Looks like both capacitors failed. Is the board ruined? Thanks, Ron

Hi,

I'm starting on a recapping project on my Meridian 557. I am a EE/CS and have done lots of systems work from prototypes to production commercial control systems, computers, etc. However, I haven't done that much work on hifi amplifiers and I've never tried to remove an amplifier board from a 5 pound heat sink.

On the 557, the main circuit board (similar to the Alex MM circuit board in "The Very Best Amplifier I Have Ever Heard" thread) has 4 power transistors (Toshiba 2SA1302) on the top and 4 on the bottom configured to lay flat on a heat sink that the board is attached to. Each of these power devices has a very thin custom square of heat tape attaching it to the heat sink along with a single hex screw. My main question is whether anyone can provide the best process for removing and reattaching these power transistors to the heat sink so I can flip it over to remove/replace the caps. There are other devices on the heat sink, some with heat tape, some with thermal compound but the power devices are the only problematic ones.

Thanks,

D

Will match tubes still be matched after say 500 hours of use?

I’m a big fan of minidisk, but I have come to a point where I don’t see a future for this format.. i mean vinyl, cd, even cassette players at still made.. but i really don’t think md players coming back, and the payers that are around will eventually die.. and parts get unviable..

Hello everybody!

As mentioned aready in the "Introductions" subforum - I'ts my 9th year here, but without writing anything... and the time has finally come 😉
I was always more into car audio. Where from one point of view active systems are even more common, but from the other I never got so deep into it as I need now.

I'm a Scan-Speak fan. Used Revelators in a few of my cars (still using in current one). Have a DIY Revelator 15W (+HDS tweeter) monitors as "PC speakers" wich I built myself based on this project from user @gornir

https://www.audioexcite.com/?page_id=59


Lately I came across nice floorstanders built on D2905/990000 + 15M/8631G00 (10l ported) and Seas CA25RE4X/DC (~60l ported) as a woofer, all ran from Hypex FA253 amps.
As they were in a bit of "unfinished project" state - no veneer (just painted plywood) and also no really properly designed/tuned x-over - the price was an absolute steal.... I just needed to have them.... 😉






I did some listening sessions. Did some (room?) measurements with REW and UMIK. Did some tuning. I'm even starting to be a bit happy with them but I know that all of it it's just wandering in the dark



I know how to use active crossover systems, I know a bit about measurements (not much but at least how to run/start them)
Once I had the Behringer 8000 mic and some phantom power XLR usb interface from M-Audio but I did sell it a long time ago.... Currently I have the UMIK1 USB microphone and access to some software but will it be enough?

In addition... I moved to a new house some time ago and my room is still untreated I'm working on it now) but even after the treatment....






I'd like to get into it as properly as possible... My main questions are.... Where should I begin (to read/learn)? Which way to go? Can I try to design a 3way crossover in a livingroom? Is my equipment enough? (If not) What should I buy? Or maybe I should try to design it in Virtuix CAD? I'm so so confused...

Thanks for any help

What are some good low noise bipolar transistors with good linearity?

9014's claim a 0.9db typical NF. but there's no noise chart.
they seem to be very similar to 2n2222's which also have around 0.9db NF.
2SC1815's meanwhile show a 1db NF and no chart. and they're far less linear too.
2SC1845's seem to have less noise, or are they just a HV version of the 2SC1815?

Good day, new member here from South Africa, need some help with a small project I'm busy with, I've got a small Bluetooth speaker that I've stripped and I'm Rebuilding it, I've added 2 additional amplifiers as I've added extra speakers and increased the battery capacity, but that's not the problem, everything works besides the fact that I need a clear audio signal for the additional amplifiers I've added, is there someone here that can maybe tell me where on this pcb I can get a clear signal? I've added some photos, thanks.I need a L,R and a ground.

I found this amp in old Radio magazine (in Russian).
It looks interesting (Vbe multiplier arrangement, VAS),
so I tried to sim it. The results don't look bad.
Has anybody seen a similar amp before?

I had to make some changes (hopefully 'improvements'),
as the original amp was clipping too soon, and bias settings
couldn't be made to work..
Sim files with models attached.
===========================


Update: This thread continued with similar amps to this one, namely Wiederhold amp from 1977, and its derivatives.
What's common to all of them is: op-amp input and folded cascode VAS.
As of Jan 2024, based on this thread, over 15 amps have been 'officially' successfully built and tested (plus several prototypes).

1) Posts #87, #117, #136 - LMK (Lomakin & Parshin) complementary BJT
2) Posts #172, #201, #206 , #1449 - complementary LatFet Wiederhold77
3) Posts #326, #313, #1735 - quasi HexFet Wiederhold77
4) Posts #952, #985, #1065 - quasi BJT Wiederhold77 with 2n3055 devices
5) Thread LatFet Amps Based on Philips AH578
6) Post #1537 , #1471, #1568 - high power and improved version of LMK amp with FQA vertical mosfets (3 pairs)
7) Post #111 (in another thread) - high power symmetrical LMK-type amp with Philips AH578 input stage
8) LMK-type with Groner input stage built in April 2022
9) Alexander-type amp with folded cascode VAS - post #1676
10) Darlington-type VAS - post #1699
11) Post #1706 - LMK complementary BJT with TIP3055/2955
12) Post #1709 - Hafler P7000 inspired amp
13) Post #1736 - mirror VAS with interesting compensation
14) Post #1735, #1744 - quasi HUF logical level fets Wiederhold77
15) Post #1745 , #1746 - 'improved' Hafler P7000 with (Hawksford Cascode)
16) Thread Fast Mosfet amp with LT1223

I am looking to build an amplifier for a pair of Fostex BK-40h fullrange desktop speakers. Initially, I was just going to buy a dayton DTA-1 but that's boring.
I am considering building the non-inverting gainclone described here on some perfboard as it is very simple and does not seem to require a lot of heat dissipation. Are there any other amp designs or gainclone variations that I should consider?
Thanks.

Hi,

I have ATTEN ADS 1062CML 60MHz 2-channel digital oscilloscope and it has a major problem - poor input sensitivity. Some applies to other consumer grade digital oscilloscopes with cost price around several hundreds USD or Euro. By a chance I found in very old Radio-Electronics magazine low-noise (300 uV output noise with input shorted) high-sensitivity amplifier based on 6AK5. Frequency response 5Hz - 1 MHz, amplification factor 100, max input voltage 0.25V. Amp is immune to high-voltage overload typical for vacuum tune circuits. I powered it from 4 x Li-ion 18650 batteries with nixieclock.org NCH6100HV (12-24V input, 85-235V/24mA output) buck step-up converter and LM317 for 6.3V filament. Both available on Aliexpress.

Article in PDF format and LTSpice files (original schematic and my mods) enclosed in ZIP archive.

I assembled original schematic on prototyping board and it didn't worked as expected, it oscillates no matter what. Additional symptom was low plate voltage on first two 6AK5 (around 45 - 50V with B+ = 135V). Verified assembly many times, replaced NOS Siemens 6AK5 with 6Z1P, no changes. I suspected noise from NCH6100HV buck step-up converter but its not the case since amp is connected with C-R-L-C filter with electrolityc, film and ceramic capacitors.

Finally I have given up and brought this amp to my friend who have more experience. He modified screen grid bias (added R14 and R15 on LTSpice schematic) so voltage (on screen grid) is about 30-31V. Amp is working now. This all is quite strange since it was assembled in Radio-Electronics test lab and they confirmed amp data.

Anyone can comment this issue? Thanks in advance.

Hello, some time ago I bought a Palladium NSP-730 turntable and gave it some basic TLC as you do with vintage TTs, and it worked, and I didn't give it much thought since. Recently, I noticed that on some records the inner groove distortion gets really apparent, and my cart adjustment were on point. I looked at the tonearm gimbal, and noticed that the arm is ever so slightly skewed at the pivot point, and it makes the arm not move perfectly horizontally, but ever so slightly upwards as it approaches the middle of a platter, causing the azimuth to go out of alignment the closer it is to the end of a record. How hard a fix this would be? I'm sure I'd need to disassemble the arm, what about bearing adjustments afterwards? Is it at all doable without a test record? Thanks for any input.

Hey all, Got a question. I hope this is not going to start some kind of flame / war, open old wounds etc. This is a question driven out of curiosity and desire to understand!

Given an amplifier of M2X - so 25 watts per channel, 24 volts DC - Why do I need a 400VA / watt supply?

Assuming each channel is going to draw 25 watts - that means I should need 25 x 2 == 50 watts. Watts to volt amps is 1:1, they are the same as I understand it. Did I miss-understand something from the thread? This question should really apply regardless of the amplifier board - this should be mostly universal right?

I was talking with a friend of mine who used to do electronics design at bell labs. When I told him about the power supply he posed the question above to me - I had no answer. I was simply going on what I thought I understood from the thread - that people should buy for 400VA worth of 18VAC.

Thoughts? Are there docs on this - if there are I was not able to find it via google searching or in the forums that I found so far.

Hi Guys,

Finally got my hands on a CD2 thats mine and I want to change the output stage. I want to remove all the opamps and join all the connections and put it in a seperate preamp like class A.

The CD2 has 4x TDA1541 and I believe each DAC has 4ma output. Total = 16ma. I'm not sure what magnification the datasheet is, it has a 1.8k resistor across it.

I don't want valves as its beyond me and high voltages, transformers would be nice but its alien technology to me. So I was considering preamp boards, there seems to be plently from China that are Naim or other based that offer some form of magnification. Has anyone tried any of them with TDA1541 or reccomend anything? It is not enough magnification?

I plan to build an external housing with its own PSU. Thanks in advance for any info offered

I'm restoring this amp. It lacks a power transformer so I'm rewiring it with an isolation transformer. (A 3 prong cord was already installed)

I noticed that the volume control puts the excess signal to the mains?!?!? Should this go to ground instead?
Any other safety things that should be done to this amp?

I'm figuring the mains side of the isolation transformer is the side that should be switched and fused.

Hi everyone,

I recently came across some old posts in this forum from people thinking about starting their brand in the Hi-Fi audio or loudspeaker industry. Since I have a similar idea, I have made this thread for those still thinking about this. Maybe we can exchange contacts and help each other.

My background as an employee includes 10 years of managing two small-medium-sized Hi-Fi and High-End loudspeaker factories in the EU. So, my core skills are deep knowledge of the market and production nuances.

It doesn't matter what region you are from or what background. If it's different, it might be even better.

It's nice to talk with anyone having the same passion and goals. Is it relevant for someone here?

Now it is possible to run lt spice in android mobile phone.
Download the winlator app file from github website and install lt spice & simply run it without any problem.
It worked perfect & smoothly.
Here are some prove.

When I generate a *.Frd file with an IIR high pass filter(boost) and a FIR low pass crossover (125 hz) even with a high tap count. The low frequency is truncated instead of boosted. I thought the tap count is irrelevant for IIR filters. The same number of taps with just the FIR filter matches the crossover transfer function perfectly.

Hi everyone,
New here and looking for schematics for my most recent purchase, a soundstream ref. 404s. I had no luck googling for it.
Hoping to find the cousin of a friend of somebody's sister that has it lying around in the bottom of a drawer somewhere. PDF will do though.
Also advice wanted on recapping and what to look for in replacement capacitors. For my Rubicon amps I ordered mostly Nichicon FG, KW and KT series and Panasonic FC and FM. Was that a wise thing to do or is there more to a good match with a certain amplifier?

Hi,




I have the following circuit and am trying to work out if I can get away with a smaller Cathode bypass capacitor on the 6c45 driver valve by calculation.


I managed to find someone quoting the plate resistance of the 6C45 at 2.5K and was using this calculator

But I got stuck on what the effective plate load is with the transformer, any help greatly received 🙂

Merry Christmas

Rich

Hello everybody!!

Got my account here like 9 years ago but never had a need to write 😉

I was more into Car Audio.... anyway... just stepped into a deep large forest called active crossovers in my livingroom... so like it or not I decided to become a more active user 😉


Wishing all the best for everyone here!

Hi! I recently went and modified the analog stage in my Pioneer PD-10 SACD Player, here's what I did for clarification:
-Electrolytic caps replaced with Panasonic FMs and a couple Nichicons FW when I didn't have correct values of Panasonics
-OpAmps (5532) replaced with LM4562 (I haven't yet bypassed them, but I was planning to put a 100nf cap on them)
-Voltage regulators replaced:
-Positive 15V swapped from JRC 78M15A to LM2940CT-15
-Negative 15 swapped from JRC 79M15A to LM2990T-15
Positive 5V swapped from JRC 78M05A to LM1085IT-5.0

Here's what I KNOW I screwed up:
-at first, I put 2 positive 15v regulators instead of a positive and a negative
-lifted a few solder pads here and there, but none of them seem to be disconnected, so I just soldered over them and they hold in place.

The result is: noise. Just noise. Nothing else. The analog out just emits a hiss, doesn't react to any disc being played, any operation being done, it just hisses from the time I turn it on, to the moment I turn it off. It didn't change even after putting in the correct 15v regulators (I changed both positive and negative) and I don't know what to do next. I got my hands on a service manual, but I'm more comfortable working with it and the advice I get from people, so any help will be much appreciated. Thank you and have a good day! (Please somebody help)

There are several inexpensive 16bit/48kHz phono to USB 1.1 devices available to record vinyl to PC, but no one step solutions for higher res files. Would need at least a USB 2.0 interface. Wouldn't really need higher than CD quality for most LPs, but it would be nice to have options for those rare master quality records.

So far I've found a decent Schiit Phono preamp and been looking at USB home studio recording A/D USB converters that do 24-bit/192kHz. The weak link might be the A/D unit's built in preamps.

Happy new year. Quick question, attached pic. Replacing/refitting components. Can I reuse the clear thermal sheet (circled in yellow)?

What is the most future-proof Sony ES from 1990 to 94 or Technics from 1995 to 2000? Think about durability and serviceability in the future?

This board isn't pretty, but is it cause for concern?

I've tried isopropyl alcohol & a toothbrush but it has very little effect.

Any experience/suggestions would be greatly appreciated.

Thanks

I have for sale a few populated pairs of to247 cascode pcbs that can be used with those lu1014 that you are stashing 🙂
I can offer also the empty aluminum pcbs on which you will solder the smd jfet, a gate resistor and gate protection diode.
All gets joined with wires, I have bad experience with strip connectors and aluminium pcbs.
It lets you adjust the vds of the jfet with a trimmer.

30€ for 2 populated cascode pcbs
10€ for 2 empty alu pcbs

Schematic looks like this


Modules and alu pcbs look like this. The wired module is not for sale.



I am getting great sound with these in my Gaincore amp.

Looking at my low noise high gain parts. Kind of the gold standard is the 2SC2240 and 2SA970.

the KSC1845 and KSA992 are definitely good, but not as high gain. How do the noise specs compare to the above pair?

BC550C and BC560C have the higher gain I was looking for, but again, how to the noise specs compare?

Now the pair that I question the most. I know that EW is a huge fan of these. ZTX694B and ZTX795A. Very high gain, I have seen them called low noise, but like the others I don’t know how they compare. Are there others that are fans of these devices? I just don’t see them getting recommended all that often, but maybe it’s because they are expensive? if the noise numbers are low enough, I would say these are a good competition to the 2240/970 pair.

Dan

Having surfed in the last few days on Dutch websites, it would appear that Stage Accompany, the Dutch factory responsible for the fantastic SA 8520 to SA 8535 planar tweeters (and other great gear) is undergoing bankrupcy proceedings (that's what announcements of public auction sales suggested). If that was true, it would be really sad unless they intend to re-establish themselves under a different name.

SA's website is silent about that. Does someone know more, perhaps some SA dealers or Dutch friends out there?

Chris.

Hello friends , as i`m quite new to this voltage reg , is it normal for it to run quite hot , it is unpleasant when touching it ? Input voltage is around 10 V DC and the output stays at 5 V DC and it seems stable , but i do suppose that it oscillates somehow . It has been used for providing a PSU for the digital +5v of the Xylink transport to DAC and the reason why i do think it is faulty is because of the fact that first it is working fine but after some minute or more it is start to add clicking to the sound . How can i check this reg if it is working properly ? I have tried looking at the outputs with oscilloscope but found nothing ...

Hi, i'm trying to design my own TPA3255 amplifier board, after seeing that most ones online are bad / terrible. One of those failed in front of my eyes for no apparent reason, while playing music well below the maximum power level of the IC (300W RMS x 2).

But i ran into a problem: i cannot understand how to feed the audio signal to the inputs of the tpa3255.

In the TPA3255 IC, there are input A, input B, input C and input D, but i dont know how to use them, i was expecting to find two simple inputs and a ground, like in the TPA3116D2.
But this one seems to be different.

Does anyone know how to use those inputs? Thanks in advance.

Hi Respected Members,
I am Sacheen from India and new to this forum .

In the quest of enjoying vinyl playback to the maximum, ended up designing and developing a MC cartridge. I want to take it to the next level by bringing it out in the market.

Please suggest your views on what should be the approach to take it forward. Need to decide the pricing , marketing strategy and much more.
Eager for your expert opinion.

Approx. Draft Specifications
Output 0.3mV @ 1kz
Coil Resistance : 12ohm
Stereo Seperation > 28 db
Stylus : Elliptical on Aluminium cantilever
VTF : 1.75 to 2 gms
Static Compliance ~ 9.5x10-6cm/dyne
Weight : ~5.7 gms
Body : Dense Indian Rosewood body
Mounting : Threaded inserts for easy mounting and tight coupling with the headshell.

I have a triode el84 se amplifier and I've noticed that the voltages on the plates of the el84s do not like it when I add cathode bypass capacitors to the driver stage. The voltages, usually on one tube get really high. As soon as I remove the bypass capacitors the voltages go back to normal. What's happening and how can I prevent this?

see with multilingual subtitles
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Hello everyone. Today I breyed to my old tape recorder and decided to assemble my own. I know, it sounds crazy, but in general I don't see anything complicated in analog circuits (except for the tape broaching mechanism). So that's my idea. Make/or find drawings of the head block for 48-56 channels (erasing, recording and reading), order the heads at the factory, build a mechanism, control unit, and add preamps and correctors (to set up the tape recorder, you don't know phono correctors). Sony APR24, Studer A80, Studer A827 became the basis or ideal I strive for. I would like to be helped here in the implementation of the experience in the creation of such mechanisms. I would share in the discussion my experience in creating this particular model. I will also be grateful if you share the schemes from such projects. My idea is very interesting, but incredibly complicated. I will be glad if I can implement it with your help.

I'm working on a class d amplifier at 300khz pwm at 0-5v and -2 to 2 v sine wave input, I've attached the schematic below for anyone who wants to have a look at it(please use the online simulator from infenion or else the schematic might not open) I understand this post is very vauge of me, but i just want some advice on how to continue and debug this issue

Hello. I'm Andrey from Russia.
I'm passionate about making various audio components with my own hands.
My items so far include:

• 3-band Transmission Line Loudspeaker;
• Power Amplifier Only Music 2.7 - 100W/channel;
• Abbado II DAC

Happy to join your friendly team 🙂

Greetings Friends. It's time to jettison the old Polks and build some speakers better suited to the low-watt amps I've been building. I have a pair of these Fostex FE206NV 8" full range and would like to build suitable enclosures for them. I'll be listening in my living room, about 12'/4m deep and 24'/8m wide, with about 6'/2m between speakers and the same distance to my chair.

Plans for Bass Reflex and Back-Loaded Horn cabs come with the drivers, but I'm more interested in the Dallas II design. It is a tad large and WAF is a factor at play. But I'm a pretty savvy cabinetmaker, if they're handsome enough she might go for it.

Are there any other designs I should know about? Perhaps in between the Dallas and the Bass Reflex they give?

Thanks for taking a look!

This thread is for discussions about the F-5T clone boards. For more information on this product, please see the product page below.

• Product Page

Threads on diyAudio that relate to this product (If we have missed one, please post it in this thread and we will add it to the list):

• Original Article: http://www.firstwatt.com/pdf/art_f5_turbo.pdf

BILL OF MATERIALS
The current set of boards available from the store comes in a set of 6 boards with the SKU of P-F5T-6V30 (that SKU decodes to "PCB, F5T, 6 pieces of revision 3 of the boards"). Please note that the fact it's revision 3 of the boards has nothing to do with whether you are making a V1, V2, V3 or V99 F5T and just means it's the third revision of the boards we've put out.

If you have P-F5T-6V30 boards and are making a V2 F5T use this BOM: F5T V2 (revision 2 of the F5T V2)

If you have P-F5T-6V30 boards and are making a V3 F5T use this BOM: F5T V3 (revision 1 of the F5T V3)

Note that the numbering of the silk matches the V3 schematic. The V2 just omits certain parts.

Hi. After an exhaustive search of this and other forums' discussions on loudness, loudness circuits, PCBs and kits and not finding much that I can understand, I conclude that I need some help.

I'm seeking a standalone variable loudness compensation control that can sit between my pre-amp and amp and can handle two channels and a sub. Preferably passive with a bypass switch. I've read through a lot of loudness threads here and on other sites and it has become apparent that I don't know enough to read a circuit diagram, understand how good of an implementation any given design is, how modify a design for my purposes and put a complete BOM together. My experience is limited to assembling kits with PCBs. Is there a kit for this somewhere? If not, does anyone know of a BOM? I might be able to figure out how to do this point-to-point or find someone to make a one-off PCB (if that's a thing).

Thanks in advance for any guidance you can provide!

Aaron

Hello and Happy New Year!

I need help identifying a component in a Mirage M-290is crossover.
The component in question is the white block in the right bottom corner (first pic).
Anybody having the crossover schematics, by any chance?
I would like to upgrade the crossovers, to what extent should I go?
Caps are 4.7, 15 and 22..., currently Hanlan.
(will replace the steel nuts on the terminals, but the steel strips will remain, unless there is ingenious way to replace/bypass them )
Thx

Hi I built a DIY speaker earlier in the year and have used the Sure Wondom Jab5 4x100w amplifier with built-in ADAU1701 dsp. I have only ever used Bluetooth with it and it works perfectly fine like that and is great.



However recently been speaking to someone who had their own DIY speaker and asked if I had XLR input so we could connect them together. And they also said I could then also use that same XLR input to connect decks to my speaker if I wanted too. Which would be a great option!

I read on the sigma studio forum something about having to have a manual switch to toggle between Bluetooth and aux input. But it wasn't explained how to program that into the software. Also im unsure if aux and xlr would be different anyway?

Can anyone please help me in how to program sigma studio in order to accept a XLR input. I want to keep the Bluetooth input as well. Sigma studio itself i am still quite new to it, I have looked everywhere before posting here. I have added my sigma studio file for how i have it set.

Amplifier (there is also a wiring diagram photo) - https://store.sure-electronics.com/product/756

Like for like I've probably listened to more speakers than most. My side-hustle is breaking speakers and selling the drivers. Like most of you I'm over 21 - my hearing is already past its peak.
Before I destroy a speaker system, I have the virtually unique opportunity to listen to them placed in an identical position, connected to the same amplifier as others.
In the modern era most of our music is compressed via MP3 or MP4a. If I'm being totally honest most of these speakers are much of a muchness - I can't often tell the difference.
My favourite bookshelves speakers (paired with a subwoofer) are manufactured by Sony.
As to the Brand of my favourites without a sub - I'm too embarrassed to say.
Rest assured, I have broken Mission, Yamaha, Tannoy, Peavey, Wharfedale and others.

I just got my hands on a set of Ciare 15 NDH 4S.

They will be used as subwoofers, covering up to 200 Hz.
The rest of the speaker system is placed directly on top of the subwoofers.

Normally, I prefer closed enclosures, but this time, I will go for a ported system.

I assume that a 10 cm port is needed, but do I need one or two, to avoid port noise?
Will there be any disadvantages, if I place the port(s) in the front…..it will make things easier for me.
An alternative is bottom fired ports.

Does anybody have an idea about cabinet size, port dimensions/length? I get variouse suggestions, depending of the calculation program used.

Greetings from Denmark, and thank you all very much in advance for your inputs.

Michael

Hi everyone!

I am a Sound Engeinneer in Montreal, Canada and currently studying in Sound Recording at McGill. I started gaining interest in electronics 2 years ago when I came across Moritz Klein on youtube who builds diy modular synths. Now I am working as a amp tech in a guitar shop and I am learning the wonders of tube technology. If anyone from Montreal would like to hang out, let me know!

Charles

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

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

Hi everyone

I restored recently my AU-5900 that is replacing electrolytic caps, replacing small signal transistors and diodes , fuse resistors etc. I’ve done it in the past on the same model for few friends with success.

On the power amp side, result was ok will all voltage levels good and bias set up right.

However during testing I noticed that the quality of sound had degraded and specially got a background HISS noise on the speakers even if the volume is at minimum.

I further investigated and confirmed the noise being from the preamp.

I also noticed the following:

1. On F2604, the collector voltage of both TR03 and 04 was 6.7V in lieu of 9.2V as written in the service Manual. All other voltages on the transistors seem ok. Note on preamp I used KSC1845FTA and Nichicon KZ , ELNA silmics

2. On F2599, the voltage readings are somewhat lower at the outputs: 20.7V and -27.6V in lieu of 22V and -29V.
Please see in attached photo complete voltage measurements on the preamp voltage regulator.

For components on this regulator :

1. A726 and C1313 was replaced with KSA992 and KSC1845
2. E Capacitors was replaced with Nichicon KZ and FW type
3. Zener diode RD-13EB was replaced with 1N4743A
4. B526 and D386 replaced with A940 and C2073

All resistors checked ok

Could you please assist as I am really stuck with this since over a week.

I do not understand as I have checked again everything

Thanks and regards

AL

Hi, my name is Julian , I’m planning a 3way with an 8” woofer. I looking to find a good reasonably priced midrange 4-5 “. Cross over point between 500-800.

I have a circuit with a 10k linear potentiometer that's used with the wiper resting at the central position. This is for a controller, and provides movement is either direction.

The problem is the first bit of stick travel away from center is too sensitive. The last half of stick travel in either direction is not sensitive. In fact, 75% stick travel left or right seems to be near 100% reading by the controller. The circuit that processes the exponential curve can't be reprogrammed.

I'm trying to find out if adding resistors in series with the ends of the tracks, or on the center wiper pin, or decreasing the resistance to either end of the track with resistors to the center wiper pin, or this plus a resistor on the center wiper pin would be a possible way to reduce this sensitivity without reducing the max reading?

Have one pair of Beyma 12P80NDV2.0 for sale.
500€ + shipping. Notice my location, can ship anywhere in the world.
This is the original V2 with a smooth cone and triple roll surround.
Very light use, great condition.
Have been stored in a controlled climate.

There is plenty of threads on here with information on this driver for use in a 2 way or large 3 way setup.
Well behaved and extended smooth rolloff, easy to integrate with the driver above.
Very linear behavior to +/- 3,5 mm,xmax is stated in a realistic way.
Can take some power and works well with some eq on the bottom end.

Can be reconed with current 12P80NDV2 kits if the rise would ever arrive.

Will be packaged very well and shipped with tracking.
Fairly lightweight.

Hello everyone! I own an English analog Soundcraft console and now that my favorite tape recorder has passed away, I decided to build my own converter for recording to digital. I'll say right away that the options on the market (ready-made) don't suit me for several reasons: price, functionality, and external layout. My console has 56 mono channels, 4 stereo channels, and 8 more groups, so I'd like to understand how the DAC/ADC works and build a custom one. I came across various schematics from Behringer for their DAC/ADC, but I didn't like the chip used in the circuit. Does anyone have experience in creating converters? Can you share your skills and schematics of ready-made single-channel converters (so that I can then install them in one case). It's also interesting to read about connecting to a PC. Installing cards into the computer itself is not an option (there are no free slots), and via USB is a good option, but if you remember the above idea of using single-channel converters, the question of combining them and transmitting information via one USB comes up. I will be glad to receive any useful information. Thank you.

Here is the building thread of my tpa3255 amplifier.
The board is bought on Amazon and the power brick is 36V 6A . The case is bought at Audiophonics, France.
Some modifications gonna be made, but this it the result so far.

Let me start by saying my electronics skill level is at a very basic level. I have no formal training and what I do understand is self taught from reading and research. And help from forum members like you!

At this point in my project I am trying to understand some things on a power supply that don't make sense to me yet. Here is the board layout from the service manual:



It appears to me that some of the jumpers and resistors are not really doing anything. They are tied to the same trace circuit? What am I missing here?

Thanks!
Axis

I've got a couple DC brushless capstan motors from a couple VCRs.

One requires a + voltage on the control pin to vary the motor's speed.

The other pulls the control pin up to 9Vdc.

I'd like to build a speed control circuit.

The motor that requires the + voltage may be easy as I can maybe use the control circuit I used with a VCR video head motor.

The motor that pulls the control voltage high has a control range of 2.133Vdc at 0 RPM to 3.70Vdc at max RPM.

The circuit I used for one motor.



Now if the voltage on the control line won't affect this circuit, I suppose that I could build the exact same circuit to control the speed unless there's a better circuit that uses the tach frequency.

The only thing is that circuit depends on the amplitude of the tach signal changing and both motors keep the tach signal at the same amplitude. Plus that circuit uses a transformer I cannot get anymore.

I used a variable power supply on the control wire and that works good so that circuit may indeed work, however the amplitude of the tach signal varies slightly once per revolution.

Hi All,

I found what I think is a neat remote stepped attenuator that is mis-described on AliExpress and Ebay and drops into the place of a large pot:

https://www.aliexpress.us/item/3256...t_main.11.363b1802RFjonO&gatewayAdapt=glo2usa

https://www.ebay.com/itm/145322085041

I prefer a remote volume control but typically want something fancier than a cheap motorized pot. The nice thing with these is that unlike a MUSES72320 kit or various other options, they drop in to the same physical space occupied by a standard pot in many preamps or integrated amps. If you want to run the display, it doesn't require as much hole as other options.

They are affordable (though they have gone up since the $43 I paid for my first one) and work on a USB supply (at least the two I got--though not the ones in the pics--say 7VDC but have a jumper where you can run them on 5VDC).

I've been looking for things like this for a while, but missed it for a long time because I typically search for attenuators. If I'm a goofball and misunderstanding this part, feel free to let me know.

Paul

Hi there, anyone here have build a zero field line input circuit with Lundahl 7101? any tips? some starting values for C? thanx!

Hi!

I am doing some diy class A headphone amplifier and would like to ask someone with more experience which power supply is suitable for my needs.

So the idea is to have two MeanWell smps modules with clclc filters feeding the regulator of some kind. The build will be small and compact - about 160x120mm


I have few ideas in my mind:

1. To have TPS7A47/33 regulators for each channel

2. To have TPS7A47/33 regulators feeding the super regulator (or kevin gilmore golden reference supply)

3. To have just super regulator (or kevin gilmore golden reference supply) with beefier filtering at the input.

4. Some better solution

Total current draw will be 300-400mA per rail and output voltage needs to be 20V.
I would like to know if regualtor output impedance has a big impact on the class A amplifier which is a farily constant load in comparison to other amplifier classes.


Any answer is appreciated.

£120 New and unused. A pair (2 pcs) of the very popular Dayton 8" aluminium cone woofers.

4 Ohm version to get the most from your amp.

Beautifully suited to a 30 litre vented box.

Shipping from UK.

https://www.ebay.co.uk/itm/335727497799

BACKGROUND:
I needed to retrofit an audio output delay to an AC-coupled headphone amplifier design. The original protracted power-on transient of 6V would be enough to destroy some lower impedance headphone drivers. There are a few schematics available online, most of them had DC-offset protection too (something I did not require). For those who need continuously active DC protection, then Ti Kan created his e12 board. There are also solid-state implementations on these forums. Then this thread came to light discussing a circuit which seemed ideal with some additional modifications. However, the space available to me was absolutely tiny. I also wanted to shoe-horn this into other line-level pre-amplifier designs without compromising space. I finally came up with this tiny design:



DETAILS:

• 29.2mm x 19.7mm 2-layer PCB.
• 15v to 35V voltage input with voltage regulator. Optionally bypass voltage regulator for 12V input or to use different voltage relay.
• Output delay adjustable up to 20 seconds with default build.
• Relay is rated for headphone/line level - 0.5A 125VAC or 2A 24VDC.
• Total current draw is 15mA.

SCHEMATIC:



BOM:
I sourced components from Rapid Electronics for a total cost of £2.83 (of which the relay is £2.22), which is a small outlay for considerable peace of mind. A more expensive Mouser cart is available: Mouser Electronics



CIRCUIT DESCRIPTION:
IC1 is a small 12V regulator to power the circuit. The output delay is controlled by an adjustable RC time constant formed by TR1 and C3 [V(rc)]. As C3 slowly charges, voltage increases at the gate of Q1 which will eventually turn on the relay [V(relay)]. D2 is a 7.5V Zener which will only conduct when the bulk of the time constant is reached [V(gate)]. This maximises the time constant and therefore minimises the value and size required of C3. R1 stops inappropriate latching of the MOSFET. D1 discharges C3 and removes issues with "warm starts" caused by switching the amplifier quickly off and on. D3 is a flyback protection diode for the relay.



OPTIONS:

• Trimpot and output delay time: Default 250K trimpot will result in maximum of 20 seconds. 100K provides max 6 seconds which should be suitable for most situations. 500K trimpot will give 36 seconds which may be beneficial for tube-based amps (delaying for warm ups). Either a horizontal or vertical adjustment trimpot can be used.
• 12V input voltage: bypass voltage regulator (jumper pin 1 to 3), skip C1, and use default 12V relay.
• 24V input voltage + 24V relay: bypass voltage regulator (jumper pin 1 to 3), skip C1, and use Omron G5V-2-24DC. Note, this will affect the RC time constant and you will need to use a larger trimpot resistance 500K-1M.
• LTSpice: The default build is quite universal and suits most situations. However a simulation file attached allows you to play with the values so you can find your ideal components.

BUILDING & MOUNTING:
Solder low to high components. Place diodes first with D2 in the opposite direction than D1 and D3 as per PCB. Remember not to confuse D1/3 with D2 as they appear identical. Then C1, C2, IC1, Q1. R1 is mounted vertically. Then add TR1, C3 and the relay. Power is connected to -V and +V. Audio input is connected to the side nearest the trimpot and audio output on the other side. There are two pads for audio ground. Adjust trimpot to suit your preferred delay time. NOTE: The board does not have mounting holes. I placed pad descriptions on the underside so that it can be mounted upside-down. I normally place a double-sided sticky pad on the relay and mount it this way. Alternatively you can heatshrink the entire module.



SUMMARY
For me, it was just a little way of playing with through-hole miniaturisation. The aim was to design something very cheap and very small, but effective enough to protect expensive headphones. Even though most amplifier designs are robust enough with low power on/off transients, I will probably "MOD" everything and end up sticking one of these in all my DIY headphone/pre-amps.



I have some boards for sale to cover costs available at this thread, and plan to release the Gerbers to the community around Christmas time.

The Vintage Japanese Direct Drive Turntable Model 'Sony TTS 8000', has a popular following and there are many users of this Model in the present day.

Like all Vintage TT's they are generally being acquired with a unknown history and a unknown amount of usage.

I thought it would be worthwhile creating a New Thread where the TTS 8000 could be discussed and be used as a reference place for Recording known of wear and tear issues being encountered on the TTS 8000, along with Methods being used to overcome any of the issues when discovered.

Hello anybody. I have vintage English console, and i seek adc/dac recorder for her. The prices for devices from presonus and others like that are crazy and you will need about 3 of them. After all, the console is large. I just remembered about the forum and thought that I could discuss with you and design an individual dac/adc for myself.

If I understand correctly, aperiodic alignments are effectively ‘between’ sealed and vented, sounding more like sealed(?).

Is the bass rolloff generally more like sealed or vented, and f3? - -

Would get close using a sealed model (eg in Unibox) are there Qtc values that approximate to ~ hole sizes relative to box volume?

Or is this planet 10 proprietary? 😉

Thanks

I have been trying to determine what brand this amplifier is. My parents bought it for me (used) in the middle early 70's. It was my first guitar amp. I have it on my bench now for some repairs, as it has been relegated to a closet at my parents house since before time began. It had quit at one point, and it was replaced with a Peavey.

My dad is quite elderly now, and I was going thru one of the closets preparing for the inevitable and ran across my old amp and one of my grandfathers (an old Silvertone 1472).

I have looked all over this amp, no markings, no label no clues. It appears Japanese made as all the tubes but one are "Ten" tubes, which I believe is Japanese. It appeared to have a logo on it at one point, as there is a screw thru the grill cloth in the upper right corner. I never recall a name being there.

I have the amp playing now after replacing a couple of blown capacitors. I still have some fine tuning and cleaning to do, but it does have a nice sound, the tremelo effect is interesting, but the volume has to be completely parked at what should be low/no volume and then it seems to set the amp at a certain volume and the tremelo effects/controls function. I will explore that later today when I fully inspect the volume pot to see how it is designed. The speaker is a 10 in. 10 watt.

I have attached some pics, the one of the back is with the cover board off (would cover about 1/3 down from top. One is of the top control panel both installed and another pic out of the cabinet.

Thoughts anyone?

P.M if interested:

Hi all I recently got a Philips cd 960 in lovely condition unfortunately it’s not working

The tray will not eject when pressing the button however it closes when you manually open it and press the close button

It doesn’t play CDs however when the cd is seated it spins for a few short seconds and then stops

I have replaced the 4 belts with the nanocamp kit carefully and lubricated the shafts and motors when I press the open button I don’t even feel the two spindles with the wire try to move to support it opening

I used the drive wheel space to minimise movement when replacing the belts

Any ideas where I can look next to get this cd play up and running?

Hello....almost finished with a nice Citation 12 rebuild...the only issue remaining is a power supply rectifier...but can't find any references to a replacement and can't find the HexFred replacements on EBay either.

..any help? is it a generic part?

Allo Kali I2S reclocker for use on a Raspberry Pi or Sparky. New nowadays €99, bought from Audiophonics on February 9, 2021. Asking price €69 60 excluding shipping from The Netherlands.

This is the 22/24 MHz version up to 192 kHz, which offers lower phase noise than the 44/48 MHz version which goes to 384 kHz. Oscillators are of NDK make.

As good as new, where I've soldered power wires directly to the board. I used it isolated from the RPi beneath it for as little noise as possible. It's also possible to feed it 5V from the RPi itself. To do so, just close the SBC jumper (which is now open).

Manuals: https://www.allo.com/sparky-eu/kali-reclocker.html#downloads





I used this HAT as extra reclocker before my Soekris dam1121-01 (see my other listing). Even though though the Soekris does reclocking itself, placing this femto reclocker before the DAC made for a significant improvement in sound quality. I was sceptical before, but the improvement was noticeable immediately.

I really don't like having to reach around the back of my amps to turn them on, this was a big incentive to design this.

A 256 step relay attenuator with 0.5dB steps controlled by a touchscreen and IR remote. A Teensy 4.1 micro control unit is used to control everything, I have been playing about with this for a couple years trying to develop a really good intuitive user interface. The board was going to use a PGA2310 to do the attenuating but last week decided to use a stepped relay attenuator. The PCB ended up at 200mm x 130mm, I managed to fit 2 PSU's, 2 buffers, 2 Amyalice filters for the buffers, 230vac 15A relay for a power amp, and a relay for speaker grounding (anti-thump). It has 5 inputs, 2 outputs that will accept SE or DIFF in or out.

The ILI9342 is a 2.8" touchscreen display and it is really hard to take photos of it. You can change the colour of all the different elements on the screen and uses BrunoSans font. For the large gain numbers I had to edit it the font to make it work, the numbers were different widths which look good if they are static but when changing looked weird. You can also rotate the screen, adjust the brightness, adjust the backlight and calibrate the touchscreen.

The input names can be changed, I have a list of over 20 to choose from. An inputs gain can be fixed so it will work well with an input with its own volume control like a TV or computer. Another thing I added is a gain offset for low power inputs, this allows you to set the apparent gain so it matches your other inputs.


The gain can be displayed in dB or as an ascending number. The gain speed can be changed and will do 3 slow 0.5dB steps when the button is pressed before faster 1dB steps.

My schematic is a mess, I haven't had time to sort it out and I have not finished the layout. I tried to keep parts count low and used SMDs to keep the PCB as small as possible. The buffers are OPA1632 opamps with the input buffer having 3dB of gain, I will add some pads so they can be bypassed. The 8 relay attenuator has 256 0.5dB steps, I chose 5k but you could do what you want. There is a mute relay that grounds the inputs. I added 2 Amyalice filters for the analogue power, not sure if I should add one for the +5v. The analogue power is from a +-12v DC-DC converter that gets its input from the +5v psu. The +5v is from a small AC-DC converter which is mounted on the board. The Teensy 4.1 is a really powerful MCU, I thought I needed the power to update the screen at up 50fps but after optimising my code I did not need it but I am leaving it in. I have 14 UN2-5NJ non-latching relays so I decided to use them.

The IR remote works really well, they are not very responsive but with a few little tricks it is good enough. Im using the Apple Remote, it is one button short so I have programmed for the menu button when held for a second to change outputs. Left and right change inputs, play/pause does the mute, up/down does gain, menu does menu and select button does standby.

The touchscreen is supposed to be intuative and clutter free. Touching above or below the gain changes it up or down. Touching left or right of the input text changes the input. Touching a symbol or MENU will mute, change output, enter the menu or standby.

When standby is selected, mute is activated, speaker ground (NC) relay is de-energised, then all other relays are de-energised. When turning on mute is activated, the power amp relay is energised, then 2 seconds later speaker ground is energised and mute is switched off. When turned on at the mains it will enter standby. Hopefully this will be quiet and safe. In standby the standby LED is on, the display part of the touchscreen is off but the touch is active and used turn it back on.

When muted the gain numbers on the display are dimmed and the speaker symbol loses its sound waves

My breadboard is simulating the relays as you can't connect the relays easily. I have used optocouplers and LEDs to check the MCU is controlling the relays correctly (they use more power than the relays would). Apart from the relays the breadboard has the touchscreen, a standby LED, IR receiver and the Backlight control for the touchscreen. The backlight control is done with a PWM signal from the MCU and a simple analogue filter. The other components I have not tested are the 3 ULN2003LVDR, these are low voltage relay drivers that contain flyback diodes and the transistors need to operate the relays. I am happy the MCU is working as it should, not sure about my buffers and need to quadruple check my schematic and layout.

Not sure if I will use this in a preamp or as part of an integrated amp. Sorry about the dodgy schematic and bad photos.

Great to be here

FreeDSP classic full kit (parts+PCB), 99 usd.
Photo of assembled board attached. Can be coupled with York USB interface for 2 ch USB in+out:
https://www.diyaudio.com/community/...put-interface-york.413504/page-2#post-7761661

I did dap into compression drivers more the last years, and noticed a big difference in sound. The high rated 18Sound compression drivers sound very harsh to me while the Faital compression drivers sound soft and smooth. I can't pinpoint why that is. Mostly it's visible in specs and measurements why a driver sounds like this and that, but with compression drivers i seems to miss that factor.

I did build some systems with compression drivers the last years, not for me but for others. I did one with the NSD1095N in a XT1086 horn, and altough the client liked it, it sounded very harsh to me. I did mount a Faital HF 108R to the same horn and it sounded a lot better after i eq'd it (like i did with the ND1095ND). Both have little resonances in the top, both are fit for the cutoff frequency in that horn (crossover with minidsp 48dB/oct at 1800Hz) but still such a big difference. Amps are Ncore amps.

At the same time i did also build a higher power garden system (see pricture) with the Big Faital HF201 in a P-sound clone of the JBL 2380A horn and a Beyma 12BR70, and it got the same soft easy going sound as the HF108R. This one is crossed at 900Hz 48dB/Oct with a DBX PA2 (is for small gigs) dsp and crown amps. I did try a Beyma CP750Ti on it that i lended from a friend, but again it sounded relative harsh (not like the ND1095N altough).




Can someone explain me how this happens, what factors make a compression driver sound harsh or smooth. I know Faital makes compression drivers that I like a lot, but i would like to find more, without having to buy them first to test. My next project needs one from 1kHz to 20kHz (or at least high enough to cover all), and i could use the 108R in that XT1086 horn (works for hifi, i did test), crossing to a 10 woofer (for home hifi, not pa) but having other options (and know how to recognise them) would be nice...

Witam z Polski jestem Piotr

Unfortunately I have too many things and because I'm crazy, I get more and more, that's the why I have to sell a lot of my stuff as you can see from my threads.
Now it's time for my beloved Spirit Winds by Jeff Bagby.
The cabinets are in good shape but there are some minor damages that you will see in the pictures. To be conservative I would say 8/10. It was painted in 3 layer car paint with glossy white pearl and it was built as specs with slanted baffle and facets.
Revelator Tweeter may have 300 to 500 hours because it was used in some previous projects, but it is in perfect working condition an a very good cosmetic condition 9/10
Audiotechnology midwoofer it is in perfect 10/10 condition. 100 hours of use.
Crosover has MOX and ceramic 10W resistors, intertechnik air core coils 1,4mm (yes, for tweeter and for midwoofer), Jantzen Z-Standard caps at tweeter section and Audyn Cap MKT at woofer.


I'm asking a BARGAIN: 1000€ + Shipping + PP fees if apply
It's impossible to build them for this money because it doesn't cover not the drivers itself ($1900 bare bones kit at meniscus) and maybe neither the cabinet itself.

Does anyone recognise this preamp or its design ?

Picked it up locally but unable to test it until I get 2 x 15v power supplies, is it even worth trying ?

What’s with the Treble and Bass inputs or outputs ?

One phono MM preamplifier with PCF802 tubes.

The package includes:

• 2 pair NOS PCF802 tubes military grade;
• phono with very good quality components (Miflex MKP, Nichicon, Silver Mica in RIAA, quality RCAs)
• PSU with soft start.

The price for this unit is 330 Euro + shipping to EU. I am sending to EU only.

For more details, please send me PM.

Hello, I am looking for a transformer for YBA 2 Alpha HC as a spare part to upgrade another one into a Dual Trafo version, does someone have any available?
Thank you very much.

Well, I can't find anything of the following AC30. No technical details, no schematic. The reverb seems to be removed as is the vibrato footswitch. Any idea some body? Many thanks in advance...

Is there a model paint version with the ability to model a rectifier.
I see it does triodes and pentodes but how about a simple rectifier?
Be nice to make quick accurate rectifier spice models from a data sheet.

Thanks for any help.

Whether current dumping or another well-known method, these concepts have one thing in common: they all claim to have found the Holy Grail.
This Holy Grail includes a current supplier, an output stage with more or less transfer distortion and a control amplifier, also known as a voltage amplifier, which trumpets the A mode into the ether.

Through tricky, almost magical bridge wiring, the class A market crier also lifts the transfer/crossover-distorting power amplifier to Olympus. So they say, or would like to.

Both concepts do indeed work, often extremely well. But what is the advantage of such an undertaking? Actually none, because why should one design an amplifier that has faults - in order to correct them later, i.e. to work very hard internally. Yes, there was something, namely Douglas Self with his blameless approach. This approach says: just do everything right from the start!

What a nasty thing to do, because with Douglas Blameless-Amps, the field of amplification tools has been grazed.


Long story short, let's play.

Here is a quick idea. It contains two operational amplifiers and two fully-fledged audio power amplifiers each, of which the right-hand part operates in true class B with very low quiescent current and the left-hand part would only be suitable for headphones - because this stage is the important class A output for high-impedance load conditions.

The result is now a 100W_peak class A amplifier, which, however, only has 10 watt losses in idle mode.

The trick here is the coupling bridge network; among other things, the left amplifier no longer sees an 8 Ohm load, but a much larger load (to put it very, very simply and casually). In reality, the whole process is not that easy to explain and it is certainly not trivial.

Here is the working approach. Have fun with it.


greetings,
HBt.

Genuine 2SK269's bought from a reputable source (Wagners in Oz), four pairs matched, £8 a pair, postage £1.90 to UK, can ship abroad.


There will be a slight delay in posting as we are on lockdown in the UK, PM me for details.


TFL, Andy.