Hello Dyers, I`m looking for the best possible schematics for the above, I'm going to build a power amp in class A and I want to know, which PSU is considered the best, and why ? Thanks !

New guy here looking for advice, education, recommendations and community. I have a small collection of various components. My main system is Furman Elite 15 power conditioner, Isoacoustics zazen 1 tt platform, Technics SL 1500c, Hana ML cart, ProJect RS2 phono pre, Audiolab 6000cdt, Audiolab MDAC+, Placette active line stage, Mac 2100 amp, and JosephAudio RM25si Mk2 speakers. I also have a set of Acoustat Spectra 1100's, the only component bought new in 30 years. I'm looking for info on rebuilding or having rebuilt the Acoustat crossovers. Thanks.

I am a complete noob when it comes to DIY audio. Got a subwoofer with a broken plate amp. Instead of repairing the plate amp it looks like its cheaper and easier to build one with one of the class D amp boards from aliexpress.
Need some help with the same and that's how I am here..

I have always used JLPCB from Hong Kong for my PCB fabrication, as they offered excellent performance at an unbeatable price. Now, with the new tariffs and USPS suspending all Chinese shipments, what are our domestic alternatives that at least come close to JLPCB?

Where do you guys buy your LP12 parts? I need to start listening again (Ittok LVII, Valhalla) .

Hi, just looking to get some help and co tinue on an old thread about fixing the old rel t5 subwoofer. If you have one, could you come and help me out?

Hi, please, are toroidal inductors any good for building crossovers?
Like the ones in the link below.

5pcs Toroid Inductor 3A Winding Magnetic Inductance 22uH 33uH 47uH 100uH 220uH 330uH 470uH Inductor-in Inductors from Home Improvement on Aliexpress.com | Alibaba Group

Thank you

Hello hope everyone has a nice week-end !

I don't think one would want to load a cartridge with an electrolytic, but what do you recommend as the type or quality of film capacitor is best at this position? I would think quality matters here since that load is part of the "signal generator" circuitry, along with the load resistor.

Currently I use polystyrene, is that just overkill? Would a high quality polyprop work just as fine or the quality doesn't matter at all ? Although I didn't check I think teflon films are still in production, Solen maybe?

I'm guessing most current phono preamps use polyprops as the polystyrenes are basically extinct and a maker wouldn't use NOS stock on a new product.

Thanks for any insights.

-Joris

Hello everyone, I have been a keen follower for some time and quite often search for answers to the questions I can’t easily find elsewhere, here!
I particularly like vintage 70’s HiFi and have a growing collection which I must start to reduce as I am running out of shelf space!
Also recently embarked in creating my own self built amplifier and it has been both a great experience and a game changer for me, very decent hi-end sounds for bargain money and a little effort and learning.
Thanks for all your past help with the posts I have read.

After 6 years of mining, while doubting that this day would ever arrive, Pi opens for trading on a number of exchanges in less than 48 hours.
If you've mined in the past and forgotten about it, drop everything and KYC right now... IOU trading has the price @~ $75 currently.
Binance is not on the current list of exchanges, but it looks like they'll be listing Pi soon.

Hi,

Does somebody know what a double diamond buffer means.
They don't use a volume potmeter but I think they change the current of the balanced input pair.
Does somebody experiment with this kins of variable gain circuitry.
A friend of mine bought this amplifier and it sounds great.
I'm going to try to build something like this and see how it works and sounds.

Rob

Fun with op amps. I present, the "Bug". Stacking is nothing new but these stacked ne5532 op amps are playing very nicely with each other. Will have a vid with proper audio examples this week.
Login to view embedded media

I have for sale a

IAN CANADA I2S to PCM Conversion Board.​

It has all ufl pads soldered and tested.
I am asking 75 euros.
Registered shipping included in europe.

Hi, I've been tinkering with this subwoofer for over a month, and I can't get it to sound right.

I have desoldered about half of the components of the boards and I can not detect what is happening....

It is a Kenwood SW-505D subwoofer. It sounds very distorted, you have to select near full the volume to make it sound something low like a trapped fly...prf prf prf prf prf prf prf

I'm just an amateur without much knowledge, but I think I put my heart into it. I think, that the failure is in this board... any help will be appreciated, thank you!


The voltages on the HIP4080 are:
P1: 11.63v
P2: 12,14v
P3: 0,34v
P4: 0,011v
P5: (not soldered on board) variable around 0,520v with the volume at 0 and around (oscillating) 4,80v at max
P6: 6,21v
P7: 9,27v
P8: 5,18v
P9: 5,18v
P10: 11,64v
P11: 0,028v
P12: 0,028v
P13: 11,26v
P14: 0,011v
P15: 12,14v
P16: 12,14v
P17: 0,011v
P18: 0,39v
P19: 0,009v
P20: 0,010v

IC3
P1: 9,90v
P2: 6,57v
P3: 6,59v
P4: 0v
P5: 5,814v
P6: 5.814v
P7: 6,051v
P8: 12,13v

IC2
P1: 6,059v
P2: 6,059v
P3: 6,055v
P4: 0v
P5: 6,059v
P6: 6,059v
P7: 6,21v
P8: 12,13v

IC1
P1: 0v
P2: 0v
P3: 0v
P4: 0v
P5: 6,103v
P6: 6,059v
P7: 5,161v
P8: 12,13v

This sale is for Jos Vaneijndhoven attenuator which was sold as a diy kit and later went commercial. It's a relay based attenuator with input selector, both which can be remotely controlled. The manual can be found here.
Because I wanted to be sure that both channels measured absolutely the same, I've ordered 10 additional RN60 Dale resistors of each value (120 total) in order to match exactly the values with my Fluke meter so I'd have identical channel volume. I'm offering these resistors too with the attenuator (most of them are there, about 110 RN60 resistors). I also added a small transformer to power the circuit.
It's of course in full working order.

I'm also offering a chassis for this, as it was used for a small project now cancelled. It's a diy but it's very decent looking. I replaced the used bottom with a new one, so it is like new with the exception of front and rear plates. The rear is been cut for neutrik rca sockets, rca and power. Because of it's weight I'm giving the option to buy the attenuator seperately.

Edit: Attenuator SOLD only chassis left wondering what it's fate will be.

Hello, I noticed I no longer have a signature. Regards.

I've found 24 x Toshiba 2sk170 BL when I tidied my workshop, there is a mixture of straight and kinked legged.

£30 posted in the UK anywhere else add £6

I recently got this Jolida JD-302b. I briefly auditioned it and fell in love with it. Seemed like a great deal at $450. I've only recently begun auditioning tube amps and need help identifying the mods on it. It clearly defers from the schematic that I've found. I'm reluctant to take it back to baseline as it sounds sweet to me. I think it goes toe to toe with the MC-240 and the Dynaco St-35 that a friend brought over. I dig it. I'd like to know if it's going to eat tubes or is potentially dangerous. Any help for a newb would be greatly appreciated.

Well, I’m new here. Grew up on HiFi with my dad playing records. I’m 54 now and I got back into HiFi during quarantine Covid time. In the last 5 years I’ve been buying selling tweaking gear. Here to learn! Cheers!

Hello Everyone,
I have an Adcom GFA 585 that has an issue with DC offset when shut down. I am aware of the capacitor issues and recapped both input boards after sonic cleaning both boards multiple times after following the instructions from several threads on this site. My issue is a little different than the other threads though and I was hoping someone could help me methodically figure out where the problem lies.

On startup, the right channel behaves as it should and settles around +/- 5mv dc offset. The left channel starts a little higher, maybe 200mv and then settles to vary around +/ - 10mv which isn't bad either. However, when I turn it off, offset can jump to between 6-20v positive dc on the left side. The output of IC101 when running is about -1v which seems pretty good, but when power is cut, it jumps to -10 to -11v like it is trying to balance the DC but doesn't have enough juice.

Based on how it runs pretty well, it doesn't seem like it is input transistor or IC101 related, so it makes it difficult to pin down the issue when turned off. How would you go about narrowing down where the issue is?

Amp design is borrowed from an old D Self design with newer transistors which are currently available from DigiKey.
QSPICE simulations Sine Wave and Square Wave are good but not Bode. I'ts unstable. After much failed 'twerkulation' to move poles and zeros, I've chosen to seek suggestions from those with more experience. Suggestions welcomed.

At sometime in the past, I read that certain axial film capacitors degenerated over time. If I remember correctly, the end caps of said capacitors were identified by colour. Unfortunately I cannot remember what that colour was.

I have some crossovers from Electrovoice which each contain three axial film capacitors - 2uF, 12uF and 21uF. I suspect they were constructed circa 1970. As mentioned in the thread title, their end caps are red in colour. Should these concern me?

As far as I can tell the variable resistors in the crossovers do function but how they affect the sound seems quite subtle to me.

The speaker system in which I installed them is a 3 way using EV 12" woofer, EV MR10 horn midrange and EV T35 tweeter. I cannot say that I am thrilled with how the system sounds. My perception is they are overly bright and adjusting the tweeter and midrange variable resistors produces a perceptible but negligable change.

The thought occured that perhaps those film capacitors are out of spec under load. The readings I obtained from a DMM with the capacitors out of circuit were within tolerance so I left them in place.

Since they are 55 or so years old, are they due (or past due) for replacement?

Hi,

I am working on a Classe CAV-180. I wanted to ask this question to Classe' Tech support but they seem to be out of business.

I got this amplifier as dead. I found that the slow start 10 ohm 50watt power resistor was the problem. I temporarily replaced this with a 15 ohm resistor and the amplifier starts up and sounds great! There is a short beep noise for say a 100ms when first pressing the power button. I am not sure this will clear-up when I put in the proper resistor.

The main question here is: on page 11 of the service manual (attached) they describe several updates. I don't know what issues these updates apply to and if I should do them?

This one is troubling me.
"4. On board B2E2X (5 PCBs), make sure that Q1 and Q2 are part number 2SK79 and 2SK216. They should be mounted on a small aluminium block, which is mounted to the chassis (see following pics). If they are printed as ECX10N20 and ECX10P20, replace them, using the following guide."

It seems the ECX10N20 and ECX10P20 are very good parts so why would they want these changed?

Thanks, Gary

Some time ago, I decided to build Tony Gee's Calpamos speaker, so I ordered a set of crossovers and started gathering the remaining parts. Since there doesn't seem to be much documented about these speakers here on DIY Audio, I thought I'd share my build.

Just within the last few weeks, I started cutting wood to make the boxes. The first challenge that I ran into is that 2x2 wood stock recently became a bit of a challenge to find. My local building supply store still had some stock of 2x4s at pre-pandemic pricing, so I grabbed a few and split them down the center.

It was a bit of a trick to make sure that everything remained square as I glued up each square and put them together to make a 3D box. More than one of my straight and true 2x4 boards decided to warp and twist a bit after being split down the middle. It took a bit of extra time checking and dry-fitting everything with my T-square before adding glue.

I also bought some caster wheels and made a 2' by 4' dolly so I could move these around the garage a bit more easily. After I built the frames, I realized that I didn't stop frequently enough to make images of my progress.

Hello there!

This is yet another amplifier noise thread 🙂 I guess you have seen plenty of them here and I beg your pardon to just be the next one you see...

I have been given an old Technics (National Panasonic) SU-3600 in nice state (except for some scratches and two missing knobs, but I can excuse this as it is a barn find and was for free)

I cleaned the beast and double checked everything after putting some new thermal grease and setting bias and IQ, and when I first powered it and listened some tracks I fell in love with it as it has much more depth than my other amplifiers

After further listening to it, I noticed that there is a background noise which is very distinctively composed of two components, a humming one and a hissing one... I guess the humming one would be some 150Hz and the hissing one would be some random noise, maybe thermal

One thing to note is that some of the noise is highly attenuated when I reach the middle of the master volume setting, so it seems that it is somehow related to the preamplifier rather than the power supply itself

As this is a somehow unobtainable amplifier at the moment I would like to make as little change as possible to it and get advice from other people before starting to replace all capacitors and co... they all seem fine and the sweet spot in the volume control makes me think that they may not be to blame

I'm suspecting the area around TR107 and TR207 to blame, maybe some resistors that would have gone out of range...

EDIT: to be noted that IQ and bias took quite some time to stabilize before I was able to get the specified values... trimmers have been lightly cleaned with kontact60 on a cottonstick

I attached the schematic for support, would some more experienced guys be willing to help?

This is a really nice amplifier, quite rare, which is a barn find, so it has become a duty for me to restore it to a hum-free state 🙂

Thanks in advance!

Have 2 Arylic streamer dacs and will throw in rack for it if you want. These little guys are feature rich and sound great for multi room setup. I’ve got them plugged into a multi channel amp. Inside it’s linkplay chip so it works with WiiM app and even groups with WiiM devices. All three plus rack $125

Is anyone familiar with the "TPA6132 Differential-Balanced Stereo Headphone Amplifier Board Single End Output" manufactured by Huanya?
It appears a lot on eBay. The link is: https://www.ebay.com/itm/264669105325?_trksid=p4375194.c101949.m162918
On the underside of the PCB it reads "+6 db: R1 R3" What on earth am I supposed to do? Butcher the board?

This happened with Both F5m and just now with F6. adjusting bias gently
then the Bias just runs away and blows the mains fuse, and with my F6
one Mosfet,

I'd like to see how close (far) a design using simulated data is (design without measurement) to one with actual data. The problem is, I have seen the actual data and don't think I could design a crossover with the simulated data without at least subconsciously accounting for some of the differences that I have seen.

For anyone interested, help me simulate a crossover using the attached simulated data. This a a two-way with a 6-1/2 paper cone woofer and a 1" silk dome tweeter. The data incorporates the diffraction model for the baffle, but is on each driver's axis. So, you will need to use minimum phase data, set the woofer at -165mm y-offset and something like -18mm z-offset. [Tweeter data is .frd and merged woofer data is .txt] Traced tweeter impedance and simulated in-box woofer impedance are also in the zip file.

Which one is good in sound quality and loudness. xy-p15w or tpa3110

For sale Automatic Electric Europe (AE Holland) 5K to 6 Ohm single ended potted pair output transformers.
Good for the following tubes like 833, GU48, 2XGM70,…etc.
Primary (Anode) current: 300mA, Primary DC resistance:110,7 Ohm, Primary inductance: 19.8 Henry.
10-30,000Hz.
Each opt 13,4kg.
Size: 15cmx17cmx15cm
Slightly used by me, in very good condition.
AE 4:1 Interstages are also available.

Hi all,

Is anybody using the FNIRSI 1013D 2CH Oscilloscope? It's a sub-$200, so the price is OK. I'll be using it mainly for t-shooting and measuring audio tube gear, so 100Mhz is plenty. Other than that any input on pros/cons would be greatly appreciated!

thx much!
/DL

Hello,

For sale is new, unused Burr Brown PCM63-K DAC board.

Proven configuration; CS8412, SM5813, 2x PCM63-K on digital side, 2x AD797, 2x OPA177 on analog. SPDIF input, dual mono audio SE output. Analog audio is PCB routed dual mono, so ideally it can use two power supplies (2x15V DC) for audio plus..one for digital. Of course simpler power supply can also be used.

Board is new, only assembled and tested. Works flawless and IMHO sounds just like good PCM63 DAC should. Dimensions are 16 x 10, 5 cm. Quality double sided PCB with separated ground planes. I can also drop in 2-3 empty PCBs for matching power supplies.

Board is laying in a drawer waiting for housing for too long, so if anyone is interested,

Price would be 200€ plus shipping. PayPal (friends&family) preferred.

Regards, Davorin

Recently, I wanted to build some compact and battery-operated headphone amp (Just for fun!!!)

Then I browse thru this website: TCAAS - The Class-A Amplifier Site and saw JLH1969 class A schematic and realized that I hadn't build any OTL amp yet.

I've been building some decent design amps and those topologies all utilize dual-rail power and dual battery operate amp is problematic (don't like the virtual ground design)

thus I saw many scale-down versions of JLH1969 class A amp (This is the one particularly good for low voltage operating JLH 1969 battery amp) and simulated it.

It's turned out very well!



Thus I went to the local electronics store bought some goodies and start build on the perf board

Also found a small case and rechargeable Li-ion 9V battery for the amp


It sounds pretty good with my DT990 pro 250 Ohm headphones!

Although I have finished this project I've some questions want to ask.

1. I know the output capacitor in OTL amp is to block circuit DC from the headphones but I still measured some 10-15 mV only at the left channel. This makes tiny noise at the left channel that sounds like scratching ear. I've swapped many output cap and didn't fix them. Never occurs at right ch tho.


2. I use MJE340 as my output stage device and quiescent current is set at nearly 70 mA. MJE340 works at about 300 mW.
I saw the datasheet said the Thermal Resistance(Junction−to−Case) is about 6.25 C/W. Should I use the heatsink?

Hello I'm Kirk 61yrs young. I live in small town just out side of Louisville KY. I'm a diy'er for just about everything. I stubbled on to this forum researching a noise problem I'm having in a circuit.
Thanks for letting me join.
Kirk

Hello all

I have a couple of latest revision V4 through-hole boards left for Marc Jonson's Simple, no-math transformer snubber using Quasimodo - anyone in the EU wants/needs, I can offer for 8€. Shipping within the EU would be 4€. For tracking add 3.65€

Hello,

I need some additional jumper for my Sofia tube tester but I cn't find the pn; I know that the old ones are marked RS but the research was bad.
Someone can help?
The RS can't help me because they don't accept the photo!
In attach the photo of the panel

Thanks

Walter

Looking at a new project.

Has anyone built or heard the Humble Homenade Hifi “The Monitor” and would be willing to post opinions?

This is a small floorstander with 10deg slope baffle. Drivers are Audio Technology 18H midwoofer with Seas SP21 passive radiator in a 17L cabinet, tweeter is a Hiquphon OW2. It is provided with three crossovers so would be interested in the differences.

And as a long shot, how would this compare to the 20L sealed version of the Zaph ZRT?

https://www.humblehomemadehifi.com/download/Humble Homemade Hifi_The Monitor.pdf

Thanks in advance for the comments.

I have been watching and reading all about DIY speakers and I am very interested in building my own desktop monitors. I have never buildt any speakers before and I am reading many different opinions about what methods, designs, crossovers, etc to use for a speaker design. I am getting a little overwhelmed by the many design options and drivers.

I am currently looking into building dome shaped speakers, using the ikea bamboo bowls as a bevel and 3D printing the backside (see attached image for inspiration). I will probably choose to build closed back speakers as this will probably be easier to design. Besides audio quality, I am also looking for a unique speaker design as I find box shaped speaker designs boring and uninteristing. I want someone to walk into my room and immediatly look and want to listen to my beautiful low cost DIY speakers.

My desk is placed in a very small (2m wide) student room with a low ceiling due to a bed being above my desk. I have cheap accoustic panels on sections of my walls to help with the interference, but I think my room is highly sensitive to this issue. I have a second hand KEF sub woofer in my current setup, with 4 KEF HTS 5001 satellites for my surround and use a Onkyo TX-SR393 receiver. I however want to upgrade the front 2 speakers as I want to be able to enjoy the full fidelity of my vynil collection. I listen to a variety of music genres like alternative rock (Radiohead), Electronic (Royksopp, Daftpunk), and rock (AC/DC, Nirvana), but I also enjoy listening to dj sets from the hard techno to trance scenes.

I am a complete beginner when it comes to speaker building, maybe its wiser if I build a kit or fully guided DIY project before designing my own speakers. I am open to hearing suggestions and other peoples expereinces or builds.

Hello!
I don't know if there is a more accurate word for explaining this "tsik tsik" noise from the turntables. If there is one, let me know. Until then I will say noise for this known to everyone I guess little noise coming from the turntables.

At first I thought it came from the friction of the needle with the vinyl, which creates static electricity. But then, after several conversations, I realized that there can be many factors that can cause it.
Certainly one more can be the bad quality of the record or a poorly maintained record. But, in my case it definitely has to do with the turntable itself. I say this because on records where noise can be heard strongly on my Technics SL D-2 it is not noticeable at all or at least at the same level as on one of the other turntables I have. Also another reason I think it has to do with my turntable and not the amp is that I have connected it to almost all of my amps.

So the first thing I want to check is if the ground (GND) is working. How could I check for proper grounding?
OR where do you believe I have to focus my research to find out why is it so noisy?

Thank you in advance for your answers and for your help.

-gio-

Hi there, I have a question for the speaker makers/designers.
I'm renovating our lounge room and planning on building a large wall unit to house the television, stereo and bookshelves.
I would like to incorporate a couple of cavities in the unit for some custom speaker cabinets. I'm thinking that I might make the spaces large enough to allow me to experiment with different speaker cabinet sizes. But overall, the speakers will look like they're part of the bookshelf.

I'm thinking of experimenting with a pair of full range drivers in ported boxes, or maybe a two way set up.

I know there are issues with placing speakers close to the walls/corners of a room, and ultimately it's best to play around with placement. But we also want the unit to look like one piece of furniture.

I've made a basic rendering of what we're thinking of achieving below. Can anyone impart any advice if they have tried something like this before? Is this the worst idea in the world? Or are there ways to get a half decent result from something like this?

(For reference, this is a very large room, 8m x 5m with a 3m ceiling height. Speakers will be driven by a NAD C320 amp).

Many thanks

Sale:
GU43B - 10 pcs. for $70
GU-50 - 100 pcs. for $5
GU-81M - 50 pcs. for $40

various magnets for many purposes

Selling magnets
price for all together


1-4 photos cobalt magnets
5-6 photos neodymium magnets
7-8 photos ferrite round magnets


I ask 25 USD for everything + shipping.

Payment via Paypal (+5% commission)

Hi all,
I bought a the BUD amplifier's PCB and I have noticed that the cathode resistor of the power tube (EL84) is 68Ω. This is resistor R18 in the schematic.
This looks way too low to me. I would use something between 330Ω to 680Ω (470Ωmaybe). This value will pull a current of 45mA through the resistor which is a lot.
It looks that they are applying ≈180V to the anode/plate and ≈160V to the grid2/screen.
What do you guys think, is this a mistake or do they really use this value? Such a large current will shorten the valve's lifetime, I guess. I would use 20mA instead.
Kind regards,
Pedro

This is the link for the build manual.
https://s3.amazonaws.com/tubedepot-...iles/BUD_Manual_-_Working_Copy.pdf?1583168310

Hi all,

Please, could someone help me with CCS in the cathode of a tube?
I want to use the ring of two type, but I'm a beginner in CCS designs. Could anyone advise me on resistor values and transistors?

Thank you

Here I put my skin on the market.

Project is in the development stage.

The objective of this project is to build a SPL dense compact solution for low crest factor music, I.E.: heavy bass.
All that reggae, bassy chill, full on PSY, techno, tekkno and other heavy stuff, in which long bass line happen to play for long loong minutes.

How do I do that?
Well, speakers are not built for this mostly at all, so some compromises must be taken into account. No free lunch, kids!
Basically, anything seriously compact in PA can only be ported or bandpass. Not much way around it, if same (good) bandwidth is to be achieved.
The issue of ported designs is, that they have significant cone excursion minimum in "most used" part of the bass band, and that reduces speaker coil cooling. On top of that, exactly at that frequency, most power goes into the speaker coil. So if full power goes to the speaker at that point on freqency scale, it is basically a toast within short minutes, sometimes sooner.

How come it wasn´t problem till now?
It was. Either the speaker burned, or heavily compressed, or strong limiting kicked in, kicking the output down by 6 or even 10db in some cases of even high end commercial products.
For "normal" content, it is not such big problem and this limiting kicked in rather gently and for short period of time. For heavy music, it would hinder the long term performance quite a bit.

What we gain: safety, low power compression and SPL compression, full bass, SPL density for box size, just 3dB limiter safety setting instead of 9-10dB. Low frequency mode giving fair SPL down to 25Hz.
What we lose: Maximum possible/peak SPL reached by about 3dB lower than conventional design. Also little of the Price/performance ratio.

How we do that properly?
In order to lower the thermal load on the speaker in compact design, it needs to operate in such a mode and way, that the impedance minimum and cone excursion minimum is avoided. In exact words, put the port tuning frequency outside the crossover pass band (lower). That will solve the issue. But of course, it will create another one. Otherwise this would not be novel approach at all. In this scenario, the speaker cone is forced to do most of the work most of the time. That means, it has to move a lot.
Most PA speakers "to date" are not built for that, so most speakers except the well chosen high end simply cannot do that. Those speakers will run out of linear excursion capabilities.

Objective in detail:
Box volume: Max ~210l / 7.4cu.ft brutto, ~92l / 3,25cu.ft net depending on the speaker.
Weight: ~34kg / 75lbs. Easy single person operation.
Frequency range: 40-80Hz flat, 35-110Hz -6dB.
SPL: 121dB/W/m+ according to Hornresp in halfspace.
This design could be made smaller, but A) for serious compromise B) If planned upgradability is dropped. More on that later.
Low power compression, low port compression.
In this case, tuning frequency will be 29Hz.

Basic sketch:



It is not my first rodeo with such design, and with RCF LF21N551 and barely with B&C 21DS115 it worked. Yet I sadly sold these, so it´s time to move little forward.
The wood used for outer walls is 15mm/0,59in baltich birch, speaker mount wall 18mm/0,71in the port, braces and back wall possibly 15mm/0,6in poplar birch.
The port is flow and "horn" optimized to squeeze little bit more performance out of the design than regular. Certain corners will be ground and smoothed some more. Thinking even about printing the port front-side into something more resembling of L-port. 🙂

Driver needs:
As mentioned, high displacement volume. We are talking here 20-21mm of one way stroke to fully exploit the design. Either IPAL class drivers or something like that in future. Actually, I am kind of counting on that the technology will catch up with the design. We are almost there. Also 5,3" to 6" coil for more "oomph" in 35-40Hz region would help. But we are doing it now, so we use what we have...

In order to fairly utilize the box, we need over 1,8l of displacement (one way) and optimum would be 2.5l. Meaning, 3dB more to reach all box limits as port flow, distortion figures for speaker stroke in such volume, doppler distortion limit almost.... That´s where this enclosure options end. And that is 21mm of excursion for 18".
The new RCF LN19S450 would qualify, but not in the current box dimensions. This is just a prototype, some changes to allow for 19" driver could be made.
I have already ordered that, but the story is unfortunate - Released in March 2024, odrered in December 2024 delivery NOT confirmed by may 2025. I just can´t. You know what I would have to say about RCF...

Drivers that qualify:
Generally these with displacement volume of 1,8l and more, and Bl²Re over 200:
That is, for example 18Sound 18NTLW5000 4Ohm version
LaVoce SAN184.50
All the IPALish drivers.

Drivers that do not qualify for feasibility reasons, but would work:
All similar drivers like B&C 18DS100/18DS115.
18SW115/4, RCF LF18X451.
Given the displacement limits, it would be just too expensive and not SPL dense anymore, or efficiency would be lower (more heating).

Why I gave the LaVoce pass: Remains to be tested, but Lavoce bass drivers allow for very large linear stroke. The SAN184.50 is marked as 15,5mm Xmax. If it is anything like 21" series, then it WILL work admirably till 16mm on regular basis. That gives it 1,95l of displacement volume. B&C on the other hand, has Xvar of 14mm, which is a bit of a stretch in my book, because suspension compliance dropping below 50% is at about 12,5mm That gives us 1,51l of displacement volume at 30% price hike. And so as much as I love the LOVELY 18DS115 it is rather out of the list. Not feasible. Would work, but at 1,5-2dB loss or more audible distortion. I am certain it WOULD stretch to these displacements, but possibly at too high distortion figure. Sad story so to speak.

Well, what if you pulled it all out of your a$$?
That´s where the reality comes in. Sims incoming, Prototype build will be done possibly by the end of this week, measurements next.
I also plan to make YT video about me rambling on audio topics and SAN184.50 review.

Suggestions, questions, opposition, all is welcome!

Germanium diodes
for high-quality playback equipment
used for biasing in transistor and tube products
also for power rectifiers
for example, d302 is often used for amplifiers on gm70
for anode circuits or a kenotron + two half-waves on these diodes
these diodes are old years of production of the 60s-70s
N - NEW
U - used

1) d7a-d7zh 1602 20$ us for all
2) d302 d304 d305 20$ us for all
3) d303 20$ us for all

or all diodes at once for 50$ us
+ shipping.

Payment via Paypal (+5% commission)

Hello all,

After noticing a very high temperature on my REGA mira 2000 (not possible to keep my hand on the lower casing after few hours), I started to check the idling current of the power amp stage.
It was a good check, because one channel was totally out of range (more than 50mV at power on). So I set both at 7,5mV (like it is described in this thread).

Since the idling current have been re-set, the amplifier is not hot at all. After few hours, it became barely warm (nothing compared to what was before!).
I think I fixed the issue.

This could have been the end of the story, but I had the chance to have during few days a thermal camera and I started to check the internal temperature of the amplifier.
The surprise was to see that the 4x power transistors stay cold, but some components are becoming very hot rapidly.
A little resistor (like 1/4w) is rising instantly up to 80°C. It is R88 named that you can see on the picture.
I am wondering if this is normal or not.
The resistor looks different from the other. It is a second hand amplifier that I bought in 2018.

Just to add that I never faced any "sound" issues with this amplifier. And it works few hours per day since 2018...

Any thought? Could be a normal behaviour of the amplifier ?

Thanks for reading !

Long time audiophile, tweeker, speaker builder, club system designer/installer. Here to learn and share.
Vladimir

I like electrostats, and joined this forum so I can make better electrostats, and electrostatic amplifiers, and energizers. I own Estatron LLC.

Have 4 of these excelent tweeters. They are lightly used in a dipool system and in excelent condition, both cosmetically and technicaly. Asking 195 euro each.

A friend left me this amp to look at was imported from the US and someone connected to our mains without a step down transformer.
The primary on the power transformer is open circuit, my question is what damage if any is likely on this unit?
There appears to be a number of semiconductors, IC's etc on this amp, its not a pure valve only amp.
Dont want to open a whole can of worms if I go ahead and order a new power transformer, but the cost of this amp its probably worth repairing, just want to know what Im in for.
What do most people find from experience in these situations?

I need some help purchasing from the Netherlands and possibly sending the small package to US. Please send me a direct message if you can help. Thanks.

I have a Marantz CD6007 that will play commercially manufactured CD's but will play CD-Rs only about 10% of the time. I have read that CD-Rs are only about 40% reflective as commercial CD's. These CD-Rs play 100% of the time in my $40 Sony DVD player. From what I have read, I need to turn up the intensity of the laser a little bit, so it can read a CD-R. The laser has this number on it "EP-C101". Several videos show a Pot on the laser for this adjustment, but I don't see one on this laser. Some videos suggest that the Pot might be on the circuit board that the ribbon cable to the laser is attached. Don't see a pot on this board either. Can someone advise me how to adjust the laser on this CD player?

When I turn on it is a big pop in the loudspeakers.
After this there is only silence.
The LEDs are lighting and the power on button works.
Everything works except for the complete silence.

Before active protection became a normal feature on home audio equipment, many speakers used fuses to protect the midrange and high-frequency drivers. A few speakers still employ them today.

Has there been any empirical evidence that fuses on tweeters & midranges may introduce perceptible distortion?

We understand the temperature of the conductive element increases when a current is present, causing the resistance to rise by an amount. I think the distortion claim may relate to that change in resistance, crossover merge point and the drop in sensitivity that may occur with some fuses.

I am looking at a modern lineup of very-fast acting fuses having a low resistance and 1% of re-rating per 10 deg C. Is there another mechanism that should be considered, or is distortion a non-issue with fuses on drivers?

Hi All - I recently bought a Harman Karon ST-8. It worked for a little while, long enough for me to start to really like it, and then the motor - a Papst GS 38.09 - conked out. I asked a tech look at it, and he diagnosed it with a bad hall effect sensor, a photo of which is attached.

Apparently, dual output hall effect sensors with leads (as opposed to SMT) can not be found. Also, replacement motors also can't be found - I have an eBay search saved just in case one pops up, but so far, nothin'.

So, I'm wondering if anyone has any ideas on how to make the current motor go, or barring that, any ideas on how to replace the motor all together? I don't mind it being a little kludgey.

Thanks!

Please I need your help, can you build this circuit as a one channel of a power amplifier?, And does it have performance disadvantages

Hello -

As I mentioned in my previous thread, I recently dug my Rogers LS4a's out of storage and have begun to investigate restoring them.

I will preface this post by saying I am definitely a novice, but I do try to research things thoroughly before moving forward or reaching out for help.

One of the speakers works fine. The other has a blown tweeter. In my previous thread I requested help with locating replacement tweeters for them. Forum member @vinylkid58 kindly pointed me in the direction of Solen that has them in stock. Before pulling the trigger, I decided to investigate further to see if I could find the reason that the one tweeter blew in the first place. I never abused them.

I removed the crossovers and purchased an inexpensive LCR meter (not for accuracy necessarily, but for comparative purposes) to test the caps. The woofer circuit consists of a 40 uF cap and an 8 uF cap. I isolated the caps and the 40's measured 41.2 and 41.3 respectively and the 8's measured 8.3 and 8.4. Acceptable values I believe.

The tweeter circuit is where the situation gets a bit difficult. To make matters more challenging, the cellophane wrapping on one of the caps disintegrated on both boards.
On the working circuit, the caps both measured 8.3 uF. One definitely is 8 uF and I believe that the other cap is also because what was left of the wrapper has a number code that matches the other. On the non-working circuit I do not get a reading for the 8 so that cap is definitely a problem. For the unknown cap, I get a reading of 4.3.

In my research prior to this post, in a very limited sample, I see that Rogers did have a tweeter crossover configuration for the LS4a's that was a 4.7 uF cap along with an 8. It is actually difficult to locate identical crossovers for this speaker - supposedly they had several different configurations. I am pretty confident that the working circuit consists of two 8's. Is it possible that the non-working one is a 4.7 and an 8? Or is it most likely that the 4.3 reading is an 8 uF cap that has failed.

Could a pair of matched speakers actually have different crossover configurations? In a repair video posted on YouTube, the pair being worked on had the same caps but one had an added resistor on the notch filter.

As far as the actual repair is concerned, my goal is to eventually re-cap the entire board. But to begin with, my plan is to recap the bad tweeter circuit and test it with the working speaker I have. I will then repeat the process on the working board so that the two circuits are identical. I saw Solen polypropylene type caps were now the recommended replacement with maybe slightly increasing the resistor. Does this seem accurate? If not, the original AlCap ones seem readily available -- if I can figure out the correct specs.

I am attaching two photos - the first is of my board and the second is of a LS4a crossover I found on the web.

Thanks in advance for any knowledge you all might have to offer.

I happened to get my hands on a Boston acoustics Soundware XS subwoofer with the plate amplifier gone missing. So am trying to see if I can build a plate amplifier using this class D amp from Aliexpress. TPA3251 High Power HiFi Digital Amplifier Board with High Power Stereo 220WX2 Bridge 350W AP2202


This is meant to be a stereo amp with an option to bridge to connect to a subwoofer. When I connect the LFE from my Yamaha AV receiver to one of the RCA's on the amp board; it works perfectly. However, I am relying on the Yamaha AV receiver to cut off all the high frequency. If I were to connect my TV audio out then there is nothing to filter out all the high frequencies. Hence, thinking of adding a pre-amp board like this.


The low frequency output from this preamp board should connect to the amp at the XH2.54 3p audio input terminal shown by the red arrow.



I need some help to decide how I make this work.
1) The amp already has a potentiometer that acts as an on/off switch and volume control. If I were to add the preamp board should I remove this potentiometer on the amp and use only the volume control on the pre-amp board?
2) How do I switch on the amp without this potentiometer switch? There are 2 wires separate from the rest indicated by the yellow arrow which looks like they might be connecting the on/off jumper and if I short them the amp should remain switched on? Is there any way of knowing this for sure using a multimeter ?


Any help would be much appreciated. And please pardon my lack of knowledge. I have no background in electronics.
Many thanks.

What is cone breakup, and what type of cones have what breakups.
Can somebody help.

So, I had a go at designing my own crossover. Or maybe just trying to do something that has to do with crossover-design 🤓 But when add some capacitors and inductors, nothing happend with the frequenzy curve. So I found a diagram (picture 1 below) and did the exact same thing (picture 2 below) and still nothing happend. Is there something wrong with my settings? From what I have seen Youtube-toutorials the frequenzy-curve will change when you add different values to the components.

Picture 1:




Picture 2:

I’ve got a slight volume imbalance on my Quad 63s. One is about 2-3 db lower than the other at 1m. I’ve had them for over thirty years and have replaced the panels myself over the years. One thing to mention. There’s a little covered hole which with the cover removed at the back shows a flashing led that has something to do with charging of the panels. The quieter speaker only flashes every 17 seconds whereas the louder one flashes every two seconds? Is this a clue to what may be the issue?

I have been watching and reading all about DIY speakers and I am very interested in building my own desktop monitors. I have never buildt any speakers before and I am reading many different opinions about what methods, designs, crossovers, etc to use for a speaker design. I am getting a little overwhelmed by the many design options and drivers.

I am currently looking into building dome shaped speakers, using the ikea bamboo bowls as a bevel and 3D printing the backside (see attached image for inspiration). I am still undecided if I want to build these openback or closed due to my room setup. Besides audio quality, I am also looking for a unique speaker design as I find box shaped speaker designs boring and uninteristing. I want someone to walk into my room and immediatly look and want to listen to my beautiful cheap DIY speakers 😉.

My desk is placed in a very small (2m wide) student room with a low ceiling due to a bed being above my desk. I have cheap accoustic panels on sections of my walls to help with the interference, but I think my room is highly sensitive to this issue. I have a second hand KEF sub woofer in my current setup, with 4 KEF HTS 5001 satellites for my surround and use a Onkyo TX-SR393 receiver. I however want to upgrade the front 2 speakers as I want to be able to enjoy the full fidelity of my vynil collection. I listen to a variety of music genres like alternative rock (Radiohead), Electronic (Royksopp, Daftpunk), and rock (AC/DC, Nirvana), but I also enjoy listening to dj sets from the hard techno to trance scenes.

I am a complete beginner when it comes to speaker building, maybe its wiser if I build a kit or fully guided DIY project before designing my own speakers. I am open to hearing suggestions and other peoples expereinces or builds.

Hello,

I am recapping a Revox B750 that I bought as junk. I’ve never used the amp before.

I have changed all the tantalum and Frakos, output transistors and few things here and there.

Today I switched the amp on. It didn’t pass the smoke test. I’ve noticed immediately smoke from, I believe, the power supply. I switched off the amp and can’t see any physical damage. The regulator are the originals, they seemed to test fine.

Now 2 things to mention, I’ve switched on the amp with only one power board plugged. The reason for that is that I wanted to set the bias separately. Could it be the reason?
The other thing is I followed advice on a mod on purpose to reduce noise.

I am sure the advice is safe, but I am unsure I have done it correctly. Thus I believe the issue could come from there. Here is the mod and 2 pictures of the power supply board. Also a picture of the schematic and what I basically have done with the diode.

«
2. Up output capacitance for all 4 regs significantly - to like 220-470 µF if you can fit those.
3. Add the customary protection diode from output to input (and reversed for the 79xx) - 1N4002 or something. This is just so that the cap from step 2 can discharge upon poweroff without damaging the reg. »

I’m very green when it comes to this, first recap for me. Any advice welcome. Thank you

Hi all - I recently recapped a Phase Linear DRS250. It powers up, and drives speakers at low levels, but when the volume goes up to even moderate levels it distorts badly. It sounds a bit like clipping, but the clipping indicator doesn't light up. Any guesses what could cause this?

I have an opportunity to purchase an Adcom GFA-8500. I own a gfa-555mkI and an MKII. Does anybody have any experience on how the 8500 is sonically ? Are there any issues with reliability. I don't mind doing some rebuilding

Hi All,
I need advice on a fried subwoofer that a friend gave me. It is a Cerwin Vega! HTS10A.
I noticed that the 2A fuse in the power plug was blown, so I bought 10. They immediately blow upon turning the sub on.
So I pulled out the plate amp to inspect the PCBs. The speaker pops, good.

I inspected the amp PCB and noticed an overheated area near where the speaker wires are soldered. There are to large resistances and two zener diodes at the heart of the toasted zone. Bingo!
So here are my questions:

• The zeners or the large resistors?
• if the zeners, how do I determine their type or voltage?
• What wattage of resistors?
• I really appreciate any feedback that can allow me to repair this. Thank you.

P.S.
I bought a fried REL sub a few years ago and put in a Dayton Audio 250W RMS plate amp. I love this sub that forced me to put my turntable on a heavy plate of tempered glass, suspended in the air with spectra kite line from the ceiling two floors up. I also had to suspend and dampen the cables (power and phono output). After trying just about everything (magnetic, floating, elastics, pillows, balloons,…), that was the only system that I found would stop the feedback. A pure joy to listen to! I can post solution if interesting.

I am trying to download a copy of Duncan Amps PSUD2. Is it real? Is it available?

I go to this page
https://www.duncanamps.com/psud2/

PSUD2 - last updated 22/11/2019

In the page banner, I see "Download Software" That download link takes me to
https://www.duncanamps.com/psud2/download.html

There I see:

PSUD2 has moved! You can now get the latest downloads and support from the Groups.IO page at https://groups.io/g/duncanampspsud
This page will stay live for the foreseeable future to host older versions

The new downloads page is a PSU Designer Group Forum
https://groups.io/g/duncanampspsud

And that looks like a software download dead end. So....... What is the story?

Radiators Japan (6 pcs.) for 3 transistors TO-3 cases each
with ribbed surface to increase area
dimensions 85mm*98MM*17MM
fin height 13mm
+ mounting screws and insulators

I ask 30 USD for everything + shipping.

Payment via Paypal (+5% commission)

Hi! I finally start with installation of phase plugs in fostex fe206en. Cuting go smoothley,but inside i have big problem. They glue small piece of felt on the magnet,with some hard white glue. I must remove it to get nice plane for phase plug?
Any idea how? I try to scrape it,but is very hard and very strong bond to magnet. Im out of idea how to remove it.
Only idea is to make hole in phase plug for glue. Glue is 2mm high cca.
Any idea how to do that with minimum risk for speaker?

Just built my first DIY audio project, an Amp Camp Pre+ and looking forward to talking about. Been buying audio equipment for a while but started to suspect I'd get better bang for my buck rolling my own and thought that getting more familiar with different parts and topologies and so forth would allow me to make more informed decisions for prebuilt stuff too.

Current main chain is SMSL VMV D2R -> Matrix XSPDIF 3 -> Drop Xduoo TA-84 or Aune S17 Pro (or now ACP+) -> Parasound A23+ -> Q Acoustic Concept 30s

Apologies if this is the wrong thread, but tech_association in California is selling quads of 'USA Stock Toshiba 2SK170 LAB Tested Quad 4 matched N FETs 7-10mA' for $19 here: https://www.ebay.com/itm/256263712435

And LME49710HA mono opamps for $3.99 here: https://www.ebay.com/itm/256652413375 I'm more interested in these but there a lot of Chinese fakes around.

They have plenty of positive reviews, some confirming genuine parts, no complaints. What do you think?

Hi guys, I picked up a pair of these Altec Lansing 1590e for FREE and thought I could make use of them (I could be wrong about that but hear me out!). The iron is VERY stout!

The manual can be found here: 1590e Manual

Looking at the "Strapping Information" table, I am fairly certain that I can omit the step-up transformer entirely and just use the 30V taps for 4.5-ohms and match it to a 4-ohm speaker without too much risk.

What has me confused is the "Strap" column. I presume this indicates internal wiring of the two sections delineated by dotted lines??

I've never worked on a 70V system before and haven't even opened them up yet. Thanks if you can help me read the schematic first and foremost!

Hello,

After a failed attempt at designing a stereo tube amp with a HAMMOND 263CX, 288mA, 360VCT, it did not provide enough power to both speakers on the stereo out.
After creating a resistive divider to power the individual amp stages, I thought I would have enough power to get a strong output from the EL34s.

After designing the new power supply with a HAMMOND 273BX, 700V C.T. @ 201ma, 182VA, which is really 980VCT using 700*1.4 because of diode voltage drop (using a two-diode rectifier by the way), I am hoping to get the proper voltages that I need for the individual amp stages. Honestly not sure how the 980V supply works both ways since I think of it as 490 on the positive swing and 490 on the negative, but like, if the voltage is rectified.. it is for sure 490V? so then how does that even accomplish what I am going for which is for both channels to have adequate voltages with no under-voltages.

Here are the plate voltages that my amp should be at:

*12AT7-1/2 PreAmp = 250V
*12AT7-1/2 PreAmp = 250V
*12AT7-1/2 PreAmp = 250V
*12AT7-1/2 PreAmp = 250V


*12AT7-1/2 Kathode Phase Splitter = 250V
*12AT7-1/2 Kathode Phase Splitter = 250V

EL34 = 400V
(left) = 400V
EL34 = 400V

EL34 = 400V
(right)
EL34 = 400V

8 Tubes in total.

Each channel has 1V of signal going into preamp.

Using ot20pp output transformer (6k6ohm)

I am more than sure I have enough voltage to power 15W into each channel...(right 😅)

In the design I have done my best to include a dual gang potentiometer for both channels.. not sure if that halves the signal power but eh...I just want to make sure I am doing all of this correctly,

and sorry for such a long post, I am a novice engineer and I don't know where else to turn to, thanks in advance!

Hi there,

after getting retired some time ago i'm going back to my roots as Radio- and TV Tech. i loved that Job .... but ...
Worked the last 35 Years for a large US IT Organisation (much better paid in comparsion to Radio -TV Tech 🙂) ....
But during that time i always worked on my own stuff (mostly US HiFi Equipment) and repaired many old McIntosh gear for my collecting friends.

Main interest still is measurement equipment for Audio- and RF-Applications.

I'm currently a part time worker for a HiFi distributor. Doing repairs .... mostly just for fun.

Hope to get some help here in the forum but i'm clearly also willing to help others .... 🙂

Hope that helps

https://audioxpress.com/news/seas-launches-toy-diy-kit-with-metamodal-tpcd-coaxial-driver




dave

This thread is for the discussion of builds of the Ultra Amplifier as described in the main development thread: Ultra Amplifier with JFET input and Lateral MOSFET out

Thanks to @lineup for the design and to @benpe who helped with testing and editing the build guide.

This is my version of the amplifier which differs from lineup's design. Changes were made to address parts availability, stability (thermal & DC), noise, PSRR and protection. However, even with the changes, the spirit of lineups original design is maintained.

PCBs for this were designed to accommodate builds in a chassis as small as 2U x 300mm deep. The nature of Lateral MOSFETs allows the design to run as much bias as the heatsinks will allow. Although it will work in a 2U chassis, as the heatsink capacity increases, the class A region can be increased with higher output bias. Refer to section 5.6 of the build guide for PSU and heatsink sizing and it's affect on the Class A region.

The design is intended for ±24V to ±30V main rails from 18V to 22V transformer secondaries. Though not recommended, it can run as high as ±41V on 30V transformer secondaries. My build uses ±30V main rails running dual mono in a 2U chassis with 600mA of bias. This produces a 5.75W class A region with max power of 40W into 8Ω. Section 5.1.1 of the build guide discusses transformer and OPS device options and their max power potential. Within the recommended supplies, it ranges from 25W to 40W into 8Ω.

Note that my version of this design runs more NFB than lineups, resulting in a lower noise and distortion, but a lower overall gain of 15.5dB. As a result, a preamp will likely be needed to drive it to full potential. Alternatively, you can use a typical source (2Vrms or less) and be comfortable that you're unlikely to have enough input voltage to see clipping.

Build Guide & BOM
A quick note on the build guide & BOM. When I first started with this hobby, I found that some things experienced builders considered trivial confused me greatly. With this guide, I tried to include as much information as possible to assist new builders. With that said, the guide also has content specific to this design that experienced builders will likely find helpful.

Any feedback on the guide or BOM would be greatly appreciated!

V2 PSU
The V2 PSU concept is a not included in lineups design. From simulations, I found that this design benefits from higher IPS-VAS rails. 5V above the main rails seems to be the sweet spot. Benefits include:

1. Boosting the ISP-VAS rails allow for an aggressive RC filter which significantly increases PSRR.
2. Lower distortion at higher power levels.
3. Increased overall output by allowing the output devices to swing closer to the rails. This also allows for higher bias settings with less dissipation than simply running higher voltage main rails.

#3 above is probably the main reason to use a boosted IPS-VAS section, rather than just higher overall rails. Especially if you combine it with the voltage drop a RC filter on the IPS-VAS rails produces.

The V2 PSU is implemented using DC-DC converters in the V2 PSU PCB. This allows the VS PSU to be established at 5V to 6V above the main rails without the need for additional transformers or a custom transformer with additional secondary windings. I got this idea from Winfield Hill's AMP-70 design. See post #20 in this thread for more info.

The V2 PSU is implemented on a separate board in the initial build for several reasons.

1. I wasn't certain if it would work until it was actually built. I consulted with the manufacturer on my use case and they couldn't give me a clear answer. By using a separate board, I could implement changes if needed without rebuilding the entire amp.
2. It's not clear to me if builders will like this idea. Section 5.1.3 of the build guide has various options for this including eliminating it and running a conventional single PSU.
3. Section 5.1.4 of the build guide discusses PSRR. It shows an variant I'd like to explore of splitting the RC filter into a RCRC for improved PSRR at mains frequencies (-6dB improvement at 50Hz).

If you have any feedback on the V2 PSU, please share. For future versions of the PCBs (if they happen), the build would be simpler if the Amp and V2 PSU shared the same board.

PCBs
I have 3 pairs of the original boards available (2 Amp and 2 V2 PSU). Boards are $25 (two amp boards and two V2 PSU boards).

Shipping in the continental USA is $5. For shipping outside the USA, it looks to in the $15 to $30 range.

Build Notes
Post #49: Discussion on increasing gain
Post #69: Discussion on VAS device selection and impact of matching.

Changes
2024-09-20: Build Guide updated to V2. Added Section 5.3.1 on alternate gain settings. Corrected R8 / R9 values in section 5.4 for KSC3503d / KSA1381E combination. Added note about KSA1381E being EOL.
Post #96: Preview of changes for V2 of the schematic and Rev1 of the PCBs
Post #173: Revisions to the V2 schematic changes.

Hi there,

After building the PL519, design of KeesB, I asked him if he had a nice sounding Push-Pull design.
Which he had and he asked me to draw up the schematic of the EL84 Push-Pull direct coupled and asked me to share this in a new thread.
This amplifier is build up with a ECC83 direct coupled to an EL84 Push-Pull end-stage. This is an interesting version which I also build and which sounds sweet.
For questions you can reach out to KeesB.