided to pursue this design and bring it into the build phase. I possess a solid foundational understanding of speaker design principles—such as crossover topology, enclosure tuning, and driver integration—but I would greatly appreciate the insights and critiques of fellow forum members to validate my approach.

Specifically, I’m seeking feedback on the following:

• Appropriateness of the chosen drivers for this application and synergy in a 3-way configuration
• Potential crossover challenges or suggestions (especially integrating a large-format mid with a dome tweeter)
• Cabinet tuning recommendations or alternate alignment considerations
• Suggestions for improving directivity control and power handling under high-output conditions

Thanks in advance for your time and expertise—looking forward to any feedback or ideas that could help refine this project further.

Not strong in electronics but have a friend who is; I have old QED and Nakamichi units I am trying to repair, and a T4A I want to sell, works well.

Troels has two 861 2.5way designs on his website with kits or just crossovers available from Jantzen.
These are much lower priced compared to Troels's regular builds, particularly the SBA kit.
In the UK, I can get parts for the Discovery 861 ( with standard XO) for £650 + some shipping
The SBA -861-PFCR with Superior XO can be put together for £430 + some shipping.
These prices exclude wood, stuffing, etc.

http://www.troelsgravesen.dk/Discovery-861.htm
http://www.troelsgravesen.dk/SBA-861-PFCR.htm

I would appreciate some thoughts on these designs, and whether the Discovery kit is worth the extra.

Hello everyone,
I am about to become a proud owner of a Bruce Moore Dual Sixty power amp.
It is a product of a certain age and I would like to check it to verify that everything is in perfect order.
Does anyone have the wiring diagram?
Does anyone have it? Can you tell me about it?
I will use it with a BMC Companion II preamp.

Thanks!
Claudio

Hi all.

First post after lurking for years... My office PC mini tube just died. It had been on almost continuously for a few years, but recently, due to these uncertain times, I turned it off and on a few times when leaving my office as I did not know when I could come back. When I came back to the office yesterday, I turned it on but only the power switch light came on, the tube remained cold and nothing of course came out of it.

It is a fairly rare version (APPJ PA0902A) with two 6J1 input tubes and two 6P1 power tubes. It always ran hot, including the transformers, but sound was alright--except for a strange intermittent 'crumpling paper' noise in one channel.

The fact that the tube heaters don't come on points to a failure of the switch-mode power supply (unless I am missing something).

So here are my questions:

1. Does anybody have a schematic for this amp? If it's just the power supply, It would be a waste to throw away the amplifier part with its transformers etc.

2. Is it a well-known failure mode and the power supply can be fixed? It is not-potted, so MOSFETs etc. are accessible.

3. If it is unrepairable, does anybody need these parts?

If anybody has suggestions, they would be welcome! Cheers.

--Christian

For your viewing pleasure.
Speaker fantasy art.

---

Some might remember my proof of concept using CDSP as a preamp. My initial tests sparked this DIY Amp project. I thought it would take some time but not this long! I wasn't even sure it would work but since its playing right now I thought I would share this build and my experiences from it. It will take several posts to cover it all so I thought I break it down into the following topics:

• Background
• Concept and Design
• Hardware Selection
• Fabrication
• RPi 2040 Pico and Controls
• HiFiBerry DAC+ ADC and UR23
• RPi Zero 2 W and CamillaDSP
• Final Thoughts

The background is already more or less covered by my proof of concept post. I will post the rest in this thread as soon as I get the time to put each piece together. Until then, a couple of images of the final amplifier, front, back and besides my custom built TD-115.

Hello folks,

I recently completed soldering a Gardo PH-1 clone, which I've bought via Aliexpress https://www.aliexpress.com/item/1005003264368348.html, but it's available form several resellers on eBay as well. But that's not the point.

I choose this one, as the same seller offers a Accuphase C-3850 kit (either assembled or as a solder kit) which has an identical circuitry in the power supply stage,
both use LM7815 / LM7915 voltage regulators and a KBP307 Single Bridge Rectifier for the AC 15-0-15 input and both came with an JRC 5532D within the kit.

As the power stage is more or less redundant, I'm looking to eventually replace the circuitry to a dedicated board. As there are several topics about the Accuphase C-3850 clone already, I won't go into details within this topic about the power stage.

But I'ld like to hear recommendations about the Gardo PH-1 implementation and to which effect the circuit could be improved to reduce potential noise.
For myself, I'm not really into electrical engineering. But I can hold a soldering iron without burning myself, most of the time 😉 I don't have advanced measuring equipment in terms of audio analysis or function generators. Only my eyes, ears and a multimeter. Thus, I definitely a beginner who is willing to leave his zone of comfort to improve upon the given implementation of this phono stage.

For the moment, the only alterations to the circuit was that I've replaced the JRC 5532 D Op-Amp with a LME49720NA, which has reduced the noise level quite a bit (just based on signal output / full volume amplification)

Here is the schematic the seller is sharing without the specific values of the components:



And the layout of the PCB

And finally, the BOM, more or less.


Sadly, the whole kit came without further instructions, thus not everything is totally clear. But soldering went without issue and the phone stage worked directly.

Otherwise, I'm still in the process to finish the housing for this phono stage as well as the clone of the Accuphase C-3850, which will live in the same enclosure and sharing the same transformer (please cry now if that is a bad idea overall).

And one simple question which I've got - as the pcb design features a common ground pad, should I solder a ground wire to it and connect it to the terminal that is shared with the ground lead from the turntable ? The Accuphase C-3850 also has a common ground pad and I'm asking myself if both or only the phono stage should be wired to that ground terminal.

I just saw this in an article and its pretty disturbing. If you live in Washington State, in the US, this is going to become your new reality. They're going to cap your speed on your car via GPS. This is just wrong on so many levels. Some of you may not care but I feel this is clearly too much control over our lives.

https://unionrayo.com/en/speed-limit-control-beam/

This is the Gated Impulse measurement of:
Tweeter Focal Audiom TD5
Mid ATC SM75-150S
Woofer Focal Audiom 15 WX

Crossover with Hypex Filter Design at 500Hz and 2KHz
Crossovers LR4 order all of them
Gain Tweeter Channel 0
Gain Mid Channel 2.5dB
Gain Woofer 10 dB

Measurement only reliable above 300Hz (if I've done correctly)
Doesn't look good to me?

Hello to all the DIY enthusiasts!

My name is Petar, an electronic engineer from Bulgaria. Interests in tapes - cassettes and reels, digital and analog stuff. Hope to find nice people here 🙂

Best Regards,
Petar

Hey y'all!

I'm Fourté and I'm a record producer, audio engineer, and studio monitor/studio designer. I'm here to soak up the wealth of knowledge y'all have and to share what little I can. I'm excited to be here.

Hello everyone, I am an engineer working in hearing aid industry. It's nice to connect with you all.

Hello everyone!
I recently bought a Dual CC 8015 deck, which does not have belts. According to the service book, it has 3 belts, but I can't find the correct way to install the belts based on the pictures. The capstan belt is fine, the other two are causing problems. Maybe someone has such a device and knows where the belts are or knows the mechanics, please help. I couldn't find almost any information about this device on the internet. I'll upload some pictures. Thank you for your attention and help!

Hi,

Does anybody know if https://www.don-audio.com/Start is still active?

I ordered a pair of Edcor PC600/15K transformers the 21 September. According to their website these should be in stock and the invoice said estimated shipping date 25 September. However, I still haven't received them and logging into my don-audio account I can see that the transformers is still pending shipment. I have tried contacting don-audio using both e-mail and the contact-form on their website without any reply.

Any of your guys bought anything from don-audio recently?

Mogens

New, unused Hammond Steel Chassis 17x10x3 and plate.
$55 free shipping to lower 48 us states

Hello Tannoy gurus!
A question for those who know the HPD cones:

As I am about to replace the HPD foam surrounds and I have two questions:
1. The ribs on the HPD cone are separating from the cone edge (where it angles back). See photo. There you can see the separation at the edge. The foam dried up and the ribs have separated. What adhesive do you recommend?
2. Is there a hard surround for the HPD 385? I will use them for mids and midbass only (above 100hz), seems like cloth would be better for this?



Thank you, you Tannoy gurus!

-Gera

I found a bunch of old audio equipment and want to know what is worth keeping and what I should throw away. There are a whole bunch of CTS pots. Some philco pots, and many transformers. I'll need to tealst the trafos though.

I have never used capacitors as big as the ones here and wonder if they are in demand.

Before I throw away something clvaluable I wanted to ask here.

Thanks

Philip

Still chasing great sounds and dreaming up the next.

Amazing plugins.

https://leomccormack.github.io/sparta-site/

I share UcD Xlite Fullbridge.
PCB Credit to Dian Arif Lufianto.

Optimal supply 80-100Vdc
Output 1500W 8 Ohm, 3000W 4 ohm

Regards,
Kartino

Hi all I’m looking for a schematic for a single ended amp using 2 nice 10k output transformers.

As I have been servicing Meridian for about 15 years in Norway, I have a few collectibles stored away.

Up for sale now are two 101 preamps, both with MC phono module, and one with balanced output. One black one brown.

In addition I have a populated 205 power amp board, missing one pair of output transistors. As they are MJ15003/4, they should be readily available. I might even have a pair myself.

No, I have not tested any of them. Strictly as they are, but there are no burns anywhere.

They are pricey at diverse forums, but I really have not priced them.
Make me an offer I can’t refuse.

If not I’ll have to restore them myself and I really prefer to avoid that.

Due to cost and practicality I prefer EU sales.

R

I'm announcing the public release of XSim, a "free-form" Windows-based passive crossover design and simulation program intended to be as intuitive and non-restrictive as possible. . The program is ***free*** for personal or commercial use. Any speaker builder with at least a basic understanding of what resistors, capacitors, and inductors do, and with decent response measurements (FRD and ZMA) of their drivers in their boxes, should be able to get useful results right away.

download from:
http://libinst.com/Xsim/XSimSetup.exe

Experimenting with "ideal" driver data (the default for each driver) can also be fun and helpful in understanding the effects of various circuit types. Some built-in multi-part "Circuit Blocks" also provide for basic pre-configured circuits to be tuned per their overall parameters (Q, corner frequency, attenuation, etc). There are "Example" files inlcuded in the XSim download (currently less than 1.5MB) as well.

XSim allows you to see simultaneous multiple graphs of your choice, including impedances, voltages, power consumptions, group delay, and frequency, impulse, step, and square wave responses. You can watch the performance and/or stress on any part vary as you tune structure or component values in real-time. The circuit network is re-solved automatically with every change you make.

The "free-form" aspect of XSim is that crossover designs are unrestricted, no particular circuit structure need be used. Essentially any R-L-C passive network you can think of can be easily entered using graphical schematic entry, with results calculated as you design. A common "ground" node is provided, but its use isn't required.



Circuit designs (incuding all in included driver data sets) can be shared by email or forum post in XSim's ".dxo" format.* Graphic files can also be saved in standard picture file formats.

Stuff yet to come: [edit: the following aren't actually going to happen now, as it is too much work to herd vendors into getting this info together and hosting it on their sites!]
The release version of XSim featiures automatic downloading of part and driver information based on vendor and part number, making it easy to find and order what you need to turn your design into working hardware. However, no vendors are as yet signed up to provide XSim access to part or driver information. XSim will be able to download these lists itself, when available. XSim can also update its own program (with owner permission) so people who use it online can always be up-to-date. ...And so I can add or fix features without asking you to deal with downloading and installing each time.

XSim does not yet include geometric features (such as varying mic position, baffle or boundary-bounce effects) as in Jeff Bagby's very successful "PCD" and other programs derived from it. But that is in the works, with some assistance from Jeff. There are also as yet no box-design features, but this is also planned so that full designs can be worked with using the infinite baffle data provided by vendors. [these might still happen, when/if I get back into programming and study mode 🙂 ]

edit: * as it turns out, this forum doesn't let you attach the .dxo files (or other files it doesn't know about). So you'll have to first zip the file and then post the ".zip" file containing the ".dxo" file. On downloads, do the opposite: unzip and then open the .dxo file into XSim. Maybe someday we can get diyaudio.com to let these files be attached? They are only text, no way for a virus to sneak onboard one of them!

Added Nov 2017: There is a procedure summary for collecting and adjusting driver FRD data for correct relative delays (which you need to accurately simulate crossovers) here -- XSim free crossover designer

Here is a very simple amplifier for desktop use.
It measures 0,001 % distortion or less at 1 kHz wich i believe to some part comes from bad shielding and the generator. Most third tone.
I tested it on ± 15v but it can take a little bit more but ideal for the speakers behind the laptop delivering 10w 8 ohm.
R7 is 1206 10 ppm so i dont think the distortion comes from resistors.

The Layout

And a 3d view. The size is 60 x 40 mm

I wound the coil of 0,75 mm cupperthread on an 8 mm drill. First layer 11 turns followed by 10 and on the top 9. Secured by glue and a pause after each layer.
Remarkable is that it does not work well with OPA 1656.

I used to own a pair of ADS L880 speakers. I currently miss them so much. I know the easiest way is to find and buy one. But, I have a number of unused speaker drivers. Some of them are car audio speakers. A pair of 10” subwoofers is planned to be used in this project—ADS RS10. The RS10 is 10” subwoofer with dual voice coils. Each v/c is 3 Ohms, so it allows to select between 3 and 6 Ohms impedance mode.

I’d like to ask everyone if there are people build a “three-way” speaker system whose woofers are 1) actually subwoofers and 2) being car audio speakers. Anyone?

If there are any, then, how about the result?

Also, I’ve heard that “normally” subwoofer drivers would have lower sensitivity/ SPL than the actual woofers resulting in requiring more power from amplifier or alternatively attenuating sensitivities of midrange and tweeter instead. Is this true?

All in all, should I start this project of using car audio subwoofer as a woofer in three-way speaker design?

Alpine amplifier as IRFZ40 in its power supply.
Can I replace them with IRF2807 or IRF3205 without changing gate resistance or any other modifications?

Hello everyone, New member, from China, DIY D-class amplifier+digital broadcasting all-in-one machine

Good evening to all of you and thank you for your hospitality!

After your acceptance, if I understood correctly, you are technicians/electronics..

My English, I must state that it is not that good, so I decided to be safe and avoid misunderstandings to write in my language (Greek) and then translate it into Google Translate.

So, I am not a technician, electronic, etc., although "amateur" and with a little luck perhaps, I have repaired various things. I do wood carvings, iconography and other related fields, let's say.

I tried for almost a week, formulating the issue I am facing in Google, but in vain, without finding a solution, until yesterday there was a link/reference to you on some blog!

I have owned, for 35..40 years (from my father) among other speakers, a pair of Technics SB10.

I recently started using them again and noticed the following: The three red buttons (to protect the units from overload) are all outside and not inside..

Under normal conditions are they "supposed" to be inside?

The speakers work perfectly, BUT to be heard the tweeters have to be pressed in, so I have to use adhesive tape..

If you can..give me your lights!

Thank you very much for your time!

Hello every one

I have a Classe ca 150 with some burned output transistors and also have some new MJL transistors laying around. is it just to swap out the 2SC4029 and 2SA1553 to MJL21194G and MJL21193G ??

the service manual is attached

Hello everyone, my name is Marvin and I'm from the USA (midwest). Audio has been a reoccurring hobby for me for sometime. I'm looking forward to contributing to this community.

Thanks,

Marv.

Hi all,

I've been pumping out cabinets for my single bass array, but needed a side quest to break up the flow and have a little fun. I really like fiddling with open baffle and I like the sound, but I also wanted to use the dipole effect for a real purpose in my upcoming room it will be in I think which is a long 40 foot room spanning the house with one end is the living room and the other end is the kitchen. I'd like to try out some large open baffles in the living room that will see daily use for all kinds of content so that the family can be loud and whatever in the living room, and the kitchen will be a far distance and 90 degree's off axis from these dipoles. So hopefully you can have a conversation in the kitchen without loud Lord of the Rails, Thomas the Engine, etc, barking from the 5 year old watching his shows and all that. Obviously not a hifi listening space lol. So this lets me satisfy the itch of building a new open baffle and experimenting and having a real place and purpose for it, and not just another pair of speakers to find a place for in the house.

With the looming economy and unclear duties shipping from over seas to USA, I was very weary to order some of the drivers I really wanted. I happened to find some Lii Song F-6's locally for a little more than the retail cost. These are budget drivers, no doubt, they're like $60 MSRP from China from Lii Song. But, I love the look and I like whizzer cones. I really wanted Fast 8's or The 12's or 15's even, but I didn't want to find out what duties I would swallow after paying, shipping and then double the cost or something from duties due to tariffs. So I just sat that out. Maybe in a few years I'll order a pair of what I really want. But until then, just gonna play with what's local. I just like the look of the Lii Songs, Tangs and a few Fostex that have that cream color bone color woofer cones, and like how they match organically in look to hard wood.

I have 4x GRS 8SW4HE drivers sitting around for projects and figured I'd try them out. They're not optimal for open baffle, but they have good power handling and excursion so I'll see if I can make it work with them instead of buying more stuff. My heart wanted 4x15's on these, but I also want to see the wood of the baffle and really didn't want to spend $500+ just to get a little bit more towards 30hz. We will see.

So experimenting with questionable combinations of drivers on a baffle.

My long term goal is to use two large mirror oak slabs that I have for the final iteration of this potentially. I'm going to experiment and develop on plywood baffles of similar dimensions to get the bulk of the effort done first though.

These are about 18 inches wide nominal and over 70 inches tall. Pretty flat. But I'll have to work them if I get to use them. My goal is to pick out about 50~55 inches of length from these and shorten it but keep all the live edge sides (bark removed). So knowing that, the shortest baffle dimension is around 18 inches. So planning around how 18 inches will factor into things.



I have some other drivers that I was interested in trying. So I did some overlays to see how it would look.

I have some PT6816 planar magnetic wide bands, a mid-woofer, the Lii F6's and the GRS 8's, so just to see how some arrangements might look. I also looked at how a MA200 Mark Audio and CHN110 Mark audio and CHR120 Mark audio might look on such slabs. They are not perfectly scaled here, just looking at how the drivers look with the slabs.

Not to scale:



I much prefer the warmer cones of the Marks and Lii's here. The Marks have low Qts and the Lii has higher Qts, so figured, for this I'll try the Lii's. Found them locally for an acceptable price so they were cheap.

I paid about $40 per driver new ($30 MSRP from China each, but lord knows what duties and shipping would have been, not worth it for cheap drivers like this).

Maybe after the tariff war nonsense if things get better, I'll feel better about ordering some Fast 8's or Fast 15's. These cheap F-6's will scratch the itch until then I suppose.

Then just for fun, how could the arrangements look with the GRS 8's and the drivers I have:

Didn't like these.



I think I like the Woofer Lii Woofer best (the look):



So will probably move forward with the Woofer Wideband Woofer arrangement on the baffles.

Very best,

Hello all,
Not sure if this is the correct section to post this in...

I am currently installing a digital organ (Hauptwerk, Caen) in the chapel of the school I am attending in Italy. I have most of the details figured out, but am really struggling with what to do for a subwoofer.

For those who don't know, the organ is able to hit and sustain 16hz for as long as the organist desires. Depending on the pipes the organist uses/picks, that can be 16hz of mostly harmonics (lots of noise, not much else), or 16hz of pure fundamental tone (almost no noise, just pure earthquake mode...lots of fun!).

The room is a rather long, somewhat low rectangle of completely hard surfaces (though plenty of soft surface area when full of people) of about 5m wide by ~20m long, and varies from ~3-6m high, depending on where you are. Tile floor, plaster walls, all wooden pews (no cushions). There are several arches that come down/intrude quite far. I will get some pictures as soon as I can and post them here for better reference.

I need a sub (ideally 2) that can produce earth-shaking bass down to 16hz while sounding good - making tons of noise and things rattle is cool and all, but I need it to actually sound good.

I have only 2 requirements:
1) shake the earth while sounding good (accurate, musical production of the notes/frequencies)
2) under 1000 euro, but I'd really like to keep it under 750...less is more obviously.

Do note that I do not have ANY restrictions on how big the box(es) are/can be. I need something the size of a refrigerator or a small car? Not a problem.


I have read every thread and resource I can find about this topic (there are quite a few of them), but almost all of them are directed toward something more along the lines of a large living room...nothing for a church that I found. I feel like I have a good grasp of the basics, but not nearly enough to feel confident in this decision.

At the moment I am planning on building the sub myself, but if there is a premade solution that will satisfy what I have detailed here while saving me a bunch of effort, I'm all ears.

I still have tons of components for sale. Any price I quote will be in * USD * as most reference this. I would prefer Wise to Paypal as a guy just paid me direct in AUD and it cost him very little to use Wise in comparison to Paypal.

Postage as a reference is $20 USD for 250g to the USA ($25 USD to Germany for 250g) / $25 for 500g total to USA.

If you can find a good price for any you are interested in on a 'legitimate' site (NOT EBay as there is so much junk on there), I will do better by at least 20%. EBay is okay if it's for a reasonable price on there, showing me an IC worth $10 going for $1 on EBay is not realistic. The numbers in the lists are approximate, but I would check and count them exactly when interested.

If someone wants to do a bulk buy for a project on here I can do them a good deal. Point me to a price even if no longer stocked and I will do way better.

ALL of the audio components came 'direct' from TI, THAT & National (before the were taken over by TI). So the National parts I have had for at least about 14 years in storage.

Here are the Lists of Components:

Audio Semiconductors.txt ----------- AUDIO Specific Components DIRECT from TI & National

For example, High Quality Audio and Instrumentation OpAmps (LME/OPA/Burr Brown) & Power National Amplifiers.

Electronics and Music Components.txt ------------ Other Components for General Electronics & Electronic Music.

For example, Rare Transistor Arrays and Matched / Dual Transistors and Electronic Music Transistors and ICs (like Rare OTAs / Filters and Multipliers).

https://drive.google.com/drive/folders/1biIKbagCNJVCQzVrnarfznPFaL4qDL4P?usp=drive_link

I have some sets of 2SA1349BL & 2SC3381BL (Hfe ~ 450).
Selling set of TEN PAIRS (10 x 2SA1349BL + 10 x 2SC3381BL) for $100 USD including postage to the US.
(Postage Tracked is $20 USD included).
If you want other stuff I have I can put it in the box (up to 250g ~ 1/2 lb).

Other Parts I have:
https://drive.google.com/drive/folders/1biIKbagCNJVCQzVrnarfznPFaL4qDL4P?usp=drive_link

I am slowly selling off most of my components so if you want some let me know.

Please bear with me. I do not have a strong grasp of the complex interactions of my audio equipment. I have never designed or built a new circuit from scratch.

I have been considering adding a tube output to my Philips CD880 for about 10 years now. I have spent a many, many hours trying to learn the technical requirements of I/V conversion and how to build a working tube output. Today, I ran across Regal's thread from 2011 https://www.diyaudio.com/community/threads/new-look-at-tube-analog-for-tda1541.194134/ and a light went on.

Why has everyone focused on building line level outputs instead of MC phono level outputs? I have never seen any discussion of a MC cartridge level output. My Ortofon Cadenza Black cartridge only has an output of 0.3mv and my CAT preamp and ARC D70 MkII have no problem driving my Martin Logan Sequel speakers to good volumes.

It seems to me that there would be more options to build a low level I/V conversion output that outputs 0.3V than 2.0V. What are the technical barriers to converting the TDA1541A's 0.4ma PP to 0.3mv and outputting that to the phono in of my preamp? Is there an insurmountable impedance mismatch problem between the chip and a preamps phono in? Even if I cannot eliminate the tube output, wouldn't I have more options for which tubes I use and which amplification cuirt I use if I am trying to build a phono level output?

I hope someone who has the knowledge will help me with this.

Due to my age, I am selling my DIY GM70 amplifiers, I just cant move these around anymore and they don.t fit in my audio cabinet.
These weigh in at over 120lbs each.
Hand wired, matching high quality components
Monolith Magnetics 7K OPT
Monolith Magnetics IT transformer, gapped for 40ma
Large Chokes
Spare Edcor power transformers(I had them wound for more current)
Pick up in Florida only
Asking $3000
6E5P PreDriver
JJ2A3 Driver
GM70 output
Class A to 25W, A2 to about 50W.
Rod Coleman supply for GM70
Arduino for startup using 4 relays (90sec warmup)
Ground lift using diode bridge
Simpson amp meters for GM70
Multiple Fuse protection for OPT and amp
A

What would be the pros and cons between these setups? I found a good deal on a pair of 10s drivers so I'm considering that....

One obvious pro is obviously two smaller boxes in my living room is def better than one huge box lol

Hi all.

What has been all of your favorite-sounding DML setups?

I have been using the excellent and free software package called REW and a sound interface card (or DAC/ADC) to measure my amps for years now. It’s fast, easy and really costs nothing if you have a sound interface already. REW is normally used for measurement of speakers with microphones, however, it’s interface, GUI, and math engine are top-notch and lend themselves to an excellent amp measurement tool. I have been asked numerous times via PM’s to assist DIYA members make their own measurement setup using REW. Recently, I was asked again in the M2X thread when I chimed in that one doesn’t need expensive dedicated distortion analyzers from HP/Agilent/etc. all you need is a decent sound interface and REW. Plus a dummy load resistor and some wiring.

First of all, I want to thank member John Mulcahy, the author of REW - what a wonderful gift he has given to the DIY community. He is also always there to answer as technical question on REW.

So what can a sound card and REW do for you in terms of audio distortion measurement? Here is a typical FFT spectrum that I took using a $99 Focusrite Solo USB sound interface and REW with the Alpha 20 amp. This is 2.83vrms into 8ohms:


The plot above tells us several things about this amp: it has a dominant second harmonic distortion signature (sweet sounding), it has a little third order (gives it some bite), it’s devoid of higher orders, or higher odd orders specifically, which can sound fatiguing; it has an overall low level of total harmonic distortion (as seen in onset window); the mains noise at 60Hz and 120Hz is essentially zero - that is, it is very quiet and hum free; finally, the noise floor is about -110dB below the signal so it has very black blacks.

How hard is it to take this data? Well that’s the purpose of this thread. To show you how easy it is to do.

Another example of how REW can tell you how to tune your amp to achieve a harmonic distortion profile of interest. Some amps have this variable knob that lets you tune the type and level of distortion to your liking:

DLH Amplifier: The trilogy with PLH and JLH amps

Here is an example of measuring a preamp driving a 7k ohm load, this is the Aksa Lender putting out 20Vpp into 7kohms:


So where to begin? Let’s start with getting a copy of REW on your computer. Works on PC or Mac but I am only familiar with the PC version. Go here to download REW, and while you are at it, please donate some funds to John Mulcahy to continue his excellent work.

REW - Room EQ Wizard Room Acoustics Software

Once you install it, install software or drivers for your sound interface. I have used even the built in sound card in a PC to do this and it can work. However, those are generally very noisy and you won’t get the nice -130dB noise floor that some standalone interfaces can achieve. I personally use a Focusrite Solo (2nd gen) and 2i4 (2nd gen). They both have the same ADC’s but the 2i4 has a front end that is more flexible. I also think it has slightly better low noise characteristics. But you can use any sound card as long as it is supported by REW - and that includes any Java supported card. I haven’t found one that is not supported yet.

Next step is to connnect your interface by plugging in the USB cable, for example. Some of you might have other interfaces. The go into the setup menu and configure the sound interface. I typically the non-ASIO interface as I find that more finicky to work. Then choose your input device as your sound card and your output device as your sound card. Choose input and output amplitude to be “Master” and set to amplitude of 1.0 - this lets the full signal be generated by the sine wave generator and the full signal be captured by the ADC.

On the input settings choose the channel where you will connect your amp’s load resistor. Channel 1 is typically the “Left” channel and channel 2 is “Right”.

At this point you can see what the inherent self noise of your sound interface is without anything connected. Click on the “RTA” button along the top. In this dialog, click on the gear to adjust the settings. I use something like this:


You can try other settings. Making the averages smaller like 0.88 exponential and choosing 32k points will give you almost real-time updates to the FFT. You need to click on the span button to set your range of measurement from say 20Hz to 20kHz. On the vertical scale button on upper left click on dBFS. Then click on the red button to acquire your FFT spectrum.

You will see a relatively flat spectrum (hopefully) but this will tell you what the noise floor of your setup is. A cheap built in sound card on my pc only gets -110dB. The Focusrite get -130dB. There are ways to achieve better noise floor and much is discussed in threads elsewhere. For many of our SS amps around here the typical noisefloor of the Focusrite is fine as distortion is typically no lower than -100dB abd typically -80dB or so.

This is all fine and good but how do we measure distortion in our amps? Well we first need to make a dummy load resistor to simulate your speaker load. You need a power resistor with the same impedance as your amp that you are testing. Typically 8ohms or 4ohms. It also needs to handle the amp’s power output. A good one is a metal shelled 25w resistor mounted to a heat sink.

Here is an example of one with the wires you will need to make to connect it to a sound interface:


Here is a sketch of how to connect your load resistor to the sound interface and the PC:


For measurements of amp power up to 1w (8Vpp) it’s ok to connect the dummy load to your sound card directly. However, if your amp ever had a burp and hits the interface input preamp with too much voltage it can fry the input stage. I would recommend adding a ~10:1 voltage divider using a 20k and 2k resistor and taking the middle node attenuated output as the signal to your sound interface.

Edit May 10, 2024: circuit for floating balanced input needed for bridged class D amps here https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-5925805

Also, if you are using Class D amp, you need a steep filter to keep the high frequency noise out while not distorting the low frequency to prevent aliasing the data. I used the filter suggested by Voltwide/Bucksbunny here: https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-6714709



Depending on your sound interface, they may be good for 20v max input so that would give you pretty good protection. Never put full 25wrms (40Vpp) into your sound interface unless you want to fry it.

Now you need a way to generate your 1kHz (or whatever frequency you like) excitation sinewave. You can use the audio output of your sound card and the built in generator in REW. Then connect the audio out of the sound interface to your amp’s input. Adjust the level using the amp’s volume knob if you have one or the knob built into the Focusrite or the level in the generator interface.

Another way is to use an independent reference frequency source. A dedicated low noise high precision generator from HP is expensive. You can use a digital audio player with a good DAC as your source. I use a Cayin N3 which has the excellent AKM4490 DAC. Create a 1kHz sound file in lossless flac format using a program like audacity. Then play that into your amp as the excitation source. Those has the benefit of decoupling your source from your measurement to avoid ground loops. Especially if the source is a battery powered DAP. It’s also typically quieter.

So now connect your audio source to your amp, connect your amp to your dummy load, connect your audio interface to the dummy load, and connect a DVM to the dummy load and set to AC volts. Increase or decrease the amplitude of the 1kHz sine wave until the DVM reads 2.83vac. That’s same as 1w into 8ohms. A typical standard at which distortion measurements are taken.

That’s all for now. I will update later as I did this post with my phone and will get back with more details. But this should get many of you started.

Update June 3, 2019: Here is a loopback using Focusrite Solo gen2 and Akitika 2ppm 1kHz oscillator at 1.0Vpp into 10k:


Update Sept 24, 2020: member Wtnh made a very nice and useful schematic and connection diagram for us to use. Although he used an EMU sound interface, a lot of it applies to other sound interfaces as well (like Focusrite, or any other with combo XLR/TRS balanced inputs):

This list is not exhaustive, so please post/share stuff I've forgotten, other circuits, favorites posts, etc.

---

Amps​

---

Aleph Jzm
A simplified, UMS-compatible version of the classic Aleph J.
Aleph Jzm

Babelfish F8
A dual rail, dc-coupled variation of the FW F8.
Babelfish F8

Babelfish J
A babelfish'd version of the Aleph J. Standard parts.
About possible Babelfish J interest

Babelfish XJ
A babelfish'd version of the Aleph J with SUSY (Supersymmetry). Standard parts.
Babelfish XJ , or JX …….. or whatever (Aleph X servo for Greedy Boyz)

Babelfish J2
A babelfish'd version of the FW J2. IRFP150's for the OS transistors.
Babelfish ᄅſ....or FW J2 on Steroids .... or Not your Father's J2!

Babelfish M25
A babelfish'd version of the FW M2. Standard parts.
Babelfish M25, AKA M2 on steroids, AKA M2-XA25 bstrd AKA M2 gone Berserk

Babelfish M25 R.2
A babelfish'd version of the FW M2. Standard parts. Different biasing scheme.
Babelfish M25 R.2/SET amp

Babelfish MF A1
A babelfish’d version of Tim De Paravicini’s classic design, minus line stage portion
MF A1 (babelfishing)

Babelfish XA252
A babelfish'd version of the XA25. SOT227 OS parts, SITs optional.
Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

Boo/Pooh
Square Law PP Follower Stage, bridged or not (which are going to drive even F4)
The marriage

Il Penitente
A complimentary BJT amp, with iron FE
Il Penitente

LuDEF
DEF amp topology w/ LU1014 power JFET
LuDEF

LuDEF P
DEF amp topology w/ LU1014 power JFET – active FE (Plethora of Pinjatas)
LuDEF P

Old Soul
Germanium output transistors; BJT outputs also possible.
Old Soul

Plethora of Pinjatas/SET P
Square law OS. ZM active FE. Standard parts. Schade option (SET)
Plethora of Pinjatas/SET P amp

Singing Bush
A variation on the SE 50W amp Nelson presented at BAF 2015. SIT version; MOSFET version w/ schade
The Singing Bush

Lazy Singing Bush
A SE 50W follower amp – mu-follower arrangement. SIT, MOS, etc
Lazy Singing Bush

Choked Singing Bush
A SE common source choked amp – USE QUALITY IRON
Choked Singing Bush ..... special one for Purists and Masochists

SissySit
DEF amp with SIT and MOSFET
SissySIT

SissySit R.3
DEF amp with SIT and MOSFET; New biasing scheme
SissySIT R.3

SissySit P
DEF amp with SIT and MOSFET; uses active FE (Plethora)
SissySIT P ..... or how I proved fact of making more Hats than Pa did

SissySit (42)
DEF amp with SIT and MOSFET; fully DC coupled; footprint for K2087
K2087 musings phase two: SissySIT 42 as a cradle

Scryer
DEF OS with single common source JFET FE; fully DC coupled; footprint for K2087
Scryer ..... or how F8 met Mighty SissySIT

Steeplejack
single common source JFET FE; M25-style OS w/ Schade FB
Steeplejack ..... or how F8 met mighty babelfish M25

Stasis OS
Newly designed Stasis OS boards
Stasis Front end

Warbler
Choke loaded source follower; SIT, MOS, or Schade MOS
Warbler MOS Schade MOS SIT choke loaded follower power amp

---

Line-level​

---

Pumpkin
Balanced transistor amp for swinging the likes of an F4
Pumpkin Preamp - Perfect for F4

Iron Pumpkin; Iron Turtle
Shunt reg + buffer + AVC
Iron Pumpkin(s) and other smaller vegetable animals

Iron Pre
Shunt reg + buffer + autoformer
What's wrong with the kiss,boy ?

PSM LS
Optical line stage
Poor Serbian Man

---

Misc.​

---

Babysitter
Easy way to cool Class A amps
Babysitter for Papa's Koan

D1 OS
I/V stage from PL D1 (Gerbers)
Pass Labs D1 Dac

Autoformer daughter cards
Handy expansion cards for integrating Cinemag or Jensen PC-mount autoformers into your project (Gerbers)
The F6 revisited

Hi
The title is essentially the issue.
A more bass than treble "thump".
No crackling when the volume is altered up or down.

Plays music well otherwise.

Now I will confess to being a novice here: basic electronics theory and kits behind me (1980/90s), soldering iron and multi meter available, and a renewed interest in electronics (nothing too sophisticated mind you) in recent years.

This amplifier is from the late 1980s. I like it because of the slim height - like the A&R Cambridge - and it fits my cabinet shelf slot whereas most amplifiers don't.

Now I'm thinking something to do with the power capacitors ... but like I said, I'm a novice.

Any advice is appreciated.

Regards

Fud

I am working on a sundown sfb 2000 however the issue I am having is that the rectifier got damaged 1640 s4 and I am unable to identify a replacement I checked the schematic for the taramp and I see that it uses positive and negative while the soundigital schematic shows it uses positive only. I just want to know the polarity of s3 and s4.


Regards,

I’ve got this SMPS3K from a build that never was and I’m not sure what to do with it. It’s the version that has 63v rails - I got it from eBay and never opened it.

Trade me for something cool! XLR interconnects, maybe? I’m open to whatever! Not really worried about comparable “trade value” as much as I am about cool trades.

Hi all, I'm a novice tube addict, and I've been scratching my head for weeks trying to decipher real Tesla ECC83s from the fakes/relabelled ones. I have read many threads and looked at all the pics I could find. I could use some expert help, as despite my reading up on it, I'm having a heck of a time spotting the genuine goods from the imitations. I also hope this post helps other newbies like me who are having the same difficulty.

Things I've picked up so far: (please let me know if any/all of it is wrong):
1- Real Tesla E83CCs have flatter tops (straighter shoulders if you will), while relabelled JJs (the most common fake) has curved sloped-down shoulders
2- The real getters should be a darker color similar to the Telefunken ECC803s, while many imitations will have lighter-colored getters
3- Real Tesla E83CCs will only have short plates (some fakes do - other fakes have long plates) Long plate Teslas may be real but would be a ECC803s, which, while excellent, is not the same tube.
4- Real Tesla E83CCs will have a frame grid design. Some/most fakes will not.
5- (WRONG - no shielding plate at all on E83CCs) Real Tesla E83CCs will have a black-coated nickel shielding plate between the triodes, JJs will have uncoated gray nickel instead
6- The fakes can be so close in appearance and are so prevalent that even an honest/reputable seller may be fooled.

The first pic is one that I can't tell if it's real or not. To my novice eyes, the top of the tube seems flat and the inner tube construction (what I can see) seems to be a correct Tesla E83CC to me, but I'm just not sure. The 2nd and 3rd pics are of a different example, and I also can't tell if it's genuine. The 4th pic is the last example. I'd greatly appreciate experienced opinions/info.

This site has a ton of information: ECC803S TESLA FAKE TUBES
and FAKE TUBES LIKE ECC803S and others
and Compare of TESLA TUBES with JJ TUBES.
I found this thread useful too: Vintage Amps Bulletin Board • View topic - Tesla ECC803s vs. new production in a Matchless DC30 results

Hi,
I bought the blank pcb with the attached schematic and picture from ebay. The seller sent the schematic as an e-mail. However, what exactly are the diodes that appear as D-V on the pcb and D4,D5,D6,D7 in the schematic. I ask the seller and he does not answer. Please what can I use instead of these diodes. Information please.

Kondo KSL-M77 phono and preamp clone project

Hey guys. It's been a while. 🙄

I got burnt out from audio and sort of took a break. Multiple reasons, and too many other things going on.

I recently put up some speakers for sale, and managed to find a deal with someone who wanted to make a trade. So for a pair of Aucharm full range 12" speakers I wasn't going to use, I got a B&K AVR 202 with hum problems, a vintage Trygon T50-2 power supply, and this KSL-M77 project. I'm happy with the trade, and it gives me some stuff to play with as I find the time. I should have a power transformer that would be suitable for this kit. Just in the value of the caps and enclosure alone I think this was a decent trade, even if I gut it and build something else without boutique parts or circuitry.

Does anybody happen to have details on these? All I really find is PCB photos but no real detailed specs on them. I'll post what I could find.

Looks like this is very close to my kit-
Audio KONDO AUDIONOTE M77 Line and Phono AMP HiFi Tube Preamplifier Board - Free Shipping - ThanksBuyer

Anybody recognize those pots used here? Looks like one volume, one balance, and a source selector.








I think this is the correct schematic. From what I can tell this sucker takes eight (8)! 12AY7 tubes!!??! I may see if I can modify it to take something like 6N1P or 6CG7 since I can mix and match those with some parts value changes.

If you line up the driver entry points and upstream TL length between them, at the high pressure points of the sound wave that resonates in the second resonator) it’s crazy!?!

This is a very potent/unique way of getting LOUD? ( But more like a science experiment than a great sounding subwoofer )

A folded Bose wave cannon does something very intersting if you connect a 3 meter pipe to a 1 meter pipe as well

Login to view embedded media

Well, the tubes forum has a photo gallery, so how about one for full range speakers?

Shamefully, I have none of my own to post yet...

No idea what to ask for these.

The Musical Fidelity A and P series amplifiers were popular in the UK in the 80s and early 90s. They had a reputation for good sound but were let down by poor reliability as some of the components were run within an inch of their rated spec and sometimes a little above which given some of them, the A series, were quite heavily biased and produced a lot of heat it was a surprise some of them lasted as long as they did. Anyway here is my take on it, the original used an LM318 which was a fast noisy op-amp, better devices exist today and an OPA134 0r OPA604 would be a sensible choice as a replacement, as I am not sensible I chose the ultra fast OPA828 which is a 150V/us device which does however work well. Some pictures of the real amp and square wave test, bench PSU limited to 2A but still not bad. Kicad files for the brave attached, how does it sound?, IMHO very good been listening to it for a few weeks using dual die FETS and 400mA bias and it sounds very good, dual mono very good imaging, no nasties, up there with class A, current dumping design and a Pass Sony VFET V2. Obviously it can be DC coupled so watch out if you try, it has the advantage of lateral MOSFETS is they can take heavy bias currents, heatsinks permitting, without thermal runaway. Do not use vertical devices, they are not suited to the design and will probably blow themselves and something else up as well you have been warned! plus the drain and source connections are different so you would need a PCB redesign anyway.

I'm in search of a decent PA/hifi type 18" LF/sub driver for a vented 160L enclosure aiming for -3dB @ low 30s. It would be nice to have 95+ dB sensitivity at an acceptable xmax to achieve at least 115dB down to F3 and possibly good F10.

Budget is up to $400-ish and available here in the US. Been looking at the B&C 18TBW100 and 18TBX100 as possible options. Neo would be nice but a ferrite motor wouldn't be out of the question. Already tried the 18NW100 but its specs weren't as advertised.

I've looked at the so called 18" Marty Cube design, which is roughly what I wanted but I'm open to anything comparable. I prefer vented over the popular horn loaded TL for more accurate, tighter low end. A larger vented box is a good compromise IMO.

Please reply here with any suggestions in line with my preferences and goals.

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.

Trying to fix a broken amp I bought. The issue is intermittent, but it's happening with increasing frequency. On power up or after a few minutes, the power amp module for one of the two channels quickly gets extremely hot. Sometimes it's the channel 1 module, other times it's the channel 2, never both simultaneously; tried swapping the modules, but it didn't make a difference. I rarely keep it on for more than a few seconds once the problem starts, but that's enough to get it to where you can barely touch the heat sink. Sometimes powercycling the amp resolves the issue, other times not.

The bias on the module experiencing the thermal problems, as it is experiencing them, is all over the place, from 200 to 600mV! I didn't adjust it. On the occasions when powercycling gets the module to operate normally, the bias is a few mV, which is correct, per the specs.

Any suggestions for things to try, or how to narrow down the problem? Perhaps this is a common failure mode? Amp is '97 vintage.

I've tried disconnecting the input board from the main board, to no effect on the thermal issue. Measuring the input DC voltage on the main board fingers where the power modules plug in, it is +/- 61.3V when the amp is on and the power modules are disconnected. When they are connected and working properly, it is +/-59V. When the thermal problem starts, the voltage drops to +/-45V. That could just be because of the power draw of the power transistors.

Schematic attached.

Hi,

i am looking for a high quality full range driver for a diy cabinet (appreciate if there is already a plans) to match with my 300b amplifier.
My 300b is a type which churns out around 11 Watts single ended Class A.
(monoblocks made by Diyhifisuply, the Lux mono max)

I am looking for quality.
Price is an issue as always, say around the 300-350€ per driver max if possible.

My listening room is 3.5x4 meter, so small room.
I listen mostly to jazz, electronic, indie, rock, classical.

Thanks for your help!

Hi all members DIY audio
My name is George

5 years ago I started exploring audio power amplifier .
I learned about class ab amplifier .
So I decided to build my own amplifier using best improvements from all big brands running multiple tests on multisim and LTspice.
I learned to use easy EAD so I can build my PCB

I end up building a pure class b amplifier with 0.000mv emitter to bias. When signal increases bias increase typically class b.
The sound is amazing
And bias output stage looks good to all frequency range.

All this thanks to a good friend from Indonesia Anton that guide me always.


Amplifier details

Input stage is ne5532.
First op amp is used as preamplifier
Second op amp is part off power amplifier
Same as BGW

Classic and simple push pull vas stage

Predriver stage

Driver stage

Output stage is bryston type but different somehow.
Predriver stage is driving three driver stage and each driver stage driving two output transistor complementary
At full power still generating heat

Next step is to use Yamaha EEEngine tracking digital power supply

This amplifier will deliver great sound and strong output power
But nothing special about that.
after all this I have strongly understood that I'm limited by components that exist on the market available for us .

So I come up with ideas for new BJT audio module. Rated for big power.

Some details about it
1200v
150A
Power dissipation 1500w
Hfe about 200
Frequency transition 50Mhz -100Mhz
And the most important base (bias)
Will behave as an any single BJT for audio
Built in base resistor
Built in emitter resistor

This module will 10 Times powerful
Small compact and practical

Isolated mounting
Screw terminal connector
Ect.........

I have contacted Toshiba about this product and I get an email saying that is on waiting list they can't generate relevant information yet..


And I like to invite MR Nelson Pass be involved in this project regarding BJT audio module
His experience will be important and useful..

Any member that likes to be involved in this project is welcome.
Thanks

Some friends are opening up a small venue where they will show films and have live music (same space)... I have a few questions regarding their setup, so that I can think about what we might make DIY, and what is better bought.

Their space is a bit of a weird size, 19'6" wide, about 45' long, and 14-15' ceilings. The ceiling at the front of the room where the projection screen will be is 12'9".

Local music store is trying to sell a pair of QSC K12.2 powered PA speakers for mains, and seems to think they will need four EV ZLX-12P-G2 for stage monitors for bands... that seems a bit excessive on the number of monitors, given that the stage will be at most 12' deep and probably less than the full 19'6" in width. I'm telling them to start with two stage monitors and buy more if they're actually needed. Any other recommendations on powered PA speakers for a space like this would be welcome.

For showing movies, I've convinced them to stick to basic stereo plus subwoofers for now, since it will be tough to get decent surround sound setup in such a long room, and a lot of the movies they want to show won't even have surround. I am going to build some subs, since what the music people wanted to sell don't go below 40hz, and they want a bunch of money for that. The same sound system will double for bands and movies for now. I've got a few drivers to try out, and was planning to build 2-4 subs for them once we figure out a good design.

I'd like to build some sort of massive line arrays for them in the future for the movie sound. Also considering something like a set of synergy horns to help control the directivity a bit, since the space is so narrow and long, and maybe those would reduce the need for acoustic treatment on walls/ceiling.

What kind of SPL level should we be targeting in there? I don't want ears to bleed, but I also don't want the sound system to struggle, either. What would be good radiation angles (horizontal and vertical) for the speakers to have?


Thanks in advance!

Hi ,I’m a student from india and am here because I’m currently working on my first DIY amplifier project and am really interested in learning more about audio electronics. I’m exploring different amplifier topologies like class A and class AB, specifically designs such as the Aleph J and Jean Hiraga. I’m hoping to get advice, tips, or maybe find some secondhand parts to help complete my build.

I'm new here. I thought that some of you might be interested to know that while I love audio equipment and listening to great music, I am a professional musician...a violinist. I am the lead violin with the Fox Theater in St. Louis and I played in the Saint Louis Symphony Orchestra for 20 years. Very few of my colleagues have high quality systems and sit down to listen as I do. Perhaps performing is enough for them.

Adrian

Oups. I fell into the rabbit hole of electrostatic headphones. Those estats sound really nice to my ears!

Estats work at high voltage and low currents, so they can (and should!) work directly off the anode(s) of some nice vacuum tube(s). No transformers getting in the way!

There are a few estat tube amps out there. However, I could not find one that fits my needs (or wishes). The amp should be somewhat compact, and I want an output stage using directly heated triodes (DHTs). So I started thinking about designing a new amp. Maybe we can pull this off similarly to the OSMC project, which was great because severeal DIYers contributed to the design. Everyone is encouraged to contribute to the design process here!

The OSDEHA design files and documentation are available at GitHub.

Here is a (preliminary) list of some design goals (that may be updated in the future):

• Use DHT tubes for output stage.
• Output is taken directly from the anodes of the DHT output tubes. No transformer or capacitors to transfer the power to the headphones.
• Input must take balanced input at signal levels of modern audio sources (mostly DACs these days).
• Input stage and other circuit elements are welcome to use solid-state parts where suitable. I don't intend this to become a nostalgia festival.
• Focus is on quality of audio reproduction and electronic design, not on low cost.
• The finished amp should be reasonably compact.
• The design is intended for use in the DIY community. If this project goes anywhere, full documentation will be provided in a public repository. Any use of the design (including commercial) will be allowed, but any modifications or extensions to the design that are used beyond one-off DIY builds for personal use are required to be re-published (and preferrably be fed back to this project).

Here's a (likely incomplete) list of some existing designs, circuits, and some other stuff that may provide inspiration:

• Auridux amplifier by @dddac
• Some great information on DHTs and tube design concepts by @mogliaa
• Blue Hawaii estat amp by @kevin gilmore, and a more recent build by @Algar_emi
• Megatron amp by @kevin gilmore
• Some (long) threads on the DIY T2 (1 and 2) and Mini T2 amplifiers
• The only DHT estat amp I found, I believe by @hpeter
• A few estat amps with/without tubes at High-Amp (Andreas Rauenbühler)
• Schematic of the Stax SRM-007T amplifier (most of the other Stax tube amps use the same circuit)
• DHT headphone amp stuff, although not for estats
• Tube CAD article on estat tube amps, and another one, and yet another one

So much for this opening post. I will post specific thoughts and questions later on, and am looking forward to what everyone else thinks!

Warning: This DIY project involves high voltage. Individuals utilizing the information provided must possess expert knowledge, adhere to stringent safety precautions, and accept all risks associated with electrical work. The authors and contributors of this project expressly disclaim any liability for injuries or damages arising from the use or misuse of this information.

Vendor-supplied SPICE models for fixed linear voltage regulators are rare so most models available on the Internet have been created by individuals trying to fill the void. I came across the following post on a KiCad forum which contains models for the LM7809 and LM7909 regulators. These were created from adjustable LM317 and LM337 models by adding parameters to produce a +/- 9-volt output.

SPICE Models LM78xx & LM79xx Series

Based on this work, I created generic models from which any fixed regulator model can be created by passing two parameters. While these particular LM317 and LM337 models are not very accurate compared to the Texas Instruments models, the supplied parameters can be tweaked to create the desired output voltage.

I spent an afternoon creating models for the most popular fixed regulators and have compiled them into a library. My library also includes the TI models for the LM317 and LM337 adjustable regulators, which I've found to be very accurate.

In the spirit of giving back I've attached my library here, along with a "universal" symbol (reg.asy) that can be used with all models. This library comes with the usual caveats: no warranties implied, use at your own risk, etc.

Edit: Library updated May 16, 2025

Greetings ✨ my name is Giannis a DJ and event planner from Greece, co-founder of a music collective in the Greek underground electronic music scene and i am here to learn more about DIY audio as i am looking to build my first PA system.

I discovered this wonderful site in the process of building my home theatre - looking for bass that you can't get in the commercial theatres.

I'm focusing on the subs at the moment, having built sealed, ported and devastator test boxes, I've chosen to go for 4 large low tuned ported cabinets.

Once they're done, I'm tempted to start looking at DIY speakers 🙂

Hi, my name is Roberto, and I’m from Italy .
I have a personal interest in all things audio and electronics.

Nice to meet you all.

I am a woodworker and furniture designer, so I have a good workshop to start building Bluetooth speakers. Would like to improve the quality of the sound of my first attempt!

There are 15 amp boards, 13 of which have LM3886TF and other parts soldered on them.
2 LM3886TF chips have not been soldered onto boards.
None of the boards or chips has been tested or used.
I do not have documentation for the boards.
$25 for all, shipped in CONUS.

Hello, I have a few DIY builds under my belt now but I’m still very much a beginner and still learning.

For my next project, I’m wanting to create a compact 2-way bass reflex loudspeaker utilizing a 6.5in -7in woofer and tweeter. The goal is create something petite in size yet huge in sound.

The enclosure will measure 12in (h) x 9in (w) x 12.5in (d)
Utilizing 3/4in thick wood.
This makes the enclosure roughly a half cubic ft.

For the woofer I’m planning on utilizing the

PURIFI PTT6.5X04​

as I’ve heard they work excellent in smaller enclosures and play very loud. Price isn’t a concern here.

for the tweeter I’m wanting to use something compact that can be mounted very close to the woofer that also will work excellent with the chosen woofer.

I need help finding a worthy tweeter for this project and also opinions for the woofer I choose for this project, if it would be a good fit.

Thanks in advance,
Michael

What is the purpose of adding these components to the original circuit.
I have the same amp so should I do the same if this improves the output?
Also I would need to know the components as well.

Hi, I am planning to build a PP amplifier with a global negative feedback. This is a general question: which tube would give the most musical sound?

AnTek AS-2218 - 200VA 18V Toroidal Transformer
https://www.antekinc.com/as-2218-200va-18v-transformer/
Unused, includes hardware. As new.
$40 shipped in CONUS.
Stock Photo:

AN-5218 - 500VA 18V Toroidal Transformer
https://www.antekinc.com/an-5218-500va-18v-transformer/
Never used. As new.
$60 shipped in CONUS.
Stock Photo:

16 - Nippon Chemi-Con Capacitors 39000uf 35v smh
Never used. 5 solder lugs on the bottom.
$40 shipped in CONUS for all 16.
Sorry about the focus.