The following is a collection of emails between Bruce, creator of the Oddwatt amplifiers, and myself regarding the general build of the Oddwatt amplifiers (Particularly the Odd Blocks) found at DIYaudioprojects.com. Bruce had been so kind in assisting me in the build of his design and has written multiples of responses to my questions over the past several days. It began to dawn on me that this was some very good info and all of it was private, address to me alone. I asked Bruce if he would consider allowing me to create a post on the forum and continue to answer all of my questions there so everyone else could see and enter in if they wish. He of course agreed. Below is a cut-and-paste of our email conversation to date with the last question directed to him. Please allow Bruce to answer it before others join in and then we can go from there. Thanks again Bruce for your time, patience, and assistance in helping build the really cool design.

P.S. Bruce has a website (Oddwatt.com) where he sells this amp in a kit. He also has a really cool new budget amp that will be coming out soon, the Poddwatt.

7/11/09 – My first question to Bruce RE: Building the Oddwatt / Oddblock amps

Bruce,
After much discussion with others and contemplation/study of your Oddwatt designs I have settled that I am going to build it. I am going to basically build the KT88 version on a single chassis with a separate PSU like you did with the KT77 amp. I realize they are basically the same with the exception of the 12 vs 6 series tubes and corresponding component values on the pre side of the amp. I had several thoughts about these two designs and was wondering if you would give me some advise. Fist is which do you prefer the 12 or 6 series tubes on the front end of the amp? Second, I found an industrial grade Hammond power trafo unlike anything I have ever seen before....it is massive and produces 250VA with 117AC primaries with a secondary winding that has 0-200-230-460 taps (could be used as a 230-0-230 if the 0, 230, and 460 taps were used with the 230 as the 0 CT and the 0 as one 230 and the 460 as the other 230) It should have plenty of power to run the 2 channels of the KT88 arrangement (I think) My question is could this be used with a few adjustments in the resistors in the PSU to give the desired B+ voltages? I haven't sat down to calculate them out yet. Last question is could I get all of the parts from you and your partner sans the trafos, chassis, and power resistors I will have to change out and tubes? It would save me time in acquisition but if you can't I would certainly understand. I have spent alot of time wrapping my brain around how your design with the LM317 and self-inverting circuit...it really is cool! Did you ever get around to building it with a FET in place of the 317? What kind of 25R pot did you use for the balancing circuit? It seems to me this should be of the highest quality. Please let me know what you think. If you haven't yet tried the FET I may try to figure it out in this one.
Thanks for your time and help.
Sincerely,
Jeff Miller
Lawton, OK USA

Hello everyone!

I want to build sealed studio monitors based on ATC drivers, but I'm not sure which drivers to choose. I have a few questions:

Midrange: Could someone please explain the difference in sound between the ATC SM75-150S and ATC SB75-150 SL? Are there any advantages of one over the other?

Tweeters: I’m considering the Seas Excel T25CF001 or T25CF002-E0011 tweeters. I know the T25CF002 is better, but I’m unsure if it’s worth paying twice as much for it. Any advice (or other tweeters)? Scan-Speak D2608/9130?

Low End: I plan to use two sealed subwoofers. Does it make sense to use the ATC SB75-314 SC, or would it be better to use the CSS SDX10 XBL2 or CSS SDX12 XBL2? Or other low distortion sub drivers? Acoustic Elegance SBP12?

At the moment, I’m thinking about the driver configuration like this:
Seas Excel T25CF001 or T25CF002-E001 - ATC SB75-150 SL - CSS SDX10 XBL2 (subwoofer)

Appreciate fo any advices! Thanks!

Hi gents ,
Picked up some mint condition 104/2’s which sadly have the wrong tweeters ( NT25 sp1413 ) instead of the T33 .
As the T33’s are unobtainable others have apparently used the morel mdt 29 or even the mdt 30 as a successful replacement . I have some mdt 30’s here but they’re 8ohm not the 4ohm as per the original T33 ( I think).
Is there something I can do with my 8ohm tweeters to not upset the crossover in anyway ?

I drove this thing until the former bottomed out (oops)….

Would port size issues and turbulence show up in a way I could recognize it with this measurement(s)?

Just received a pair of Goldwood GW-1558 15" woofers and decided not to add the bass driver to the same baffle as treble/mid driver for my open baffle project.
95.6dB/ 8 Ohms, QTs 0.63, Fs 31Hz, Vas 14.12
So I will likely have a separate open baffle for the Goldwood, rear-mounted, and I seem to recall slot loading with opening about 1/3 of driver area may improve the bass performance. I've seen people use rectangular slot for other woofers rear-mounted on open baffle, so I'll try that first.
Anyone ever try slot-loading Goldwood woofers with success?

​

NOTE WELL: this is not a big deal

In the Swap Meet forum, you can select to see only WTB or FOR SALE postings (very useful).
It looks to me like MOST of the unwanted posts are missing, but a few seem to slip through.

https://www.diyaudio.com/community/forums/swap-meet.2/

In the image below, you can see the first post and the last post appear as "WTB" even though I have selector set to "FOR SALE"


Many thanks to everyone keeping this the best publicly available forum on the Internet.

Kind regards,
Drew

It's a closed box speaker, connected once through a 20 ohm resistor, then directly to the amplifier. The impedance plots are self-explanatory.




The distortion measurement shows the harmonics in the current to the speaker. Once connected via the series resistor, then directly on the amplifier in the overlay.




Have you ever measured current distortion on a loudspeaker?

Hi everyone,

I'm trying to repair a Pioneer DJM 600 mixer, which has a really bad and "off" sound... I've desoldered all the rotary potentiometers (they're Alps, I believe...) and cleaned them by completely disassembling them, but they're really worn out, and the result is not conclusive.

Before cleaning, they were giving off really loud crackling noises... after cleaning, no more crackling, but the sound is scratchy on the high frequencies...

So I'd like to replace all the potentiometers, but the cost of original replacements is really too high...

Can anyone help me identify a compatible replacement?I'd need both the ones that control the HI - MID - LOW frequencies (Pioneer Code dcs1054 djm600 gain DCS-1054]And the one that controls the gain (Pioneer code: DCS1053)

Could they be B10K B103 from (10kΩ-B)? but of what type? 12 are needed that lock in the center (hi - mid - low) ... 4 are needed that are linear ...

Can anyone help me please?

PS: is it necessary that I attach the sound coming out of the speakers?

PS2: I attach photos of the official spare parts... one potentiometer costs from 10 to 25 eur

thank you in advance

Here's my on-going Mini LM3886 Stereo Project. using SMT 1206 for easy DIY assembly and reduced PCB size.
The design includes, Power Supply rectifier and Speaker Protection. Preamp will be added later.
I am assembling the prototype then testing, Gerber will be available open source.

Hi all,

I have quastion about Mundorf capacitors.
Anybody try the M-Cap Supreme series Vs M-Cap Supreme Silver/Oil and the M-Cap Supreme Silver/Gold?

The difference in price is very big, and is really worthy for the price?

Anybody try it?


Thanks

Hi Everyone. I'm brand new and learning about the audio world. I've been in the computer industry for over 20 years with all of its quirkyterms. But the terminology in this area is really cool. I'm looking forward to reading and learning mainly about photographs and speakers.

Hello all,

could you please explain what is the difference between the models in the subject? The website is not showing anything obvious on the topic, front panels looks similar, comparing specs is somewhat laborious and gives counterintuitive results. Please answer, if there is someone who has experience.

Thank you,
A.

Some of us prefer non-oversampled(NOS) DACs, while others prefer oversampled. Whichever you prefer, it's my sense that most audiophiles can hear that there is some sort of characteristic difference between oversampled(OS) and NOS DACs. The overriding subjective characteristic which I hear from NOS is, an immediate and obvious sense of psychological (hence, physical) ease, while OS DACs too often sound subtly annoying, or, what’s almost as bad, boring, I find that there remains a subjective advantage for NOS, in terms of dare I say, a vinyl-like musical ease, over most OS DAcs. I don’t readily notice that such ease is lacking from OS DACs, that is, until I switch to a NOS DAC. Not everything, however, subjectively favors NOS over OS. For example, to my ears, OS presents a much wider soundstage, albeit not as deep nor as 3D as NOS presents. In addition, NOS bass tends to sound relatively unfocused, for lack of a better term. The bass is fully present in terms of energy, it’s just not as punchy or coherent sounding as OS bass.

There are well understood reasons for the OBJECTIVE technical differences. Prime among these are the repeating image-bands, ALL of which are ultrasonic, so, are not only inaudible to the human ear, but are not reproducible by most loudspeaker tweeters anyhow. The lowest image-frequency enabled by the CD standard begins in the ultrasonic, at 22KHz, but CD standard recording anti-alias filters usually only maintain flat signal response up to 20KHz, which means that the lowest flat (non-rolled off) image-frequency is: 44.1KHz - 20KHz = 24.1KHz, which is even further in to the ultrasonic.

Another technical difference is the infamous NOS band-edge response droop of -3.16dB @ 20KHz, which is due to the SINC aperture inherently produced by Zero-Order-Hold (sample then hold) multi-bit NOS DAC operation. However, this droop is also largely near the ultrasonic. Also, while it does rapidly decrease in effect with decreasing frequency, it should be noted that uncorrected, the droop’s effect extends all the way down to 5KHz. However, the droop is easily corrected via simple analog-EQ without harming the NOS character. There are other less gross technical effects as well, such as a decreased in-band quantization noise floor for oversampling. Also, some there’s some differing jitter character between OS and NOS.

I want to make it explicitly clear, that I’m not expressing any set preference for NOS over OS. The issue here is not that one may sound better than the other, but rather, why do they sound different at all? A particularly perplexing matter with sounds that fall well short of the upper frequency band-edge, within the midrange. Such as it does for the human voice. For sampled audio signals, the lower their frequency, the higher will be their ultrasonic image frequency. So, we’re talking about image frequencies far in to the ultrasonic for vocals. I want to emphasize the point that the audible difference between NOS vs. OS persists even with lower frequency content that have no overtones near the OS filter’s ultrasonic cut-off. Maybe there are intermodulation effects being produced by some stages in the subsequent amplification chain in response to unsuppressed image-bands. However, he NOS character persists even when the DAC’s output signal is passively band-limited to prevent that.

The only explanation I can readily come up with that fits all of the observations above is inadequate implementation of an OS DAC’s on-chip digital interpolation filter. Which was long ago identified by researcher, Lagadec, as producing odd time-domain artifacts not present in sampling theory. Evidenced by the seemingly inconsequential, uniformly repeating, frequency response ripples, manifesting across the entire pass-band of almost all on-chip interpolation filter implementations. To be clear, these ripples are NOT the familiar and overt, impulse-response triggered time-domain ringing of an FIR interpolation filter. They are very shallow, frequency-domain ripples which appear inconsequential to the eye when seen on most OS DAC’s on-chip digital filter’s pass-band flatness graph. If that is the reason for the subjective difference between OS and NOS, then perhaps, NOS is how OS DACs SHOULD sound, and would sound without having certain processing artifacts of typically implemented, silicon co-resident digital filter design. That, however, is only speculation.

What is YOUR thinking on the technical reason for the subjective difference in character between OS and NOS DACs?


HELPFUL THREAD LINKS: ---===========================================================================================
1) Initial Suspect List. Post 153: https://www.diyaudio.com/community/...os-sound-different.371931/page-8#post-6654353

2) Reconstruction/Image-Band Handling. Post 344: https://www.diyaudio.com/community/...s-sound-different.371931/page-18#post-6668363

3) Comprehensive Results Document for 44.1kHz, 88.2kHz and 176.4kHz Resampling Experiments. Post 1773: https://www.diyaudio.com/community/...s-sound-different.371931/page-89#post-6775491

4) Suspect List, with item assessments added. Post 1149: https://www.diyaudio.com/community/...s-sound-different.371931/page-58#post-6734286

5) Implicated Suspect Category. Post 1192: https://www.diyaudio.com/community/...s-sound-different.371931/page-60#post-6736142

6) Filter Signal Echo/Reflection Experiment Introduction, and Results Analysis. Posts 1043, and 1518: https://www.diyaudio.com/community/...s-sound-different.371931/page-53#post-6727251
https://www.diyaudio.com/community/...s-sound-different.371931/page-76#post-6761338

7) Investigation Concluding Report. Post 1783: https://www.diyaudio.com/community/...makes-nos-sound-different.371931/post-6777645

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

8) Frans Sessink’s Settling-Time Error Mitigation Presentation. Post 229: https://www.diyaudio.com/community/...s-sound-different.371931/page-12#post-6658063

9) Marcel van de Gevel’s Dither paper. Post 1720: https://www.diyaudio.com/community/...s-sound-different.371931/page-86#post-6770852

10) Improved, ‘Sonic Scrambling’ Subtractive Dither Concept, Developed by Marcel van de Gevel and Hans Polak. Post 1692 and 1756: https://www.diyaudio.com/community/...s-sound-different.371931/page-85#post-6769819
https://www.diyaudio.com/community/...s-sound-different.371931/page-88#post-6773204

• Remastero's PGGB-RT: A Free, High-Performance Interpolation-Filter plug-in for Foobar2K. Software-Tools sub-forum. PGGB upsampling software
• Announcement of new and improved higher precision 64-bit version of PGGB-RT Foobar2000 plug-in module. https://www.diyaudio.com/community/threads/pggb-upsampling-software.376376/page-2#post-7316157

Hello guys,
I'm Jimmy from Indianapolis, IN. I'm a electronics hobbyist that got into the hobby 5 years ago when I bought a Arduino. I've built a bunch of class A pre amps and recently got into power amplifiers. I'm glad to join this forum

Hello everyone, another enthusiastic hobbyist here, trying to learn as much as I can. Greetings to all!

I note most of LJM amp boards use the Polymer electrolytic capacitors for the Input capacitor? ( I am assuming the one I show is one?) The value seems to be 33uF, obviously not easily swapped for a film type due there very large size at this value. From what I have read they are considered be quite good sound quality-wise and superior to any Electrolytic types even Bi-Polar? QUESTION: How do I find out what actual type this is please?

Hello,

in my hunt of filtering USB i wanna try this:

a usb C to C cable with something like this on each end:


im currently halfway trough designing it, currently it looks like this:

- Data
-- Common mode choke on usb lines (i just found out ferrite beads are forbidden by usb specifications, so probably not much more i can do here?)

- VBUS
-- Pi filter with ferrite bead and 1uF on either side, only 1uF because usb specifications dont allow more than 10uF

- GND
-- i kinda wanna try the same ferrite bead here as in the vbus line, while its usually not recommended there are some scenarios where it could be beneficial

- Shield
--
there are some schemes, cap, ferrite bead, connected trough, disconnected....

i think ferrite bead like in the schematic doesnt make "much sense", a cap seems more reasonable (lets high frequencys trough but elimates ground loops/dc current)
tho, im just sure right now that i wanna make disconnected/connected switchable via solderpad

also there needs to be a shield soldering pad (probably on the backside)



Goal is really to throw as much filtering at USB to isolate the dirty PC, as long the eyepattern holds up there shouldnt be a problem with the data delivery, tho some could argue that ferrite bead in the power line could have some negative effects on bus powered dacs/interfaces, i wanna try this and the ferrite bead is easly bridgeable via solderpads on the backside
instead of spending hundreds of dollars on fancy usb cables that have different RFI/EMI pickup and therefore sound different i find this option much more reasonable (tho dont get me wrong, the cable will probably still matter a bit, im currently fairly happy with his one: https://www.audiophonics.fr/en/digi...pper-ptfe-double-shielding-o78mm-p-11077.html )

Do you guys have any ideas/opinions on this? (tho, please keep your "inaudible" claims to yourself)

Out of misery in searching for best driver for my unconventional project, I bought two of these (four if they appear to be good and suited) nice looking drivers.

The looks:
Very sleek, strong looking driver. Heavy duty basket appears to be indeed rather heavy duty, very close to what B&C speakers does with their SW and DS product line.
It looks like a copy in many design parts, and given the outbreak of these 4,5" CCAW strong motor of "eurodrivers" as I call em, it might be so, or some license deal kind of thing.
Apart from basket, the glueing of the dust cap looks somewhat thicker and stronger than what is done on the B&Cs, and tensile leads are made in its own way, which I would classify somewhat worse (pictures and more below). I am not in peace about "which terminals are best", but this time push terminals are used, and I am liking it. Magnet venting is done with fairly medium-thin grille in the center vent, this time similar to what 18SW115 has. The 8 small vents around the coil circumference are guarded by the grille too (inside)
Generally, very nice strong looking well designed driver.





Spider is well soaked in the sillicone, that seeps out a bit:



The mechanics:
Apart from the classic design of B&C, it has somewhat thickenedd dustcap glueing, at first feel I would think the cone is just a tiny teeny bit sturdier.
On the back side, of the gasket, some kind of foam tape is applied, and so it releases the nuissance of putting some on the speaker enclosure myself. Very nice touch.
That´s all basically good news. What´s not good news is the tensile leads. They are guided and bend in a way that does not look like very sturdy. Maybe I am mistaken, but If torture test were done on the B&C and this, I would not bet on LaVoce.



Though general feel is that the customer is getting 95-99% of the originals. Hopefully chinese did not learn the European quality management - must look quality, doesn´t matter what it really is. Yeah, heard that from MANY quality managers. But that´s besides the point.

TS parameters:
Pre burn-in:
One driver Re was 5,05Ohms, the second one 5,0Ohms. Interesting difference. One or two turns of the wire on the coil? Measuring the 5.0Ohm piece:



DMM used is Uni-T UT171B with very good leads and ΔR calibration on the leads/itself. I trust it quite a bit.



At this point to me it looks like 18DS115 on hopefully 18SW115 suspension. My 18SW115 clocked at 36,89Hz pre-burn-in. That would be the most awesome combo LaVoce could put together. What I or almost anyone would want from this driver, is to behave well into excursions of about 16mm. If that appears to be true, it makes this driver immense value choice over competition.

No conclusions yet, but the initial feel about this driver (except for worse leads) is very impressive.
After burn-in measurement on weekend.

Ok, since the email asked for me to tell my story, I'll bore you all with a bit of it. As I mentioned in the title, I'm an old-timer with decades of electronics and software experience. I have a nice workshop and electronics 'lab' where I can repair just about anything. Job-wise I started at Hammond Organ Co in the '70s, then on to Motorola Automotive, then to Quantum Data Inc, then back to Motorola Base Station and ending with CMC Electronics Aviation. Lot's of electronics of all types as well as software since software existed.

I've made 2 of these stands out of plywood for the rear speakers pictured in the background, each stand is filled with sand and weighs about 25kgs.

Since they are going on laminate flooring I was thinking of putting something underneath the stand just for extra protection, I was thinking of lining the bottom with one of the following rubber mat, carpet square, lining with weather stripping, or screwing in some rubber feet.

Probably over thinking the process but since this is my fist time building both speakers and stands I thought I better ask for some guidence on if there's a preference for material or if it really doesn't matter.

To save a double post, ontop of the stand I was thinking of attaching a thin rubber sheet, and then placing the speaker ontop of that, or is that overkill and its fine to just sit the speakers wood on wood.

Hello,
I need help, the R150 and R137 are heating up
R150 tested = 22 ohms and R137 = 470 ohms (i had replaced the R150 with a 4.7 ohms)
Sorry, i speak french only, i use ChatGPT for translation,
Thank you

Hi!
I was thinking on building a passive 2 channel (L/R) soundbar for watching tv and movies and stumbled across this forum, so I thought I might aswell ask the experts for advice 🙂

My plan is to buy a Denon AVR with crossover (X1800H), plus a sub (maybe if this build goes well I will build one).

I only have a 120cm (47 inches) gap for the soundbar (it will be very close to a wall on one side).

The room is about 13sqm (140 sqf), and the distance to the soundbar will be about 3m (10 feet).

I asked deepseek and it came with this recommendations:

• Use 15mm MDF.
• Position full-range driver and tweeter at least 5–7 cm from the sides and top/bottom edges.
• Put the driver and tweeter on top of each other, to minimize interference between drivers and provides better vertical dispersion. Is this something to bear in mind or doesn't matter much in this context?
• Angle the left and right channel drivers slightly outward (e.g., 10–15 degrees) to improve stereo separation and soundstage width. Is this also worth doing if we're going to watch movies in direct line with the soundbar?

It also recommended the following drivers and tweeters (from cheaper to more expensive):
Drivers:

• Visaton FR 10-8 (4 Ohm, 10 W, 4" Full-Range) Frequency Response: 100 Hz – 20 kHz
• Dayton Audio PC105-8 (4" Full-Range, 8 Ohm, 30 W) Frequency Response: 85 Hz – 20 kHz
• Tang Band W4-1337SDF (4" Full-Range, 8 Ohm, 30 W) Frequency Response: 75 Hz – 20 kHz

Tweeters:

• Visaton SC 10-8 (8 Ohm, 10 W, 1" Soft Dome Tweeter) Frequency Response: 2 kHz – 20 kHz
• Dayton Audio ND25FA-4 (1" Soft Dome Tweeter, 4 Ohm, 25 W) Frequency Response: 3 kHz – 20 kHz
• Seas Prestige 27TFFNC/G (H1212) (1" Soft Dome Tweeter, 8 Ohm, 50 W) Frequency Response: 2 kHz – 30 kHz

Are there any better alternatives (available in UK/Europe)? is the difference between the medium priced ones and the most expensive noticeable for just tv and watching movies?

If I build the enclosure deep enough, can I just put the tv on top of it or is this a no-no?

If I use an AVR with crossover I assume I don't need any other kind of electronics, right?

Should I add an extra centre Driver/Tweeter, or just L/R will be enough?

Many thanks for you time!

Hi - I am trying to understand the frequency response of a prototype box I built as part of my Overnight Sensations build.

I'm using the quasi-anechoic guide over at ASR.

When I do the sweep measurement, I never see a clearly defined reflection that everyone refers to. This is supposed to happen around 5-10ms, depending on the room you are taking the measurement in. I've attached the raw REW impulse response graph, and you'll see that there is maybe a spike around 7-8ms, but there is also a bunch of noise between 0 and 7ms. Other graphs I've seen have very little noise and a very clearly defined reflection point.

I'm taking this measurement in my garage, with a calibrated mic on the end of a pole to limit reflections form the mic stand. It is about 5' away from the closes wall and floor. I do live on a noisy street, where you can subtly hear cars at all time, but I'm measuring at a pretty high volume in an effort to improve the signal to noise.

Can anyone tell me if my measured response looks even close to right? Does my setup look ok? Any thoughts as to what the problem might be?

Thanks!

Hi all, I need to remove the dustcap from a subwoofer driver so I can mount a motional feedback sensor in the voice coil.
I found a rather drastic way here https://www.diyaudio.com/community/threads/how-to-remove-a-dustcap.397165/ .
But I really would like to salvage the dustcap to put back after the surgery.
Any idea how to best do that? Soften the glue with a heat blower, or will that damage things?

Jan

I stumbled into some great info here on the problems with these amps and hoping some guys are still around? I am trying to spec the problematic D11 diac on the daughter driver board for the PSU mosfets? It is now black and cannot read it.

If anyone has experience with these, I might have a few other questions.

I'm looking for a small sized and low voltage phono cartridge pre amplifier to be placed inside a Numark DJ turntable. I thought of ssubminiature tubes such as 6N16B or 6N28B, and would like sugestions of schematics of RIAA circuits based on those tubes or other subminiatures, prefrebly with 2 stages.

Hello, I've been interested in speakers since I was a teenager, but never had the funds to indulge. I've recently been scouring eBay for bargains, or spare or repair, speakers to work on. I currently have some Wharfdale Triton and KEF Cresta 2's to play with and have just placed a small order with Falcon Acoustics for some new capacitors to get me started.

Cheers,

Bob.

About two years ago, or so, I guess eBay started to charge sales tax on private sales for used stuff.

Today I bought a tonearm... the price was good, the seller seemed quite honest about the provenance of the arm -it was his- and I made an offer and it got accepted. Then as I checked out, the %&&* added over 100 bucks to the price for sales tax.

Mind you, I had made the offer about 150 less than the original price and even with the sales tax, it came to about 50 bucks less.

BUT!!

Given the that tonearm is not all that common and the price was reasonable I'm not too peeved.... BUT, as I told the seller, it came out of his pocket, He will likely lose 250 bucks or so... if he had posted the tonearm on craigslist, audiogon, audiomart or so, we would have done the transaction differently, I would have paid less and he would have gotten more.

Often times, when I see an item on eBay that I like I'll let the seller know, buy playing around the eBay filtering, that they'd better better off selling it on a different site.

I hate eBay, BTW. I begun using it in Y2K and it's the ONLY place online where I've gotten scammed, twice.

And then they started charging sales tax and issuing 1099s. So, either it's audiogon, audiomart, even Amazon, or nothing.

Hi, I have a Krell Evo 302 with a faulty power supply. Does anyone have a diagram or any information on it?

Very nice pair and working as they should. Asking $200 plus shipping. Thanks.

Thinking about something.
What happens when you tune a box below the resonant frequency by a driver?
The same for above the resonant frequency by a driver?
Is it only the base that is affected?
Thinking of a box that has a base tube.
You can calculate the length using the resonance frequency as a starting point.
If you make the bass tube longer or shorter, the tuning is lower or higher, respectively.
How will the sound be affected if the tube gets shorter and longer?

Some time ago I bought a box of hardware on a second hand site , that contained a Quad 303 enclosure , among other interesting hardware.
I allso had some Quad 405 sinoclono boards and I decided to assemble a Quad 305, which is the Quad 303 enclosure with the Quad 405 boards and a
2x18V toroid , allso found in the box of hardware. To make things interesting I decided to use my small supply of ancient silicon and germanium
power transistors. Those were the BC141/341/361 NPN/PNP transistors the 2N2219A as the class A amp and the germanium 2SB361 as current dumpers
and maybe the AC151. For the opamp I plan to use an allso very old NEC C157c , which is a LM301A clone. All in nice TO-99 and TO-39 housings and the power transistors are TO3,
The 405 dumpers are NPN types , so I have to inverse the layout of the 405. I took the Keith Snook modifications and reversed all the NPN and PNP transistors
to comply with the PNP current dumpers. See attached schematic. I removed some windings from the 2x18V toroid to become a 2x15V transormer, supplying
ca. ±20V to the circuit, enough for a 2x15W amplifier. In the schematic the 1n60p diodes are germanium if I can find them, otherwise I will use 4 of the 8 AC151 I have as diodes.
Question, is this a valid circuit. I tried to make adaptations to the values of R14/15 to get ca. 20mA in the class A stage and R12 to get ca. 0.2 Vce for the 2SB361. Is that correct ?
Because the dumpers are essentially working in class C , I thought germanium transistors are excellent for that, being fragile components. Their (very) low Ft is nicely appropriate too.
I tested the boards with the normal components with the keith snook mods and it works very well on ±26V, with the bootstrap resistors scaled down to 280 Ohm to get to the 50mA
for the class A driver, it delivers 4Volt in 8Ohm resistive load without the dumpers installed, but at that level the driver was starting to release fume, or the cooling paste , I switched off before I could
determine where the smoke originated from.
I plan it to be the stand-in for my 8Watt Taylor T20 based SET amp, that is quite energy hungry, with a constant power draw of more than 100Watts. This one will use hardly 5Watts under normal use. My average listening level is 0.1 to 1 Watt so the 15Watts it might produce is more than enough and is on par with the amps I had all my life , the sansui AU101 and AU117.
I have only 4 2SB361, salvaged from a Nikko TRM-40ic and they are no longer made, so I have to be carefull. Is the reversal of the polarity of the transistors done correctly ?
Is the bridge still valid in this reversed setup and low working voltages and decreased class A standing current? From several sources I understood that for the bridge to be balanced the 500 and 47
Ohms resistors multiplied needs to be equal to the inductor 2.82uH and the capacitor of 120pF divided, which is true for these specific values , but when I read the schematics of the Quad 306 or 606
it doesn't need to be seemingly, because there the equality is far off, or are there other factors involved in the bridge balance besides the values of the two resistors and the inductor and capacitor, like e.g. the gain of the amplifier or the input circuit, which are seriously different between the 405 on the one hand and the 306 and the 606 on the other.
In the schematics , the BC361 pnp is the input of the dumpers gain block. I contemplated using a AC151 germanium pnp there , but the AC151 has half the Hfe of the BC361. Would it be possible to reduce the gain of the dumper block and increase the gain of the opamp, or is the gain of the dumper block of influence on the bridge balance ? E.g. decrese the 500 Ohm feedback resistor to 300Ohm and increase the 120pF capacitor to 200pF. I only need 11V to get to the 15Watts in 8Ohm , so a total gain of 11 is enough for an input sensitivity of 1Volt.
Thanks for reading and commenting, and just to be clear ,I don't expect or want a magical sound improvement because of the use of germanium transistors , just a fun project with old parts, to see if it works and if I understood the workings of the current dumper principle.
Systux

Posting here due to this being a very early PCB revision for the GFA-555. There is no silk screening on these. Back terminals instead of bright red/black are a reddish brown/black.

I picked up this amp from the original owner who claims it has never been touched.

I was using this "good" amp to help me reference and troubleshoot another I have, same early board.

The question is, there is what I assume to be R23 - 22.1k. on the right side, but on the left it is not installed. Amp works fine. Should I put it in there to match the right side?

Not sure if the later schematics I keep running into match this.

I'm looking to buy a 3D printer to make PCBs and considereing an AnkerMake M5 but need to find PCB design software as the package I'm using, ExpressPCB does not allow exporting of a file suitable for printing.
So 3 questions.

1. can you recommend a free software package for PCB design; snothing fancy to design single sided baords is sufficient and would be useful to have a library of components: resistors, capacitores, pads and IC packages.
2. can you recommend a 3D printer - I'm sure that one I list above will do the job providing I can send to the PCB layour files (.dxf? .stl?) to it.
3. have you done this, what is your set up?





I so I'm going to have to look at an alternative.

I am considering lining the inner walls of a bass-midrange enclosure with 10mm hard wool felt (solidity H3 = density 0.6). How should this material be considered in volume calculation - is it porous, solid or something in between?

Hello!

How can one convince the external USB module “Creative Sound Blaster SB1240” and "Audacity" to actually work with 24Bit/192kHz? fh is always exactly at 22k05Hz. Does win11 need a special driver or does the internal digital filter always take care of this limit?

It would be really nice if one practically didn't need any real measurement technology anymore, just a notebook, a bit of software and this external ADC / DAC even with an analog phono equalizer on board.

Does anyone know anything about this blaster?

kindly,
HBt.

Due to the graph is like CA18RLY which has cone breakup high?

Then can I make 2-way? With 91db tweeter vifa XT25BG60-04 which has fs about 600 hz

I'm trying to make an Apex AX11 amp. My knowledge to make a quasi version of this amplifier for comparaison is not sufficient.
Can you help me with a schematic?
Thanks in advance.
Alain

Hi everyone! I'm happy to join this amazing community! I have some good experience designing PCBs and working with sensors and microcontrollers, but only recently I have started repairing audio equipment. I'm also a musician and I'm very keen on learning more about audio and analogue electronics. I hope to make some good friends here.

Thanks!!

Good day everybody!

Happy to join to forum!
I have a lot to learn and am mostly focused on guitar amplification!

Thanks for hosting.

I finally pulled my project aa-50 to take a look at it.
It ran fine all day.
I shut it down.
I pulled each tube and cleaned, tested and replaced it in its socket.
I came back the next day and powered it back on.
No sound came out.
I looked over and the rectifier tube was glowing bright red and something was burning.
I shut it down. The fuse is still good.
I pulled the rectifier tube and turned it back on.
The heaters all lit up.
I checked the ac voltage on the rectifier socket and there is 5v on one set and 400 on the other.
I put a new 5ar4 in and turned it on. Instant fireworks in the tube.
How do i go about diagnosing this problem?

Hi there!

I have a citation 16 with huuuuuge problem it seems. Picked it up cheep. And works che thereafter unfortunately

first the usual problems with these amps it seems. The variable resistors were bad. Replaced them and recapped the hole machine, But after it seems that I shortened an output transistor 😑 it is at least my suspicion because I have around 30 volt on the output rails 🥺???? And cannot change the idle on Channel A

channel B is another story. There I can change the idle current. Problem is that as hotter it gets. The lower the idle current is!!?. Why is that? And soon as I cool the heatsink on channel B, let’s say I just blow on it a little, the idle current rises?!? Is it the emitter resistors they gone bad? And they change value with temperature ?

Another suspect is the IC/Opamp ua739pc…. Wherever I read about the Citation 16 it seems that these ICs seems bad. Anyone here that have successfully replaced them? Or know where one can get original?

Thanks!

My first power and pre kit was a Hafler DH200 and a DH101, most recently I have built the GR Research XL-S Encore speakers and I just finished the LM3886DR from Neurochrome. just checking in. Cheers

Hy,
I want to use switches from 70s radio for my project. There will be no more high voltage running thru. It will be used with mcu analog read 0-5v.

I know that there are many many threads over the internet about what to use for cleaning and lubing the switches, but opinions are so different.

I'm including the picture of switches and stating that radio is from 70s in hope that type and materials will narrow down the options.

Can I use isop. alcohol or will it make the plastic brittle?

Can I lube the contacts with vaseline? There will be no real current flowing thru, so sparking wont happen.


Thank you

I bought this amp a while ago for $100 but it came like this. I just replaces the valve and nothing has changed. Also seems that the main sound I'm wanting to fix (OD-2) only happens once a plug is inserted into the amp. Doesn't have to be fully inserted to start the sound. I'll leave a link to a video here:
Login to view embedded media

I´m building a 2 stage phono preamp using a Siemens D3a (triode) as first tube, and a half russian 6H6P as the second.
Not decided yet if I shall go for passive or active load.
I have about 220-250 Volt well filtered B+ to play with. What idle current would you chose for best sound?

Hi there,

I am actually by designing a multichannel DAC (form my active speaker system) with the newest ESS chips, the 9017 and the pin compatible 9027. I'd like to make it DIY friendly, and as flexibel as possible/practicable. If you have any ideas what all should be considered, please let me know! Perhaps we could develope and realize it together...😉

Some main aspect of this chips:

• they have solder legs, so easy to DIY
• they have hardware mode, so a controllel is not absolutely necessary
• they have the newest Hyperstream IV architecture
• performance is quiet good: 110-114 / 120-124dB (THD+N / DNR)
• they are pin compatible, the smaller one is quiet cheap (but without ASRC and SPDIF input)

The design is almost ready, but the output filter pcb, that will be placed beneath the DAC pcb must be finalized yet.

Cheers,
Bela

Dear diy folks
some of member may knew,years ago we put tpa3255/51 design into one high-integrated design and many people used them in their build, with some user are expecting higher-end design with higher performance, especially ti release a design note to achieve higher performance by adding extra feedback.
with this background, now we are happy to show you our new fully new design that many things looks exciting.
some of Key Features are:
• 18uV (TPA3255) Output Noise (AES17,A-weighted)
• 15uV (TPA3251) Output Noise (AES17,A-weighted)
• BTL/PBTL configuration for best audio performance
• MELF resistor for audio path to get best performance and audio quality
• Fully compatibility one design for both BTL and PBTL (TPA3251 and TPA3255)
• 7G23B or VER2923,APG2923,HA3588 inductors compatible design
• Fully differential signal chain from input to output for lowest noise and distortion
• Extra optional input buffer for single-end input source

hello,

I've picked up a pair of Chris Pelonis model 42 mk2 speakers and amp, used them for a while, then rearranged things a bit and changed power cables.
when I plugged them in the light went on, then out, and now theres no life in the amp.
usually there should be no problem with polarity, and the cable works fine for other things.

has anyone else had the same trouble?
is it just the switch??
there is no fuse.

I'd really like to fix this, as these are great little speakers, which I've dialed in to be flat from 20hz-20khz in my very small and well treated space.

Chris didn't have any suggestions when I heard from him before, and when I picked up the problem later I have received no response.
drawings are not available.

thanks


https://www.chrispelonisspeakers.com/model-42-mkii.html

Here's my on-going Mini TDA7294 Stereo Project. using SMT 1206 for easy DIY assembly and reduced PCB size.
The design includes, Power Supply rectifier and Speaker Protection. Preamp and Bluetooth will be added later.

SOLD

SOLD

Sold

Hi,
I come from Croatia and after hearing some amazing and very expensive speakers I'm wondering if I should try and build a set myself, for a lot less money 😅

Hoping to be able to fix my Klipsch Sub-10

Hello!
Recently a fellow friend is highly recommended I order a power transformer which has a very low DCR on the secondary winding, and then LCLC and all 10H choke has a low DCR around 10 ohm.

He says the result should be way better than any electronic regulator.

At first, I'm thinking about to use a multiple stages (3 stages) CRC with 5000uf for all C based on suggestions by local tube builder. See attachment

Which one is really do the job well?

Thanks 🙏

It's been a while since I posted here. I'm fixing a 5E3 guitar amp clone for a friend. It had a bad hum, which I finally traced to a bad "shorting" jack (is there such a thing as a good one?).
Along the way it seemed a good time to replace the volume controls.
I've got a pair of Clarostat 2M linear pots. If I have it right you can taper these with a 1M resistor from the wiper to ground and get something resembling an audio taper.
So far so good.
The catch is that the Clarostat pots are 60 years old if they are a day. They were salvaged from a pristine piece of late 50's Tektronix test gear. Heavy greenish plastic with a mirror shiny metal case. They look brand new.
Can I trust a component this old to last? They measure out OK.
Thanks

Hello,

I have some older Chase VS 18.1 subwoofers in my theater, 4 total and I am looking to replace the drivers with something that digs a bit deeper with lower distortion. I am a bit surprised that at times they can sound a bit boomy. I don't think the amplifier would be the culprit. The amp is a Crown Macrotech 3600VZ, damping factor is greater than 1000 at 400hz. It could be placement which is in the from left corner co-located but I am thinking it's actually the drivers themselves.

The current drivers, I've linked to below are made by Eminence

https://data-bass.com/drivers/5bef3fc0b666190004d5d41e

The drivers I am considering are the Dayton Ultimax and the Stereo Integrity HT 18.

https://www.parts-express.com/Dayto...C-Subwoofer-2-Ohm-Per-Coil-295-718?quantity=1

https://stereointegrity.com/product/ht-18-v3/

The sub boxes are about 8.5ft3 net tuned to 19hz.

The Eminence drivers have a super low QTS of ,245

The Dayton Ultimax 18 is listed at .53 QTS and the SI HT 18, .59 QTS

I do not care for boomy bass but as it a theater with ported subs, I guess I may get boom whether I want it or not. I am concerned that the QTS specs of both drivers I'm looking at may not give me the sound quality I'm looking for. I guess it sounds like I want my cake and to eat it, too.

I am not concerned that the Ultimax is more expensive and I have to admit the carbon fiber cone is good looking. Stereo Integrity has always been great bang for the buck though. Which sub would you choose and why? Thanks in advance for your help!

Looking for some help with a Punch 45HD amp. I have about 4.5 v DC on both speaker leads.
In idle and no speakers connected on turn on the current ramps quickly past 10 amps and the fets get hot.
I have pulled the fets the DC is still there. I replaced the caps C16,17 C21,22, the DC went away with them out but returned when I replaced them. On the PPM of both channels I have
Pin 1 >> 1.2v
Pin 2 >> 5.3v
Pin 3 >> 15v
Pin 4 >> 4.5v this is the pin that has the voltage on the speaker wire.
Pins 5-11 seem normal?

Any help is greatly appreciated

Normalization can turned off-on in settings of your Tidal account. I was wondering if something is lost when using this feature. According to SageAudio, Tidal does not boost the sound, it only reduces it if too loud.
Tidal normalizes audio to an integrated -14 LUFS but can be set to quieter -18 LUFS settings by listeners. At the time of writing this, Tidal does not turn up tracks on their streaming service - it only turns them down, meaning some tracks may sound quieter than others.

I use the Tidal web player on Linux. Sometimes I notice distortion which is more likely with vocals. Perhaps the music producers are not doing enough to output quality for music streams. SageAudio which does mastering explains that recordings may not work the same on different streaming hosts.

https://www.sageaudio.com/articles/...al use Loudness,may sound quieter than others.

SALE OF THIS ITEM IS WITHDRAWN

Miro USB interface stack PCM1704 DAC board for sale.
A pair of PCM1704 with one white dot => J graded chips on the board, and these are very difficult to source these days. These are recycled chips from a reliable seller, removed with proper care. They are not bought from random sellers in Ali or ebay. They work properly and nicely.

What you need to provide :
1. Chassis, wires, connectors etc
2. You will need to give it PSU with rails +/-5V (Analog) , +/-5V (Digital) and +/-10~12V (IV Op amp supply)
3. Compatible USB-I2S interface board that can be stacked on the DAC board, which are not offer in this sales. The two such devices are :

http://jlsounds.com/i2soverusbFIO.html

and

[IMG alt="eclipsevl"]https://www.diyaudio.com/community/data/avatars/s/104/104467.jpg?1709846720[/IMG]

Thread 'USB UAC2+HID Multichannel input/output interface York'​

2024-06-05 4:19 am
Hello DiyAudio community,

TL;DR: This is a USB transport for audio output (up to 8ch) and input (2ch for now) and user device control (e.g., DSP management) from PC (MacOS/Linux/Windows) thru I2C/GPIO. Including bootloader for remote firmware update, flexible device configuration, HID interface, multiple audio output options, integration with SigmaStudio (simultanious audio playback and ADAU DSP configuration). Compact module available in USB-C and USB-B versions.

So, the story started when I needed a USB transport for audio output and another channel for device control, such as for...

• eclipsevl
• 

Board fully populated with good quality caps eg. Nichicon KZ and FG, Wima Mkp, Panasonic acrylic caps, Amtrans AMCH copper foil etc

The IV Stage has a pair of AD811 op amp with heatsink mounted. Design is posted by Grunf, and discussed here:
@
2023-01-11 6:54 am
First, let me introduce my DAC, some have already seen it, but for those who haven't, it's a classic old-school DAC with DIR9001 as a digital receiver, PMD100 digital filter and 6 PCM1702s, three in parallel for each channel. The output current of 3 PCM1702s is 7.2mAp-p max. The power supply is given the greatest care, the PCB itself with DIR9001 has three ADP7118 regulators and they are the only IC reg. in the DAC. Other regulators, two +5V for PMD100, +/-5V for PCM1702 and the new +/-10V for AD811 are low noise shunt regulators, slightly improved, made according to Mr.Walt Jung's article...

• @grunf
• Replies: 297
• Forum: Digital Line Level
• 

Payment by PAYPAL FF only please.
DAC + shipping registered & tracking = xxx USD or preferably xxx SGD (Singapore dollars)
Again, please note that the USB-I2S interface board is not included in this sales.

Hello all,

Long time member but it's been years since I've logged in.

Anyway, I've just got a pair of Markaudio MAOP 11.2 and they are burning in now on my bench with music and volume as recommended by the manufacturer. This is my first pair of Markaudio drivers so I have no experience with the brand. As per the title, do we generally follow the parameters that is given or the ones published in their product page? My units have higher Fs than most I've seen posted here and compared to the factory. Most of you have ones that are close to the published factory specs. Mine has a higher Fs (53 Hz vs 42-ish), higher Qts (0.34 vs 0.29-0.3). Modelling off the factory specs with a box designed for mine shows quite a different response.

So, which do you guys usually go with? My initial guess, the ones I got. I doubt my units will change that drastically towards the factory average.
Apologies in advance if this has been discussed before. I've first tried a search but didn't find anything that helps.

This thread is for discussion about the new book and any errata. It was a rewarding and learning experience for me helping Bob by reviewing the manuscripts. But none the less a few errors got by me and were introduced past my review, as I discovered when the book was in hand.
Cheers to Bob for his dedication in creating a large collection of information for us to enjoy 😉

Errata:
1) Chapter 3, p56, Figure 3.16(c) should be "ring-of-two LED" since D1 and D2 are shown as "Blue" and "Green"
2) Chapter 15, p336, Figure 15.13 was changed from my review. Text in book was for attached fig 15.13
3) Chapter 15, p339, Low-Frequency Monoaural Merge, first paragraph, last sentence, "The outputs are then bridged with (R3) to mix the signals at low frequencies"
4) Chapter 18, p396, Figure 18.11, should read "THAT 1510/1512 IC Microphone Preamplifier" to match what's shown in the figure
5) Chapter 21, p483, Figure 21.6, the function block should be labeled as "TA7328" and not uPC1237. uPC1237 example as attached
6) Chapter 26, p616, 3rd paragraph, "Applications for compandors can be found in Philps/Signetics NE570/571/SA571 AN174 and Onsemi AND8159,AN8227"
7) Chapter 28, p642, section 28.10, to clarify a FPGA is defined as a "Field Programmable Gate Array" but it's true that they are logic elements

I have TWO (2) of these Harman Kardon AVRs
https://www.hifiengine.com/manual_library/harman-kardon/avr3550.shtml
One of these units is working perfectly well in two channel STEREO mode and other modes. I use this regularly to listen to music.

The other unit has a problem:
The other one is working in 5 channel surround sound mode - BUT - only CENTER channel & Surround LEFT & Right channels are working and giving an output of Sound.
FRONT Left and FRONT Right channels are not working and not outputting sound.
Should I get it repaired? I got the reference of one Mr Jagmohan who is a good repairwallah in Kalkaji, New Delhi.
Jagmohan AVR repair Kalkaji Electronico
Or should I junk it? I just came in possession of it recently, this weekend.

This are Fairchild very hard to find KSC3503 ESTU & KSA1381 ESTU gain grade. The Hfe verified to be between 160 - 175. Minimum selling 20 pair . The complement KSA1381 ESTU is available from Mouser and plenty of those in stock, the KSC3503 is only available in D grade. One pair KSA1381 ESTU and KSC3503 ESTU will be 1.50 euro.

The prices do not include PayPal and shipping costs. Shipping from Finland. PayPal is accepted, the buyer pays the additional 5% PayPal fees. Or Payment as PayPal / Friend than the shipping costs for the EU are 9€ as standard ( PayPal friend) or 19€ by registered mail up to 100gr. Outside the EU it may vary by country. If you are interested send me a PM.

Sorry wrong thread

hello everyone .
I would like to understand in detail how to build an AMT (Air Motion Transformer) .
I visited some links but they make a summary description both in words and images and it is not clear. more than anything they describe the operating principle .
can you tell me where to look for images or videos in which it is clear?.
hi thanks .

This feels like a dumb question, but I've pretty much finished designing my forthcoming B.E.A.N.S. amplifier, and just putting the finishing touches before I post it here.

So far, my amp design just has a fixed gain of 20 (26dB) so needs 1.42V pk for 50W into 8 ohms.

What is a normal line level input for a power amp? I've looked around and there seem to be different standards. What is normal for a hi-fi amp?

Also, I may not know much about amplifiers, but I saw a picture of one once, and it had a big volume knob on the front, so I'm guessing the amp can accommodate a range of levels. My design doesn't include one but I suppose if it ever gets built then it might need one.

Hello,

So I was looking for suggestions regarding the following setup that I am building :

Power design : Mains - 3 x center-tap transformers - 3 x power supplies
Stage design : Pre-amp stage 1 -> Passive tone control -> P88 Pre-amp -> 2x P3A amps

1 supply handles a pre-amp stage before the passive tone controls and the P88 pre-amp after the passive tone controls
1 supply handles a P3A amp
1 supply handles the other P3A amp

Obviously all power supplies have their grounds connected to their respective transformer's center tap, and all components ( pre-amps and amps ) have their grounds connected to their respective power supplies, which eventually goes to the center taps.

NOW, the question is, where to ground to chassis in this setup ?

My idea to prevent ground loops would be to connect the mains to chassis , for safety obviously, and the connect the P88's ground to chassis.

This means that the P3A amps would be floating, with their grounds in the center taps. Also the preamp stage before the tone controls would have no chassis grounding, it would be connected backwards to the power supply and forward to the tone control gnd which is connected to P88's gnd.

Also, would I connect the speakers to chassis ground in this setup ?

I find this part really complicated.... Can you guys give me some help ?

At a certain level, all ground are actually connected to each other through PCBs and/or wires. I mean the P3A has a common ground for power and signal, which connects through the wire to the P88's common power and signal PCB trace, which connects backwards to the tone'control's ground bus , which connects backwards to the stage 1's ground trace, and since each of these ground planes are connected at a certain point to their power supplies, that means that all center taps are also connected to one another through the circuit.

My question to you is where do I actually need to connect all this insanity to chassis ground ? 🙂

Thanks !

Hi all,

new to the site and hope someone out there can help me with my issues.

I have a NAD 3020 series 20 purchased new here in UK in '82/'83. I am no audiophile rather listen to the music but the NAD has been well paired with a Project 2 TT and a couple of Mordaunt Short speakers.

About 5 years ago it developed the buzz (light sabre) at power on in both channels that disappeared after about 1/2 sec, didn't really bother me and had no effect on the playback as far as I could hear. Roll forward a couple of years and the buzz grew to about 2 secs and faded but the right channel would cut out and then suddenly cut back in and be fine. The volume control made no real difference and all the tone controls worked fine. No distortion on playback. I could live with it just.

Moved house last year and after 18 months set up system and buzz still there but right channel now totally dead and can't be coaxed into life. If you have the amp switched on and power up at the wall socket then the buzz disappears and fades to a hum if you on/off a few times and if you pull the amp yokes at the back there is no buzz. I have also connected a separate phono/preamp to the power amp stage and both channels loud and clear so issue is in the integrated pre amp stage. I have had it apart and looked for bad connections, burnt out components, leaky caps and reflowed odd connections to the board but no luck. Also this seems to be a hybrid as the internal layout follows the 3020A but is badged as a series 20 with a mute button? Trawling the net there are fixes for certain issues re the problems focussing on the caps C513 – 518 and C531-533 but as I cannot find a service manual for the 3020A can’t check the circuit.

I am fully capable of carrying out repairs/ replacing components but before I start pulling them all out could any of you give me a heads up as to where to start? I really like this amp, could just buy a replacement but it has been a good servant and want to get it up and running and then maybe move on to a total recap. I always prefer to fix rather than dispose.

Thanks in advance

Looking for ATC SM75-150S.

Loking for an ATC SH25-76S tweeters.

I need to part with my studio monitors due to space constraints and personal changes. They are active studio monitors built based on the ATC SCM100 model. They were assembled and tuned together with a professional. The result is absolutely outstanding - the speakers sound phenomenal! Here are some brief specifications about the components used:

• Woofer: ATC SB75-314 SC (12 inches)
• Midrange: ATC-SM75-150
• Tweeter: Seas DXT
• Amps: Hypex FA503
• Enclosure: 100 liters, fully braced

SOLD

Since one speaker weighs around 60KG, shipping is not an option. I'm happy to answer any questions via message.

so I understand that it can be foolhardy to put a horn and a reflex, or a reflex and a sealed sub next to each other and have them play the same passband. i have a situation where I would like to place a sealed and a reflex sub about 15-20 feet from each other in a somewhat small room. i would like the reflex to handle the lowest frequencies by itself, so they would blend in the 40-80hz octave. the sealed sub (Dayton UMII-18) crosses over quite high at 250hz. is this a bad idea? thanks.

Create better speakers with this exquisite passive/active electronic component.😎Entreq Max Mix T2

About a month ago I posted about how I was making high voltage umbilical cables because I want to make a PSU that is separate. One mechanical advantage of that form factor is to make a truly very heavy choke input tube rectifier (enclosed tube) PSU LCLC for use with maybe a few different "old school" projects. To get all that heavy iron and magnetic fields out of the amp which can now be compact with the big PSU on the lower shelf or floor. In todays market what chokes might be best for choke input? I'm thinking Hammond 193MP potted, 10H, 300ma, 63 ohm model (10.5 lbs heavy!). My intention is to make a fine, old school, PSU, with umbilical that I can re-use across a few different amps I want to make. A PSE 300B, an 807 Amp, a 6L6 family PP amp (compatible with sweep tubes), and others all getting their raw power from this PSU, plug and play. I'm talking a PSU that is a boat anchor here, suggestions on the making of a boat anchor PSU would be appreciated. Toroid power or EI? I'm thinking 300ma output, fixed voltage TBD or perhaps a way to buck/boost series/parallel the power transformer to obtain 2 or 3 different voltages (with 2 or 3 different circular output connectors)? What would be a good 'set" of maybe 2 or 3 voltages to target (600V or less)? Lots of things I need to consider and hoping to tap into folks knowledgeable in big old school PSU's. Duplicating it for a worthy dual mono project may be in the future too, dual boat anchors.

Hello,

I have a standard Ghent Audio EVAL-1 amplifier on the tweeters of my active system, but want to do some upgrades. I have absolutely no knowledge of electronics. I understand my questions have long been discussed but I'm having a hard time finding my answers so feel free to link to some threads/posts.

I want to add standby/softstart functionality. I always just leave it on but whenever I have to disconnect the amp because I'm switching stuff around I miss the standby. Luckily my speakers have some beefy tweeters but man is that POP scary loud sometimes.

I've been reading a little bit and what I have found out so far is that there are different types of standby. What is the difference between amp standby and power standby? And which should I use, or both? And how to achieve it. I found out that in order to put the SMPS1200A400 in standby one must apply 3,3 to12 V to two certain pins on the side of the SMPS. So right now I'm thinking of just taking the smallest BRZhifi 5 V LPS, putting its internals inside the amp and then its on/off switch would become the amps inverted on/off switch. Which I would then mount on the front bottom. But I'm not sure if that's all I have to do.
I read about something called ampon and something else to that have to be connected in order for standby to work. What are they? Or are the connected as standard of the EVAL-1 / SMPS1200 combo?

And I'm torn on whether I need a softstart module or not. Some people use one while others say it's already in the SMPS functionality. Do I need one or no? Are there advantages to using one? And if so how do I implement it.


I actually came to this because I was comparing whether I like the amps better on or of my power conditioner. I have the Purifi for my tweeter and two Hypex FusionAmp 502s for the mids and woofers. I always used to have them on my NuPrime PURE AC-4 power conditioner. But lately found out that class D amps are not always the best match for PCs. So I tried it with the amps off the PC since a long time and feel like the sound has ever so slightly more warmth, dynamics and "flow". Especially the mids and highs seem ever so slightly compressed on the PC in comparison. But man the silence with that PC is so good. And it gives everything better clarity and longer decay to instruments, slightly airier soundstage. As per right now even though it doesn't sound as pleasent or lively with the amps on the PC. The advantages are still kinda worth the tradeoff. But would like to have the best of both worlds obviously.
So as I tried to do some research into the standby thing. I fell down the rabbithole of possible upgrades. But again, I am no electrician.
I read alot about buffers. it seems to me the Neurochrome is the best, but that the EVAL-1 is not far off and is still one of the better options? Anyway, I'm not gonna be switching nuffers because those modules with shipping to NL would be a whole ~€500 project and I'm not looking to spend that kind of money now. But what are some of the less expensive possible upgrades that could have some of the benefits of the PC? Like could I upgrade the transformer on the SMPS to a better one? Do you direct solder better quality wire as an upgrade? Twisting the wires, making the cable management more neat? Maybe something to do with shielding?
One thing that I read about is putting the opamps on a LPS. Seems interesting to me. What would I have to look out for when selecting a LPS and how to connect it? Which voltage?
And after all. Could I do similar upgrades to the FusionAmps?

Thanks in advance

Hello, Audio fans! Warm greetings from the Rocky Mountains.

Hi!

I felt that i might share my Troels Gravesen Revelator 851 speaker build and share my experience with the finished speaker when they are done so here we go.
Link to Troels project page: http://www.troelsgravesen.dk/Revelator-851.htm

Troels is a quite reputable DIY speaker builder from Denmark. Lots of useful information on his website and I can highly recommend it.

This is not a cheap build. It consist of a bass driver and midrange driver from Scanspeaks Reveleator series and tweeter from Scanspeaks Illuminator series. Crossover components are from Jantzen audio. It is made of 21mm birch plywood and Valchromat MDF for the front baffle (Valchromat has a very high density). Total cost is somewhere around 4000 US$.

Unfortunately my phone broke and a lot o pictures from the early stages of the build was lost expect a few that I had uploaded to my Instagram.

My original idea was to stain them black so that you can see the structure of the birch, but in my tests stains it turned out quite bad and ugly so I decided to paint them black with a high gloss finish. Birch is very nice in as it looks but do not fit in my home.

Just in time to treat yourself well for the holidays! For pickup only, please plan for a friend with some muscle and bring at least a mid-size SUV or a van. The pair will fit comfortably in a Honda CRV or similar.

I'm located in Madison, Wisconsin, right off of I-94/90.

These are in very good shape. They were used in a church, hanging from the ceiling, so not mishandled by well-meaning roadies or bandmates.

Asking $2700. Thanks for looking - Pat