Late 20s something year old guy from Amsterdam. Looking to build a full soundsystem used for gallery openings to raves in the distant future 🙂)). Not in a hurry, just trying to soak up as much info as I can. Right now trying to figure out my Art Welter keystone build!

I have a Schiit Saga S preamp which sits in a closet in my room with the rest of my sources.





The problem is with the closet door closed (blocks the noise of the PC and the noise of the relays in the preamp clicking) I cannot see what input on the preamp I have selected or whether the active mode is on or whether mute is on.

I use an IR extender for the remote.

That got me to thinking. Is there something I can put in front of each LED that will drive LEDs on a board mounted right outside the closet door?

Hi all,

I encountered a problem with my latest development I never had before.
As any part of the setup may be the root cause I do not really know what sub-forum fits best.

In the last years I created several variations of active speakers always based on the same approach.

A single ended ADC directly as input, a Teensy4.0 microcontroller for audio processing and 2x30W Raspberry Pi hats as amplifiers with the chassis directly connected to the amps.
The microcontroller does some equalization and the crossover calculation.
For powering that stuff switching power supplies are used.

Audio comes from a very old denon pre-amp in my home office and a Marantz AV-Receiver in my living (cinematik 😀 ) room.

The last variation has three 2x30W amps so 6 chassis connected. PSU is a 24V/220W desk PSU connected throu a DIN-4 connector to the carrier board.

The problem now is that I have high pitched noise, but only if I connect both speakers to the pre-amp and have both powered on.
I can cut the connection at any point, the audio line or the power line and everything is fine.

With a simple scope measurement I could not see anything on line.

I read a bit before come here for some advice what to do next and it feels a bit as of the PSUs lift the ground level. If the ground level even lifts some 100uV it would create a difference on the single ended ADC result. I even suspect that the PSU keeps the 24V stable. So I can not see any noise on the power line.
This lift would be at the switching frequency of the PSU. As long as only a single speaker is on, switching frequency is simply to high to change anything to the result.
But with both PSU connected it would create interferences on the ground, connecting both speakers through the pre-amp. The result would probably the differences of the switching frequencies of the PSUs and than would make it audible.

As I can command the micro controller to turn off the audio by writing zeros to the amplifiers, what kills the noise, I am somewhat sure that it happens on the analog part of the setup.

One idea I have seen somewhere in web, to add a low value resistor into the ground line to the pre-amp. As I have different audio line length in my homeoffice and my living room, I also have different levels of the noise. With the longer cables in the living room it is lower.

I already thought to switch the ADC to differential mode. But as I have a hardwire setup for the ADC it would need a complete board rework.

Another thing, where am I not sure if I remember it right, because it was before I came to the point where I accepted a general problem here, was that the setup does not had the problem as long the carrier board was not mounted to the back of the speakers. As the dayton audio chassis have a massiv magnet, could this create this behaviour?

I think I explained enough so you may have an idea what my problem is.

Any suggestion would be great.

Hi all,

Chances are low, but maybe someone out there and can help me with checking something from a local seller. Thank you!

Summary: Lots of amps produce error that can be dominated by PS ripple, including some forum favorites.

PS ripple can couple into the signal path through various paths. Some paths are capacitive (worse at HF) and some, like Early effect, are not a function of frequency.

You might think that if ingress is worse at HF than LF, then we only need to check PSRR at the treble end of the spectrum. This turns out not to be the case, since PS ripple amplitude is probably larger at LF. Let's assume a linear power supply where the rails are fed from large reservoir filter caps. And let's assume some upper bound on the amount of current flowing into or out of those caps. That puts an upper bound on the rails' slew rate, which in turn limits the amplitude of rail ripple to lower levels at HF than at LF.

If you model PS ripple as a signal that increases in level at LF -- and of course it'll have a substantial 120Hz component-- you'll find that many amps have more PS ingress at LF than at HF.

I've been simulating PSRR by modeling the rails as an AC voltage source with a large DC offset, and an AC amplitude of 333/FREQ so it's largest at LF and small at HF. (That figure assumes a 10000uF filter cap, and 20A peak charge or discharge current, which should be nearly a worst case.)

Lots of amps perform worse at LF. For example the spectrum below is the Wolverine. Its B+ rail is driven with a 40Hz ripple, amplitude 333/40 or about 8V. Its B- rail is driven with a 60Hz ripple, amplitude 333/60 or about 5.5V. There's no input signal. The output has an amplitude near 1mV peak to peak, all noise. That's not terrible, but it's a larger error than we expect from distortion, given this amp's near-ppm distortion performance. If we're driving program material at nearly full amplitude, 100V peak to peak, the 1mV error due to PS ingress is 100dB below the signal and still 20dB above the distortion floor.

Is this a real problem? Maybe not, but it's worth paying attention to, given that PS ingress can be worse than distortion. At least given assumptions that are somewhere between conservative and wildly pessimistic. :^)

(Left as an exercise: what is the actual spectrum of ripple, and is there a better way to model it in simulation?)

Probably most of the people are not interested in what I am about to write, so to save you some time:
LoCHAid stands for Low-income-countries-hearing-aid.

Why I have built has been inspired by an article referenced below and is based on cheap, ready made modules as in the article.

The disclaimer: every audiologist will tell you that a hearing aid is not merely a microphone with an amp and headphones.
Amplifiers amplify all frequencies, hearing aids amplify only what is required by a certain patient. Audiologist warn you against simple amps as they can be used too loud and cause more damage than good.
Audiologist are supposed to measure the patients hearing loss curve and set up the aid properly. This is what you are paying for. $$$ are not just for the actual device.
You have been warned.

I have two older member in the family who suffer from hearing loss (my father and my father in law).
My father in law lives in Very-high-income country and has state of the art hearing aid which he does not use very often. My father lives in a decent income country and refuses to buy a hearing aid.

The first impulse to do something for them came from the realization that my father in law listens to TV using headphones and the volume control in his TV is very cumbersome. So until recently he was listening to the sound at full volume.
I thought I can make him a small phone amp which will be used more like an attenuator. Not a hearing aid but in this case an attenuator should be beneficial. The result is here:

Then being a diyer I started looking for a diy hearing aid solution. I have found this article
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0238922

The idea is to use a small class d-amp (MAX98306) and a MAX9814 microphone module. The article contains links to a mother board pcb and a 3D printer enclosure. The authors use some high pass filters and show some results that this fits majority of the patients.

When I inspected the schematics I realised that the class d-amp used is in fact stereo so I thought I would make a stereo version. This cannot be done easily with MAX98306 because it is a "power amp" i.e. it is designed to be used with speakers and is (very) unhappy with the common ground connection in 3.5mm headphone jacks.
So instead I purchased MAX4410 which is a headphone amplifier. All the boards with MAX4410 I have seen use an on board 3.3V voltage regulator. I have decided to ditch it as I wanted to keep the whole device as small as possible - it was supposed to be powered of 2xAA batteries and all should fit in a a 4xAA battery holder.
The MAX 9814 modules can be programmed to 40,50 and 60dB gain. I ended up setting the lowest.

The device works fine. I suppose setting the volume to a level that one barely notices amplification should prevent extra hearing loss but should allow to have a decent conversation at a family table.

I will present teh device to my father next week and will inform how it was received.

PS My father in law is very happy with his headphone level attenuator.

I handed out PCBs for this BJT Simple Matcher jig, during talk#3 at Burning Amp yesterday. For those who couldn't attend, I've attached the Gerber .zip file below. You can send it to a PCB fab and have some boards shipped straight to you.

If you haven't yet ordered PCBs from an online fab, it's fairly easy and painless. Here's a brief explanation: Ordering PCBs online (using Gerber files): A walkthrough -- featuring the fab "JLCPCB"

Unfortunately, some of the figures in my "slide deck" didn't render very sharply on the projection system, so I've included the entire presentation below in .pdf format which features infinite resolution vector graphics. The presentation slides are fairly self-explanatory, so this Forum post includes only a few addenda:

1. There are sockets for four transistors on the board. Two 5-pin sockets for PNP transistors, and two more 5-pin sockets for NPN transistors. These are arranged so that if you happen to own some 10-pin DIP sockets {which are uncommon}, you can fit two 10-pin DIP sockets on the board. Otherwise just fit 5-pin single inline "breakaway" sockets as shown in the picture attached below. I handed these out to BAF24 attendees; they are inexpensive if purchased from eBay. Here are a few eBay product titles:
2. The circuit schematic diagram in .pdf format is attached below. That's the one to print, since .pdf has infinite resolution. Instructions for using the Simple Matcher jig appear right there on the schematic. And of course, also in the presentation slides.

3. To maximize the life of the 9V battery, I'm deliberately running the LED indicator at very low current. Please compensate for this low current by fitting a super bright LED. The LED part number called out in the Parts List attached below, shines at nineteen thousand milli-candelas. That's pretty bright.

4. As promised during the talk, I've included an image of the inexpensive handheld meter I purchased for matching, which has 0.1% basic accuracy and whose DC voltage display goes down to tenths of a millivolt. It's not the only possibility, it's probably not the very best, but it's relatively cheap and relatively easy to buy. However, as emphasized during the discussion, you will get "a lot better than nothing" matching results, even with the cheapest meters that only go down to 1 millivolt resolution.

5. The schematic includes printed instructions which tell you how to use the BJT Simple Matcher PCB. Just print out the (.pdf) schematic and bring it to the measurement lab, on the day when you're doing the matching work.

6. "AIR LOCK BOX"?? During my BAF presentation, an audience member's question (@ timestamp 27:29 in the YouTube video) included a remark that in his own matching efforts with another jig, it was useful to cover the entire test jig with a (removable, 5-sided) box made of insulating foam or foam-core. This minimized air currents around the two transistors being measured, and therefore sped up the thermal equilibration of the transistors. If I'm remembering correctly, his arrangement took about 60-90 seconds to get a stable delta-VBE reading {on a different jig}, whereas my slide deck says 90-120 seconds for this BJT Simple Matcher jig with no box. So it might be a quick and inexpensive experiment that you may wish to try; possibly a box could speed up your hour-and-a-half marathon of matching. Several attendees were also concerned that the human test operator's breathing, might create unwanted air currents which slowed the equilibration process. An insulated box separating human and jig, might mitigate these concerns. I speculate that a box 125 x 125 x 75 mm (5 x 5 x 3 inches) would be a handy size to easily cover the BJT Simple Matcher board and wire leads.

_

Hi my project consists of adding 2nd order harmonics to a stereo signal to achieve a more tube like sound.
I would like to use two RCA inputs and two RCA outputs for the signals and a DSP that has enough memory and calc. power to allow me more complex operations.
I am planning to use SigmaStudio from Analog Devices as a graphical platform.

My questions:

• has anybody experience, suggestions which operations (in SigmaStudio) would likely achieve desired result of a more tube like sound ?
• I am thinking of finding a proper board based on the ADAU1466/1467 to have more memory available, has anybody a suggestion where to get a less expensive board inluding of the programmer and the RCA adapter ? AliExpress is pretty confusing, I would like to find someone who actually has experience.

Thanks
Bjoern, Singapore

Hello.

I have too many projects with too little time.

1- Two PCB for Kevin Gilmore's Dynalo MK2 "through hole", populated and in working condition.
It has to be adjusted with the final PSU.
Mix of Takman REY and Dale resistor. THAT340 input stage, genuine MPSA06/56.
90 € with EU shipping

2- Two Kevin Gilmore's UBAL/BAL boards, "through hole"
Same parts flavor as above, with Silmic caps.
60 €with EU shipping

3- One toroid 230v, two 25v secondaries, electrostatic screen. Hand manufactures on the UK, new never used, just tested.
60 euros + shipping

4- A pair of USSA amp, suitable for both USSA3 and USSA5 buildings. Populated for an avorted USSA3.2 project. Uses mainly Dale resistor, and features matched genuine NOS Toshiba Jfets. Does not incluse the heatsink-mounted transistor. 150 for the pair, shipped in EU.
Will provide Fab's documentation with the boards.
Ready to be used if you go the USSA3 route: just solder the second stage transistor and output LatFet, no other parts missing.

5- Four RIFA New old stock PSU capacitor, 33000 uF 70v. Huge! 20 euros per piece without shipping

6- Krell KSA-5 "clone", Class A headphone amplifier, Kevin Gilmore PCB, original parts and fully working.
Cased in black Modushop, with Schaeffer panel work (same company as frontpanelexpress in the USA).
Toroid with linear PSU (original style with TO3 transistors), and Alps volume pot. A pair of RCA input, output is 6.35 Jack and 4 point XLR to suit every cable termination.
Was one of my first DIY project, so decent work even if casing job and layout inside can be improved, price reflects that.
Original circuit, without the recent proposed revision to improve bandwith detailed here.
350 euros, shipping to be discussed (about 10 Kg).

Hello ,I am a new member of diyAUDIO family,I come from China.I am very interested in audio amplifier diy.

Do you know what capacitors are they black. MKP perhaps?
Also, these (1.5uF) with cream color what is the manufacturer?
They are from crossover pcb.

Why wasn't Stig Carlsson's ortho-acoustical approach more widely accepted at the time both concerning commercial products and diy projects ?
Are there a large amount of disadvantages and only a small amount of benefits ?

Some URL's concerning this approach:
https://www.carlssonplanet.com/en/speakers/produced/carlsson-oa-58/
https://www.carlssonplanet.com/en/everything-about-the-carlsson-loudspeakers/
https://www.lbtechreviews.com/news/speakers/stig-carlsson-and-the-listening-room
https://teenage.engineering/products/od-11/carlssonstory
https://minimalissimo.com/moods/sounds-of-stig-carlsson
https://www.stereophile.com/content/larsen-hifi-8-loudspeaker
https://www.stereophile.com/content/larsen-hifi-8-loudspeaker-measurements
https://www.diyaudio.com/community/threads/larsen-speakers-clone.322270/
https://www.diyaudio.com/community/threads/carlsson-speaker-sonab-oa14.23681/
https://www.diyaudio.com/community/...roject-on-ortho-acoustic-design-ideas.231571/
https://www.diyaudio.com/community/...simple-two-way-unity-corner-waveguide.315446/
https://www.larsen-speakers.de/technologie/
diy-project: posting from 2016-01-23, 17:46:
https://www.faktiskt.io/phpBB3/viewtopic.php?f=17&t=62606&start=240
https://www.diyaudio.com/community/...s-of-floor-coupled-up-firing-speakers.121385/

Thanks for comments.

I have been reading audio forums for years, in my search for more knowledge on how to build a great used stereo system. I like Marantz, NAD, and B&W equipment, that is what I use right now in my home system. I'm big on used quality and cheap used horsepower, rather than super-fine fancy 20-watt amps for the price of a car. I will need help fixing my surround sound amplifier and getting my B&W speakers in perfect order, they aren't working properly right now.
Thanks for being here, thanks for letting me read the forums, and thanks in advance for help.
Ferris

I want to share the amplifier schematic designed by Mr. Iwan Kamil. Hopefully, you like it 🙏.
According to Mr. Iwan Kamil, this schematic shows a "Stereo Amp Full Range 80 Hz—5.5 KHz" equipped with a bandpass and bias control set. Those who follow Mr. Iwan Kamil on social media (Facebook) must be familiar with the functions of these components. See the schematic in pdf no. 1.
Maybe some people think that this schematic is simple, just an ordinary OCL. However, for me, this schematic is very authentic. Each circuit has its own uniqueness. Please share with your friends to be creative with this schematic.
For the op-amp supply, you can refer to Mr. Iwan Kamil's tutorial on "Super Low Noise DC Supply" or use the references I have attached. see picture No. 5.
For capacitors C1 and C3, it is better to use tantalum or other types of good quality so that the signal is more linear. Resistors R15, R16, R27, and R28 can be replaced with 220 Ohm if using a 24 VAC CT supply.
Let's use this group as a place to discuss and share knowledge about DIY Audio.
Thank you.

Hi all,

Trying to locate a service manual/schematics for the Mark Levinson 332 I'm currently working on. I'm able to locate the 331 service data but that is missing a few of the adjustments and TPs that are present on the 332. Any help would be much appreciated.

1. Constant loop gain for no THD both @ LF and HF,
2. No coupling capacitors at all, MC-like sound with MM cartridge thanks to
3. aperiodic non-resonant HF correcti on with lowest input capacitance.
Thanks to that, the unwanted resonance of the input circuit is shift ed far into the ultrasound region and
does not manifest itself in the audio range, and the input resistor R1 can be increased to 150 kOhm, thus
forming a "passive cooling", which reduces the input noise current in SQRT (150 kOhm / 47 kOhm) = 1.78
ti mes compared to typical Rin = 47 kOhm.
4. At the front end uses a matched pair of Dual, ultra-low noise, low-gate-current audio N-channel JFET -
the latest JFE2140 from Texas Instrument. It's allow to achieve a record IEC-A weighted signal-to-noise
rati o of 85 dBA relati ve to a standard 5 mV@1 kHz input level with an att ached 0.5 H+ MM head
equivalent. 1 kOhm
5. and THD less, then 0.00006% with fantasti c overload capacity (64 mV@1 kHz < 0.0007%).
6. The frequency response exactly corresponds to the Enhanced RIAA not with three, as usual, but with
fi ve -ti me constants, in additi on to 75 + 318 + 3180 µs, a Neumann pole compensator and a rumble -
reducing 7950 µs - IEC 98 Amendment are also implemented.
7. Double differential stages scheme : high PSRR , but stabilized bipolar +-(15-18)V power supply with low
ripple is required
The preamp board must be installed next to the tonearm to ensure the stated performance

$200​

Discussion here

MM
Frequency range: 1 Hz - 45 kHz
Ku at 1 kHz: 49 dB
Rated output voltage: 1.4V
Signal to noise rati o: >85 dBA
THD: <0.00006%
MC
Frequency range: 1 Hz - 45 kHz
Ku at 1 kHz: 68 dB
Rated output voltage: 1.4V
Signal to noise rati o: >73.9 dBA
THD: <0.0004%

Welcome to test it in Dresden, Germany

In order for the parameters of phono stages to be compared with each other, they must strictly comply
with the regulati ons established in parti cular by IEC 61938. In this case, the input of the device should not
be short-circuited, but should be loaded onto the equivalent - for MM this is a circuit consisti ng of
inductance 500 mH, in series with a 1 kOhm resistor and a capacitance of 125 pF connected in parallel to
them. For MC - 10 Ohms. The nominal input signal level for the MM is 5 mV, for the MС - 0.3 mV. Noise
parameters must be A-weighted.

Here is a very simple MOSFET amplifier. I don't have the name for it. The output is similar to JLH output stage, but it can actually work in class B with MOSFET. Achieve good performance with relatively small number of parts. It also has the capability of almost rail to rail voltage swing, which is the weak point of most other MOSFET designs.




[EDIT] Added constant current source for the bias. Thus, the power rail fluctuation will not affect the bias.

Hey guys,

I have a sinus live 12 inch subwoofer, an SLW365K, and a hypex DS 4.0 plate amp and I’m trying to put together a sub for hi-fi, basically a 2.1 to go with some monitors I built.

I’m looking for some help coming up with an enclosure, I know some of you are wizards with simulation, and can point me in the right direction.

I found some TSP for the sub from Hobby hi-fi from years ago,

Fs: 31hz.
Qms: 10.4
Qes: 0.36
Qts: 0.35
Vas: 97
Mms: 135g.
Re: 3.2+3.2
Sd: 590cm2

I am assuming ported would yield better efficiency?

Can anyone help me out with coming up with a simulation for a ported box? Or point me in the right direction?

Thanks in advance for the help!

https://a.aliexpress.com/_EuLOKYC

Has anyone got experience of this preamp as I can't find any information or reviews on Google.

I specifically need balanced outputs and this board generally looks like a one stop shop for that and number of inputs.

Thanks in advance.

Hi
somebody knows what driver is inside d&b q7 top?
De900,910,914 or TN version of one of them?

Hello,

Has a push-pull regulator pleased features to power a masterclock clock ?

I know it always has a good PSRR, what has it more than some inntegated reg TS7A, ADM75xxxx/LT3042/etc.

Thanks

I built a front 2-channel surround speaker.
The drivers used are SPL Limited's LSE77-20R (4.5 USD).

Box name is MTX-0806 (TQWT with Damp-Duct).
The front is L+R, the left side is L-R, and the right side is R-L.
The surround effect varies from source to source, but the surround effect is not as good as expected.
I am wondering how to improve the surround effect in the future.

Note to moderator: I hope I have posted this in the relevant section - otherwise I apologize, and please move it.

I was interested in trying out Nelson Pass' analog XO/EQ for the LXmini (Analog XO/EQ) . However I don't have enough of the 2SK170/2SJ74 JFets, which is problematic for two reasons: they are quite hard to come by, and if you find them they are very expensive. So I tried some Fairchild J113/J176 - they are not really complementary, but they might work anyways.



In the test set-up I used matched FETs with about 12 mA Idss.

With +/-12 Volts supply it'll supply around 7 Vrms without visible clipping. Soft clipping occurs around 8 Vrms.
THD and noise is below 0.025% at about 3Vrms (I cannot supply a higher voltage distortion free).
Frequency response: Flat from DC to at least 1Mhz. 100kHz square wave shows a tiny amount of ringing, but this could probably be removed if the bandwidth is lowered.
Rise time estimated at 0.5 µS.
Output impedance is around 35 ohm. This rises to about 70 ohms if a trimmer potentiometer (100 ohms) in installed in the sources to balance out small differences between the Fets.

These specifications are, of course, far from as impressive as the Toshiba pair - but we're talking about line level signals and how audible is 0.025% THD after all?

Is there anything I have over-looked?

So I recently heard some truly superb Kroma Jovita speakers being driven by an amp from a brand I’d never heard of - Orpheus Lab. The amp was the “A Four 1200”.
The sound quality was really outstanding and I was immensely impressed. I already knew that Kroma makes great speakers so I was of course curious about the amp. I subsequently did some research and go hold of this doc which provided an overview of the topology:








I am told that some of the tech people at Orpheus are ex Goldmund and CHP and my guess is that they have brought some ideas with them . . .

Hello everyone, starting a new project. I picked up a pair of lowery organ amps. From 1958 holiday ls models. Going to run as mono blocks. Power tube are 6v6gt pp. But the power supply ran 20+ tubes in the organ. So was wondering if the PS. Would support tubes with higher output? Maybe el34s?

Thanks for your Input.

Hi everyone. I have been missing for a few weeks as everything that could happen... happened twice. So, I finally managed to get back home, and also back to tinkering and playing around with my vintage stuff (including the Citation 22 that I have not touched for the last month...). But I digress.
So,
I got a nice Nakamichi MB1 cd player, that had a bad laser, I replaced the KSS210 laser with a chinese part and that kept doing weird stuff (scratching noises in the playback, stopping altogether playing etc) although it read the TOC most of the times. . So I downloaded the service manual (of the MB2, since the MB1 manual is unobtanium), since I wanted to check eyepattern, rf and etc. maybe to adjust it.
And this is where I realize that the manual calls for an obscure object called the Nakamichi CD Test Set DA09155A, that features a few switches, BNC outputs for a scope and convenient connectors that latch on the MB.... I try to find some info on it (the MB2 manual only has a line art drawing of the thing) and find that is rarer than hen's teeth and that the one that surfaced a couple years ago went for like five times the value of the MB1 I have. Looking around, I find the manual for the Nak CD Player 2, which is basically the same thing as the MB2 in a different box, and inside, along the same drawing, there's a full schematic with part values and semiconductors of the set. First thing I realize, the thing is complex. Find the schematic below.
So I try to understand what it does, and it seems to have some oddball resistor value on many inputs, a full active filter that can select two slopes (I think), and a FET on the RF signal that I figure is amplifying the signal? Bottom line, I started designing a PCB for this and actually sourced all parts, including the op amps and the SK241 FET before asking myself: do I really need this? Is this something maybe other could be interested if it works? I know Nak used to build special a numbers of test sets for their decks to service them, that are expensive and difficult to find.
Point is, all the values and levels disclosed in the SM are relative of the signals as they come out of this box, and i have no idea how exactly the filters influence the original signal.

So here i am, can anyone hep me out? Opinions? even just to say, forget about it it's useless.
If instead it's ok, maybe this could be used to service all those Nak cd players out there, so why not, can you please help me out in making it a working set? I'd post full pcb files and BOM here.

Note, there's an error in the PCB I'm posting now, as for connections to the FET. I just need to correctly move the GSD terminals

The ones for sale on eBay and AliExpress.. are they any good?
I read a buyers' comment stating that the tubes don't fit in these (wrong holes' positions?).
Please let me know about your experience with them.
TIA!
S

Hello, I’m a 23-year-old electrical engineering student. I found this site while working on my final project, and I believe it can be very helpful. I’m trying to create a wireless sound distribution system using lasers. The challenging part for me is that I promised my professor I would design the receiver and transmitter circuit boards myself. Any help would be greatly appreciated.

Hi,
i have build two Amps with a Connex 500R/+-45 Volt SMPS and FH9 XRK Mod boards.
The Amps are working without any problems, but the offset is rather high on all boards. Two boards get an offset of 19/21 mV the other two boards get 26 and 29 mV.

What have i done before...

Tried to measure VGS of the Mosfet belonging to the schematic of Mr. N. Pass. Got luck i could find enough matching pairs for example 4,00 volts VGS for one pair IRFP240/IRFP9240 for a board. The other pairs are not very VGS different, say 4,02 and 4,04 volts VGS or similar.
Took T6 MPSA92 out and choose a 2N5401 as replacement. The 2N5401 has a litle bit higher hFE.
Soldered out the KSC 1845 and matched every pair with my Peak Atlas, without heat and with heating. Finding matched pairs and put them in. For example hFE 420 and Vbe 727.
Nothing helps..the offset remains at high 26 mV.
Changed the KSC1845 to 2SC2240, yeah...50 mV offset...ok, seems not to be the right way....
The mosfet drivers are matched Toshiba TTC004B/TTA004B instead of KSC1381/KSC3503

If i measure PIN 1 to ground at IRFP's i got different voltages. 3,96 volts at the IRFP 240 and 3,74 volts at the IRFP 9240.
Chris, Cherman, gave me an advice to change the gate resistor at IRFP 240 from 220 Ohm to 330 Ohm as a try. Done without success.
If i do that and change the gate stopper both IRFP have less voltages in the same proportion. 3,92 volt/3,68 volt
Another idea was to change the resistor R15 at the driver to the N channel from 47 to 56 ohm or more....nothing...no success
Surely i have controlled every component, resistors, diodes..and so on...
Amp is stable with its offset about 20 mV or a liitle bit higher, no problem to adjust the bias. I choosed 120 mA, 26,4 mV over the 0,22 ohm resistor.

Has anyone an idea what else i can do to lower the offset ? Any idea to make something better is welcome.
Many thanks to Chris, cherman, helping as far he could ...


Greets
Peter

Hi Thanks for reading Two sealed back midrange drivers i am thinking of purchasing, the dayton audio RS52FN and RS52AN.
Do you know the differences between the two, have you heard them, or seen any information about them
How well do they perform against other sealed back mids at or about a similar price
What kind of crossover frequency would you use

At the weekend I went to the Audio Deluxe show in the UK and heard one of the most impressive systems I’ve ever heard. I’ve heard Kroma speakers on previous occasions and invariably been very impressed. The model in this system was this one: https://kromaatelier.com/jovita/
It uses 2 x Purifi 6.5 and 1 x 8” plus a Mundorf AMT. Despite using just one 8” woofer the bass was superb and went plenty deep enough for 2 channel hi fi.
The real surprise was the amp that they were using at least some of the time. it was a Swiss brand I’ve never previously heard of - this is it:https://tw.my-hiend.com/純淨透明的不凡氣質-瑞士orpheus-absolute綜合擴大機/

It was only later that I found this review and discovered it uses LM3886s. As the owner of some Neurochrome amps I know just how pur and transparent these can be when implemented well, and Orpheus certainly seem to have done that.

This combo produced truly awesome sound. I went back to the room 3 times and it was noticeable how long people were staying in the room to listen - much longer than is typical at such shows. I think I have only ever heard one other system that impressed me more and that featured the Vox Olympian speakers . . . .

I'm new to DIY audio, where should I start?
Maybe I could start with a headphone amp from a simple kit?

Hi all. I've come into possession of a 2016 VFET amp. It has worked perfectly while on test in my system. Last night however, I went to power it up, nothing. No blue LEDs no suggestion of power to anything. Almost like a fuse had gone... but if course, no fuse.

Which leads me to suspect the soft start circuit, or the traffo (a Toroidy). Ive tested the switch, because it was easy. Its fine.

I did not build this amp, but I know the person who did - sadly passed away - and his workmanship is super good. I am no expert but I can soldier, and solder away.. but I'm really keen to get your opinions on where I should start.. the soft start circuit is buried and will require a bit of strip down to test..

What's your gut thoughts? Thanks!

Hi All,

I recently acquired Monitor Audio B6 (bronze series) that has no crossover (for both).

I would like to build one same as the original.

Does anyone has a schematic design of the crossover / kind enough to be troubled by posting picture of the crossover in an original one?

I've tried to search with no luck.
The closest one I got is MA BR6 (bronze series that comes after B6) from youtube video disassembly - not sure whether it would be the same design and value.


Photo of the Monitor Audio B6 (come from google search)

,

Regards,

I was in a shopping mall the other day and in one store, the music sounded very good. Clear and articulate with nice bass. I normally don’t give a second thought to muzak playing from store speakers but these sounded different. They also played some interesting acoustical tracks with great dynamic range (usually dynamic range and ambient background store music don’t go hand in hand). I looked around and saw these 2 way MTM speakers on the wall every 10 feet or so. The store must have had 30 of them. I also saw some subwoofers installed hanging way up in the ceilings painted white so you don’t notice them.

These wall speakers had a unique 4 tweeter array in a crossed axis arrangement. I think that helps to give good angular dispersion. I took a photo and did a reverse image search and turned up a brand I never heard of. James Loudspeakers. Apparently, a 4in deep sealed cabinet and very high sensitivity but 4ohms. Just wondering if anyone has heard/seen these and if we have seen this tweeter array a somewhere else. I think a 3D printed housing and 4 smaller Nd dome tweeters could be made to DIY this approach. Certainly would increase power handling a lot.

I think this is an older model not currently made anymore as the latest from the James Speaker website has similar looking units but not the same. The one on the reverse image search said it was an OW63 which goes for $1500. Might be a neat tweeter design to DIY and do an MTM or even a regular TM speaker with wider dispersion.

According to my practical tests about inductor cores at 200khz switching of which is my best preference for class d amplifier, i noticed too much noise at (music pause) using a phone as audio source charger plugged in then thru a mixer to my class d prototype using sg3525 as signal generator & ir2110 & buffers as fets drivers. There's too much noise using t130-2 core carbonyl than when i changed to a blue aph33p60. Infact this blue core is absolutely quiet. Some things are better done practically than reading theories to actualize outcomes.

Hello DiyAudio community,

I’d like to propose an addition to the forum rules to help protect designers of printed circuit boards (PCBs) from having their work copied or repurposed without permission. I’ve been reflecting on a few situations I’ve seen in the community, and I think this could benefit us all by fostering respect for original design efforts while still encouraging collaboration and innovation.

For context: many of us spend significant time—sometimes 100+ hours—designing a PCB to share with the community. Typically, we organize group buys so members can purchase boards directly from the original designer/s. This process works great until someone takes that design, creates a near-identical variant, and presents it as their own work—often without credit or permission. Not only does this undermine the original designer’s or teams efforts, but it can also confuse the community about the origins of the design and dilute the value of the collaborative spirit we’re known for.

My suggestion is to add a rule along these lines:
“If a member creates a variant of an existing PCB design shared on the forum, they must (1) reference the original designer(s) and (2) obtain explicit permission from the original designer(s) before selling it or starting a thread about it on DiyAudio. This applies to designs that are substantially based on or derived from the original work.”

This wouldn’t stifle creativity—folks could still build on others’ ideas—but it would ensure transparency and respect for the time and skill invested by the original designer. I think it could also encourage more people to share their work, knowing their efforts are safeguarded.

I’d love to hear your thoughts! Have others run into this issue? Do you think this rule makes sense, or is there a better way to handle it? I’m open to refining the idea based on feedback.

Thanks for reading, Stuartmp

Hi im new around here !!
Have this Amp , came in protection !!
NOne mosfet burn or Bad .

Following Mute from Output drive card ,
Find a M6 transistor bad , replace it and the amp turn on !!

Testing the amp find out that output lowside mosfets are a little bit warm , putting signal in and speaker they gone more warm than usual , HIGHSIDE not they have normal temp.

Pullout output mosfets and test all drivers , follow waveform from drivecard to mosfets pads , its fine square.

When I load the output fets the waveform on gates of low side get distorted .
The Highside are ok completely square .
Any idea whats going wrong on it
Thanks







Low Side Gates loaded!.

Here are more pieces of a project that is not going to come to fruition.
For sale are Acoustic Elegance 10" (TD10S) woofers. I have two, 4 ohm (TD10S-4A) woofers and four, 8 ohm (TD10S-8A) woofers to sell.
The "A" denotes the Apollo upgrade which all woofers do have. All of the woofers have a black phase plug and not one driver was ever used.
The drivers were delivered 2 years ago. Located in Michigan.

I would love to get $1,000/pair and shipping will mostly likely be covered by me depending on specifics.

I am repairing a Denon AVR-5700 which appears to have suffered some sort of overload or short as there are a few resistors that are burnt/melted and capacitors that are popped/blown.
Tracing the circuit it appears that either the voltage spike came out of the MP1715 to damage the resistors/caps OR it went into the MP1715. (as I am not sure what happened to this unit picked it up cheap "not working" to repair)

I'm replacing the caps/resistor, but I also wanted to check the one MP1715 (and since they are typically paired with the MN1715 I should test it's pair)

I can't seem to find any sheet data on these...
Does anyone know what the E/B/C is on these two? And what sort of reading I should be getting across the pins?

Thanks!

Hi Folks,

I engaged an an AI online to see if I could get it ti design a Phone preamp. It then walked me through this layout on KiCad. Can somebody tell me if this looks like it would work? I'm pretty amaized. This is the left channel.

Tim

Hi Guys,

I'm stumped. Whenever I turn on the amp the ground thermistor starts to glow cherry red and the fuse blows.
Obviously, a lot of current is going to ground, but I have no idea what's causing this.
As far as I can see, I have assembled and connected the power supply properly.
So far, I can tell you that the transformer output voltages are 18.5VAC and 18.6VAC.
Has anybody had this problem, or does anybody see anything wrong?
Like I said, I'm stumped.

Thanks,
Dave Chorney

So these were my first speakers I ever built and they have done excellent duty as party boxes for a long time, over 20 years now but the foam surrounds on the drivers are starting to go and I need a cheap but effective Australian replacement driver.
The original are some Tandy drivers I got on clearance, sold [ mislabeled] as subwoofers but with an decent enough sound that The Boss still thinks they are one of the better efforts on my part. 32mm Voice coils and 6mm X-Max P2P
So around 200mm cutout and usable to 3k with the XO I have already which is first on the mids and a second on the tweeter.
I need a quad of them in 8R [ 7.6DCR] or close
The Faital Pro 8FE would work if I could afford them and there were enough available but a bit above my budget; ditto the locally made Lorantz Audio and the Eminence so I'm hoping somebody has something my Google-Fu hasn't found and the cheaper the better at this point

Hello,

While preparing new plans to release in the website, the model Manifold/MTB called my attention with a good response without any optimization, pure lucky. I'm calling Manifold/MTB because thy are basic the same layout with the horn difference, one is flared and the other is straight. But to add even more flexibility in the model I added flare option in the vent port too. Currently the model is available only for single driver.

I took a Tapped Horn SS style I built using 15" driver and it's total box volume to be used as reference and I started to adjust the Manifold/MTB design in order to see what I could achieve with this kind of layout and for my surprise the SPL curve is definitely better for the same total volume ~300L. Maybe it can still suffer a little from port compression, even with the flare, maybe it can suffer also a little from thermals once the driver is inside a chamber, but the layout is very simple to build and with the option-1 I think it's possible to torque the screws from the horn. In the option 2 the bandwidth is wider (3 octaves) but it may requires access panel and compression ratio is probably too small. Particles Velocity in the vent port is around 24m/2 at mouth @ 800w witch is the driver limit.

What would you guys optimize in this design? for it's build simplicity and better SPL curve, wouldn't be this single driver Manifold/MTB be a better option compared to a Tapped Horn?

You can find additional data in the attachments.

Hello everyone,
I'm Christoph from Germany and I've been building loudspeakers as a hobby for about 3 years.
I particularly enjoy comparing the speakers I build with each other and enjoying my music collection in different ways, because there is probably no such thing as the perfect speaker.
My hi-fi journey is only just beginning, so to speak, but I've already learned a lot about the technology involved and my own preferences.
I am looking forward to all the information I will find here.
In particular, without wanting to rush it, I already have a question for "planet10" about a construction plan 🙂

Best regards 🙂

ok long time member under old name and lost logins and all my data in flood so back on here and starting back in finishing several many yrs old on hold projects

1) Revel F36 blew my speaker budget for the year ( $1200/ pair, lol) and yes I have read , reread, all the reveiews , data , spinorama on all the revel/harman speakers I could find.
the only thaing that bugs me abotu the F 36 is that 4 k broadband hump, esp when compared to the F 35 and others that hit the target curve a bit better,
I have a very large room and high ceilings and sit about 13' away but that hump is still noticible, not enought to make me not love the seakers,But..

There has to be a easy way to DIY those factory crossovers to get rid of that hump. I know Revel had to cut costs somewhere.. I have seens some pics in a vid of the x.o
and it doesn't look like too many components and maybe even bi-polar caps>??

So anybody up for a project? I have Holm RTA REW a nice focusrite DA , calibrated mikes old 50mhz scope ,etc.

I'm thinking, just pull the board, put a R that matches the DCR of the tweet and measure it then work to get a shelf filter in and upgrade the parts while I am at it?

Few hundred$ would be worththe investment to really amke these beauties sing?

The marking is LA on top and 9A on bottom.

I'm working on a Audio Control LC-5.1300.

Hi all,

I have a pair of Purifi PTT4.0X08 and 4x SB16PFCR-00 6" Passive Radiators for sale. Price is $580 shipped in CONUS + PayPal fees. The drivers are brand new and never installed. Thank you.

The last period I played a lot with output stages. The last one which entertained me a lot was the Warbler which is a more advanced Mofo.
Initially the Warbler was used with 3.4r/88db bookshelf speakers and needed a lot of bias to give out something.
In the meantime the story with the speakers changed and I got something else that has a minimum impedance of 6r and and a lot more spl, 96db.
Now with these I started to really enjoy the Warbler but unfortunately(for me) another used wanted the modules so had to sell them.
So what to do now?
I was simulating since some time a Warbler with a front end and global feedback so it was time to put it on a pcb.

So this one doesn`t need a preamp in front of it.




Here you can see the modules assembled. The ones from the right are A2Cmx-V power supply filters and negative rail generators.
The amp requires a positive high current power supply and a negative low current one so the A2Cmx-V takes anywhere between 16-32Vdc on its input and gives ~3V less on the high current output and -30V on its negative output.


Here you can see the noise on the output of the amp when powered with laptop brick smps and A2Cmx-V


Initially I went for too much open loop gain and feedback that gave some ringing


The problem was solved by increasing R13



So now was time for some thd testing to see what I get.

With 2A bias you can get a bit more than 10W/8r at quite low thd


For 10wrms a 20v power supply is enough though a bigger power supply voltage will give better thd performance so I opted to do the testing at 29.5V

If you need more power then no problem, you can increase the bias to 3A which will get you 29W/8r which with the right speakers(like in my case) can bring down your roof.







If you don`t dissipate more than 40W you can use to247 devices instead the so227 like I used.

Here is a pic of the amp at work.

The inductor in the picture has 150mH/0.7dcr/4A but actually does 3.6A before starting to saturate. These were quite cheap when compared to hammond, I think half the price.
Depending on the needed power, a 2a/70mH choke is the minimum that can be used with this project, or at least this is what I seen when simulating. I have only these 150mH inductors for test.

If you listened to the Mofo you know already how nice and warm sounding it is, this amp comes close to it but at the same time it has much better control of the speaker.

I'm building the streamer using these instructions



However, all I need is a spdif out to the DAC.

I understand that I can use the TransportPiAES board instead of the HDMI board. But I'm trying to cut costs - can I use the TrasportPi MkII instead? The author mentioned it, but it looks like it's a different shape. Will it fit? Or what can I use for the spdif out with this configuration?

Thank you
Ken

I’ve spent my life using audio gear and servicing the mechanical side of turntables but since Covid forced early retirement I’ve become interested in learning more about the electronic side of things, so that’s why I am here.

Hey there!
I just became the owner of a very wonderful Threshold S/200 optical bias amplifier. It is in great shape, but clearly could use a tune up. I have either a very low hum or maybe a static noise, it's hard to tell. This is through 98db speakers, so they are a bit sensitive. This may just be a limit of the power supply, but I am ready to learn about this amp.

One major issue is the lack of a printed schematic or service manual. It would be extremely helpful for those who need to update their amp as things get out of spec.

Are there any capacitors that fit exactly where the the Mallory caps are? Diameter seems easy, height less so. If I just need to search, I can on Mouser and Digikey. Just hoping for an easy solution.

Is there really any point in replacing the tantalums? Depending on the schematic, they seem to be used just fine.

So far I was able to set cold bias and temp. Both of those readings are good.. Dc offset seems high. I should have recorded them, I will tomorrow.

I realize now that I must get many tests done tomorrow and update this post.

Hello everyone,

I'm an audio enthusiast with a deep passion for high-fidelity sound and DIY audio projects. My journey into the world of audio started with a love for music and evolved into an obsession with high-quality playback, digital-to-analog conversion, and building custom audio systems.

I have a particular interest in DACs, streamers, and high-resolution audio, especially working with ESS Sabre chips, Raspberry Pi-based streamers, and Ian Canada components. I'm always looking to optimize my setup, explore new technologies, and learn from the experiences of fellow audiophiles.

I'm here to share ideas, gain insights, and collaborate on projects that push the boundaries of sound quality. Looking forward to engaging with this amazing community!

Best regards,Riccardo

Hi all.

Originally I was looking to build a double 12" sealed woofer enclosure to go between my BMS 18n862 sealed subwoofers and, perhaps, multiple types of midrange and tweeter combos in a separate enclosure. But I got interested in passive cardioid enclosures after looking through several threads.

In my use case the requirement is 100hz to 300hz/500hz, but the wish is 80hz for low end extension. The specific dispersion goal I'm not fully sure about yet.

The options for woofers I shortlisted for the sealed version was: SB Acoustics SB34NRXL75-8 and Oberton 12NSW600, but after reading about the The Bitches Brew Open Baffle Live Edge Speakers by Perry Marshall I started to wonder if perhaps woofers optimized for open baffle use would make more sense in this case.


For the sake of a more general discussion though my question boils down this:
What would be considered an optimal woofer for a passive cardioid enclosure between a subwoofer and midrange?

Hi:

I am new to this forums here at DIYAUDIO, I found this site searching help for some issues I was having with speaker's crossovers.

Now, I have learn a lot from you all, it's been really nice, and this have encouraged me to experiment and learn more.

I recently purchased a XY LM3886 amplifier kit at eBay. It is composed of 2 amplifier boards and a regulated power supply unit. I have attached a picture of the actual kit I bought. I have not received it yet, but I want to know your opinions about this kit, and if there is anything to improve it.

I also purchased a ALPS potentiometer for it, I have seen that they also sell "speaker protection boards", do I need one of those?.

I also know I will need a transformer, I was thinking about a toroidal from Antek, the AS4222 22V 400VA, is this OK for this setup?.

Thank you very much.

Currently I have an original M&K MX105 (push-pull dual 12") running off a newer Dayton 250watt plate amp. My music system is in my mostly open basement (1000sqft). I would like to upgrade to dual subwoofers for better bass balance but am not sure what would be the best for my system. I have mostly fullrange-ish tower speakers, listen to all kinds of music fairly loud (mid 90s db avg) (mostly rock and classical, but honestly all genres). It's been really hard to find a used MX105 but I can find MX125s a bit more often (maybe just higher power handling but not sure what difference is). I was thinking of getting a used MX125, replace the plate amp to a matching Dayton 250watt or getting two SVS SB-1000 Pro subs (with dsp). I would have to sell a bunch of stuff (include the current M&K) in order to afford the SVS's.

Even though the M&Ks are much older and lack DSP, just one has two 12"s and a box more than twice as large as a single SVS SB-1000.
Would the SVS be comparable in output, midbass impact, etc?

I can afford about $600 now, but as mentioned, I would have to sell a bunch of stuff in order to get two SVSs. I prefer sealed box sound.

What do you think would be the best choice? Another 30 year old and slightly different M&K or two SVS's?

I was wondering if anybody had some kicking around they could trade or sell. I have four but need more.
Cheers.

Hello everyone.
I want to make a very low-noise linear power supply, 5 volts and up to 1 amp.
I've been thinking about integrated circuits like the LM78xx or LM317, but I'd rather put two or more in series to combine their ripple rejection and the low noise of both.
For example, an LM7812 followed by an LM7805.
Can the 70 dB ripple rejection of each be combined?
Just curious.
Regards.

I’m building a switch box to do A/B comparisons of two amplifiers as well as two preamps. I’m including a diagram of the relay contact assignments of the relays that handle the audio signals that I am routing through the device. The two selector relays (3 and 4) are turned on/off remotely from two different remote control units. At this point I have the preamp relays (4 and 5) wired up and switching properly from its remote unit. The signal path is correct and I am able to switch between two preamps, but there is a loud pop each time signal relay (5) turns on or off. Using a scope (without a preamp attached), I’ve measured the spike going into the RCA plugs of my device at the moment of the relay switching and it ranges from 50mv to just under 200mv and lasts 250-300ms. If these spikes indeed account for the popping noise they shouldn’t be enough to harm a speaker, but they are quite unpleasant.

I have 1N4148 flyback diodes across the 12v voltage input pins of the relay, but I’ve actually tested for the surge without the diodes and it is about the same. My best guess is that voltage from the switching pins is able to jump to the signal pins. I would have thought that they would be well isolated. I’ve tried installing .5uF caps across all the connections (power and signal) but hasn’t helped.

Is there any way to fix this problem?

Is the problem that 12v relays are too high powered for my application? I haven’t found any 5v 4PDT relays in the format that I’m using now. Low power relays signal relays could potentially work, but that would completely change the design and scope of the project. Or is there something else that I could do to supress the pop?

I’m attaching a diagram showing how I configured the relays and a couple of photos of my build so far. I’m really a beginner with this stuff, so please please excuse any shortcomings. I welcome any advice you might have regarding anything in this design since I dreamed this up on my own. Thanks, in advance, for your help!

--Jonathan

Hello everyone,

I’ve recently started a company focused on high-impact house parties and drum & bass rave events. With a background in software engineering and a love for system design, I’ve been diving deep into live sound, especially subwoofers, and I’ve come up with a novel solution I’d love to share and get feedback on.

For my last event, I built and deployed a 20 Hz tuned tapped horn to deliver deep sub energy from 20 to 50 Hz. As you probably know, tapped horns are monsters when it comes to efficiency and SPL per watt. But they come with a tradeoff: they lack transient clarity and can sound sluggish or boomy compared to sealed or front-loaded designs.

That’s where my idea comes in.

I’ve thought about a modular correction system that adds a small secondary driver into the horn path, which is fed a predictive, DSP-shaped signal designed to:

• Sharpen transients
• Cancel low-end ringing
• And tighten up timing below 60 Hz — without sacrificing the tapped horn’s natural output

The correction driver acts more like a subwoofer tweeter injecting carefully timed bursts or phase-inverted pulses to clean up decay and enhance punch. Think: servo sub tightness inside a horn-loaded monster. The driver will be smaller with a smaller MMS.

It will be DSP-driven, with a signal split and tuned either manually or with a convolution-based predictive model. Long term, I want to open this up to the community, make it modular, and maybe even build AI-driven tuning tools to match different horn alignments.

Would love to hear your thoughts — has anyone tried anything similar? Interested in collaborating on testing or refining the idea?

Thanks!

I am currently in the process of building my Mechano23 speakers.
So far everything has been going decently smooth. However, before entirely sealing the box I wanted to test the crossovers.

When testing the speakers everything was working fine. However, with the the box sealed using clamps and the crossover attached to the box. I noticed the tweeter started making a cracking noise when playing at higher volumes. After some re-adjustments of the joints I noticed the mid woofer was doing the same and the cracking in the tweeter had almost entirely stopped. After some thinking I presume that the issue is caused by a combination of bad joints on my crossover and internal vibrations.

The attached image was taken before the entire circuit was soldered. But for all the joints I twisted and then soldered the wires.

Could anyone provide some tips or help on how others have tackled this issue? I want these speakers to last a long time, so I want to make sure I do it right.

Thanks for the help!

Hello there everyone,
I have never installed or used software for drawing electronic circuits.
For an upcoming - simple amplifier project, I am going to need to learn & use circuit drawing software > to present the project to the DIY community.
I would be very grateful for any recommendations or advice regarding this.
Thanks in advance,
Mark

Hey people,

did some of you made experiences with the B&C 10MBX64 10" Driver? I like the exceptional efficiency eta_zero=3% in the 16 ohm version.

FS: TKD Stereo 50K Linear Taper Potentiometers PRICE DROP!

I have a few TKD potentiometers available. All of them are dual linear taper 50K resistance made with conductive plastic. These have been installed once, but never used. Pricing is $60 for the 2CP-2500 (25mm size) type and $25 for the 2CP-601 (16mm size) type.

As of 04/02/2025:
QTY: 17pcs 2CP-601 50k
https://www.tkd-corp.com/en/products/pot/cp600p-spec.html

QTY: 1pcs 2CP2500-P
https://www.tkd-corp.com/en/products/pot/cp2500p-spec.html

Shipping in the USA is $5 via USPS and outside of the US will be rated based upon location.

Selling 1x pair of very nice sounding Unitran 7U21 SE Output transformers

5K/7K Primary (60/45ma gap)
2,5 - 5- 8 Secondary
6W Output

Taking offers, will ship worldwide

New version of the Universal PreAmp arrived. I've had these on Ebay for years under HVFORLESS. I took down my listing during COVID for personal reasons. Then I noticed a project that kicked up in my absense. A few folks here reversed my board and added a few features. I would have loved to be in on that, but I noticed the thread too late. There were good ideas there. I took a few of those and added some of my own. 100 boards are already in hand, so any good feedback won't show up until the next revision.

• Octal socket on the board for optional tube rectification!! Options on board are now full wave, center tap, or tube.
• HV and LV ground planes.
• Grounded heatsinks for safety and heat dispersion (must use an insulator pad).
• Vent holes where needed.
• Gate resistor in Miada circuit (allows for MOSFET if preferred).
• Additional pads and larger diameters for electrolytic caps to accommodate multiple options.
• Trimmer resistors and jumper moved to more accessable locations.
• Fully scrubbed BOM with alternates listed for most components. Cost reduced with highly available parts.
• Optimized layout. Routing on top side with few exceptions, and no VIAs.
• Same 4" X 6.25" footprint and 2 ounce copper.
• Trace widths optimized for worst case currents with at least 50% safety factor.
• Spacing and isolation optimized for worst case voltage differentials.

https://www.ebay.com/itm/146473988873

Greetings DIY Audio forum; I've been in DIY and audio for a long time; nearly a 15 year career in live sound; DIY eurorack synthesizer builds of others design and aspirations to put together original designs eventually. I originally learned I was into all this apprenticing for an old hammond organ/original synth repairman; and have a passion for that original analog circuitry and resulting sound. Also Tape. Tape stuff is really cool. My biggest problems are usually finding enough time; the patience for surface mount soldering (when required) and some of those "well I never had to think about that - rats, wish I'd have known" kind of situations - which will probably be a decent amount of my posts here - the idiot checks and asking for input on how to improve a design before I go stubbing my toes over it. Can't wait to make more cool stuff!

Hi everyone! I'm an old professional woodwind player who loves audio. I do semi-pro sound and recording. I have 4430 JBL Studio Monitors, JBL mains, Mackie 450s, Marantz 2252B, Soundcraft Ui24, Tannoy bookshelf, assorted microphones, etc. In the 80s, based on jbl literature, I designed and built a high-frequency box containing two jbl 2105 and a 2405. I'm using a 3106, 8khz crossover for the 2405 and an aftermarket 500hz crossover for the bottom. I came here for advice on rebuilding the high frequency boxes. I plan to couple it with JBL 4430 which has a 2235 15" woofer. It has the sweetest bass I've ever heard.

Hello everyone, I came here looking for tips or ideas for fun electronics. I'm a fan of anything that runs on electricity, including appliances, computers, cars, and industrial controls.
Greetings from Mexico

Howdy gang,
Not quite sure of the words to describe my issue but I’ll do my best. I’ve also attached A Video Here which shows the problem in action.

The Cd player has been in my dads loft for over 20 years at least. We switched it on and when we tried to open the tray there was a jittering mechanical sound and it didn’t open at all. The belts were disintegrated so we replaced them, now the tray opens and closes smoothly. But when it closes fully, the jittering happens again.

Not sure why it’s happening.
The little switch that the end of the white plastic thing pushes when it closes does work, as if we trigger it with a toothpick before it starts moving, that part doesn’t move.

Little bit hard to describe but the video should help.

Any advice or ideas would be super appreciated as we’re at a bit of a loss of what to do next.

FS: Complete Drivers and original crossover to build the Dynaudio Finale speaker kit. I was saving this kit for build this great speaker, but frankly I won<t have the time, neither the space to use them, so my lost is your luck. This kit is long gone, impossible to obtain, I bought the drivers and the original Dynaudio Crossover over a period of 5 years, way back then.

READ CAREFULLY: Both the woofers and the passive radiators had their original foam surround destroyed, but was able to source the original Dynaudio replacement rubber surrounds. I had both woofers reconed by a professional in Montreal, using these rubber surrounds, so both are back in perfect condition, BUT>>> Both passive radiators still have their damaged foam surround, and need to be reconed. I have the replacement rubber surround, still in their original packaging, and it is quite easy to replace the surround since their is no voice coil to carefully align on passive radiator. SO YOU<LL HAVE TO DO IT yourself, (DIY you remembered 😉

So the kit contains all the drivers, in the original Dynaudio packaging, drivers where never installed, were stored in perfect condition, and boxes where rotated over the years to prevent any damage to the suspension. Drivers are virtually new (except for the passive radiator surrounds...) READ>>> What is missing are the <Variovent> ports, as listed in the kit documentation. I asked Solen in Montreal and they said it is quite easy to build using a simple round plastic ventilation vent, and add a few sheets of loose absorbent material, such as the losse felt inside speakers. It is just a loose restrictive port, such as a normal port stuffed with loose foam. Quite easy to build...
See discussion here: https://www.diyaudio.com/community/threads/closed-box-vs-aperiodic-box-variovent-dynaudio.408624

Kit Contains:
-2X Dynaudio Esotec D-260 tweeters
-2X Dynaudio D52AF Dome mids
-2X Dynaudio MW150 Mid-Woofers
-2X Dynaudio 30W100 XL, 4 ohms woofers
-2X Dynaudio 30W100 SL passive radiators
-2X Dynaudio original rubber surrounds, to repair both passive radiators
-2X Dynaudio Finale Crossovers, assembled
-Kit documentation kit enclosure drawings, etc...
Not included Dynaudio Variovent ports

I have tons on pictures, showing all drivers, I posted here only a few to show you how nice they are.

So you just need to build the enclosure, recon the passive radiators, and you"ll have a pair of great Dynaudio speakers costing easily 5k$ and more!

Shipping is possible, and would need to be done in probably 2-3 separate boxes (I already have the boxes). Local pickup in the Montreal area is also possible.

Asking 700U$ or 1000$ CAN, plus shipping (and 3.5% Paypal fee if outside of Canada), within Canada EMT bank transfer (no fee) or cash in person accepted.

This price is way under what I paid, just the crossover pair was 200U$ at the time, on ebay

Thanks for looking
SB

This amp is in for repair, in circuit test are blown output, amplifier has power but going on protect. My problem is I’ll like to know the part number original or solid substitute for the output mosfets.

Hey guys, I just started planning my first DIY speaker build, so I'm a complete beginner. To keep things easy I want to build a little active desk speaker with a full range driver. It's supposed to be a standalone speaker without a subwoofer. I'm also aware that I won't get a lot of bass from such a little speaker. I'm already set on a 2.8 liter housing as well as the amplifier (Acrylic Up2Stream amp). The only thing I'm not really sure about is which driver to choose and whether to go closed or ported.

For the drivers I'm considering one of the following but I'm also open to other suggestions:

• Markaudio Alpair 5.3
• Tang Band W3-2141
• Dayton RS100-8
• Dayton PS95-8

Which one would you recommend?
Thanks a lot, appreciate the help 🙂

I have various items of hifi separates dating back to a Dynaco valve amplifier from the 60's. I try to keep them working and need assistance sometimes, hence my appearance here. The detailed technical knowledge available on the forum will mostly be beyond me but simpler questions do come up........
Terry

There must be a hundred threads about the lm3886 basic implementation. Some good, some awful. Wouldn't it be nice to have a fool proof pcb-schematic-BOM set we can refer beginners to ? Maybe not the ultimate fidelity or the most tricked up design ever but just a solid, decent performer ? The pcb would provided as tested gerber files.

Here's a first suggestion up for criticisms/improvements. It's based on a smaller smd design which works quite well in practice but for a simple board I moved everything back to through hole (except for the muting resistor).

Nothing extravagant. A few options are provided for the input cap and the output/PS connectors can either be screw terminals or faston. The board is 65*50mm. All electrolytic caps are sized for 50Vdc caps. The resistors at the input are 125mW, the ones in the feedback network 500mW.

Final version:
I leave this first post pretty much untouched but the layout attached isn't perfect yet of course. The final version can be found here: An open source layout for the lm3886 ? - Page 6 - diyAudio

Eagle and gerbers files:
The files are attached to post #235, as I cannot attach them to this first post anymore.

OSH Park links: OSH Park ~ (amp) - OSH Park ~ (psu) - OSH Park ~ (dc protect)

Acknowledgement:
- This layout for the lm3886 has been made possible by the wealth of information given by Tom Christiansen, on his website neurochrome.com and on this forum (see especially this seminal thread, among many others).
- In this thread, I'm particularly indebted to the contributions of Mark Whitney and bozoc who pushed things in the right direction and corrected me when needed.

Sorry removed

Hello everyone.

I started making sound systems in 2019.
Last year I installed a CNC and are making speakers in 3D CAD using fusion360.

I feel that here is at the cutting edge of sound system research.
I am very much looking forward to reading your productions and discussions.
I would be happy to contribute to the accumulation of knowledge, even if in a small way.
Best regards.

Here we have an AU217 old model that in one case shows approximate voltages to expect during service which is not shown on service manual. As a former Sansui Authorised Service Center (1980~1990 steel city PA) I sort of remember some of the amplifiers service bulletin. This Amp used a 2SD188 and 2SB545 complementaries for outputs. Sansui used 2SD358 and 2SD528 as drivers. While it works, a service technician could substitute drivers by 2SA and 2SC type drivers.
Voltage reading at each transistor point approximately are as follows. Notice that I have used three 1N4149 type diodes as opposed to two 1N4148 often mentioned in various forum. Remember this Amp uses two DC rectifiers from the same AC source. For this design simplicity I have connected the Voltage Amp and output section to relay on the same DC power source. This unit has no DC offset pot but can be trimmed using R13.

What is you could not find the 2SB545 version or the 2SD188.
In this case you can easily modify the amplifier to use either NPN or PNP outputs only. You just need to rearrange a couple of components. See example below. I have done this for years, especially amplifiers that are heavily used in production, field music shows such as Bluegrass festival.
Here is an Example: -

All componet values are the same except I changed Q6 to 2SD188. Notice where I placed R41. It is now connected to the collector side of Q15. Q6 emitter and collector connection wires have to be reverces as well. That is it!

The structural diagram of the dual-channel 200W PWM DAC with ADAU1452 chip is shown below.



The board looks like this.



Measurement results, R load=4R, Vcc=48V.





Performance parameter PWM DAC:

• Output power: 200 W per channel, with a 48 V supply and R load = 4 Ohms.
• Speaker impedance: 2 - 8 Ohm
• Frequency response: 20Hz - 20kHz
• THD: less than 0.005% on 8Ohm load, and less than 0.008% on 4Ohm load
• SNR: 105dB(A)
• Spdif Input : 16-32bit 44.1-96kHz
• Spdif Output : 16-32bit 44.1-96kHz
• I2S Input : 16-32bit 44.1-192kHz
• Power supply: DC 12V - 48V/ 5A-15A
• Consumption power: Idle mode 16W, sleeping mode 2.5W
• Efficiency - 83%

The board in idle mode consumes 16W, which requires the use of a radiator with an effective area of 400 square centimeters. It is not recommended to supply 48V to the board without an additional radiator.

The price of one board is 95 US dollars.

Shipping at my expense.

Only two boards are available.

A starter project for Sigma Studio is attached to the message.

First off, I should start with a disclaimer saying THIS IS MY SECOND DIY PROJECT!

I am most certainly aware that this forum is full of much more knowledgeable, experienced folks, and I guess that this is exactly the reason why I am even posting this thread.

So, after this far too long prologue, let's dive right into it.

I have been lucky enough to get my hands on a couple of JBL 2206H drivers and an Eighteen Sound HD2000. A friend of mine owns a sound system, and these drivers were once part of two PA loudspeakers that are no longer in use.

The idea for this project is designing a new enclosure—one that would house the JBLs with a ported baffle, the HD2000 mounted freely on top, and a folded 15-inch subwoofer. ATM im looking at any subwoofer i could find aroung 120$ a piece (I'm on a low budget for this project)

I am looking for any tips, subwoofer suggestions that are budget-friendly, and anyone with experience who would love to give me good advice, etc.