Have an Adam P22A woofer which makes a harsh clicking sound when being driven hard, but sounds fine below a certain threshold. No visible damage to the cone, makes the same sound when i put it into the other active cabinet so its not the amp either. What could be going on?

I received 3 pairs of AD1862 from Chip1stop . I will keep 1 pair for me and i am selling 2 pairs .
Asking for 80€ per pair (2xAD1862) .
Registered shipping with tracking included in price .
PM me if interested .
Thanks

Hi all,
I exchange a pair of CSample's PCBs for DIY version of FW F1 (for a stereo set) with F2 PCBs.
EU in preference. Thanks.

All the major vendors have listed lm3886 as nonstocked and their prices have almost doubled. Yet nothing like that indicated on the texas instrument page.

Anybody have details on whats going on?

Dear Everyone,

Some of you are probably familiar with the works of AMB Labs. One of their project is called the M3 headphone amp which is a 3 channel hybrid opamp-MOSFET based headphone amp. It is a pretty decent amplifier which I have been using for 15years now. I decided to build a fully differential DAC which could directly drive a fully diff headphone amp (https://www.amb.org/forum/my-gamma3-build-with-a-built-in-fully-balanced-m3-amp-t4735.html) without issues with volume control and the low input impedance of the fully diff headphone amp. This is where my struggle began.
I found a design where a user on head-fi designed a fully diff amp based on the M3. He called it the M4: M4 head-fi link I decided that I wanted to put this into my Gamma 3 DAC until I get an AMB B22 or something similar done (there nothing similar I know, but I have something in mind).
I designed and built the module but I cannot figure out what is wrong with it. I get stuck at the very first initial setup step where the opamp bias current needs to be adjusted. On one side of the differential amp, the one which has the positive input, everything seems fine. On the other side, the R5 resistor (R3 in my design) is stuck at 2.5V = 25mA no matter what I do. The trimpot U$2_1k has no effect on the voltage. If I remove the R3 resistor, the trimpot adjust the voltage on the JFET current source's leg (although it's not a current source at that time). When I removed the MOSFET stage from the amp, I got the same symptoms. I tried to bias the JFET current source (CW pin of U$2 trimpot) to the positive PSU_OPA (V+) instead of the negative, same result. When I removed the Q2 MOSFET bias transistor, the currents were the same and were correctly showing 0.5ish voltage on both R5 resistors (R3 and R10 in my design).

Could someone take a look at my circuit and the PCB design if some error is screaming at you instantly?

I already found the following issues, but resolving them didn't resolve the issue with the CSS or the fact that I couldn't force any current on the MOSFET:

• MOSFETs are mirrored
• Capacitance multiplier is wired wront at the JFET
• VOCM on the OPAMP shouldn't be connected to GND

One solution I was thinking about is to remove the two constant current sources because the JFETs have high tolerance with the Idss and probably ruins the symmetry but I don't know what would happen to the OPAMPs behavior if it was not biased to class A (AMB is saying that is the CSS for but I have never seen any other design having this feature).

Please don't bash on me for not knowing what I am doing. I already know that 😀 although I am trying to get up to speed with the fully diff opamp behavior and basic principles.







This is how the module looks like IRL (the PSU doesn't have a GND wire to avoid the ground loop, would come from the same GND as the balanced input):

I would appreciate if someone could help me out. Also, after we find the error(s), if you are interested, I could send you a pair of PCBs for free so someone else could build this, as well.

My first set of floor standing speakers. Ignore the guinea pig cage, it is time for its cleaning. Using a pair of Tang Band W5-1611SAF 5" Full Range Speaker each. Hindsight being 20-20 I know I made some design errors but it doesn't seem to have affected the sound any. Cut out for the speakers was much better using circle jig and razor to cut the veneer. What do you all think about the way they look. Total of 16 ohms each. Random question, is there anyway to re balance the speakers to 8 ohms using resistors? Either way I'm happy with what I've made so far.

I am planning to build one of the preamp/headphone amps from the diy store.
Was wondering if these linear pots would work as volume control or I really need a log pot?
These are 5K pots, and I have 6 of them. Not sure what else these are usefull for.h

Hi all, Does anyone here have the schematics / service manual covering SA3/S300 amps?

I am working on an hybrid amp
iTube Fatman carbon edition, without an output signal. After sometime of troubleshooting I found one part that was burned labeled U6 on the board near the TDA7265 amp chip and with a smd code A1xx encircled in red in my photo. Can anyone Identify this part since it was burned I can only see A1 but some letters after it are not visible. Since the label is U6 on the board I believed this not a transistor.

Hello all
I am personally sick of the increment system on home sized table saws. I wish they had an indent every mm so that every time I set 10mm I get 10mm, not try to point a dull needle to a wide 1mm mark!

A saw where you can set the fence electronically would be perfect. A small brushless circular saw would make the perfect donor, together with an electronically adjustable fence on a pair of threaded rods. Similar to 3d printer head height mechanism

A good system like this would be faster for panel cutting than CNC, especially for prototyping. I am making a non-electronic system using indentations every mm. Would be awesome if there is collaboration to turn this electronic

A newby here hoping to see if I am on the right track with this schematic and advice. Firstly everything to the left of the JFET came from the LT3080 datasheet application notes. The LT3080 is unique in that it can regulate down to zero volts instead of the usual 1.25, thats why I want to use it. I need a simple variable regulator board that can output from 0 to 35 volts, the 0 to 3 volt range will be used most often in fact so an LM317 wouldn't work here.

This circuit will be for biasing tube grids experimentally, so there will be no current draw when its used, bias on a tube grid just creates a negative field no current draw. This presents a problem, the LT3080 wont work unless it has a minimum load of 1mA. So I thought I would add a constant current sinking shunt at the output, as simple as I can.

So, I want to ensure that 2mA of current is being drawn at any output voltage setting. I want the simplest possible current sink to do this, I think a JFET with a resistor is simplest correct?

If I am on the right track here what would be a good JFET device number to use? I suspect the resistor will be somewhere in the 100 to 200 ohm range depending on the JFET used correct?

Thanks for any help on how I can sink the output of this supply to a constant 2mA so the LT3080 regulates, even in use it wont be drawing any more than that unless I have a gassy tube.

(I corrected the original schematic in post #6)

I received an NAD M3 in a small pile of broken gear. It is in mint condition otherwise, it powers up, but won’t come out if it’s protection mode. It isn’t very old, but seeing the four main filters all bulging I had an idea of what was wrong.

I disassembled it and am currently working on the two amplifier boards. Nearly every capacitor on the board has very high ESR, like a 330uF 16v with and ESR of 27 ohms. Not sure why they choose to use garbage caps, but I find more bad caps in NAD gear than anything else lol. Other than that it seems to be a really, really nice dual mono design.

I was thinking that while I had it apart that maybe I should do some modifications to it, see if I might be able to get some audible improvement.

First: transistors, it uses decent signal transistors throughout the board, mostly being 2SC2240, 2SA970 and 2SC1815, 2SA1015. It also has a pair of 2SA1360 and a pair of 2SC3423. For drivers it uses 2SC4793 and 2SA1837, which I’ve read are actually pretty decent and make good drivers for the outputs I’m thinking of swapping to.

So it originally came with 4 2SC5200 and 4 2SA1943 in each channel. When asking about a transistor sub I learned that while this pair is okay (would have been a downgrade from what I wanted to sub), that a far superior pair would be the MJL3281 and MJL1302. I have several of each from Onsemi/Fairchild. Would this be a worthwhile improvement? Would there be an audible change noticed? Or would I just be wasting money and parts?

Next would be the opamp on each board. Currently uses TL082CP and thinking of an upgrade to maybe a an OPA device like 2134, maybe a 5532, maybe if I’ve had a few too many to drink order the Muses02??? I’d love to hear some suggestions as to what people think would be the best replacement in the $20 or under per device would be. Unless you think of something that is worth more than it’s cost like a Muses02 or a Burson Audio. I wouldn’t mind trying one of these exotic as long as people think it’s worth it.

I think I’ll keep it at there before this post gets too long and add to it as I make progress on the amp.

So first what are thought about upgrading the 2SC5200/2SA1943 to the MJL3281/MJL1302 and while we’re at it if anyone recommends upgrading the drivers or any of the 1815/1015 with lower noise devices. Have plenty KSA1220/KSC2690 and KSA1381/KSC3503, and more. Haven’t peeled at the spec sheet to see what would be a good drop in from the originals, and neither may perform as well as the originals. Just asking though.

Next would be the upgrade to the stock opamp. Would love to hear some suggestions.

For the capacitors I’m using Panasonic FC and Elna Silmic II (or I have Nichicon FG, I have Muse too, but they’re physically too big). Oh which brings me to the film caps. They’re small and grey, unsure of brand or film type. Was thinking of swapping them all out with Wima polypropylene.




Unsure about resistors. They use your standard metal film. Any benefit to upgrading them as well? Basically looking for improvements that can be heard.

Thank you much!
Dan

Greetings !! I am new here and hoping someone could help. I am in need of a schematic for a Monster MPA 3250. Any help, please? Thank you !!

I have a Paradigm Seismic 110 with a broken rear switch, someone else had removed it and soldered on 3 cables leading to a connector box. I'm presuming this was to bypass a broken 3 pin 3 way switch as you can see in the picture. I can't seem to find the right kind of switch, would it come up as a different name for home AV parts?

Any help would be excellent and, on this what someone has done with this connector, would I just join one piece of cable to the left or right and then tough the centre with the other end to activate it?

I have a Ct sounds 2k amplifier. I am trying to sort out issues in the power supply. The ps mosfets are shorted, a few gate resistors are out of spec and it appears that half of these small transistors are burned. I am having an issue identifying the transistors, I can see L6 stamped on a few of them, I think they are 2sc1623L6TP. Can anyone confirm? Also I can’t confirm the part #’s on the burned ones, any thoughts on how to figure those out?

Anyone built the Bugle2 ?

I went to hit start on my long standing Scott Thompson modded Technics SL-1600MK2 turntable and the tonearm moved straight across the record and plopped itself down near the spindle.

I caught it quick enough. While holding the headshell lift, i hit "stop". It kept pushing back and clicking. Turned it OFF and it STILL clicked all the way back to the rest.

Tried it with the stylus protector down (Shure V15 MKIII) and a crappy record. It seemed to work again, but it would yelp out a click close to setting the tonearm down on the rest. the arm would momentarily stop moving when clicking.
The auto lift rubber O ring is not even a year old. It was easy enough for me to install myself.

Something tells me it has a cracked gear. like this one:
https://www.ebay.com/itm/323707146252?i ... R8bpnZDrYw

IMPORTANT: Scott has since retired and moved out of state... he did just e-mail me, saying the above gear is not exactly right and would have to be modified a bit to fit. does anyone know of the EXACT replacement gear? should i have one 3D printed?

i know this forum is literally called "do it yourself", but is anyone in the san francisco bay area willing to do the job? i'd pay you, obviously.

Regards,
Robby

Hi for sale are two of Alan Wrights books. Asking $30 for Super Cables book (3rd addition) and Tube Preamp Cook book (2nd addition) asking $45. Or both for $70 plus $7.00 for shipping US only please. Some pages Super Cable book are underlined and Tube Pre Amp book has loose page but all pages are there.

hello to the whole group.
is it possible to use the electronics of a cd player as a DAC?
let me explain: I have an old Philips player that no longer reads CDs so I would like to use its DAC (2xTDA 1540) as a DAC for my system.
2 or 3 selectable inputs (optical and coaxial).
possible or impossible?
Thanks in advance.

I need to replace a failing Sanyo SFP1 6/6 in an Audiomeca Kreatura CD transport.

I cannot find a direct replacement anywhere but some vendors are advertising the SF90 as being cross compatible.

Can anyone here confirm?

Hello All...

I need Black Gate N series 1uf 50V. Please message me if you have one.

Thanks

Avr 5805

Anybody out there who is able to help with a question on the Denon
AVR 5805?
Last weekend the unit suddenly stopped output to the speakers.
The part of the movie being watched was not even overly loud.
For several reasons i can not afford right now to bring the unit to
a repair center, plus every time it ends up costing about $ 600.00 .
So i got the repair manual and started to check it out.
I found that the main transformer (which runs the output amps) did not get any power. The power to it is controlled by a relay. The logic circuit controlling the relay have several inputs. Two of these signals are called "POWER" and the second one is called "AC_P.DOWN". The later seems to be used to shut things down.
Does anybody know under what circumstances that signal will be send out?

Thanks Gernot javascript:smilie('😀')

For sale 2 pieces of SiderealKaps Premium Audio Grade Capacitors. 5.0 microfarad +/- 10% 200 V.
Used but fully functional (burnt-in 😉).
15 EUR + postage. EU buyer preferred due to customs.

I have a diy store universal power supply that I built for my aleph j. It was the first thing I built for this diy hobby. I haven’t had any issues with it, I just wanted to try something else. I would love it to go to another diy’er. No strings attached, no guarantees, US shipping only, totally free.

Im on search for a pair or 4 pieces empty or completed boards of chipamp aka gainclone with Lm3875 or Lm3886.Maybe some boards from Brian GT(chipamp.com) or some other good boards maybe some Neurocrome Lm3886 (doit right)......
If you have some for sale plese contact me.😉

I want to start by saying thanks for those who responded.

I’m attempting to build my first speaker setup. I have chose the TDA7850 IC due to its simplicity and have concerns about multiple audios sources.

I’m planning on adding a Bluetooth module, 3.5mm jack, and an iPod connector since I have it lying around.

My question is how do I handle the different audio voltages. For instance if I feed the 3.5mm input and have the volume set at a particular level, when connecting Bluetooth wouldn’t the volume level change if it has lower or higher input voltages?

How would I handle this? I’ve stumbled across Automatic Gain Control so would this be a viable option? Or does anyone else have a recommendation?

Hi,
I received a powered subwoofer for service.
It has an opamp input stage followed by collector output.
Kindly help me get the schematic.

This amplifier was damaged by shorted output leads.
Kindly help

Hello all...

I would like to make this project, but I don't know what to use as a bluetooth module with APTX LL

I have to have:
Blue socket - Black 3.5 mm jack cable (used to operate remote controls)
White RCA jack - White RCA cable
Red RCA jack - Red RCA cable
Black 3.5 mm jack - AUX port ( will turn everything else off)
Pink 3.5 mm jack - Microphone
Black DC jack - Black 12V DC power cord

a few questions, wanting to proceed using the BK8000L, I don't know where to connect the two wires from the blue socket for the steering wheel remote controls
it is appreciated to be able to program the bluetooth name how to do it?
Thanks

Translated with DeepL.com (free version)

Just found, maybe of interest:
Vorverstärker mit diskretem OpAmp und komplementärer Differenz-Eingangsstufe

A long time ago I purchased an MC cartridge from a seller on ebay - I forgot all about it until recently and then found it hidden away somewhere - I fitted it to my Pro-ject turntable (needed additional weight - I don't think that is optimal so further work to be done).

I can't find anything in my e-Bay purchase history and there aren't any identifying marks on the cartridge itself so I was hopeful that someone could chime in and tell me what it is.

Hi guys,
I am going to start a new project a subminiature Fender Champ clone, but with tone control (more similar with the 5F2).
Regarding the valves, the 12AX7 will be replaced by a 6N21B and the 6V6GT by a 6P30B-R. I like to use a pot on the cathode of the valve, so I can change the bias of the first stage. With the bypass cap, I won't loose signal level when I mess with the pot.

I've done a first schematic. Please tell me what do you think?

Cheers,
Pedro

Hi, I have a Velodyne Impact 12BG sub with a rattling cabinet. I'd like to make a folded horn cabinet for the driver and amp and was wondering if anyone has a starting point I can use?

I am not a designer, but am very good with wood working and minor electronics

Thanks in advance,

Why no such comparisons here? Too anxious about the results 🙂

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Around 05:00 is a nice mid-tempo sequence for testing!

Greetz - The ReSultanz of Zound

Still unbeaten til today :

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I ve googled around a bit, but did not find e.g. the monkey from Th.Loesch in PP anymore as the lnks are down...basically a DRD, but in PP. But besides this, any direct-coupled version would be interesting to compare...especially if you can comment the sound as you have build it !

Thx a lot

Is there a way to use a touchscreen monitor with Daphile without using another computer? I'm trying to build a music player (not server) and would like a all in one solution.
I might not have explained my question well enough. Nothing is wrong with the computer I have Daphile installed on. Daphile uses a web interface to control it. I want to use my touchscreen monitor to control it.

John

Hi all, been off the forum for awhile but slowly getting back into DIY, something that will enable that, is getting my main "family" friendly, commercial system to the point where I am mainly happy 🙂.

Looking to finish it with something for sale on Subito, but I have sofar been unsuccessful in getting an account. If someone has an account could you please pass on my contact details? Please pm me if able. Cheers.

I built a few different Pearl 3’s and wanted to try one with a VRDN in the same chassis with Wall Wart instead of the transformer and I was very happy with the result and built one the same way for a friend. This is a spare one I do not need.

Galaxy 1 U chassis
VRDN PSU set to 18V
16 Volt AC-AC Triad Wall Wart (with added ferrites)
Opa 1656 dual opamps
Closely matched resistors and Caps on both Pearl boards.
Xlr and SE outputs

Asking $425 with free ship anywhere in the continental US.

FS Twisted pair Audio Metronome ASRC new in box

Again from Job lot, don't know what it's for but here's the link to the products webpage


http://www.twistedpearaudio.com/digital/metronome.aspx


£25 plus shipping at cost anywhere

I'm redesigning my system starting with speakers. I have just purchased a set of black Rogers LS5/9 stand mount speakers which will be on 600mm custom stands. I know having these on high stands will effect the lower frequency. I'm thinking they will roll off around 80Hz. The plan is to build two passive enclosures running a set of classic AD12100W8 12 inch Philips drivers per box, one each channel that will be placed horizontal behind the Rogers against the wall that will cross from around 120Hz but run the Rogers at their full frequency response. I want to achieve these to go down to around 30Hz. The room has terrible bass response reason why I want to go this way.

Has anyone gone in this root?

I have 1,5 of these boards. And yes, the LM394 is intact. And lots of other components.

$150 + shipping at cost.

R

Hello there,
I have noticed the ever increasing use of 'simulation software', with both success and problems.
I would like to hear peoples thoughts & opinions.
EG. Are cheap USB microphones really up to task?

I can cast music from my mobile to the Chromecast Audio device using the Google Home app on Android (for connecting) and BubbleUPnP (for the actual streaming). However this doesn't work for Youtube. Strange thing is that I can send Youtube picture and sound to my TV as screen mirroring.
Digging in the net it seems others have the same incompatibility issue between Youtube and Chromecast Audio.
(Chromecast Audio is not the same as Chromecast. It has a 24-bit 96 kHz DAC and analog L/R outputs, while Chromecast has no DAC but has HDMI output).
Has anybody any working solution?

Do we really need fancy bias schemes other than a simple voltage divider with two resistors and a bjt mounted on heatsink? Do we even need a capacitor across the voltage divider? The answer from my side for both questions is no, but it depends. Whats yours?

For reference here are three schemes
https://pcbwayfile.s3.us-west-2.amazonaws.com/web/24/04/06/2151267095210.png
https://pcbwayfile.s3.us-west-2.amazonaws.com/web/24/04/11/2340230765654.png
https://pcbwayfile.s3.us-west-2.amazonaws.com/web/24/04/10/0433204760624.png

Hi guys

So a few years ago I picked up a pair of Decware ZKIT-1 2 channel amp kits that I got about 80% finished before sitting on a shelf for the next 3 years. I have some time off work and decided that I wanted to try and finish them.

I have one amp fully assembled and wired in a state good enough to test. Unfortunately it does not turn on, the tubes do not light up. I've checked all my component values and all seems correct. The manual lists a few points to measure, points A and B both measure 430VDC, they're supposed to be 346V and 309V. The other points all measure zero. I have very little circuit troubleshooting knowledge and I'm sure I've missed something dumb, so I'm trying to learn.

I have attached the circuit diagram and my measurements. Any help is very appreciated.

This past weekend, I placed an order for a small part with Gary from his VOM site.
Never had any issues for years with him.
However, it's the USPS that I'm disgusted with.....
From Gary in Michigan to my place in Philly Pa.....it's not a huge distance, yet.... Tracking says my package is now in....
SAN DIEGO?

Getting to the end stages of building 10p Pensils and am going to veneer. Question for those who have done this before: am I better off 1) leaving the edges square and veneering the sides and front separately or 2) rounding the edges and veneering the sides and front with one large veneer sheet?
Thank yiu

I am considering the following teflon caps for the 50/500 portion of the RIAA network. Does anyone have any experience with these or lower values?

https://solen.ca/en/products/solen-...ors-s3q330n-0_33uf-1000v-teflon-film-tin-foil

hi i have a system one w120 where the transformer blew yesterday on, the transformer is 5 pin and the only to go of is the model and some specs which i do not get any hit on google on. ive attached a pic of the transformer.

Deleted

Hello there,

I have a set of speakers I intended to use in a DIY project - each has one 8 ohm 20 watt and the tweeter with 8 ohm 10 watt (or would that qualify more as a mid? I don't know 🙂. But, I haven't got the idea on how to connect them, and if if I need a crossover or a resistor between them. I've looked inside some older speaker and saw the tweeter/mid is connected to the woofer from the right and left, and on the right side there was a resistor. Any advice is welcome and please be patient with me 🙂

Thank you!

Hi All,
Through the years I know most power tube makes but picking a box up from flea market, who made this version of 6550 with a pellet getter. Is it Sovtek or another ? There is not an origin mark or clue on the glass, but certainally Russian origin. The ones I tried on the jig varied enormously. I hate tosay this, but they seem like redressed 6L6 variants, as anodes start glowing at 30W.

Any ideas ?

Bench Baron

Hi all!



So I just purchased a new denon 6700h. I will be upgrading from a 5.1 setup using a denon 1600h.



The denon 6700h as 11 channel. I plan on going with Auro3d speaker placement (or the placement that you can use for atmos, Auro3d and dts x)



I plan on using the Auro3d speaker placement. (Or the one that you can use atmos, Auro3d and dts-x)



Currently I have CSS Audio Criton as my left, center and right and paradigm ADP-190. I really love the adp-190 because as my couch is right on the back wall, the adp-190 diffuse more the sound behind us instead of screaming in our ears.



I’m the next couple of months, we will be moving.



I need to build 6 speaker. + 2 to be replacing the adp-190, as I’ve heard there not very good for surround when having the correct distance between you and the speaker, which I will have in my next set up.



So, I started talking to a friend of mine, and he ended up giving me 7 eminence alpha 4-8, and 2 in ceiling mica 8 inch. (I already have 4 other mica bought a couple years ago and ended up never using installing them.



My question are:



1- would I be better to build boxes for the mica and to use as my surround and heights? Can’t remember where, but I’ve read that it’s not a good thing and in ceiling speaker are not meant to have a box.



2- if building for emicence alpha 4, there’s 3 option I’m thinking.

2.1- building a regular, prism, sodden box.

2.2- going with the sonotube / 3D printed angled bracket.

(https://www.avsforum.com/threads/diy-cylindrical-angled-atmos-speaker-enclosures.3255712/)

(https://www.avsforum.com/threads/cr...rsl-c32e-in-ceiling-speakers.3293578/#replies)



2.3-

Speaking with my friend about the sonotube version, and that it’s not a good thing having a cylindrical (circle) baffle has it has lots of diffraction. So I suggested I could 3d print a half-sphere to go over and install the driver. Then he suggested that I print a bower will in shape:






So with the proved eminence drawing tonight I tried to model the 3d printed “bower wilking” enclosure.





(Since those pictures, I rounded the corner inside the speaker, back wall and port)

Volume and port diameter and length is provided by eminence.
(https://cdn.shopify.com/s/files/1/0270/8665/1462/files/Alpha_4_8_cab.pdf)
See page 10


I want the build to be “quick” . I don’t want to spent all my free time making boxes for those speaker, but I want the best sound possible. Going 3D printed route would allow me to start the printer and do other things. When all pieces are done printing, I could glue them, install driver and binding post and call it a day. When I have more free time, I could sand them and paint them.



If going wooden box, I feel like I would need to spend “a lot” of time doing cuts and assembling, also, I could not finish the box, but I feel like they would be uglier unfinished mdf box and 3d prints.





What you guys think?

What about the bower will in shape?



Let’s talk!

I’ll add pictures after posting, the website on my cell phone doesn’t let me upload picture?

3-4 years ago I bought this 35 watt amp kit.

https://store.qkits.com/electronic-kits/audio-kits/35w-mono-power-amplifier-kit.html

The circuit shown is stock except the filter caps.



I wasn't satisfied with it just barely doing 35 watts and the heatsinks getting real hot, so with the help of a solid state amp builders group on Facebook I modded it to produce 93 watts into 4 ohms.

I used one of the Legacy car audio amps that cram a maybe 30WPC or less amp into a thick rather large aluminum chassis with VU meters and a fan that due to the chassis design didn't blow air out of the chassis.

One amp channel installed.



Part of heatsink cut so that the fan would actually blow air out of the chassis.




Here's the modified amplifier.

The filter caps are 20,000uF not 40,000uF. I know there's some things that aren't exactly right.

The interesting thing about thick film resistors is when they get overloaded they simply go open circuit which is what happened to the amp when I was testing it at full output. Speaker leads briefly shorted and all four thick film 50 watt emitter resistors went open circuit.




Question is do I keep this amp and build a second channel or do I go with this 100 watt kit amp?

https://store.qkits.com/electronic-kits/audio-kits/100-watt-mono-power-amplifier-kit.html

Schematic

http://www.funnykit.co.kr/bemarket/shin/menual/fk666.pdf

Two issues.

1. The amp requires +/- 50V versus the +/- 35V the current amp uses.
2. Only one pair of output transistors are used.

I purchased this Onkyo M504 a few years ago and recently it just powered off, no sound and nothing to the meters. When I opened the amp the top fuse on the board attached as pic 1 noted a blown fuse, I searched this site and found several posts regarding a faulty switch might be the cause of the blown fuse, I replaced the switch, attached the wiring and original snubbers to the new switch, placed a new fuse in. When engaging the new switch, the VU meter lights came on, but within a few seconds the same fuse blew again. I am far from technician level, and it has been a long time since I built a couple of Heathkit amps, so my experience is old and limited for sure, but this amp seems pretty straight forward and I am in hopes it is something I might can repair.
From looking at the wiring, it appears the board that the fuses sit on has connections from the power switch, grey and brown wires which connect to posts at each fuse location, the AC power cable has conections to both sides and the accessory AC outlook on the rear of the amp does the same. Then from that circuit board yellow and white wires go from each fuse side to the two transformers.
I would presume with the wiring and the fuse location that the issue is prior to the transformer stage and if not the switch causing the fault, is it the AC power cord, or something else?
The solder joints look to be OK, and none are loose. There is no apparent or noticeable damage to the circuit board. Any help is greatly appreciated, I do love this amp, I have other options to run, but I do want this one back to working order. Thanks in advance

Hi!
I have this DMC-80 on the bench with a hum problem. I usually only do hifi gear but as I know the person I wanted to give it a try. The filter caps were in pretty bad shape so I replaced them but as the hum is 50Hz this didn't fix it. When I plug something in the line in the hum disappears so I'm thinking it's in the drive/tone stage. Turning up the volume does increase the hum somewhat. I did check for cold solder joints but didn't find any, removing safety ground (just for testing) doesn't improve things either.

Logitech has just announced that they are shutting down MySqueezebox.com next month. Their players can still work with a local music library but they won't be able to access streaming services.

I'm curious if someone in the community will come up with a workaround for the different services.

As much of a bummer for users of their streamers, it is impressive that they kept it running for over 11 years after they stopped making the streamers.

To all my Mexican friends, on this day of celebration. May 5, 1862, the day the Mexicans repelled the French in the city of Puebla. It was the last time a nation from off the continent invaded the Americas.

We will be celebrating with traditional dishes and garb, (no, not tacos) music and dance and remembering how lucky we are no matter our current conditions. I hope you do the same.

Buenos dias, buenos noches.

Hello,

I have 3 brand new, spare preamp boards left over from a recent project. You can find out more about the board in my thread here as it profiles my new build. The detailed features and more pictures are included in the thread. Here are pictures of the new double-sided board.



The pre boards are professionally made and are fully populated with SMDs from the factory (JCLPCB), except for 9 devices that were not available for fabrication. These 9 devices (SMDs) will be supplied (unsoldered) with the board. In addition to the populated boards, there are several through hole parts that will be needed to complete a functioning preamp. That parts list will be supplied with the board, and as of today, are priced in total, at around $75USD at Mouser.

I'm asking $125 for each board including the 9 SMD devices, plus postage ($12) to anywhere in the continental US.

PM me more details if interested, or have any questions.

Thanks for looking,

Rick

My house insurance carrier has offered me a free power monitoring service including $1000.00 damage coverage due to electrical faults.

The service is provided by Ting Labs .

I get a weekly event summary, daily graphs of voltage variations as seen by the monitoring service.

Does anyone else have this?

Thoughts on it?

Where do I pick up the pre-amp output?
Is it just the same as the headphone out?
Thanks…

I just tried to attach a Word file .docx to a post in the PM area and it was refused as not allowed.
Changing it to a .doc file (Word 2003 or something) made it acceptable.
I don't know if the same goes for regular posts, but it should be possible to attach .docx files I believe.

Jan

Hi everyone,
I am the original owner of a Philips CD101, which I have owned for approx. 37 years. All these years the player worked great and I love its sound.
Recently the player refused to turn on. Reading about similar issues on this and other forums, I understood this is a common issue due to old capacitors drying out.
I have reasonable experience repairing electronics, so I thought I could do this myself. I bought this recapping kit: Philips CD 100+101 Player Power Supply Electrolytic Capacitors Vishay Power Supply recap recapping Kit | eBay, unsoldered each capacitor separately and replaced with the corresponding capacitor from the kit, while observing the polarity.
When I plugged the player back in, the LED's flickered on and off and the player made some strange sounds. When I carefully checked the board with a magnifying glass, I found several "cold joints", especially around the power supply transistors, so I resoldered those joints.
When I plugged the player back in, the LED's came on and stayed on. I inserted a CD and pressed "Play" but the CD did not turn. I tried several times, until I saw smoke coming out through the top of the player, in the back, approx. mid-way. I immediately turned the player off, unplugged, opened it up again, and found that capacitor no. 2291 (100 uF) had popped.
After unsoldering, I checked its polarity and found it was incorrect. I must have made a mistake when replacing this capacitor.
Not having another new one on hand, I replaced it with the old one (I do not have a way to check whether its value has deteriorated but the old capacitor does still seem functional). I tried the player, and now it comes on properly, but the CD still doesn't turn. I permanently shorted the contacts of the CD door to check that this wasn't the issue, and indeed, even with the door contacts shorted the CD doesn't turn. I was able to observe the laser assembly moving back and forth and up and down, attempting to focus. And when I power off the player, the CD turns a little bit, as it used to, so the motor is apparently working.
What could be the issue? Any help would be very much appreciated.

Hello guys, i have an amplifier D class Impact that have as a driver board DLM4000a, i have checked everything on this board but without results, no swithicng impulses, I have already desoldered IRS2113 but it's not a problem i have no input signal to this IC. Audio input arrive to pin 9 of DLI4060b and after i don't understand what formed signal to HEF4001BT? Anybody could help to me? Thank you in advance

Anybody with a Counterpoint SA 5.1 for sale? Please send me a PM if you're thinking to selle one!

Hello,
I was wondering if anybody knew of a great 300B design that uses the D3a as the driver. I have searched this forum and eleswhere but I continue to only come up with a DRD topology.

I recently sourced all the parts to build the JEL 300B and bought an extra set of OPTs from James (6123HS). I was toying with the idea of using this D3a in a 2A3 project I am completing but went a different direction with that one. In the process I picked up 4 of the Siemens D3a drivers and now I am thinking I might try them in a 2 stage D3a/300B amp since I have the parts (some of them at least).

Any suggestions for some designs? I wanted to stay away from the DRD designs b/c my power transformer selection I have won't get me the voltages I see with most of these designs.

Thanks,
Jeff

Triggered by the frequent criticism from gr-research of the simple two-way loudspeakers, especially the standard hi-fi floorstanding speakers from Klipsch, I took a pair of old RF15s from the cellar and put them on the measuring table.

That was some time ago now.

After a lot of back and forth, I decided to follow Danny's general recommendations. I designed several concepts of potential crossovers/filters. From the two-way system to the three-way to the two-and-a-half system, everything was included.

Everything was recorded using measurement technology; I use CLIO and both a Dayton and a well-known Bayerdynamic measurement microphone. The entire program was used as methods: ground plane, tripod, various excitations, distances, just the normal madness -> measurements in a low-reflection room/chamber (RAR) would also have been possible.


The HT with its horn differed a lot from the two speakers, let's get this out of the way right away. This difference in SPL was clearly audible later with the new crossovers.

(...)

Selling 3 pcs Uni-Q drivers from the original Kef Blade.

This is a very rare find for anyone interested in making their own DIY speaker of probably the best engineered coax driver on the planet (except blade/ref meta uni-q)

Used roughly 3 years in a dedicated listening room. (active system, with security capacitor on the tweeters)
Rest of the time it was stored dry and safe.

Two of them are 10 years old, and 1 of them is 6 years old.

One of them has a slight dent as can seen in pictures, which i did not notice whether in measurements or listening.
Besides that they are in good working condition.

Asking 1500 USD / 1400 EUR + shipping for all three drivers.

If anyone needs only 2, they will need to buy all three


.

Building Elvee's Circlophone: Documentation, Parts, Accessories, & beginner friendly

Intro
Circlophone is a new topology (a more efficient Class A, dynamic class AA), with a live sound character and an easy build. These are fun!

♦ The Original, optimized Circlophone
♦ The Germanium Circlophone
♦ Inverted Jfet Circlophone

Sample schematic:


Parts options
♦ Q9, Q11 Driver: KSA1220, 2SA1930, 2SA1837, 2SA968, 2SB649, Philips/Harris BD140, and ST's BD140.
♦ Q5, Q6 VAS (cob 4pF~16pF): 2SC5171, 2N3019, 2SC3421, 2N1893, MosFet; Or if < 5pf like 2SC2911, BF819, add this cap.
♦ Q12, Q13 Sensor: BC546B on 25+25vdc rails, With higher voltage use KSC1845, 2SC1845, 2SC2240, 2SC2705 or 2N5551.
♦ Q4, Q3 Input: A Philips/NXP BC556B (post 7) is on the original, or nicely HFE matched BC556C or BC560C with a multimeter.
♦ Q8, Q10 Output: MJE3055, BD249C, MJ802, MJL21194, MJW21196, MJ21194, MJ15022, MJ15024, MJ15003 or the classics.
♦ D4, D5: Low voltage drop and high current handling is important, like 5a, 7a (MBR735), 10a (MBR1035) Shottky diodes.
♦ D8, D9: see convenient sizing chart.
♦ D7: BAT type "Signal Schottky" like a BAT86, BAS86, BAT85 or BAT54, available at Mouser & RS. Or there is an alternative.
♦ R21: "The value in KΩ ~ = 0.9 times the total AC supply" Or review Elvee's selection guide. Or, see convenient sizing chart.
Build specific:
♦ VAS on Piersma's Circlophone CFP build can be Sanyo 2SC2911 or 2SC3955, or similar specs.
♦ Terrangima's Darlington & MOSFET Circlophone has its own devices listed on the schematic--See post#226.

Notes
♦ Discussion of topology and modifications: Circlophone discussion thread
♦ Various brands of 2N5551, 2N5401: Quality Control--check the HFE
♦ Various brands of 2SB649, Quality Control: Click Here
♦ If using faster output devices, click here and install C11.
♦ Other parts selection questions? Here is a link to Elvee's build notes.
♦ Checking R21, Elvee said: "Measure the voltage, divide by the resistor value, if it's 1.5mA +/-50%, it's OK"
♦ While you're measuring, it is also easy to check the idle current.
♦ Elvee's LTSpice Circlophone simulation file for the original Circophone.
♦ For an example parts list, aka BOM (Bill of Materials): Click here.

Accessories
♦ A Jfet buffer isn't mandatory but if you want one for constant input impedance, click here.
♦ To solve offset bounce versus power issues, Elvee has published an optional offset trimmer circuit.
♦ Circlophone has Class A sound but if your sound is too mellow there's compensation in the LTP soft clipper.
♦ If you have efficient speakers in combination with big gain for big dynamics, you might want a limiter to stop x-max.
♦ Circlophone has very simple power supply requirements so regulated is unnecessary, but if you wanted regulated click here.
♦ To block thumps from single rail sources (computer) power up, and block some RF too since it is slightly capacitive, look at this.
♦ Circlophones go in the house, at work AND: Boostor, a companion for a Circlophone on the move, rock the the car, RV and boat too!

Hello. I have a problem with this machine, while I think about writing the query I think that maybe I have the answer in front of me, but I don't know. I changed all the belts (4 in total) and pinch roller, I adjusted the speed with a cassette with a recorded 3KHZ signal and after about 10 minutes the speed began to decrease until it reached about 150Hz less (2850Hz), I replaced several motors, all with internal speed regulation (I clarify that they are not new motors) and the symptom is exactly the same without differences between them, the supply voltage is fine in absolute value and ripple (unregulated voltage), all the parts that rotate do so with Total smoothness, the consumption of the motor without cassette is about 90mA (the motor always rotates when turning on the machine) and rises to about 130mA by dragging the tape. As an additional detail, if I adjust the speed as soon as I turn on the machine, and leave it with the motor running for a while but without the cassette, the result is the same, that is, the speed decreases. I also tried cooling parts with freezing spray without success. Everything seems to indicate that the motor is the problem, but do all the ones I tried do the same thing? Am I missing something? Thank you so much.

Hi

I just got hold of a 15 steps Plessey make before break rotary switch and intend to use it as a stepped potentiometer for volume control of my passive pre-amp.

I am seeking advice on the resistor value required.

Using the HiFi Collective 50K Shunt 46 steps as a guide, I decided to skip every 2 steps on their 46 steps, and used the remaining for mine. Is this the correct way?

(Number rounded)

1 - 0R
2 - 18R
3 - 50R
4 - 100R
5 - 200R
6 - 400R
7 - 800R
8 - 1K5
9 - 3K
10 - 7K
11 - 11K
12 - 17K
13 - 27K
14 - 50K
15 - 121K

Thanks!

Hello Forum Members,
Looking for advice for future reference. I recently drilled a 3/4 inch (19mm) hole through a 10mm modushop aluminum front panel. Unfortunately the bit chattered terribly giving me an adequate but not perfect hole. (Rough edges).
I am assuming my main mistake was not having my work clamped down tightly. The trailing edge of my panel rested against the pedestal of the drill press so the work couldn't catch and spin, but the bit did chatter.
I used a decent drill press, decent (and expensive) cobalt bit, and aluminum cutting fluid. I had previously drilled a 3/8 inch pilot hole.
Next time I will clamp my work. Any other pointers? Thank you for helping out a construction novice.

For local delivery only. Seattle
Frugal horn Mk 3 built from Flat pack. Includes FE126eN and also mark audio drivers (can't remember what model). Also includes the outrigger and removable baffle for driver swaps. Seldom used and time to pass on to someone.
$200.

Hi, have been hunting high and low trying to obtain a service manual for a Denon PMA-255UK amplifier, circa early '90's, without success.

Appreciate any help anyone might have.

Yes I have tried searching the internet! 😉

I've been looking at ways to get output powers above 20W or so (the output of my TDA8932 implementation) for quite some time now and last week was getting quite close with my idea of stacking TDA1566 amps (putting them in series with isolated PSUs). The TDA1566 has the great feature of being able to drive down to 1R loads in mono mode which means it has a very generous output current capability. But several of my prototype builds of TDA1566 failed unexpectedly (before I even got to stack them) so I've become suspicious of the quality of chips I have been getting. The TDA1566s from Taobao are new, not recycled so I'm veering towards the conclusion of them being sub-par devices.

The other very nice feature of TDA1566 is it has a low-gain mode (16dB) with impressively low output noise (~22uV). No other chipamp I've seen delivers such low output noise, mostly because they don't have the capability to run such a low gain. Enter TDA1521, its unique in NXP's chipamp line-up in that there is the apparent capability to run it at a lower gain than stock (30dB) but how low it can go before it goes unstable is anyone's guess. Hence this project in which I hope to uncover how low it can be pushed. The ability to trim the gain channel by channel opens up the possibility of running these devices in parallel - to minimize cross-conduction the gains of the parallel elements do need to be very closely matched, much better than the DS gain variability (0.2dB typical).



Here's the internal structure of the 1521, only one channel shown. The unusual feature here is that 'INV1' pin is brought out of the package rather than being returned directly to AC GND on-chip. Which means some extra series resistance can be added which will have the effect of lowering the gain. The resistors on-chip are not close tolerance so the 680R and 20k could be anywhere within 30% or so of their nominal value which means the external R needed for a particular gain will have quite a wide range of possible values. Therefore I'm going to use a multiturn trimpot to realize that. My initial target is to get down to 20dB gain and see if that's still sufficiently stable....

This unit has one damaged channel. U1 is a IRS20124S. Is there something else I can use without needing to replace them in every channel? Also, D32 has JS written on it. Not sure what that part is. Q21 says 2Q and Q22 says W1A? I have to go out but will try to look up the 3 in the code book later or tomorrow. Biggest issue currently is the IRS20124S. I got the output transistors.

Thanks in advance!

Pics coming in a minute 🙂

hi, based on these graphs what frequency of xo would you use for the crossover? Thank you

No burns seen on boards. Solders look passable. Any quick and easy checks? I am electronics novice.

I'm designing a 3-way box, and for the 4" speaker (which will be the mid-range speaker in the box) I will use a full range with crossover, and I would like this specific speaker to be in a sealed box, so how can I design a sealed box for a mid-range speaker?
I will use a GHXamp speaker from Aliexpress for this project
I was thinking about using WinISD to do it, but I have my doubts...

I was thinking about using WinISD to do it, but I have my doubts...

This power supply features DDDAC boards, twin transformers, 4 x Llundahl chokes amongst other things, all in its own chassis with umbilical connection to supply a separate DAC. This PS is designed to power a dual stack ie one multi-DAC board stack per channel.
Ideally I would like to sell this PS as it is. if you are interested in buying it then let me know and we can discuss the price.

If no-one is interested in buying it as it stands then I shall take it apart and sell the parts: