I have 4 sets of x bosoz boards partly populated. I had gotten them from another member and never tested or used them.

$20.00 usd plus shipping
Thanks,
Evan

Pretty different drivers from a design standpoint but both intend to satisfy in a fullrange environment

Anyone challenge the two head to head?..... both are highly regarded and very similiar in price point.

Working Pete Millet Sound Card Interface.
Mu-metal layers in chassis to reduce noise.
Costs around $250-$300 to build

Asking $110 shipped

Hi. New to this great website and new to audio electronics.

I have a Denon DRA 685 receiver that won't get out of protection mode. After I push the power switch, the protection light blinks 8 times and then stays on. I also hear a click which I believer is the power relay. Thats it - no display, no sound,nothing.
Following the recommendation of another website Denon DRA-685, I replaced 2 resistors on the main board (R105 & R106), but that didn't solve the problem.
I am not getting the required "+15V" and "-15V" at test point CN1. I am getting .137V and .567V respectively. This is the same reading I am getting at the power regulator transistors IC1 and IC2.
I am getting the required 6 volts at IC 4.
To make matters worse, the service manual schematics that I downloaded from HiFi Engine are very blurry, thus I can't read the required voltages at different test points.
I am stumped.
Any help would be much appreciated.

Thanks

Hi guys and girls

I'm working on my first project and have come to the speaker build ( going great ) - but have come to a dead stop.

Crossover!

As I have 10 thumbs and I'm not really happy about beginning to build a crossover from scratch - too much can go wrong when I'm doing it.

People are really good at showing why 2 and 3 way pre-build crossovers are crap, and I get it.

But if we look at a simple straight forward oneway crossover, what can go wrong?

https://www.soundimports.eu/en/dayton-audio-6000-lpf-4.html

Can they be used ?
Can you just wire them in series so they will split for bass, mid and tweeter?

My logic says

Crossover 1 splits the signal 2 ways
Crossover 2 takes signal from the first crossover and splits it 2 ways

Crossover1: bass
Crossover 2: Signal to mid and to tweeter

Or is my logic failing me yet again ?

Hi All - I recently came across a pair of Zenith Allegro 3000 speakers at a thrift store. They have (supposedly Fostex) 16 ohm, 10" Alnico woofers and a horn tweeter. I'd read on a few forums that these are very efficient and they ARE much more efficient than my Advents. Does anyone have any specs for these or actually measured them. I'm guessing they might be 96-98 db/w/m. Is that close? I took the backs off, as someone suggested, but I'm wondering if anyone has tried these in a different enclosure. If so what design and dimensions? I'm thinking of eventually building something that's simple (since I'm not much of a carpenter) and is efficient enough for my DIY "budget Bugle" 45 SET that I recently completed. Any info or suggestions would be greatly appreciated . . . Charlie

Hey, guys. I have no idea what other sub-forum to post this to but I hope you will forgive me my transgressions if this isn't the right place.

I test loudspeakers and raw drive units. I recently tested a Dyn MW172 8 inch mid/woofer. It's car audio marketed but with this group being so technical I thought you might still appreciate seeing the data/results.

My full review can be found here:
Dyn Audio MW172 Drive Unit Review


And if you're in to watching YouTube videos, I am trying my hand at those as well and this is the review for the Dyn:
Dyn Audio MW172 8-inch Mid/Woofer Review - YouTube


Anyway, just thought I'd share. It's cool stuff for us audio nerds to bug out on. 🙂

- Erin

Does anyone have a pair of Magnequest EXO-03 plate loading chokes that they want to sell?
Please PM me if you do.
Thank you,
John

I have a chance to buy PCF80 and PCF86 NOS tubes for very cheap.
PCF80 I guess can be used as a replacement for ECF80 (only heater voltage is different?)

How about PCF86?

Should I bother to get few?

Thanks.

What would be a good quality, nice sounding amp module for a portable 2.1 Bluetooth speaker?

It would need to be able to work from Li batteries as well as mains.
thanks!

Sold

I have two sets of ba3 boards. The front end and bias boards are populated and Had been working. The output boards are unpopulated.
$50.00 plus shipping or local pu.
Thanks for looking,
Evan

Hello Everyone,

I'm going through some of my old boxes and found a pair of old Naim phono board left behind after I sold my NAC62.

Found this component which is unknown to me, can someone help to educate me if this is a capacitor and if so what type?



Strange Component | What is this component? | Roy Browne | Flickr

Thank you.

Hey everyone,

I am totally new here 🙂

M trying to build an enclosure box for 6.5 inch 2 way compnent car speakers.

The drivers are from Morel
Morel Maximo Ultra 602 Maximo Ultra Series 6-1/2" component speaker system at Crutchfield

Can anyone share the exact dimensions for sealed or ported box? Need to place them in my living room.

Thanks

I'm interested in seeing what other people have done to incorporate subwoofers or large speakers into furniture for saving space. I just built my 1st enclosure yesterday for a 12" sub. Being a beginner, it's sealed and pretty big, 38 x 48 x 61cm to get a flatter response. The XED12V2 has Qts=0.55, and needs a 153 liter enclosure to get 0.707 Qtc. It sounds loud even with a small 100W TPA3116 amp.

Being a huge fan of making things multipurpose, it occurred to me I could've just bought and modified a storage cabinet, which would allow storage in addition to being a table.

I looked at the offerings on hidemysubwoofer.com but none of them allow storage. I'm trying to think what type of gasket you can use to seal the doors and what other issues you'll encounter.

mercury Iv stage for Ess 9038 pro dac test only. (not in use )
price $130 plus shipping

best
myint

Could someone tell me how to select the two end points of a load line using a transformer as a load ?

Let say I want to draw a load line for GM-70.
My OPT is 10k primary single end. Primary DCR is 305 ohm.
B+ is 1100VDC.

Do I use 305 ohm as the load resistance ?

No one else started another thread so here you go. A lot of good ideas have come out of the original thread so lets keep it going.

Does anyone remember the Lumenlab focal calc II?

I found it very handy for creating and working on my projector when it was undergoing creation, is it still around at all?

Here is a basic faq I typed up. If you have any suggestions or parts to add on please do.





DIY LCD PROJECTOR FAQ


General Questions
Q: Isn't this the 100" TV thing I tried and the quality was horrible?

A: No, this is a completely concept the most common type people build use an overhead projector and a LCD panel.

Q: Why haven't the projector companies done this if it is so cheap?

A: They used to make these panels for several thousand dollars but people wanted portability so they started to make compact projection units. The ones that retail today for several thousand.



Q: How much is this going to cost to build?

A: It all depends on how much you want to spend but for a majority of people $200 is about the limit.



Q: How good is the quality on these projectors??

A: Depending on how you build it and parts used it can be as good as a rear projection TV or better.



Q: Right... are there any pictures of projections??

A: Here is one page that shows some ok projections it is hard to take pictures of projections.
http://www.justexportcontrols.co.uk/andrew/projector.htm

Q: So I can do HDTV??

A: No, panels that can do HDTV are still several thousand dollars.



Q: Can I hook my computer up to this?

A: Yes, many panels have computer input. Awesome for gaming. 🙂



Q: How dark does the room have to be?

A: The darker the room the better the image although with higher lumen projectors mild lighting can be used.



Q: How big of a picture can I project?

A: There are many variables here but lots of people project at 80" or more.




Q: What can I project my image onto?

A: Walls,bed sheets are some of the common screens but a real screen is quite a bit better.




Q: Can you give me the plans and tell me what to do so I can have a big screen projector?

A: Unfortunately it's not that simple peoples building level,funds,vicinity on deals and parts all vary from person to person. There is no master plan. But there are plenty of people on the forums that will help you out the best they can.

Q: Can I make my own DLP,laser,CRT,D-ila or other technology projector?

A: These types of projectors require much more work,knowledge,money,and time. We are simply making LCD projectors because they are the simplest to make.






LCD PANELS





Q: What is a projection panel?

A: A projection panel is much like a normal LCD panel that you see in a laptop with small changes that allow it to be projected. Such as the cables being moved out of the way and fans. This allows it to be put on top of an overhead and projected.

Q: Where can I get these projection panels?

A: The most common and most expensive place is on ebay. Others include normal auctions,universities or offices that are getting rid of them.

Q: How much does a projection panel cost?

A: You can get a decent panel for $100. More features will cost you more money. The best panels generally go for around $300.

Q: What makes one projection panel different from the next?

A: There are several factors involved:

Resolution: This is how many actual pixels are on the panel measured the same way a standard computer monitor is. Higher resolution will yield a better looking image while costing more. Typical resolutions are : 640*480,800*600,1024*768. There are some panels that offer resolutions higher then the "native resolution" this is sometimes called scaling or compression it is not as good as a panel that normally runs at that resolution.

Colors : Colors are the amount of color a panel can display. Generally measured in millions of colors or bits. More colors create a much better looking image. More colors will cost more.

Contrast ratio: This is a big one. This is how much range there is between a pixel on the panel being completely on or completely off. The higher the contrast ratio the better the image especially for white scenes and dark scenes.

Inputs: This is what kind of sources the panel takes. Most panels take VGA input while some have VGA and other connectors such as composite video and S-video. Composite and S-video are used for hooking a DVD player or other video source directly to the panel without the need for a computer.

For reviews on panels check the good panel / bad panel thread here




Q: Can I use a laptop panel??

A: Unfortunately laptops use proprietary connectors and pin outs. You are not
going to find a pinout and hook it up directly to your desktop computer. Driver boards for these panels that allow connection for a regular computer range up into several hundred dollars.

Q: What about a desktop panel?

A: Most desktop panels are 14" unfortunately most projector beds are not this big. Desktop panels also have special ribbon cables which are very very fragile and some are not long enough to allow the panel to be used for projection. The only panel that we know of that allows is the viewsonic vg150 but even then several people have had serious problems with this panel's cable breaking from being flexed one too many times.












Overhead projectors

Q:What is an overhead projector?

A: Commonly seen in schools an overhead projector is a projector that takes a transparency and projects it onto a screen. The LCD is semi transparent which allows it to be projected.

Q: Where can you buy overhead projectors?

A: You can buy overhead projectors from thrift stores,garage sales,office stores (expensive) and ebay.

Q: What is the difference between models of overheads?

A:


Projection type: There are two different types of overhead projectors transmissive and reflective. Reflective type overheads will not work for LCD projection.

Lumens : Lumens is probably the biggest factor in buying an overhead 4 thousand lumens is generally considered the minimum lumens for a overhead more lumens means a brighter image and having more ambient light allowed.

Bulb : Most cheaper overhead projectors use halogen bulbs these are somewhat bright but do not produce the lumens or color tempature that metal halides do. Plus halogens run very hot. Premium overhead projectors use metal halide bulbs these bulbs run cooler,produce better color tempature, more lumens and last longer then halogens. But they also cost more per bulb and require a ballast to run. Some metal halide projectors produce as much as 10,000 lumens!

let the pics speak first.

this happens to be my third attempt and worth to share.🙂

this time with 13.3inch ,1280x850p ( hd) lcd .

work in progress.....🙂

A while ago I purchased a Soundsmith Zephyr MK III cartridge used on Ebay instead of sending my Denon 103R to Soundsmith for an upgrade. What I didn't realize was that the Seduction preamp does not have enough gain for the Zephyr which is a Moving Iron cartridge and requires 38 - 44 dB of gain.
I do love the sound of the cartridge and am looking to keep it in my system.
I purchased a Schiit Mani as a temporary - possibly permanent solution, but after listening to it the first day I think I may need to go back to a tube preamp. I am willing to build one from a kit as I did that with the foreplay. The new phono preamp from Bottlehead the Eros starts at $750. I was hoping to get the kind of performance I want for less than that but if it is the best option I might be willing to spend the money.
I am looking for some guidance and suggestions from the community before I make a decision.
Any help would be greatly appreciated.

Hi,


I am trying to fix my ML383 because it is making a loud pop when you turn it on and sometimes (getting progressivly worse) it makes noise from the right channel.
It sounds like a noisy transistor but the weird thing is the noise is independent of volume or input.
I have been searching the web for 2 days and I'm unable to find any schematics for the amp.

I have opened it up and took out the VG boards and they are quite complex, so
very hard to figure out without a schematic.
Also I found that the left and right boards are basically the same but are a different layout, which I find a bit strange. I would think the left and right channels would be exactly the same but okay because of the construction of the digital control they had to mirror the boards and in doing so they had move things around and also screwwed up on one side because 2 transistors that need to be thermally together they forgot to put next to eachother and botched them on the underside of the board


I also found that the PCB on the front the selector knob is on a seperate PCB which they did not break from the main PCB and because of that is now deformed. Is that normal? does anybody else have that?



So if anybody can help me with schematics or any other input that would be greatly appreciated.


Thank you.

I have searched but didn't find anything.

Its been like 4 attempts now to try and register with audioheritage forum. i always get an email that my registration does NOT fulfill some condition...I didn't find anything in the registration form that states some conditions.
Whats up with this group of people?
Anybody knows what is that secret condition? Donating $1000 to the admin?

Honestly, Im not even that keen anymore to be a part of such group. Its just bugging me.

Danny

Hello All,

For a long long time NOS tubes like the 12ax7 prices had gone through the roof yet the use of NOS compactrons, some can perform the same function is relatively low.

New amps can be constructed and perform very good using them.

Any idea why?

BR

Glass_painter

I'm a beginner so please be kind and straightforward.
Building a Bluetooth Speaker from a kit but only using one Woofer and Tweeter.
The kit is a C-Note bookshelf speaker (stereo) and the Amp is a Dayton Audio KAB250v3. So the amp has 2 sets of speaker leads, but I will only be using one tweeter and woofer. I have built the crossovers, but want to know how to wire the speaker from the Amp without causing any amp damage. Should I just pair the -ves together and do the same with the +ves or do I need to build a stereo/mono converter? thanks! Tom

HI hear is amplifier when i browsing i found this amplifier i want good discation on it
i want to build it please help me on it
link http://www.siliconchip.com.au/cms/A_101765/printArticle.html

I had a lumpy idler on my Garrard Lab 80 so I threw on a different one that I had trued and cleaned with CaiKleen RBR. The thing slipped so much it almost would not drive the platter at all: slow start up and slow final speed. Tried cleaning and recleaning and minor roughing with 320 emery cloth - negligible difference. I took some solid rock rosin and smashed it between two aluminum plates until it was as fine as talcum powder, rolled the idler's edge in the powder and brushed off the excess. The result was instant startup to perfect speed, and great resistance to slowing from finger drag on platter edge. Dramatic, instant and complete cure. No idea about whether this might help belt drives, too, or about long term issues, but for now, it's incredible. YMMV

Greetings,
I am embarking on a center LS project.
I have not found a great deal in the diy sector on the subject so I'm hoping to get some pointer in the right direction here.
This will (eventually )integrate into a 5/6.1 system.
Should it match acoustically with all speakers; my preference leans toword this.
Or is there focus on reproducing vocals?
Generally there are two woofers and one tweeter, are two woofers(in parallel)nessesary? I could guess this helps directionality.
I would like the cabinet to be very long, as to blend in with other aesthetics. Small speakers seem to me to be obtrusive and don't fit in anywhere.

Thoughts and suggestion?
Thanks

Hi all,

My next project (as an amateur "premade module connector") is a guitar power amplifer designed to take a signal from a preamp or a chain of pedals etc.

These are becoming ever more popular as more and more people are using modelling preamps etc to get their sound, and then just need a compact no frills power amp to power the speakers.

So, my idea is to connect one of these:

DC 24V Universal Regulated Switching Power Supply LED Strip for Printer CCTV | eBay

... to one of these:

60W TPA3118 Digital Amplifier Board AMP DC 10&24V Module PBTL Mono VVP ul | eBay

... and also use one of these:

Male Power Socket Fused Rocker Switch IEC320 C14 Inlet Useful #NP | eBay

Can anyone see any potential issues so far?

If not, my only question is how to add a passive volume control to the input of the amplifier (or to adjust the gain of the circuit?), so that there's some adjustment if the devices connected before it are too loud, and to give a "soft start" on powerup to avoid any unwanted bangs. I'll be mounting it all in an aluminium stomp box type enclosure.

I welcome your comments!

Cheers,

Jim

First step in 120*3cm ribbon. The ribbon is made of 4my aluminium with glued 20 my capacitor paper on both sides. This done so it only needs very little corugation, and to prevent it from bendig as it heats up. The metal is 1*4 cm and magnets 1*1*15cm

I own a pair of Tannoy D500 Series 2 for nearly 20 years now. Still sound great, lately collaborating with a newly revised Quad 303.

Now my Tannoys need a refoaming, see pics. First action: have a look inside to learn what's inside, and what to order. My problem: I can't get the speakers off the front panel. All four screws were removed easily, but both concentric and bass unit won't move a bit.

Accessing it from the bottom plate or the crossover panel failed, because the damping material (foam) cannot be removed from there.

Any ideas how to proceed?

Pair of Mundorf tweeters, barely used. I went to a Cube audio full range unit.
New cost €429 each. They can go for €429,- for the pair + shipment and PayPal fee.

Hello Everyone. I hope everyone is doing well? I had a engineer person I know tell me that the F3 has to match the FB in the design program. I am using the Tang Band 3W-2141 and its cut off is 75hz. I have it at - 2.48 DB at 75 hz. Does this sound right? A lot of speaker company's do minis or plus 3 DB. I thought you would want the curve as flat and even as possible? So here's a example. The Dynaudio Confidence 20 is 155hz at 6 ohms and goes down to 42hz and up to 22khz at + 3 DB. So where is that plus or minis 3 DB in the frequency response?
Am guessing the curved line is not as flat as mine but, maybe am to anal about this box building? Can you please help me out here. Thanks Jeff

Just found out the hard way these are 100% fake. I have no idea what’s inside, but definitely not a 10M45S chip! 😡

No more Chinese counterfeit for me, bye bye Aliexpress.

Take care and watch out!

Regards, Gerrit

I want to shake my walls. Want louder sound with more BASS.My speakers are 4 ohms

1.Can this little 2.1 subwoofer board can do this?
2.What is the correct power supply to use?
3.Do I need a speaker protection ? Will it burn my expensive speakers when output stage falls?

Going to buy this..!!
WAVGAT New Amplifier Board TPA3116D2 50Wx2+100W 2.1 Channel Digital Subwoofer Power 12~24V|Amplifier| - AliExpress

I'm having my first go at building an amplifier I'd like to build a power amplifier-I take it thats easier if anything than an integrated amp? Its to power a pair of older Acoustat electrostrostatic speakers that suck power like nothing else😀 so I was looking for recomendations for a simple kit or plan of a kit where I can buy the bits that has enough power to power the electrostatics

Hello,

My question is: What is the best method to add networking capabilities to my non-networking DAC?

Current setup:

Internet -> Workstation USB port -> USB Cable -> USB Port of SMSL SU-8 DAC -> Receiver

I would like to eliminate the USB cable piece of the above setup and replace it with some sort of wireless solution. My first thought was that possibly some wireless USB solution exists. Does anyone have experience with such and what specific device would you recommend?

Is there a better method of adding networking capabilities than wireless USB? the unit also has optical and coaxial ports. If so, what would you recommend?

I am moving my office to another room and the new setup does not allow to run a USB cable from computer to where the DAC would be located. I also use my workstation as a CD player.

Thanks in advance.

Best

Alien

My goal is to hit 105 dB @ 30 Hz/1m, before reaching Xmax. This will be for a 3 way studio monitor, crossed over @ ~200 Hz to a Beyma 8CX300Fe coaxial. I will use the Eminence Lab12c as it is (luckily) available here in India at a price that makes sense. I want to use a 4" Precision port kit because of it's off the shelf availability. I would like to limit box width and depth to 19" and 17" respectively, height can be anything up to 36". Response below 30 Hz can be compromised. It will be driven by a Hypex FA253 if 250W is enough to accomplish what I have in mind. If not I will opt for the 500W version.

With these things in mind and my half baked knowledge of the stuff, I have been chasing my tail with WinISD and other tools... flummoxed with finding a solution with optimum Qtc, port length, port resonance, group delay etc., and I realize that there is too much I do not know...

I'm hoping it is a simple thing for you experienced people to chime in with an optimum cabinet volume and port length and equalization settings (the Hypex has 15 "biquads" available), given the above design goals.

Please be kind and let this noob climb on to your collective massive shoulders.

I just discovered this manufacturing problem in the main panels: There is a plating on the bar magnets which partially peels loose and causes a buzz.
A couple of days ago, I persuaded a friend to sell me his MM-1000, and while dusting and running a 200-300Hz tone through them heard an annoying buzz from both. (I had heard the buzz earlier while playing music: Israel Kamakawiwo'ole's 'It's a Beautiful World' is perfect for exciting this buzz.) Wondering if it was a track that had come loose from the diaphragm or something, I began poking through the rear slots (with the rounded end of a small plastic tie wrap so that I didn't damage the diaphragm) and discovered that the magnets have a plating which had begun to peel and separate from the magnets, and this partially loose piece of plating was now vibrating in the gap. Each unit oddly had only one area which was separating, and it was actually visible through the slots in the rear once I realized what I was looking at. (You can't see anything from the front as there's a sheet of black felt between the diaphragm and stators.) With a lot of patience and some bent wire ties of different sizes (I bent the end of the wire ties into an L, so that I could actually scrape the far side of the magnet facing the diaphragm.) and a pair of tweezers I was able to push, scrape, drag, and pull out the offending pieces of plating, and now the speakers sound good again.

I am using Canare L-2B2AT wire, it has one +, one -, and one ground. 3.2mm total diameter. My dad's kind enough to solder it together for me, but he asked a question I don't know how to answer.

For a 3.5mm MMCX cable, for this Canare wire, do I have to double up the wire for it to work? Meaning, for example, 2x1.3m?

Help would be appreciated.

Thanks alot,
Kasper

I have two pairs of woofers that are dual voice coils. Each voice coil is 4 Ohms. I want to install them dual-woofer floor-standing speakers and need 4 Ohms per cabinet. So, what should I wire between?

A) series wiring dual voice coils together to make each driver 8 Ohms, then, parallel two drivers to make the system 4 Ohms.
B) parallel wiring dual voice coils together to make each driver 2 Ohms, then, series two drivers to make the system 4 Ohms.

Thank you

ELROG 300B + Telefunken ECC83X 1 + ECC82 X 2 $1,950
ELROG 300B + Telefunken ECC83X 1 + Seimens ECC82 X2 $1,650
ACME 300B + Telefunken ECC83 X 1 + Seimens ECC82 X2 $1,200
ACME 300B + WE5755 + RCA 12AU7 X 2 (clear Top) $875
Psavne WE300B + Telefunken ECC83 X 1 + Seimens ECC82 X2 $975
Psavne WE300B + WE5755 + RCA 12AU7 X 2 (clear Top) $750
LINLAI/COSSOR Black Plate 300B (MADE BY LINLAI)+ WE5755 + RCA 12AU7 X 2 (clear Top) $285.
LINLAI WE300B (MADE BY LINLAI) WE5755 + RCA 12AU7 X 2 (clear Top) $625

ACME 300B, PSAVNE WE300 & NS WE300B

Individual Tube
300B Tube per pair
ELROG 300B/$1,475.00
ACME 300B/$ 875.00
Psvane WE300B/$775.00
COSSOR Black Plate 300B/$195 (MADE BY LINLAI))
COSSOR WE300B/$495 (MADE BY LINLAI)
WE5755 with Adapter $45 (with getter)
WE5775 + RCA Clear TOP
RCA clear top 12AU7 $45
Gold Lion (B749 X 2 + B759 X 1) $100
EH Gold ECC83 X 1 + ECC82X 2 $60

Coupling Caps
Mundorf EVO Supreme Silver Gold 0.1 X 4 $150
V-Cap ODAM (Oil Damped Advanced Metalized) 0.1 X 4 $200
V-Cap CuTF Copper Foil and Fluoropolymer Film 0.1 x 4 $380

Carbon Resistor
Takman 2% $65

Volume Pot
TKD 2CP601S with conversion Kit $65

I received my new 8600SVK. Upon opening one of the LL2785s, I noted that a number of the solder pins had been bent. In partucular, a solder pin on the primary had been flattened against the board. Despite carefully trying to straighten the pin, it of course seperated at the board level. 🙁

There looks to be just enough remaining copper lead to pull through to establish a new joint. It also appears the lead is held in place by resin? Presumedly, i would have to apply some heat and carefully push / pull through the remaining copper lead and then build up a layer of solder? I also presume that soldering will melt the insulation?

Has anyone tried this repair with success? (solder temps etc.)

I'd like to hear some comments on the local NFB scheme in this schematic I found.

I'm also wondering about its use of a 1N4007 in both the B+ and G2 supply. What is their purpose? Would there be a problem if they are omitted?

I have a SE VM that originally had the preamp section connected with an umbilical. The amp section only has a 5Y3 and a pair of 6BQ5s. I want to drive it with either a stand-alone tube pre I built or a SS pre. So I won't be using global NFB like the one that went to the stock preamp through the umbilical.

My amp does NOT have an UL tap like the one in the schematic. I want to get as much power out of it as I can so I want to stick with pentode instead of converting it to triode.

So it's either pentode with no FB or some type of local FB. Are there other local FB methods that I should consider?

I am about to move and will not be able to complete my Amp Camp Build that includes Tungstenaudio's modifications and stuffed Cap Multiplier boards.

The ACA Boards include Nichicon Super Through Caps (C2), Organic Polymers (C4), and Nichicon Gold Tune Filter Caps (C1). I used mostly Vishay/Dale resistors and MPC71 Futaba resistors for R1/R2. I made the resistor changes to R3, R4, R11, and R12 according to the new schematic and added a 10pf silver Mica across R12. Mosfets are IRFP140s and rubber pads used for heat dissipation. Both boards were tested and biased perfectly to 12V.

The Power supplies were designed by Rudi Rozek based on Jason Kuetemann's Cap Multiplier. I have used this design on all of my amp camps with an Antek AS-2222 Torroidal Transformer and way prefer it over the Meanwell Power Block.

The heatsinks were cut from a 8Hx9Dx3W heatsinks. I cut them in have to measure 4Hx9Dx3W(fins). The heatsinks had some pre-drilled holes but they are not noticeable.

To finish the amp, build a nice chassis, add the rca/speaker posts, and buy the transformer.

For all 4 boards and the heatsinks I am asking $165 SHIPPED in the CONUS only please.

Hello.
I would like to have some help with those capacitor in the pictures (negative side on the right).
Anybody knows what if the third pin is just for stability or is this a shield?
Also how can I test them. They are probably 20 years old and I would like to be certain I will not blow anything if I use them.
Thank you very much.

Can someone help me to identify this tube amp power transformer?
There are no markings whatsoever but I have verified that it is good. The lead insulation is braided cloth. I'd like to try and get the ampere ratings for the windings.

The core size is EI-96 80mm x 96mm (3-1/8" x 3-3/4")
The core thickness is 41mm (1-5/8")
Weight: 5 lbs., 5 oz.

The primary measures 3.5 ohms
The HV secondary measures 168 ohms total

Here is what I measured:
BLK - 120V input
BLK - 120V input

RED - 380V
WHT/RED - CT
RED - 380V

GRN - 3.2V
WHT/GRN - CT
GRN - 3.2V

WHT - 5V
WHT - 5V

Thanks.

What is available at affordable cost ( say < $10 ) with lowest TC.
Tolerance does not matter.
I would love a servey at costs
<$1 <$2 <$5 <$10

I thought I had fixed my noisy USB port issues when I added the iFi iDefender+ (powered from a separate USB charger) between my computer & my DAC. However a new noise has recently started coming through my speakers, this time a continuous high pitch (maybe ~1KHz?) rather than the previous noise that was related to mouse movement/screen activity. After a lot of frustrating troubleshooting I have discovered where I think the problem lies & could do with a fresh set of eyes trying to come up with a solution!

My DAC has RCA outputs on the back, which are connected to my amplifier for my speakers. The DAC also has a 1/4" TRS headphone output on the front. Both outputs are volume controlled via the knob on the front.

I noticed that the new high pitched noise was only playing through my speakers, not my headphones. So as an experiment, I connected both the RCA output & the heaphone output of the DAC to a small passive mixer (eg no power supply connected), so that I could easily listen to each output in turn through the speakers. This is the first picture; on the mixer, output is going to my amplifier, ch 3 input is coming from the DAC's RCA output on its rear, ch2 input is coming from the DAC's headphone output on its front. To my surprise, there was absolutely no trace of the high pitched noise in the speakers when listening to either input.

After some more experimenting, I discovered that the high pitched noise in the RCA output disappeared as long as the ground of the headphone output was connected to the ground of the mixer. When I disconnected the headphone output, as in the second picture, the high pitch noise came back through the speakers.

I did some more experiments. Just touching the ground of the headphone output to the ground of an input on the mixer was sufficient to remove the high pitch noise (third picture), likewise when just touching the ground of the headphone output to the RCA connector going to the amplifier (fourth picture).

However, when I removed the mixer, connected the DAC's RCA output directly to the amplifier & then touched the ground of the headphone output to the RCA output (fifth & sixth pictures) this did not remove the high pitch noise.

So, what exactly is happening when joining the grounds in the mixer (remembering that this is a passive mixer with no power supply), which isn't happening when joining the grounds at the DAC? With no cables connected there is continuity between all ground connections on the mixer. I even opened up the mixer (final two photos) looking for hints, but couldn't make heads or tails of it.

Essentially, why is the result of the fourth photo different to the result of the fifth/sixth photos?

Any ideas, please enlighten me - it's late & I'm thoroughly confused!

Hello All,

I have 3 matched pairs of NOS Vaic AVVT 302B tubes. I am wondering if people might have a sense of how much they are worth.

TIA

Firstly thank you to the folks on here who have introduced me to the dim bulb tester. If only I'd found this earlier I would have saved my self from quite a few pyrotechnic episodes!

So to the point of this post, my faulty 3240. Being a newbie to electronics I'm on a steep learning curve. I purchased this amp with a silent left channel, however, as I intend to keep this one for my own use in my study for a while, I decided to go to town on it, expecting to locate the faulty component(s) along the way.

So, I replaced all the electrolytic caps, testing as I went. All still measured to spec, so this is purely for quality upgrade, not fault fix. The main power caps I up'd to 10,000uF from DNM.

I also removed all of the transistors and tested them using the voltage drop on my diode tester. Again, all measured okay. The power transistors were replaced from a reliable source, not eBay(!) with like for like.

I fitted an external IEC power socket to get rid of the original NAD mains cable in favour of one from Lapp. Finally, I added new speaker binding posts in solid copper with 14 gauge wire running directly from the underside of the board from the speaker connection points for speakers A. This bypasses the horrid originals and the truly nasty four way plug on the speaker post board.

I also hard wired the preamp out to the power amp in, eliminating the need for external links going through RCA sockets on the rear panel.

So to the issue. I connected the amp to the mains using my freshly built dim bulb circuit and switched it on. The lamp came on and stayed on. This seems to me to be indicating a short.

I carried out a quick visual inspection and found a horrific error in my wiring. I had reversed live and neutral on the socket. A complete brain fade on building it. I put it down to being made redundant by C-19!

Anyway, I rewired the socket and went for it a second time, ensuring the DBT was safely in place. Unfortunately it failed to bring the amp back to life and the DBT shines brightly.

I now need to diagnose the issue and I would welcome any suggestions.

Got a problem with the second coil. One fet keeps going faulty when remote is applied. It’s not the buz10 side of the power supply. Any idea what’s causing this?

It happened 10 years ago when i made a mod to my newly refurbished Realistic STA 2250 .Although the power amp was completely up to date-nichicon muse, ultra low noise and high ft transistors, the eq had way too many electrolitic capacitors in the signal path, actually 11(eleven) 40 years old capacitor , so before changing them i thought of rewiring the tape- monitor switches to be able to bypass the entire tone stack.After doing so and leveling the input output signals, my complete and utter surprise was that i wasn't able to hear anything wrong with the tone eq in.There was somewhat of a different sound, but the differences weren't in favour of removing the tone stack...they were completely irrelevant, like 0.5... 1db out of tune circuit, but nothing to criticise .From that point on to these days i simply disregarded any claim of a better sound due to dc coupling.

Hello DIYers!

I’d like to start playing with my first DIY Amplifier, I know they’re outdated and there are more efficient packages out there but I love the looks of TO-3 power transistors.

So with that being said I’m wondering if you knew about a design that could work with low voltage high current transistors that I may modify the output stage a bit to make it work, it could be Class A or Class AB either Complementary or Quasi.

I want to use it as a learning experience and if possible, and that’s why I mentioned low voltage high current transistors, I’d like to use the transistors I have 2N5302, and I have a TON!!!, my understanding is that its complementary is the 2N4399.

And please if you think those transistors just won’t work I’d understand but please provide details about why, remember I'm trying to learn 🙂...

Thanks in Advance!

Been attempting to identify these units but my search skills aren't up to the task apparently. Any comments will be appreciated. Thanks

Hi there, I'm just wondering what you might use if you were doing this.

Just got the PT in and gathering parts and components for amp project #3, a monoblock line level single instrument amp, probably use a pair of KT88's UL in the output section - preamp stages, eq etc to be determined by experimenting.

I'd like to kick this off as a hi fi amp and see how the 6SN7 tubes work in the preamp.

My question is, if you were planning on the final amp using NOS tubes, which current production 6SN7's would you use for the initial experimentation/design phase? Reason I ask is that I often see that some current production tubes are not thought of as having similar electrical characteristics as their older counterparts. I'd like to work with modern 6SN7's that will have a similar performance to any or most NOS ones that are substituted. I'm probably worrying over nothing and thats probably true. But where I'm certainly no expert on these tubes I'd be interested in comments from those that do have a long term familiarity with them. Plus, if I do something crazy during the experimental phase, I'd rather take out a 15 dollar JJ than a nice old expensive NOS tube.

Which current production cheaper 6SN7 would you use for design with the possibility of trying much older ones later on?

Thanks very much,

Phil

This connector is particularly in Germany very expensive - go to
L1904A/8/FP - BELLING LEE - STECKER DIN RASTKLINKE 8POL | Farnell Deutschland
STECKER DIN RASTKLINKE 8POL Typ: L1904A/8/FP bei Mercateo günstig kaufen
https://hbe-shop.de/Art-1178502-BELLING-LEE-L1904A-7-FP-STECKER-DIN-RASTKLINKE-7POL

Who know the genuine website of the currently manufacturer of this connector?

Hi All.

Got broken smps180, no output voltage. Checked fuses, bridge and power fets. Stuck in the middle. Any repair guide available, or, possibly, schematic?

What were DIY speaker builds that you made that you compared to production speakers and were impressed with how well the sound stood up to the production speaker?

Here's a bothering problem I'm searching a solution for. I've been an audio transformer coil winder since three years. I'm putting a lot of light around the winding process to follow the tiniest details and constantly watch over the wire for crossovers, especially with ultra fine ones.

The coils are rectangular and there are surface glares from the magnet wire copper layer directly into the eyes while the coil rotates. This becomes really taxing on the nervous system when one has to wind thousands of carefully placed turns per day.



You can slightly get the idea of the glare, which is visible on the top part of the coil

One thought I will be trying soon are polarized anti glare glasses.
Do you think of any other tips?

Any one have Datasheet or know possible modern replacement

Anyone in Toronto? Help!

Hi,

I am looking for someone in the Toronto area that can pick up and ship to me a Sugden A21a, a small integrated amplifier.

The owner had a transplant , is recuperating and cannot help. I'll pay via PayPal.

Best regards,

Horacio
Miami, FL

There didn't seem to be a more appropriate place to post this, so if it needs to get towed elsewhere, let me apologize in advance. My frustration has been mounting as I take on projects. I don't want to muddy any of my other threads.

I have a hard time learning electronics. I have grown up around it, I have some amazing friends that are very into it, and I've tried very hard to pick it up myself. I have an above average IQ and lots of general knowledge about everything. I just have a hard time specializing. I've really worked my tail off trying to get past my study obstacles. I don't get discouraged but I do get frustrated, and my way of dealing with that is to apply humor. Hopefully people see that.

In the past few months I've been studying and seen some progress. I have the basics covered on passive components. I've learned what a voltage divider is, and how a rectifier bridge works. I can find them on a schematic, and I can also identify input and output sections on schematics if they're well organized. Those are things that I had a hard time with so I know progress is possible. I've reached sort of a plateau now, though. I know what a generic "transistor" does on its own but I can't tell you the difference between all the different types, and I lose my mind when I try to figure out what they do in the circuit. When I start reading about using a transistor to boost current vs transistors to boost voltage, my brain shuts off. I have to decompress for a while, and then go relearn the difference between current and voltage, I kid you not. And if you asked me right now to explain voltage - even though I can use a DMM and diagnose problems with a basic circuit - I have to go review it before I discuss it. You have no idea how many times I've read it over, watched waterwheel metaphor videos explaining it, and passed tests proving that I had the knowledge, only to forget it a few days or weeks later. Its not really an issue - as long as I know how to use the meter, and I can look up those explanations, I can get by. Its no different than having a calculator to do the math for circuits instead of doing it long-hand.

I think the reason why I can't move forward now is I can't get past the whole "voltage goes in here, goes out there" mindset when I study circuits. I'm a linear thinker. Things go from one place, go through some work, and end up on the other side. I know what that rectifier bridge does, and if I sit and map it out I can even explain it. But its still difficult for me to follow because there's four traces, one at each corner instead of one wire going in and one going out. So I had to learn the concept, look at it as a single device, and just pay attention to the values going in and coming out. Thats the only way I don't get stopped there every time I see one on a schematic.

Pick something exceedingly simple, like a GFA-535 (one of the simplest high-performance designs in existence) and can I try to follow it. My brain sees the signal coming in from the input, going past a handful of passives and into a transistor. But right next to it on the schematic is another transistor (making a differential pair), and there's a signal going in to it from somewhere else. Where the heck is that coming from? Its from that spaghetti mess to the right of it on the schematic. I think "why isn't the differential pair turned on its side, with all that stuff from the right now placed to the left, between the input and the pair, so that I can follow it from left to right?" And thats where I stop understanding the circuit. Now all I see are these traces that jump over each other, blend with each other, diverge from each other. Its very hard for me to follow because I keep looking at the circuit as a rollercoaster track for electrons, when I should be looking at it as a web of interconnected things that all affect each other.

But thats just the signal - what about the power that runs the whole thing? Well, thats over on the right side of the schematic. Why isn't it listed on the left side with the signal input so its easier to follow? Or put it above or below on the schematic so I'm not trying to pick the speaker outputs out of the power traces. Having the power come in the diagram on the output side seems like a restaurant kitchen: all the orders come in the same door that they go out, with the deliveries on the other side of the kitchen. Or something like that, I'm still working on the metaphor. In any case, it looks like a mess to me, while to you guys, you can follow right along. I was trying to figure out my Hafler preamp, and Maaco here said to me "start with the basics - follow the circuit". I couldn't, because there wasn't a linear path to follow.

I understand my major issue here - I look at the circuit from left to right, and follow the electron. This is completely wrong, and yet I have no idea how to get past it. Dahl tells me "don't look at it that way, the electrons are always there, they're just not moving until the circuit goes on. You shouldn't be following an electron through the path, you should be looking at what current and what voltage you have in any part of your circuit." Great! I know voltages and currents move and do things, but I still look at it as "moves from here, goes here".

At one point I learned I had been looking at amplifiers the wrong way: I originally thought that the AC was split by the power supply to positive and negative legs of DC, the whole amp was divided into a positive side and a negative side, and then those two sides were combined after the output stage to make an AC signal again. (Oddly, that actually worked in my head.) Then I saw this brilliant little animation that demonstrated how a transistor worked in an audio circuit, how the DC ran one way, but there was an AC signal in there that ran the opposite way, against the DC power that was coming in. That really helped me to understand that the amp was running off DC but the signal was going through there as AC. I had no idea! Then I lost the link to the animation so I have no idea where I should have gone next, and the stuff I learned is slowly disappearing out of my brain.

While I'm talking about it - I still don't understand AC, believe it or not. Since I'm a linear person, DC is easy: Its either there or it isn't, and it moves thataway. Put a negative sign there, and its moving the opposite direction. But AC changes back and forth, so how do you get anything done if things are going back and forth? Using the stupid waterwheel analogy, if the water flows in one direction the wheel turns, there's your current - but what if the water runs backwards? Will that waterwheel run backwards and turn flour into grain then? This isn't even touching on the whole "its not really just negative and positive, you actually have 360 degrees of phase, not 180".

I'll leave that for my doctoral thesis, I think.

And don't get me started about the little directional arrows that distinguish PNP from NPN. To my tired little brain that says "goes in here/goes out here", I can't get myself to see it any differently, and of course it doesn't mean that.

I've been studying this, on and off, for at least 6 months. Its not sinking in. How do I get past this? How did you guys get past it? You all had to start somewhere and go through the steps, so how about letting me in on your "aha!" moments.

TIA.

Jensen CI-2RR IsoMax Stereo Audio Isolator. Great tool to have in your toolbox.

I have had this for probably 12 years now. I have never installed it in a system. I even forgot about it until today when I was cleaning out my garage.

I am asking $160 shipped, CONUS. Online prices are $190+.

Pictures attached.

PM me if you're interested.

Hello diyers

Currently working on this double peerless xls 12 850000 driver loaded double slot ported cab with single chamber:

IMG-20200812-144336-01-2 — ImgBB

As of now its tuned to 25 hz, but id love your input on what kind of performance i can expect here, if i should brace it alot more etc. Its made from 19mm MDF, glued and screwed ☺️

Thanks alot in advance - also, is the crown xls 1002 a good contender for power? With its inbuilt bandpass filtering etc.

All input is highly appreciated!
Thank you.

Hi Everyone

I'm building woofers section for my Line Arrays Towers.
Towers are 78" Tall with Left and Right Design with drivers per channel:
16 x Tang Band W4-1757SB 4" Aluminum Cone Driver
20 x Bohlender Graebener Neo3-PDR Planar Tweeter Open Back

Passive crossover 200/3000Hz

The woofers section will have 2 cabinets per channel with 2 Peerless NE315W-08 in one box. Sealed 4 CuFt (2 CuFt per woofer ) should give me F3 around 40Hz

I'm asking how you will design the woofers section for those Towers?
Same high means build 2 cabinets 39 inch long, or 2 cabinets 30 inch long and dont care for high match?

Hello, need your help boys.
I bought the amplifier for cheap from a guy on used market, he tried fixing it. He bought 4x5w 330ohm resistor 2 still new . But the problem is they get red hot like they are gonna blow up . I don't see any indication that the amp is actually on , no light and relays don't do anything. I checked if transformer primary wingdings might be bad , but i don't know both 115v primary wingdings says 1.8ohm and i don't know what it means. Also if i disconnected primary wingdings from the board the resistors didn't heat up anymore , but i checked the board and it seemed resistors should get some voltage even if the transformer is disconnected . The transformer primary has 130c fuses maybe that's the fault, maybe they are burned .

Transformer link : http://www.samodelka.ru/pictures/data/hypex_tr501a_9234.pdf

Amplifier link : http://www.arton.info/DS80_manual.pdf


Thank you for your help ! 🙂

Hi,
I recently completed an Aleph J build and it sounds great and is stable. But one issue I've noticed is that when I measure the bias over the source resistors on each channel, they are not even.

For example, the source resistors on the right channel are at .38V and .42V.
The difference on the left is slightly larger at .36 and .43V.

I used matched MOSFETS from a reliable source.

Any ideas on the cause or whether this is something to worry about? Where would you set the bias given that they are not even?

Any thoughts are greatly appreciated.

There are a lot of sellers offering matched pairs of output pentodes but none of them defines which parameters of the tube pair are matched.

My question is a general one:

In a PP output stage with two independent adjustable CCS (one in every cathode) for automatic bias, I could adjust the plate current of the two pentodes to arbitrary equal value.

Isn't that matching enough?

A comment by Perry in another thread raised an interesting question, what parts are run too hard, by design, in various car (and home) amplifiers?

Resistors heating up


It would be perhaps interesting to expand on the theme a bit to design flaws in general.

For example, the Soundstream rubicon series seem to pack dc protection on the output, madness!!

Hi And thanks for reading.
Concerning the smoothing resistor capacitor combination found in most power supplies after the bridge rectifier, designers do add one resistor or more as a cap by itself does not get rid of noise instead shifts it to a different frequency. Adding a resistor does reduce noise far more effectively.
I am wondering if the resistor can be ommited altogether and high esr caps used solely, using the high esr of the cap in place of the resistor.
Is this possible, does it reduce noise effectively.
I have always paid extra and purchased more expensive caps in the belief that lower esr is better, but am wondering now.

The goal is to make a 'pig-tail' adapter to convert AES3 (110 ohm) to S/PDIF (75 ohm). It seems that both impedance and attenuation need to be corrected. This would require resistors. Currently, the two components work fine together with a cheap off-the-shelf XLR/RCA adapter - with no corrections. I'd like to make an adapter with corrections and with better quality parts .

Below is a link to a webpage with more info. I know how to solder. And that 's all. Unfortunately, I have no idea how to read a wiring schematic. Hopefully, somebody in the community can offer instructions as to what value resistors to put on which leg? I don't wish to use transformers. This is AES3 - not AES3id.

Thx for your help.

It appears that Figure #1 applies to my project. It would be appreciated if there could more specific guidance as to:

- How to interpret the numbers so that I can order the correct parts.
- How to interpret the schematic. Are there resistors between the two legs in addition to within the legs?


https://www.ranecommercial.com/legacy/pdf/ranenotes/Interfacing_AES3_&_SPDIF.pdf

The seemingly never-ending saga of my JLH Monoblocs continues...😱

Both Power supplies are 100% now....and +/- 50V and 55V rails working as they should be 🙂

So...I'm now at the "Power Amplifier Setup" step in the user manual.
DMM set for mA...I've inserted meter into +55v rail....but there is NO CURRENT when switched on.

Circuit diagram is here....https://i.imgur.com/wCcCg5j.jpg
(Pencil annotations not mine....an on-line scan was the source)

Another...better circuit diagram can be found here...scroll almost 1/2 way down, circuit labelled "JLH 80W Mosfet...."

A Paul Kemble web page - JLH mosfet amplifiers.

I am given to understand that the driver may be at fault.....is that Q10 VN1210M? Can these devices be tested 'in-circuit'....or must they be removed please??

All info. gratefully received.....I will get there in the end😀

I was expecting to be successful searching on the subject, but found nothing here, AA, or Google. The only thread was short lived, and provided advice to use coax (which doesn't excite me).

So, what has experience shown us with input/output wiring to RCA's? Is twisted pair sufficient, or is shielded recommended? If we are able to neglect the effects of capacitance, it would seem to me shielded would be best.

On the one hand, a low impedance source should have no problem driving a little extra shielded wire; so we should be able to use shielded for output wiring. However, it can also be argued that a low impedance source is not susceptible to induced pickup, so twisted pair would be fine.

With inputs, I see a better case for shielded, as the nodes are typically of higher impedance, therefore more likely to pickup noise. As long as the additional capacitance won't adversely affect our FR, I would think shielded is the way to go.

I ask because of course I'm in the middle of a preamp, but also most of the pictures I have seen of DIY projects use twisted pair.

I just came across these “brake resistors”, available in 4, 8 Ohms (and many other values). Power 500 Watt or 1000 Watt. Available mostly on Amazon, Ebay, Ali...

For audio I need at least a 150 Watt dummy. Currently I’m using big metal wirewound resistors with a heatsink and a lot of cooling. I’m thinking of putting them in a can filled with oil for better cooling, like I did with large RF dummy loads from Heathkit. I still remember the smell of boiling oil 😀.

I wonder if anyone has ever tried these brake resistors as dummy load. I guess they will need extra cooling too?

Regards, Gerrit

I have a couple of high quality (Audio Grade) toroidal transformers cluttering up the place. Neither actually made it into a finished project.

1: 150VA, 230VAC Primary, 2 x 0-20VAC secondaries



2: 150VA, 230VAC Primary, 2 x 0-22VAC secondaries



£12.50each or both for £20 - plus postage and paypal fee at cost.

Hello chaps, I've been reading some of the other threads on this forum with interest to see if anyone had had a similar problem. I didn't really find anything so I hope you don't mind me asking for advice. Some electronics experience here but a beginner with audio systems (except for plugging in and listening).

My Cyrus 8 (vs2) has been misbehaving. It was happily running for years then occasionally it started displaying the sequence of lights shown in the attached picture. Then sometime later when it was switched on it would only display these lights with no audio output, except for a small pop when the output was enabled.

Then I took it back to England and had a professional look at it and annoyingly it worked perfectly there and for a few more weeks it ran fine here. Then back to the strange sequence of lights and no output.

Cyrus gave me the very helpful response of "sounds like a needs a service". Do any of you have experience with these types of amps? I'm just looking for advice about where to start fault finding so as not to break anything. Thanks!

Hi everybody, I'm new here 🙂


So my NAD stopped working without any warning after 8 years spent together. The power indicator turned red. After a cooldown I tried to turn it on and to my amusement the light turned green and the amp worked for 20 second or so, then I heard a crack, light went red and music stopped playing. After turning the thing off the red light stayed on and slowly faded for quite a some time. I turned it on again and the same thing happened, but green light only stayed for about 5 seconds. During the next try, the light came off almost immediately. After that it wouldn't turn green at all (but the whole scenario repeated when i tried to turn it on next day).



I've read some posts considering NADs 304 common faults and repairs (potentiometer, resistors and relay upgrade), but my situation seems a little odd (the amp works for a little bit).


I will be grateful for any advices and tips.

Here is a very low distortion class A headphone amp.

This design is similar to the design I've used in my new Symphony preamp (still to pusblish the write up)

Top level specs:-

Distortion at 3 V peak output ~500 ppb
At 1 V peak 20 ppb

Class A operation up to 12V peak output

SR ~ 20V/us

no pcb - but I'd be happy to help anyone who wants to take up rhe challenge - the circuit is simple.