I've been using a Raspi as my source for a while now. Had a DAC HAT earlier, then got a Allo digione. Then added a Soekris. The Bahringer DEQ2496 made it's entry a bit later, all of which is to say that I ended up with a medley of boxes and wires - which made sense only to me. Zero WAF, to be honest, it was zero Anybody Acceptance Factor.
So, earlier this year, I decided to put everything into a cabinet. In addition, had seen some streaming source solutions, and thought their LCD screens displaying album art looked very attractive. I think there are special albums released with amazing album art just to make these products look good......

So here is all that needed to fit into the cabinet:

• Raspi + Allo digione
• Soekris R2R DAC
• Soekris I/O board (Normunds) with source selector and LED indicators
• PGA2311 volume control board with analog input selector and volume control
• 1 power supply for the analog board (just transformer)
• 1 power supply for the Soekris (DiyInHK)
• 1 power supply for the Raspi+Soekris I/O board + LCD (Sigma 11)

I also wanted to be able to shutdown the RPi gracefully when the front panel power switch was pressed. So I incorporated a delay circuit that maintains power to the RPi for 1 1/2 minutes, when power to the rest of the boards are turned off - the loss of power also triggers a GPIO shutdown in the Pi.
The Pi runs picoreplayer + LMS + squeezelite + jivelite. LCD is Waveshare 5" touchscreen.

End result below

I began clean out my storage contain and discovered many items that I forgot I had. So much for being in audio since the 1970's LOL. I found a PS Model 1 with an attached note that indicated it needed love. When I asked Paul about this a few years ago, I got his standard " I cannot remember". I guess it will be the same with the Model 2's and 200c that I also discovered. Hey, I lived through the 70's as well, and can actually remember what I did back then LOL...

I like DACs powered directly from USB in small case/design and I like sound based on R-2R. This was reason why this toy was created.

Here in gallery are pictures: DAC gallery

Once again small description:

• NOS R-2R AD1862 DAC
• LINE-out direct from I/V
• headphone out based on TPA6120A2 with potentiometer, easily drives big headphones with a lot of power (AKG K701)
• no additional filters (only RC)
• no caps in series with signal line
• switch between line or headphones (no need unplug something when I choose between headphones or amp), with relays
• for USB/I2S conversion is used PCM2706 (on board are also pins for another I2S), simplicity, no additional drivers, I like Plug&Play and I am listening mostly in 16bits
• power from usb is converted with isolated DC-DC DCP0205xx, regulated to +-5V for digital and AD1862 digital, +-12V for AD1862 analog and I/V, +-5V for headphones amp TPA6120A2
• it can handle custom I/V boards in small design, +-12V
• 4 layers board

I am not sure if it is DIY project, becase it is full of small 0805 SMD parts and few SMD ICs, board is 4-layers

Some build hints:

• first mount USB/i2s part and test with scope if some data signals are going out from i2s
• continue with power supply part and test, if all voltages are right
• dont forget for thermal pad holes
• mount DAC portion with relay, switch and I/V
• connect it to PC and measure with scope if sine is right (or test sound directly), because in this state it must working
• if all is right, mount headphones amp part, better if you buy 3 potentetiometers and measure them for resistance offset (left and right) in few places and choose best one (with lowest offset), dont forget carefully solder TPA6120 through thermal pad hole
• connect it to PC and measure dc offset on headphones connector, it must be small offset, about few mV
• if you wish, you can clean board from solder resin using isopropyl alcohol
• I used SMD thick resistors
• as I/V opamp choose something good, like LM6171, LME49990, ADA4898-1, and many others ...
• if you use external USB/I2S (for example asynchronous XMOS) resistors R6, R7, R8 can be disconnected and also PCM2706 power jumper opened ... on board are pins for I2S https://ctrlv.cz/shots/2017/09/19/DGlu.png
• output voltages can be easily set with change in feedback resistors R9,R10, or for headphones in gain R17+R18, R21+R22
• when you use fast I/V opamp, like AD844, only to be sure - check output for oscillations, I have no oscillations
• only to mention, here is no headphones protection circuit, so after every change in I/V measure headphones output if there is not big DC offset, must be few mV
• in normal condition, there is no clunking in headphones when switch position is changed or device is disconnected
• use linear potentiometer (if there is a link for logarithmic, use linear)

I need thanks to pavouk.org site from where I got I2S/PCM logic and thanks to Dohny for hint about DCP0205xx DC-DC.

Hi - I'm considering using an existing chassis for a new build. With the valve holes already cut I need to consider using a 9-pin noval double triode as driver or driver/phase splitter for a 6AS7 to provide a PP output. I would normally use a 6SN7, however that's an octal base big valve. I've read that an E88CC is a sort of 6SN7 equivalent but would love to hear suggestions, especially from people who've done this.

Final question, is a 6SN7 a good choice for the pre-amp stage? I would look to use a single 6SN7 to provide L and R channel pre-amp, to then feed the noval phase splitter/driver, in turn driving a single 6AS7 for a PP configuration.

I know it all sounds a bit a$$-backwards, hence some sanity checking.

Thanks in advance!

I like this stuff, but what Id like to know and havent been able to find out, is whether it sticks to PVA glue?

Ive got some cabinets to paint which have been previously stained. I dont really want to go down the route of sanding off all the wood stain if warnex wont stick to it. I have a suspicion it may not (just to be annoying) since it's definitely a bit funny about sticking to the wood filler I've been using.

I either have to PVA the cabinet first and then paint with warnex, or I have to sand the entire thing first and then paint. I'd rather go down the PVA route since sanding is tedious but if warnex is funny about sticking to PVA I may be forced to sand them.

All,
I am planning to build Eli Duttman's Phono Preamp, which is, as I understand it, an update and modification of the classic RCA phono preamp. I already have many of the parts from when I purchased parts to build RJM's 6dj8 phono (does everyone else always buy a few extras?), but I have a few questions before putting in a final order. I would be grateful for any advice and help in clarifying:

• Are there any suitable substitutes for the ZVN0545A Mosfet? I'm not seeing any in stock at Mouser, Digikey, etc. I could search for alternate devices, but I just don't know what characteristics are necessary (polarity, Vds, Id, Vgs, etc.?)
• It looks to me like there are 2 coupling capacitors on the output -- one at 0.47uf and one at 5uf. Is that correct? I don't think I've seen that before. Could anyone help me understand why it's done this way in this amp?
• How critical are the values of 30uf of the capacitors connected to the B+? Would 32uf be ok? I see Parts Express has a cheap electrolytic can capacitor w/ two 32uf caps inside. Would that work? Is using a electrolytic here a bad idea? Also, would it be OK to use one of these capacitors on the cathodes of the first triode stages?
  • Generally, I'm not sure where and when to use the different types of capacitors (electrolytic, film, polypropylene, paper in oil, etc.) and where it makes sense to spend a bit more money. I would be grateful if anyone could point me in the direction of some useful readings on the matter. My initial searches didn't find much.

Thanks in advance for your help!
Best,
Dan

THD Out=5Vmax 10Vpp F=1.6KHz
------------------------------------------
Output ---- 0° - 0,000 004%
Output -- 90° - 0,000 011%
Output - 180° - 0,000 022%
Output - 270° - 0,000 011%

A like button, reactions, and/or other variations on the topic are a contentious and much discussed topic.

We presently have this functionality turned off, while we carefully review all the options and evidence and try to work out a way that the community can benefit from the introduction of something of this ilk that will result in a better community experience and make finding good content easier.

Hi all,

Recently I revisited a mini-aleph I put together years ago from a BrianGT set of boards. Anyway to cut a long story short, after a few bits of fixing up I was pretty amazed at how good the amp sounded. It got me thinking about what would a higher powered version sound like, and so I began on a journey of reading and finding the parts needed to build an Aleph 60. I managed to get a few BrianGT boards (thank you to those who searched their parts bins), plus the extra output boards and I have most parts now to assemble it. So there is a monumental amount of Aleph info out there, and its all jumbled in a million different threads, which makes it hard to find some answers - so I'm being cheeky and asking here some fairly basic questions which I'm hoping someone who has lived and breathed the aleph air can probably answer in their sleep:

1. I plan to build with 2 separate supplies in a 5U modushop chassis and bias it to stay just below 60degC.....
2. I have 2 of 2x25V 300va transformers lined up, and planned on using a pair of cap multipliers as supplies (planning on the mark johnson/prasi boards with 2sc5200/2sa1943 and the minimum possible voltage drop, about 2.5V I think to minimise dissipation). If the cap-mx doesn't work out, I have regular CRC boards I can use.
3. I think I can use the BrianGT mini-aleph boards with pretty much no changes on the main boards, and then just add the satellite boards populated with the matched mosfets (irf240) and 1r0 source resistors.

Does this sound correct to the experts here?

I decided to recap and install new binder posts in a pair of vintage Rectilinear speakers. I discovered one of the tweeter control potentiometers is shot (corrosion and evidence it overheated some time in the past).

I need help identifying appropriate replacements. While there is a lot of information on capacitor replacement, I am finding very little on this topic.

The current version appears to be 32 Ohm version. It's marked AM-3352 32Ω 137 7207 on the back. No indication or wattage. I assume it's an audio taper but, again, nothing obvious.

Finding no options available at 32 Ohms. Most start at 1K and progress to 5K, 10K, 100K, etc. 250K 500K seem typical for guitar tone controls. Closest I seem to be able to find new are either 25 or 100 Ohm in the 3 to 5 Watt range. I also have some old pots out of other speakers that measure at 16Ω, but no idea re watt limit.

I'm assuming I need audio taper and not linear taper, but don't seem to find any. How close do I need to be to the 32Ω of the original? How much impact will higher (100Ω) or lower (16Ω or 25Ω) values have on sound? Do I need to be concerned about Watts in this application. Are their other options/suggestions? Any recommended sources?

Im a noob and looking to build some growling bass horns for myself, hoping to bring some good vibes to the world as this covid thing lifts.

I used to have a double stack of martin 115B bass bins and matching tops.. Looking for that sound again in a modern smaller more efficient package.

Someone on speaker plans recomended the punisher mkII..But I cant seem to find a frequency response plot to back up the 50-200hz claims or to see how flat it is. Does anyone have this Frequncy respose plot data??


Does any one have more info on this design? Or can they direct me to the designer ? Is this design dependent on a high end expensive speaker to get the enclosure to preform? Seems like slim pickings on info....

Im also open to recommendations on other cabs that will bring that horn dub growl in a modern package

Thanks folks!

Good morning everyone ! Can you recommend a thd meter that has the same functions as the 2015 keithley from other brands?

Hello guys! I removed the input switch selector to clean it from a Cyrus One issue 07, and now if I have a source for example in aux and I switch to other sources it have sound but at a lower volume. Any ideeas? I took a picture before removing the switch
https://ibb.co/60h3fHc
https://ibb.co/z7xQrTM

Hi,

I'm thinking to dedicate one room as amp building/modding and rehersal, and I had an idea on how to place a pair of speakers to hear music.

Imagine one corner of the room and place a single wooden board at 45° with gaskets on its sides: isn't it a TL with triangular shape and the lenght of the floor-to-ceiling height? Will it work?

If it works, with straight walls it would be quite simple to be built.
With 90° walls and 45° baffle, the section of the "cabinet" will be the baffle width squared and divided by 4.

Ceiling is 273 cm, that it's a quarter wavelenght of 31 Hz, so that should be the Fs of the speaker, correct?

Is there a full range, cheap speaker that can fit the requirements?
It will be something I would like to play with during the winter, to be able to build it in 2022.

Thank you in advance,
Kind Regards

I have a Sony VFET built using the boards from the Store. I'm using SK60/SJ18 instead of the originals. Bias is .5A (half the amount of the original version). All is well and it's been working fine for about a year. It runs extremely cool. I've read a couple times that the K60/J18 like a 16 ohm load better. Most recently Nelson mentions this in the article for the upcoming VFET kits for this who already have VFETS. Should I consider some sort of modification to this amp to take advantage of this load characteristic?

I have decided not to have my designs made into PCBs in China. So I am looking for an alternative low cost source of PCB fabrication.

Cheers

Ian

Dear All,
I´m building a 3-way speaker with mid range and tweeter path based on seperate LM3886 (XO at 240 and 3700 Hz)
Would it make sense or do any good (stability, ...) to limit the bandwidth of the amps or is this even negative and better to run them in full range?
THX for any thoughts!
Best, Josef

Manual says to adjust at 1/4W output to 0.1% THD. I do have an analyser, but seems a flaky way to set bias.

Anyone here got some experiance with these? Perhaps a suggestion on an actual bias current...?

(tempted to set it for abour 25-30mA and assume it's in the ballpark)

Most information on distance has to do with air core inductors. The little information on iron core I've seen is conflicting, so I'm hoping for a consensus here.

Specifically, for an ERSE Super Q 2.7mH laminated iron core inductor and Altec 416 woofer with flux density of 11,000 gauss, what would the recommended distance be between them?

I'm a simple DIY'er with very limited electrical measuring tools, so thanks for the help.

Hi All,


I have a Carvin TS100 that I swapped over to JJ 6l6GC's and I'm using it with my Axe FX III guitar modeler.

I biased according to the instructions but at 50mA per side (there's 4 power tubes) it seems very cold.

I have 468vdc B+, so 50mA's is about 55% bias point.

I'm not sure why Carvin wants this so low and my only assumption is to prevent any distortion or addition coloring of sound.

So should the bias be set higher?

2nd question.....although there is nothing wrong with the current fan which is 80x80x25 dc24v, I'd like to find a replacement that's quieter, and has better cooling.

thanks,
dinky

Long story short, amp started pulsing the output loudly while I was listening to a podcast at low volume wired at 4 ohms.

took it to my test bench and found the ka7500 had a bad output, almost all irfp 064n's exploded along with the relative gate resistors, I replaced the ka7500 with an lm494, replaced the 064n's with 064npbf, replaced all gate and pulldown resistors, replaced all resistors in the drive buffer circuit and have changed buffer drivers from c3228/a1275 to bd139's and bd140's.

Upon testing with a variable power supply at 10v everything appears to work fine so far, however with a 4 ohm mid connected for testing there is a faint white noise coming from the output? it's loud enough that you can feel it with your hand on the speaker, could also hear it up to a foot away, The only thing that makes it louder or softer is voltage input, gain doesn't effect it, also
during power down there is also a fast 1 second audible sweep from high to low.

Scoping my variable supply doesn't show any noise, so I doubt it's that, idle current at 10v settles at 2a which seems a little high right? It goes up when I raise voltage.

All transistors input and output did not make any heat on the test bench, the only thing that got a little warm was the power supply transformers.

Anyways how would I go about finding the source of this white noise? It is rather annoying and I don't remember this amp doing that.

I'll try to post an audio file when I get home

Hope it's OK to post that here.

Im looking at one thats for sale on another site. I know they're really good, but have no clue on whats a fair price. It has the optical bias. I did some searching but a lot of the sales were from many years ago, so price probably changed.

Physically looks great.

This is an Extreme Low noise core, slim designed - compact transformer.
Potted winding with flux shield.
Can ship to International destinations.
Height - 4cm
Diameter - 12.5cm
Weight - 2.2kg
Price - $165

Specs sheet also attached with clear images
contact cpg@rfwaves.com.au for further information
Now in stock!

This is to redirect the following posts (15, 16 and 17) to prevent contaminating another thread.
https://www.diyaudio.com/community/threads/kicker-06-zx750-1.383505/post-6972814

Post with attachments:
https://www.diyaudio.com/community/threads/kicker-06-zx750-1.383505/post-6973521

The templates will help you compile notes in a fairly standardized way and will be valuable in future repairs as a reference. I generally just wrote the values and notes in by hand but doing so in the XLS spreadsheet file is better (especially if your handwriting is as bad as mine).

For those who don't have the Microsoft office suite, you can download (for free) Open Office.
https://www.openoffice.org/download/

To minimize the required hard drive space used. Only install the applications you need. 'Calc' is to read/produce spreadsheets. Writer is a text editor.
https://www.openoffice.org/download/

As for photos, everyone should be taking photos of the amps they're repairing. The photos are another great reference to find the values of missing and burned parts. The photos need to be of high enough resolution to read the values and markings of the parts. Take photos from multiple angles and pay special attention to driver boards. Attached is an example.

The text documents can be notes or key components that help me find all relevant files. This one only has 6n137 but if I want all files with information on amps that use the 6n137 (specific design), the text file (or any file that WIndows will read and cache) will be returned.

The .ods file attached is an editable template (remove values and rename). You'll need to make whatever works best for for you. At the bottom of the file, you can see a note about the ground. For some amps, you'll find that the primary and secondary grounds are not connected. For those, you can either move your ground probe/clip or install a jumper between them. This is just a reminder.

Musical frequencies as in music sounds very staticky ,garbled but I can tone generate up and down thru the frequencies and it sounds very clear and I don’t have the connex switches. I think I’m missing some components .c-13, c-14, R-32, R-33?
Thank you

03/20/22 Update- SOLD.

For sale: Adelphos Satori MTM Speaker Kit by Jeff Bagby, with Parts Express 1.0 cu ft curved cabinets in cherry finish. Featuring the Satori TW29R tweeter and MW16P midbass. I bought the full kit with upgraded, assembled crossovers from Meniscus Audio. And several extra feet of the Meniscus upgrade wire. Unfortunately I just have not gotten to assemble this and by now need to clear out space. It stalled at routing the baffle cutouts due to lower back issues (not getting any younger- sigh).

https://meniscusaudio.com/product/adelphos-mtm-speaker-kit/

The cabinets are these: https://www.parts-express.com/Dayton-Audio-MTMC-1.0BK-1.0-ft-MTM-Curved-Cabinet-Gloss-Bla-302-751

Looks like PE no longer does these in the cherry. I also used same (in black) for the Dr K MTM kit I built years ago. They're great for DIY IMO.

These kits start at $491.37 x 2 = $983 lately. As mentioned, mine is the full kit with crossover upgrades, extra wire, plus new curved cabinets in the original boxes.

-I'll do $695 for everything, includes Fedex shipping lower US 48.

Pictures of the actual stuff coming soon; meanwhile information at the link above and the project pdf attached.

The Dr K MTM is a great sounding speaker, if driven cleanly. It compares very favorably to the excellent Concept 500's I have, believe it or not. It was way too transparent for its own good in most cases though as the PE reference alum drivers were ruthlessly transparent. In similar fashion, I have no doubt the Satori MTM kit likely sounds excellent. Wish I could have heard it..

For those asking privately the speaker would be flat front, not slanted like the Kairos. It would look similar to the Dr K MTM in this link except of course Satori drivers and cherry cabs: http://projectgallery.parts-express.com/speaker-projects/dr-ks-mtm/

I was using the Dr K on a heavy duty wood stand of appropriate height made for me by Vapor Audio, if anyone remembers them 🙂 Speaking of, I guess those could go too. Not a good picture but there's the Dr K MTM on the Vapor stand, next to the C500 recently. And I have another set of wooden stands, nib and not assembled yet; can choose a custom height. Forgive the clutter please, I do N America service for a couple of high end audio companies lately and the audio setup is always in flux.

Thanks, T

Hei.
im trying to reverse engineering this black box preamp driver for elac speaker.
Its has 8 pins and has a predriver circuit.
I been cutting it out and tried identify all transistors and resistors and one cap.
my problem now is that's something is wrong, i got a circuit board mounted temporarily on a pcb with the components, but it draws way too much current, and its humming a lot.....
there could not be a major error, but i attach the spice model, to see if someone can maybe identify some errors. ?

as you see, in the spice file, i have made the box and outside its the rest of the circuit.
best regards Niklas.

Hi. My old Nad 314 has some channel problems, it seems the speaker relay needs changing. While I am at it, I was thinking to change all the electrolytic capacitors, the amp was sitting idle for about 8 years. There are 38 caps on Preamp + Power Amplifier which I am thinking to replace with caps of same voltage and capacitance, a mix of Elna Silmic II, Nichicon KA και Nichicon FG (I can’t find the same model for all on Mouser).

In the Power Supply there are 16 caps, many people suggest that bigger caps in V and uF are used, so I’m thinking of changing the originals with a mix of (available on Mouser) caps as below:

10V 22uF ---> 16V 27uF Nichicon PW
25V 10000uF ---> 35V 12000uF Cornell Dubilier
50V 100uF ---> 63V 120uF Nichicon HE
50V 10000uF ---> 63V 12000uF Cornell Dubilier
100V 4.7uF ---> 150V 6.8uF Vishay
100V 47uF ---> 100V 47uF Nichicon HE
100V 680uF ---> 160V 680uF Cornell Dubilier

Do you think it’s better to stick with the original values or increase them? Does the above list seems ok to you? Something else I am not entirely sure is that some of these larger caps replacements I have found are snap-in types, how can I check if the originals are of the same type? Thank you.

Got this amp in for repair and someone has been in it before .

Antone have any ideas on what U2and U3 are ?

Winding up on my first speaker build. For anyone that has built these, i have a couple of questions.

1)Did you use the foam damping?
2)Should i use the adhesive foam under the circuit board before i snap it on the provided posts?

Thanks
Paul

are there plans out there for shallow, full range, sealed bookshelf speakers?

or am I hoping for something that is currently unobtanium?

I'm looking for something to hang on the walls of my small bedroom. I'm not sure what this room was before the reno that closed in the carport and added many more rooms to the basement, but was 9' wide and 11' long before the added a 3' x 6' closed closet in one corner, so I have next to no room for anything beyond mt twin bed, dresser and chair to sit n listen to my headphones in. listening to then would be when lying down reading n winding down for the day.

also some back story on me to help you understand why I will likely be infuriating at some point while being totally unintentional.

I'm not sure how weird this is, but due to injuries survived almost 25 years ago my brain no longer works like most. I share this as I need to start at the very end and work myself back to the beginning to learn something. this can be frustrating for many helping me as it essentially means I need to be told exactly what I need for a solution and then experience the rule's / law's that need to be understood and worked with to be successful. it's frustrating for me because thus inevitably makes learning something take longer than usual. it's also a pain in the *** because I'm financially of smaller means. not destitute, no debt, but still living check to check.

yes, it does mean that project will be more expensive than it needs to be, but that is the curse I live with after crashing my mountain bike while bombing down a hill and crashing at 45mph. I remember nothing of it, only what I must cope with and overcome since I regained consciousness 2 weeks later.

lastly I'm clumsy n have hands full if thumbs...but fortunately have a patient son in law who is clumsy, but very capable hands that take joy working with wood.

oh, I'm 43, smart yet stupid, live in Canuckistan and pleased to meet you all! 😀

Hi all,

I need some attentuation between my MiniDSP 10x10 and 3eAudio TPA3251 (4 channel) amp. The MiniDSP is very noisy and the drivers in my active setup are sensitive (10" pro driver and compression driver). I have my MiniDSP going balanced straight in to the TPA chip bypassing the onboard op-amps. MiniDSP is fed by SPDIF. The amp is dead quiet.

The MiniDSP input gains are down 18db, I have a 10db L-pad on my compression drivers and yet I still have my windows volume level hovering between 10%-30%. Something must give.

I would like to put some passive attenution on the balanced line betwen MiniDSP and amp and having read everything I could find here would someone mind looking over my sums, please?

MiniDSP output = 560 ohms
10db attenuation K factor = 3.16
Rshunt = 560ohms
Rseries = 560 * (K-1) 2.16 = 1209 ohms
Rseries/2 = 604.5 ohms



R1/2 ≈ 600 ohms
R2 = 560 ohms

I plan on using 1w metal film resistors.

Cheers! 🙂

i want to build open baffle with two full range speakers and i want to know the difference between parallel connection and bi wired connection .Two 8ohms drivers in parallel give 4 ohms is it the same if i bi wire them.The speakers are Lii audio F15 and fast 8.Thanks

Maybe someone can help me out here. I've been building my Icepower amp, https://www.diyaudio.com/community/threads/why-do-i-have-56v-on-my-vdrive.383620/latest and things have been going pretty good. I've got it up and running but I noticed today that while I was watching a video on youtube that was all dialog so the woofers where hardly moving, that from time to time the woofer cone would either push out or pull back in unrelated to the video. It did this kind of slow and didn't make any noise but it is acting like a speaker does when you put a 9 volt battery to it'd terminals it either goes in or out so I am assuming it has to be DC that is getting to the speaker. Does anyone know what might be causing this to happen? All of the specs for the amp are at the link above on the other thread if you need to know. It has me concerned because I know it shouldn't be doing that. Any help with this would be greatly appreciated.

It was love at first sight

When I first saw the Autograph's enclosure at http://users.bigpond.com/tunnelgap/Tannoy/autograph.html

it really made my juices flow. Then, when I began to understand the principle behind (and before) them, I simply was captivated. I had to make them mine!

And now I built my first Autograph:

I've been trying to identify the source of a popping noise in one channel when the amp is idle. It appears to be mostly positive excursions that last around 1ms or less and are about 1V on an unloaded output. The amp has a jfet input using 2SK170/2SJ74 put those are difficult to find so I have not swapped them out. I've replaced the 2SC2240 and 2SA970 in the differential pair with KSC1845 / KSA992 and the issue continues.

Power rails seem ok and I've tested the caps on the differential section which is regulated. I believe that it is either heat or voltage related as the issue happens more often as the rails approach the 60v limit of my bench supply and it almost never happens in the first few seconds after applying power.

The amp is direct coupled so it is more difficult to isolate the stage that is causing this. I'm hoping to get some suggestions to track it down.

Hi everyone
Regardless of any other performance.
ES9018S refers max 135dB SNR in mono mode when all 8 channels are tied together. DSD1794 refers max 132dB SNR for 4 channels. I suppose both DACs are equal?

Hi guys
I’m new here and I’m looking for a new optical pick up laser for my CD.
Took it to the repair shop and said I need.a replacement and he can’t find anything, So any help locating it or fixing it would be much appreciated
Thanks Tong Tirone

Used once, years ago....
Gathering dust.
ECM8000 with has, mic stand mount and wind blocker.
Comes with MXL Mic Mate XLR to USB adapter.
Located in Kitchener ON
$75 shipped

https://www.avshop.ca/recording-audio-interfaces/mxl-mic-mate-classic-xlr-to-usb-adapter

https://cosmomusic.ca/products/behringer-ultra-linear-measurement-condenser-mic

Shouting anyone shouts, but shouting in tune like Wilson Pickett did is not easy ! Good soundstage too !

Just found this nice collection of driver measurements:

http://www.dibirama.altervista.org/le-prove.html
What I've found challenging with regards to driver measurements on the web is that measuring conditions are never the same, which makes it hard to do reasonable comparisons.
Here however, we have a huge collection of measurements all presumably done under the same conditions.

Looking through a large portion of the measurements, what stood out to me is how clean of a waterfall some metal cone drivers provide (up to breakup of course).
But despite this there seems to be a general preference of paper cone drivers in the industry.
Buchardt even changed from aluminum to paper cones in their latest speaker iterations.

Best offer, pickup in GTA.

Hey all,

some of this may have already been discussed, so apologies if this is the case and please just point me to the rejects discussion thread:

I’m in need for a decent tube preamp. Unfortunately my taste for music is very wide, ranging from classical to metal and anything in between, and I’m aware that some tube designs may lead them better for done music than for other music styles. Fortunately, if going the diy or Chinese modified stuff route, that should be cheaper than buying brand new well establish stuff.

My immediate thought goes to buying one of those 12ax7 12au7 units, also sometimes referred to as marantz 7 clones. They’re affordable and relatively easy to modify.

Other options include:
https://a.aliexpress.com/_mOTfK6M , which seems to be a triode based design, and could be a decware clone.


https://a.aliexpress.com/_mOTjWjO , which I’m completely unfamiliar with.


https://a.aliexpress.com/_msm2w3e , another one that has my interest.

I’m aware that some people consider these rather inferior, but as I’ve never build a tube amp before, and don’t have the skills to design one, I’m looking for some advice on what my options are.

Chinese stuff and play around with upgrades, or full diy?

thanks!

Long time ago I started this project, originaly with R2004 and MW16P, but after working on another projects and experience with T25B without WG, I decided to revive this project and update drivers to textreme and Be Bliesma.
I plan LR2 between woofer and mid at around 300Hz, and LR4 at ~2200Hz between mid and tweeter.
From already available measurements of TX from hificompass, and my measurements of T34B in larger WG, I have really high hopes in this driver combo and expect superb results, both measured and sonically. TX and T25B should be good sonic match but I am little bit afraid of Scan Speak and Satori combination, as I had already troubles to match 28W and MW19P. Ok, one never knows until it is tried and listened to.
Measurements will come soon, tweeter mounting adaptors are in progress.
So for now, at least some images of drivers in the cabinets.

Title mostly says it all. I am completely new as far as DIY audio is concerned, but I know my way around a soldering iron and can print my own PCBs. I am looking for a schematic for a great-sounding, class-A, single-ended MOSFET power amp, with preferably as few components as possible. Hope that someone here can help!

Helo friends it is simple but very complicated l just want to know that what is the purpose of these diodes in amplifier from negative to ground or positive to ground. or what are benefits by using this toplology??
Thanks..

Hardly used.

Hello,

After reading so much about this little driver did pull the trigger on 8 of them.


Goal is to build a WMMTMMW or WMMMMW + T beside configuration.

Bass would be SB20 with active filtering, drivers aligned for 90DB. No external sub.

Crossover W-M would be 160 to 200Hz


And crossover M-T could be:

around 2000Hz if MMTMM
around 4000Hz if MMMM and T beside, due to closer mid drivers (wanting to avoid comb filtering)


Side tweeter looks more appealing because 4000Hz gives more choice, and leaves a wide range to the TC9 for a more coherent sound

What would be the impact on imaging of not having the tweeter on same axis as other drivers ?


My experience so far is WAW (crossed between 80 and 160 depending on projects), mostly with Jordans.

Tweeter not selected yet, will depend on configuration.

Thanks for advise!
François


BTW did already simulate and all excursions are fine even at higher SPL than needed (measuring 85DB at 3 meters when watching rock concerts)

Hi all,

I currently have a pair of Event TR-6 bi-amped monitors and I am having a problem with one of them. As soon as I power the unit on, I hear a loud fuzz/static sound coming from both speakers. It does appear that the fuzz is louder from the tweeter, but that could be due to the nature of the fuzz (i.e. not much low freq. stuff).

When I run an audio signal to the unit at a normal level, if I listen closely (head next to speaker), I can barely hear the audio underneath the fuzz. It seems like it would be something in the signal path before the speakers and possibly before the amps.

I have tried swapping power and signal cables with the working unit, but it did not change anything.

One possible thing that may have caused this is electrostatic discharge. I noticed this problem for the first time after I felt a shock when I pushed on the power button.

Unfortunately, this problem started right after my warranty had expired. I know I could send the unit in for repair, but I fear that the cost of shipping plus the actual repair combined would be close to that of a new unit. That is why I would like to know if there is anything that I can do to repair the unit myself? I do have some background in electronics, so I would be comfortable if you could give me a starting point or have any ideas of what could be wrong based on experience.

I have contacted Event and they gave me the schematic (attached), but had no ideas for what could be wrong.

Thanks in advance for the help, I would love to get back to making music!

Please let me know if you have any questions for me.

Thanks again 🙂

Good day,

A long time ago I bought 60 pieces of the D3a 7721. The idea was to use them in a phono (RIAA) amplifier, and have more than enough spares, but I do not think this will ever happen. So I am putting 50 pieces of the them up for sale, the whole lot for 1250 Euros. Is that doable?

best regards, Erik

Hello,

Here is the V2 of my modular TDA1387 DAC, but even this one i dont consider released but a development version which is why im making this thread.
I'll then release the gerber files and anyone can make their own if they want to.


We're using PSU -> cap multiplier -> Jung superreg. For I2S, we have the JLsounds I2SoverUSB board.

Using 5 x 6 dacs in parallel in little towers, parallelisation averages the currents and improves SNR, but more importantly increases current, meaning we can get away with using a lower value passive resistor, The dac wants to see as close to 0R on its outputs. Also, we dont need further voltage amplification to line level, here i used a 51 ohm resistor.
There's footprints for pin 7 (VREF) decoupling caps but i dont hear a positive difference and some others practice this same method.

Im still troubleshooting some parts though, as simple as everything is i managed to muck it up apparently.
With 30 dacs, current is +-30mA. On 51R that should be almost 1.5v p-p, however on full volume i only get 30mA (what we should get with only one dac). So somehow we managed to break ohm's law here.

I also tried TDA1543 (non A, that one is EIAJ) since they are pin compatible and appear both are I2S. I have some NXP branded ones, but they dont seem to work at all, just get some white noise (although its volume changes slightly with what should be music playing, but its still pure white noise). I tried a lot of combinations according to the connection sheet like left and right justified and different word lengths, but all is the same, so i dont know if anyone else has experience with this..

The opamp I/V (passive and opamp I/V is switchable via jumper, for evaluation) also seems to have an inexplicable 1.75V of DC offset and sounds crunchy.
J5 selects what gets connected to the non inverting output. When used with +-15V (like i do), i connect it with GND. The other is just VCC/2 for single supplies.
The feedback resistor is low because there should be a lot of current so we dont need a lot of gain, after that there's the optional buffer (connect 3 and 2 on J7 and J8). Anyway problem happens before the buffer so it doesnt seem to be the issue. Its probably something really silly but i dont see it..



Best regards

Hey everyone, I am just a guy who has loved listening to music since a kid. I have a goal of assembling a system from component parts from a tried and proven design used by the community here which may sound as good as something several times it's price that I wouldn't be able to afford otherwise, whilst also be proud of building it and enjoy the process of doing so. Who knows, maybe it will turn out a hobby? I have dabbled into this idea a bit and even gotten intimidated because I can only describe myself as a guy who is a complete beginner but wants to DIY something that would rival a flagship system in a renowned Hifi gear maker's showroom. Anyone who has been there done that or wants to point me where to begin?

Trying to replace rectifier in my amp/dac. I came across the Germanium (SiGe) rectifier PMEG120G. Just wondering if anyone try it and compare it to say the schottky or the SIC schottky type.
Thanks.

The microphone need 48V 70mA(but I want to use minimum 2), sensitivity -48dB, self noise 5dB. So I think I need smaller than -137dB noise from power supply. 94-5=89; -48-89=-137

Does anyone have anything more about those amps other than it is written on their site....

http://www.asraudio.de/


thanks

regards
daniel

Hello, I have build a CS8416/CS4397 DAC configuration in hardware mode. This is working fine.

My next step was to ad an external clock so i connected a 33mhz clock to omck that is routed to the clock to rmck (at no spdif input). So far so good.

But when i apply an SPDIF signal, the LRCK wont lock on the 33Mhz clock but does fall back to the SPDIF/PLL clock. 🤔

My best guess is that i also have to toggle the HW/SW mode of the CS8416 OR to set a register to "use" the external clock instead of the SPDIF regenerated clock.

So, how can i get the CS8416 (which is in HW mode), that it will use the external 33Mhz clock to lock the LRCK.

I like to use the external clock in CS8416 hardware mode. Can it be done?

Hello all,

I have been following the composite amplifier topic on this forum for a long time and was able to gather many a thing from the experiences of other members. Naturally, I then started trying LM3886 / LME49710 simulations of my own, based on the following starting points that I was able to gather from various threads on this forum.

• The LM3886 needs to be operated in a closed-loop manner, for "more predictable clipping behaviour", and most of the amplification needs to come from the high performance op-amp and not the power-amp chip.
• Many power-amps are designed for a minimum gain (10 for 3886) and therefore their gains need to be reduced without affecting stability.
• Since LME49710 obtains only a limited voltage swing of 15-16V, the LM3886 needs to be operated at a gain of 2-3V/V, for the typical home / studio amplifier.
• In order to obtain any significant improvement in performance, the composite audio-band loop-gain needs to be at least 100x (+40dB higher) than that of the power-amp.
• The composite amplifier needs to remain stable even when presented with a highly capacitive load (e.g. 4.7uF) that emulates the capacitance of typical speaker cables.
• The capacitor across the inputs of the LM3886 is necessary for large signal stability, clipping recovery and noise/EMI suppression.
• The compensation capacitor should not be a critical circuit component, but only a means to fine-tune the transient performance of the system.
• In order to maintain a high excess loop-gain, the net amplifier gain needs to be minimal, e.g. 10V/V (20dB) for a typical domestic application.
• For a stable composite amplifier, the op-amp cannot be faster than the power-amp.

However, lately I happened to find that TINA-TI does not show proper results for the open-loop responses of many parts, possibly due to DC offset saturation. Consequently, my amplifier circuit has not been able to make it to reality, as I am unable to confirm the accuracy of the simulation results (attached).

Though the simulations look good, how accurate are the National / TI models and how far are these from reality? Since this is the first time I'm using TINA (I used PSPICE for over 15 years), I would like to know some of your experiences with this topic.

Looking forward to your comments,
Thanks.

Hello,

I have an old sony MHC 1600 stereo system that seems to be working fine with the exception of the Display on the main componet assy. Does anyone know where I could find a service manual? I know it is an old obsolete system, but I would like to fix it, if it something simple.

Thanks,

This screenshot is showing a poster that hasn't visited the site for 25 minutes but has made a post 19 minutes ago.

Hello. Can anyone comment on the quality of this thermal wire stripper? I have been burned in the past with two units (not this make) which did not perform ..barely heated up at all.

Hello users,

I have problems with my Stage Echo and would greatly appreciate any help / ideas for this one.

cheers

Which woofer to use crossing to Pyle PDS442/Dayton H70E in a two way. Michael Chua's (Ampslab) review of that combo.
https://ampslab.com/blog/2018/04/12/pyle-pds442/
I realize the Pyle would have to be padded down a lot to work with either one.
I have two 8" woofers at my disposal Visaton W200S-8 and Dayton RS225-8
https://www.visaton.de/en/products/drivers/woofers/w-200-s-8-ohm
https://www.parts-express.com/pedocs/specs/295-356--rs225-8-spec-sheet.pdf
I've built two cabs, both BR, one 32 liters and the other 42 liters.
Here's a pic of the cabs.
I would re-do the one on the left to eliminate the tweeter and move closer to the horn.
If anyone has any suggestions regarding XO that would be great.
Thanks for any and all suggestions.

tubav

What time zone is used in the forum? I can post something and it will say that it was yesterday at when ever.

Dear,

I can't find any data for this tube. Can anyone help me?

Hi All,

A few bits for sale:

1) Furutech FI-1363 UK plug

"This item is made to exacting standards and fully CE approved, audiophile grade.

Featuring copper contact pins and cryo treated and de-magnetized using Furutech''s patented Alpha process which removes internal stresses from within the material and helps to improve conductivity as a result.

The plug can accept a wide variety of cables of varying diameters up to 15mm and beyond. The plug is perfect for DIY as it has a patented cable clamping system which is very easy to adjust"

Used for around 3-5 hours, then taken off to repurpose the cable it was on.

As good as new, £50 delivered UK

https://uploads.tapatalk-cdn.com/20220314/59f2a49cb6f160829f6f2e396a95f4b3.jpg

https://uploads.tapatalk-cdn.com/20220314/308bd242cc93073168d6adad8e9ef625.jpg

https://uploads.tapatalk-cdn.com/20220314/7165f18547d27f8614815e16986780e3.jpg


2) 20K TKD 2CP-2511 Dual, Stereo Potentiometer.

"The TKD (Ko-on) potentiometer is highly regarded, probably one of the best pots in current manufacture, as used by Audio Note. Please note this is not your standard taper potentiometer but is a shunt attenuator/taper type to give you better performance than your standard taper potentiometer."

This pot is a massive step up from the Alps Blue that seems to populate so much gear. Genuinely resolving, Excellent accuracy of tone and has a really honest sound. I was genuinely impressed with it in the Prototype BT2. No longer required, solder once and now removed. Used for 8-10 hours max.

This cost me around £100, so £75 delivered UK seems fair.

https://uploads.tapatalk-cdn.com/20220314/323d6f2950f95770c651dac9122fbf0b.jpg

I run a nicely modded Trabscendent Sound GG preamp that I built. It currently only have one set of outputs, and I'd like to add another set, along with a selector switch that will allow me to choose between the 2 amps (to allow me to use the same front end with different amps driving different speakers) or to run the 2 amps at the same time (to biamp one set of speakers). I haven't yet decided on whehter the 2nd amp with be tube or SS, but my main amp is a Finale Audio EL84 SE design.

I need help knowing what type of switch I would need (I assume it'll be a 3 position toggle with the center position sending the signal to both amps), and what the wiring schematic would be. A picture of the internals of the GG is attached. There is a lot of room to work inside the chassis, as well as a lot of room on the back panel to add a toggle and another set of RCA outs. I am not at all concerned with drilling holes in the back panel.

I just want to make sure I do this right, and I'm not sure what the potential pitfalls will be. I would appreciate any help!

Edit: the offer is: you pay Parts Express price for the 15inch Definimax drivers (they are just broken in) and you can have the OBs for FREE!!

As much as it pains me, my GREAT sounding OBs got finally kicked out for their low WAF: so before I cannibalize them to reuse the drivers, I thought I would check for a few months if there is someone out there that wants them. The baffles were made by a carpenter, solid mahogany trim all around and veneered baltic birch (mahogany on the front and walnut on the back). The 15inch bass driver is mounted by the magnet (to take the weight and the vibration off the baffle); that was a feat in itself. I can tell you how they were actively XOvered in my application. I would prefer to sell the Visaton B200s and keep the AL200s to repurpose them.

They are in Windsor (ON), across from Detroit, MI.

You can see them at these links.

https://www.diyaudio.com/community/threads/ultimate-open-baffle-gallery.123512/page-130#post-5670164

and what they looked like before:

https://www.diyaudio.com/community/threads/are-you-active-multi-way.266524/page-3#post-4158184

https://www.diyaudio.com/community/threads/ultimate-open-baffle-gallery.123512/page-112#post-4970383

SOLD SOLD SOLD
Dual mono version of F5 First Watt power amplifier
Pass clone copy diy -
amp is 8 Ohms 25 wpc Class A
and 40 watts 4 Ohms

Used as a power amp with a multiple of different types of speakers
- amp played very well with 6 ohm floor-standers!

The final image is before my friends made and fitted for me the face-plate.

It does not run overly hot for Class A, as case has side vents and four [one each transistor] very large heatsinks.
J-fet and Mos-fet in construction.
Amp has board for speaker protection.
Zebrano real wood veneer-to-ply faceplate, with a perspex top.
{Metal front plate avail. thru' CAM, but not supplied}

All parts used are of good quality
F5 is a two Plitron [now Noratel] power transfo amp and very quiet in operation (only noise will be your source and pre-).
Amp is like two power amps in one case, each side has its separate board/ pcb.
It has 96k EACH SIDE m-f of main caps = 192k m-f in total - an unreal amount!
Amp will deal with 2-3 Ohm loads as it delivers sufficient current when needed.

To make one like this amp would cost 550-600$ in parts alone.
Sound is really very good, the like of which you will not get for less than 1,500 dollars. Fact.

Want to hear it? You can have an audition.
Seriously interested, I'll seek to weigh it - 17x7x13 inches at approx. 30+ lbs.

Price is firm at 725$ CAD - incl. Canada shipping;
NO TIMEWASTERS, Please

I can ship it FROM EAST PART OF CANADA, but it's heavy;
USA Buyers need to pay extra 75$ CAD for shipping. ie 800CAD$ in total.

EMT preferred, but F and F on Paypal is possible.

Hello, welcome to my first post on this website.

I'm contemplating my first real DIY speakers, and it seems like a router is a good thing to have for this. Otherwise I will be cutting my holes with a jigsaw. However, I'm somewhat hesitant to just buy a Porter-Cable or something, when there's a chance it won't really get used again. I currently don't have room for a router table, either.

So I've seen some cheap routers. Are they usable for non-heavy work, like the cutting involved in making speakers (cutting holes and insets, possibly rounding edges)? The ones I've seen specifically are:

Ryobi R161K, $59 (1.5 hp)
Craftsman 17504, $49 (1.5 hp)
Craftsman 17574, $59 (1.5 hp)
Skil 1823, $63 (1.5 hp)
Chicago Electric 1hp/$39, 1.75hp/$60

Another option is to use a router base on my rotary tool, but I'm unsure how suitable this would be, and I can't seem to find the router attachment for the RTX tool anyway.

Any advice out there? I've used a router before, but not much...

TIA!

Maybe someone has repair experience or ideas what it could be.

The problem has arisen recently. When listening to the newly purchased disc, the player stopped in the middle of the first track, naturally I decided to get the disc and see if there were defects on it. When opening the tray, the disk did not leave, but remained maximally shifted inward (working position). The disk can be removed in this position. Having de-energized the player, turning it on again, the disk drive spindle returned to its usual position when the tray was removed. After trying all the options for loading / unloading a tray with a disk \ without a disk, with a clamp \ without it, the result is as follows: the tray always leaves without problems, without any defects and slowdowns, but the spindle sometimes stays in place, sometimes leaves without problems as with regular work, sometimes, if it does not leave and wait for some time (tens of seconds), it can leave, sometimes it leaves as if with difficulty. The spindle with the disk always drives without problems in the usual mode with normal speed without jamming. After that, I listened to at least 10 discs playing without problems, disc detects without delay, tracks are looking for as usual, rewinding is also without problems. No extraneous noise was noticed during operation. The player is not dug, it is not used often.
I noticed that there are traces of grease on the tray exit mechanism, there is no disc on the spindle drive gears, I added a little silicone grease to check (although after looking more closely I came to the conclusion that no grease is used there) nothing has changed.

What else can I see, check?
Thanks!

(the text is translated automatically. Sorry for the inaccuracies.)

Hey guys - was wondering if I could get a (hopefully!) quick question answered.

I am looking at L pad tutorials and calculators and they all assume you have a single driver behind the L pad. If I am designing an L pad for a mid range section that has two 8 ohm drivers in series behind it, I am assuming that I would be impedance matching in the equations/calculators to 16 ohms, correct? Thanks!

SOLD Thanks for looking. I am selling my working Equal Opportunity (EO) moving magnet tube phono preamp. I “completed” this project in 2016 and it has been my main phono amp since then. “Completed” needs to be in quotes because I never got around to making an enclosure for the signal boards and they have lived on a piece of plywood. The power supply is complete in it's own enclosure.

A couple of notes for buyers unfamiliar with the design. My power supply is for 120V mains and the EO is a balanced in/balanced out design. The transformers can be rewired for 230VAC. Balanced input may mean minor rewiring your turntable to get a balanced signal from the cartridge.

You can read about the EO here and I highly recommend spending the few bucks to buy Linear Audio V7 and V8 for SY's articles about the design. In summary, it is a hybrid tube design that uses jFETs as input devices with 6DJ8 tubes doing the amplification. The design uses 2 amplification stages with a passive RIAA filter in between.

My build follows SY's design exactly using boards from JP and proto board for power supply and regulator boards. Premium components were used throughout with matched, genuine Toshiba 2SJ74 jFETs on the input. All components/circuits were matched where recommended. I will include 4 National 7DJ8 tubes (also matched), although it is worth your while to do a little tube rolling.

The power supply has 3 Triad Magnetics transformers, one each for the B+, B-, and DC heaters. Each has it's own diode bridge and reservoir caps in the supply housing, followed by voltage regulators and additional reservoir caps on the regulator board. The power supply and regulator board are connected by an umbilical cord using MIL spec 600V wire for the high voltage circuits. The old song goes, the components cost more than the asking price, which is true, but then this is DIY.

What easy options are there for getting a reasonable-looking finish on MDF? I have neither the skill nor the patience for anything that will take many hours to complete, and I don't have a dust-free environment in which to work.

Given these constraints, I realise a showroom finish is unrealistic, but I would like my new speakers to look at least half-decent. The finished speakers will be constructed entirely from MDF, comprising four enclosures, two of 45l and two of about 10l which stack to make a pair of floorstanding speakers.

A supplier I've used in the past (Just Radios) has these new jb JFX Premium Metallized Polypropylene Film Caps.
https://www.justradios.com/jbJFX.html

They seem pretty attractive, having good specs and a very reasonable price. The caps affordability is most likely due to the fact they are made in China.
I am looking at using them for the coupling caps in a Pass B1K.

Anyone have any experience with these caps?

https://www.justradios.com/jbJFX.html

Just got this amp in. The owner stated that there was a "little something wrong" with it.
I first made sure that there was no continuity between B+ and GND.
I removed the cover and checked all MOSFETS on diode check and then with the ohms setting and all checked good.
I applied 13.8vdc @ 2A current limit. It maxxed that out, but I was able to see good square waves on the power supply FETS and it was building rail voltage.
I increased the current limit to 4A and it powered up with no problems pulling 2.68A with the remote on and has +/-77.2 vdc rail voltage.
I input a 50Hz sine wave @2vpp and have a good output signal.
I started increasing the gain and as I got to 160vpp, just before clipping, on the outputs I can hear a "buzz" and the peaks of the sine wave get "squiggly".
I do not have a load on the speaker terminals.
I can't pin down exactly where the buzz comes from, but it is in the area of the output filter caps and inductors.
Any clues on where and what to check next?

Rockford 250, circa 2001, PC-3080-E. Had a blown IRF540 on right channel, blown trace & diode on the RCA shield, etc. Replaced the 540, diode, trace, and checked everything I thought necessary.

Amp works and produces clean output, but I have dc offset 10mV on the left channel and 100mV on the right. I checked and even swapped MMBT5088L Q202 and Q102 side to side with no change, and also compared them out of circuit and they seemed fine. I was looking at these because when I was checking components I get different readings from left & right when I have positive probe on the base and negative on the collector. On the left channel I get around 22k ohm and on the right I have around 6k ohm, but I haven't found anything else out of spec in close proximity to these.

How do I track down DC offset issues when it's relatively minor and still have clean output?

Hi guys,
I have a car radio that has a jack aux input. I want to solder a 5 / 12V bluetooth module (I will definitely find these voltages on the board), but I don't know which one to choose. I had a module for $ 1-2, however the quality was average (car has good sound system), but most importantly - there was a lot of noise. What module (from aliexpress) do you recommend? Should I add a choke on + voltage? 1uH or something?

Thank you in advance and sorry for the translator