Some of you may remember talking with Carol some years back when she did phone service and answering, shipping, and general office duties at Liberty Instruments (for IMP, LAUD, and PRAXIS products at the time). If you called us then, Carol was the friendly voice you talked with most of the time. We even had some people calling just to talk with her as she was such a good listener and conversationalist!

Carol's also did the voice identifications on the Omnimic Test Signal tracks CD.

She was the highlight of my life and I know I'll never be the same.

Bill Waslo

I am missing a part in the circuit board and was hoping that it could be identified I have other parts on order I would appreciate any help thank you

I'm truly curious, this day and age we can't test a lot of gear. I wanted to DM Mr. Pass, for his opinion and keep it to myself but I'm not seeing how to message privately on the board, so public it is. Please no inflammatory opinions, I'm not trying to start some Audiogon ******* contest.

I just spent 2 years building new cabinets and Pass crossovers for my JBL 4333a and looking to find a good match for them. I'm a rock and blues guy, not a lot of jazz, but I love most music.

I've tried a class D amp that was not cheap and it sounded harsh, too much gain, hissed, not a good match. I'm currently running my refurbished M-504. Almost purchased a Pass XA25 from Reno but hesitated and it sold. It's hard these days to spend thousands on an amp you have never heard. I am truly open to anything and my budget is decent. I am also open to building my own, vintage, or used.

So please, you guys are a very knowledgeable and friendly group, help me make a short list.

Thanks

hello, folks
i have toroidal transformer with two secondary windings .
I need two make fullbridge rectifier with capacitors .
The PCB must be single layer ...
What do you think about this PCB design ?

Hello

I have an inexpensive 10" woofer which I am planning to use as a subwoofer for some increased low frequency extension. I measured and calculated the Thiele/Small parameters for the 10" woofer and it seems like it could perform fairly well in a 32 liter/1.13 cu.ft. sealed enclosure.

I enclosed a WinISD .wdr file for this woofer, but here are the main parameters.
Qms = 3.4
Qes = 0.538
Qts = 0.465
Fs = 30.4 Hz
Vas = 48.3 L

Fs / Qes = EBP
30.4 / 0.538 = 56.5

The other two pictures show a loudspeaker enclosure principle which utilizes two sealed chambers which are connected to each other via a "resistive" port. Does this kind of alignment have certain advantages when compared to a regular sealed enclosure?

I would be interested if somebody has more information or experience regarding this type of speaker enclosure.

Best regards

I am repairing an older Emotiva amplifier. In one stage it uses a 2SC4793 (NPN) and 2SA1837 (PNP) complimentary pair. These transistors are obsolete. I have read that they can be replaced with TTC011B and TTA006B, respectfully. Mouser has TTC011B in stock, but I can’t find anyone who has TTA006B in stock. Is there a reputable source where I can purchase the TTA006B? If not, is there another complimentary pair I can use instead?

Thanks.

I've seen it mentioned here and there on the net, that people use, let's say;
2x transformers with 0-9VAC 1,5A secondaries...they then hook those up back to back with the 0-9VAC secondaries in the middle. The point being getting 0-230VAC(230Vac being mains voltage here) from the primaries of the transformer not connected to mains voltage.

Could one use different voltage secondaries to "bump" the 230Vac to...say 260Vac at the output of the second transformer?

Is this a reasonably safe practice?

yup, as I said , bad influence of Cyclotron emanation , all the way from Bubba Bob's Davis ...... 'Talian names popping as mushrooms after the rain

anyway, what's better to put on pizza than mushrooms .......

So, last one in series of autoformer gain amps (you can call them all - M2 on Mushrooms ) , this one differing on outputs being classic BJT complementary pair, so sorta blasphemy in Papaland ......... he sinned heavily eons ago ....... while my Sin is recent........

Anyway, here's funny diagram, showing nothing else than bunch of multilegged fuses and some nice iron

hm, yes, my prototype equipped with first genuine ones I snatched from drawer - 2SA1491/2SC3855 ....... but pretty much any "for Audio amp" complementary pair should work well ........ 2SA1943/2SC5200 , TTA/TTC (newest Toshiba incarnation of 2SA/2SC)

rails +/-23V, Iq 1A5

2nd is clearly neg phase, not seen from my gigglywiggly, but I stumbled on nice routine in LTSpice showing just that behavior and didn't yet found reason to doubt it

edit on 20.01.2022. - C109 and C110 are not fitted, neither here nor in schm in post #6, so ignore them; these were "precautionary parts"...... which I initially forgot they're needing investigation (with or without); measurements shown were made with them in place, but after trying without, I can happily toss them out; as result, Freq. linearity (logically) being better without them ..... for instance , 8R load - everything stays in 1db envelope

Working from the target of 0.7*Fs, I came up with this. Target is a large box that can play to 17hz. Appreciate any feedback. Amp is the Dayton 250W DSP plate amp.

Driver is the Dayton RSS265HF-8 10"

Powered on, with BD modulation, each of the +, - speaker outputs sits at 1/2 Vcc. I was using 24V and observed 12V, referenced to Vcc ground at the speaker outputs.

With the amplifier on, I connected the outputs across two, 220 Ohm resistors to ground, each having ~50 mA going through them, with a ~10,5V voltage drop across each. The voltage drop then simply shifted up to 12V...the output Z of the amp being much, much lower than 220 Ohms. Amplifier functioned driving into this situation without issue.

Then I got the bright idea to turn off the TPA3116 amp via its power switch, figuring the outputs would simply go "tri-state", or non-conducting. Voltage drop across the two, 220 Ohm resistors resumed back to the ~10V value. Looks like tri-state to me.

Turning the amp back on I expected it to go back to 12V, but - nothing. No output, audio or DC. Nothing after power cycle, connected to ordinary speakers the ordinary way - something killed it dead.

I was powering it using a battery, so it was truly floating relative to the other circuit. Battery Vcc (-) was the only connection to the same ground as the two 220 Ohms resistors were connected to, each with, again, ~10.5V across it.

TLDR; I backfed 10.5 V into the speaker outputs of my TPA3116, relative to its ground, with a whole 50 mA of umph behind it - and it killed something inside the chip. How could that be? No magic smoke, noises - just no functioning output anymore.

Any ideas what happened to the chip in that amplifier? One could go 'round killing them all with a 9V battery and some clip leads - apparently!

Can any one tell me what quality of cap this is. Would a upgrade be audible. coupling cap i think

Back again & sad day for me today, I messed up on my driver board and damaged the pad for pin 12 on the ka7500, anyone selling one or know where I can find a replacement?

Also, on the aq2200 diagram I noticed pin 11 and 12 appear to be in parallel, could I just bridge them together instead?

Thanks

Folks, when there's a rod between the front panel and the potentiometer, what the heck is it called? Is there a place to purchase these or do people manufacture them DIY?

like this:

For sale are the Lundahl transformers I'll never get to use. Building that dream Push Pull 300B interstage coupled amp just isn't going to happen. The whole project was always just a bit too intimidating to start, and I'd never quite figured out power supply and output transformers, nor did I want to spend even more money on something that wasn't getting built.

So I'm offering these here at the price I paid for them when I bought them used and prices are firm. The 1544A has wires connected for one of the standard configurations but I couldn't tell you which anymore. The 1692s are blank and according to the seller I got them from were mounted and tested but never really used. For all specs visit the Lundahl or K&K audio websites. I myself never used them in any way.

The 1692A PP pair is $141 $125+ Shipping ($230 new)
The 1544A pair is $100 + Shipping. ($170 new) Sold

Paypal only. Combined shipping if you take them both. USA or Canada only. Prices are USD.

No cashiers checks, money orders, wire transfers, etc… Don’t even bother to ask. If you are “out of town” and need shipping to some obscure place and will pay “extra”, fugheddaboudit. All standard eBay and Craigslist scam precautions apply.

Meet the PecanPi DAC and Streamer

Improvements over previous generation DAC include:

• Fully linear ultra low noise power supplies
• Re-clocking with Crystek femtosecond jitter oscillator
• Built in HW volume control (no Volume-Clocker needed)
• Built in high performance headphone amplifier
• Full size XLR connectors
• Ability to back-power the Raspberry Pi
• Improved thermal design
• Aluminum case available

The PecanPi Streamer is a ready to go plug and play streamer, that uses the PecanPi DAC, and will be available with the following software options:

• Volumio -- • Audiophile Music Player | DAP | Volumio
• Rune Audio -- RuneAudio - Embedded Hi-Fi music player
• moOde Audio -- moodeaudio.org
• piCorePlayer -- piCorePlayer
• Roon end-point -- Roon Labs

Discounted preorder will be available shortly through Orchard Audio's website

As my English is not the best, I believe the photos and video will say for me. 🙂

Below is a video with the entire construction...

Login to view embedded media
🙂

I am trying to construct this https://diyaudioprojects.com/Solid/...ozhound-Labs-JFET-MC-Pre-Preamp-Schematic.png MC cartridge pre amplifier using J201 instead of 2SK170. Thought it would be a good substitute, for some reason. But when I tested the amp with 1 kHz sine wave, I measured a voltage gain of only approx 14-15 dB. Should be around 30 dB. What am I missing here, and how to increase the gain of this circuit. Increase the drain resistor value?

Hi, I'm repairing an ancient AWA Record player for a mate, The input stage has a Grid-leak biased 6AV6 running at 85V. The grid resistor is 10M, input is a ceramic cartridge.
I've already converted the output stage from Back Bias to Cathode Bias, and it seems to be behaving. I'm just concerned that doing the same to the input stage may stuff up the loading of the ceramic cartridge - however, there is a pi pad of ~ 820K & a 500K vol pot between the cartridge and the input cap, so my guess it's not an issue. Perhaps lower distortion with Cathode bias?

if we confirm continuity between mains earth and the DUT intended probe earth point, are we safe to proceed testing using an earth referenced Oscilloscope? Is this a bullet proof way of knowing we wont create a hazardous earth reference with our probe earth?

I appreciate the need for differential probes when testing floating ground devices, but does this continuity test confirm we are safe to proceed without the need for differential probes?

Hello all.


If the thread does not belong here, please move it to what is more suitable. I have had such positive experiences with the help from diyAudio before so I wanted to check here, the level of professionalism is a whole lot higher than on other forums.

So, I am repairing this DJM-700 DJ mixer for a friend, who gave it to me and said that the channel faders were glitchy and not behaving right. Sure enough, looking inside there was a little bit of drink spillage that had gotten into to half of the faders' housings. Luckily the spill area did not cover a lot, only these faders and one push-button had been affected. So I ordered new parts from eBay and replaced all 4x channel faders (as well as that one cue button), and they are again working fine!

There had been some minor spills onto the upside of the PCB board, only in-between components, no corrosion on the parts nor the traces. I easily cleaned that off, and I must say that the boards look nice to the naked eye.

Thinking I was done with the repair, I put everything together, but when testing it out, there is no response from a number of buttons to the right of the mixer. I have attached an image to make things easier. There is no response when pushing the "MASTER" cue button, and the same goes for the "EFFECTS" cue, as well as the small "FILTER" button which activates or deactivates the frequency filter next to it. The "TAP" button for tapping in a BPM, works fine during testing - but the beat quantizer arrows also seem unresponsive (Though for these I am not sure if I need to have something playing for them to work).

The buttons do click properly, but don't light up at all. Unluckily, I cannot remember whether they worked or not before I begun the repair.

I would prefer to try and fix them myself as I've come this far by now, is there anyone here on the forums who might have an idea what parts of the mixer to be looking for potential faults? Perhaps someone is better than me at reading schematics, so I will attach the service manual below as well.


Thanks a lot and enjoy your Sunday!
A

I'd like to know if anyone knows where i can get a guide, pdf or book, of transistors and their complements. Im tired of searching datasheets that often don't give the no of the the complement. Any help appreciated.

Hi,
I'm trying to mix three headphone level signals with a passive mixer and then use a small headphone amplifier to output to one pair of regular headphones (32 ohm impedance).
The passsive mixer is easy to build with resistors and and requires no power but for what I need, the headphone amp needs to be really small and powered by a single lipo cell.
I was looking at this https://www.ebay.com/itm/254884876406 but there's no US vendors of that product and I'm short on time for this project. Could you please recommend a similar single lipo cell powered, tiny headphone amplifier board that's readily available to ship from the US?

Thanks to everyone in advance!

Dear all,

I am searching for a datasheet for the jan 6832 subminiature tube.
as far as I know it is a double medium mu triode.
Can anyone help me for this information ?
Many thanks !

This is the new thread for the 2x 21" down-firing-port subwoofer build(2x B&C 21SW152-4), it was previously discussed HERE in regards port design suggestion.

This 21" subs will replace the current single Ultimax UM18-22 in a 5-FT^3 sealed enclosure, wanted some lows, strong midbass and low distortion on my 2CH music setup.

Final project specs:
Material: 6x 5/8" MDF-Light 4'x8' sheets.
Measures: 42" H x 24" W x 27" D, (46" H with feet), nominal.
Walls: ~1.25"(dual 5/8") thick walls, ~1.9"(triple 5/8") baffle with braces.
Finish: Black-mate laminate.
Volume: ~9.5 FT^3 Net. after port/driver/bracing.
Weight: ~222 lbs (~180 lbs without driver)

Initial subwoofer testing/setup:
DSP: DBX DriveRack PA2
High-pass xover: 16Hz BW4
Low-pass xover: 60Hz LR4
PEQ's: Off
Delay: Off
Subharmonic Synth: Off

My "subjective" listening impressions:
After getting them in place and connected, I've played some EDM and Pop music and I was a bit skeptical at first, then I remembered that I had to invert the subs phase, after inverting the phase resulted in an instant jaw-drop followed by an ear-to-ear smile, one box just blown away the sealed UM18-22 and I've disable the PEQ's previously boosting the 20~28Hz range on the sealed sub.

Notes worth mentioning:
The B&C 21SW152-4 drivers were installed without any breaking-time, so the subs will significantly dig lower overtime as expected.

The room measurements are 10'-9"W x 9'-2"D x 8'-4"H, just small.

The enclosures were tuned to ~19Hz regarding WinISD, however since the 8" port clearance from top wall is 7.75", port clearance from floor is 4" plus 2 large pillows, the final tuning dropped to around~17 or 18Hz, while I don't had at hand DATSv3 nor a diy impedance jig, I've tested with an adhesive tape and cranked up the amplifier and used a tone generator, so far when the tone generator was set to 17Hz, the woofer drop excursion dramatically and everything in the room was insanely shaking and I feel the high pressure, I didn't hear any port noise/compression when testing so far.

Complete step by step build log HERE

Some build images:

The triple front baffles.

Deluxe 6 prong T-Nuts epoxied.

The Ankh shaped braces and port support.


Gluing started next to a 16oz glue bottle for size reference, I've used my favorite glue TB3.


The braces in place.


Interior view of the port supporters embedded on the braces.


Spreading a generous amount of glue per brace and top/bottom walls.


Internal preview of one box almost ready, back wall non yet glued.


Port dry-run test before sealing it with RTV and gluing the back wall.




Port top/brace clearance.


Port being sealed with 100% RTV.


Applying few turns of Scotch blue tape for port tighten.


Port being evenly pushed gently with a small piece of wood scrap and a rubber hammer.




Port back view.






Complete step by step build log HERE
For reference the mains build log HERE

Regards

whats the average lifespan in years or hours of an output transformer like lundhal? how would you know when it needs to be replaced?

Does anyone have any info' about a "Cosmos" amp. (Not the new huge version reviewed in Stereophile) It is about 40 yrs old. Uses a pair of 6BM8s in each output stage. (around 6-7 watts) It is an intergrated/hybrid model with a pair of Germanium transistors runing off a negative supply rail for the mag' preamp.

Hey i was thinking about a sort of controller (with a arduino) for raspberry pi streamers, which mostly act as keyboard for multimedia controls and maybe (maybe as optional thing) receive data over serial from a little script to display current song/volume etc, just connected over usb so it can be put on desktop with the raspberr pi in its own case
i thought about maybe a 3,5" touchscreen display and do everything over that

beside the usual multimedia controls it would be kinda nice to do more things like, switching inputs, switching radio stations etc, i think the easiest thing would be to still just use the ardiuno as keyboard but bind different key(combinations) to some actions of the streamer via a script, so possibly also easy adjustable to all kind of streamer softwares

unfortunaly browsing the filesystem for example wouldnt be possible but the display connectors needs to be in close proximity to the display and a display on the rpi unit itself would be kinda pointless in my case, i need some seperate station/controller on the desk
is there maybe a way to make a seperate unit with a minimal rpi like the zero 2 and actually couple it with the main rpi over usb?

What you guys think about this idea, would there a more easy way todo things? (maybe a hdmi/touchscreen display? to actually support the streamer interface or should i just settle with a cheap tablet to open the webinterface ? (i think that would be actually the easiest solutions, no software required working out of the box))

For "sale" is the bare working circuit for a Korg NuTube B1 I bought and built from the diyaudiostore, with an additional power conditioning board, Mark Johnson's PO89ZB, I added separately. I repurposed the chassis, the switches, the pot, the RCA and power jacks, and the wall wart for one of Papa's B1s so I have only the circuit available. This B1 Korg was working and stable when I pulled it, and very rarely had any microphonics. Please don't complain about the solder joints though, not all of them are pretty!

Now here's the catch. I will "sell" this to anyone in the continental US who can show me a receipt for at least a $50 donation to diyaudio. It's fine if it's a month or so old but I'd rather it be recent, as in since the site upgrade. So if you want this thing & have such a receipt, talk to me. Happy Tuesday!

Hi,
could someone help me locate the signal capacitors of the YAMAHA A-S701 amplifier?

thank you

Hi everyone.

I have a few questions regarding subwoofers, amplifiers and mainly overload protection.
It is going to be a big post here, so I've marked all my questions in bold.
Since I'm new to PA systems and I'm only doing this as a hobby I still have a lot of questions regarding all the PA stuff.

My setup and how I run it:
Speakers:

• 2x JBL PRX 412M for the high frequency
  • 1200 W Peak, 600W Program, 300W Continuous
  • 8 ohms
• 1x JBL SRX 828 for the low frequency
  • 4800W Peak, 2400W Program, 1200W Continuous
  • 4 ohms

Amplifiers:

• the t.amp E-1500 (for my tops)
  • Running in stereo mode
  • 950 Watts per channel
• Crown XTi 6002 (for my sub)
  • Running in bridged mono mode
  • 6000 Watts

I usually set up small events (~30-50 people) where heavy bass music is played (Techno, Psytrance, Hardstyle, Frenchcore and Uptempo etc.). That's why I bought the XTi 6002 (Class I amp). I've read in a lot of forums that there is a big increase in the quality of the sound compared to a D-Class (or other classes) amp. My goal is to get a huge "woah" regarding the sound quality from the attendees of my events and I think the decision to get a class I is leading towards that goal.

The problem now is, that the amp is can deliver a lot more power than my subwoofer can handle. So I've activated the limiter on my XTi 6002 at -3dB with almost instant attack (0.1s).
I thought -3dB is half the amount of noise, so it should cut the power in half (3000W). I'm pretty sure it doesn't work that way.
Is there any possible way to calculate at how much watts my amp is limited at what limiter (decibel) configuration?
I found the following calculator from crown (dB Power Ratio):
https://www.crownaudio.com/en-US/tools/calculators

The calculation is dB = 10 * Log (Pout / Pin). I think this is the right calculator to use, is it?
Is there any article that can describe this calculation and how decibels and power output are "connected" with each other?
I really want to know what I'm doing, so I won't break anything.

I recently did my first few events and I had the limiter set at -3dB and put the volume of the amp all the way up (because it will limit anyways, if I hadn't any limiter active I'd never do that). At the events I noticed most DJs tried to get more bass or volume and just turned up the gain, low-end EQ or volume on the DJ controller. At some point my limiter on the bass amp did his thing and stopped increasing the output.
However I didn't have any limiter active on my high frequency amp. So this one just kept going and got louder. This resulted in a lot louder high frequency and the bass felt like it wasn't even there.
I read on some forums that a subwoofer should be able to handle a bit more power than it's peak value (in my case 4800W). Is this the case and how much power over the peak value is too much? Would I even be fine with no limiter at all?
I just don't want to break my subwoofer. And if that means I have to set the limiter a bit more aggressive, I'm fine with that.

I'm also looking forward to getting another subwoofer and change my amp. For this the Crown I-Tech 4x3500HD looks nice (4-channel amp).
It delivers 4000W per channel at 4 ohms and I wouldn't have to upgrade my amp if I want to get even more subwoofers.
However, if I only connect 2 channels onto a 4 channel amp. Will the unconnected channels just do nothing or will the power be "transferred" to the other connected channels (so that I have double the power on the other two channels in this case)?
I'm pretty sure the power won't be transferred but I want to be 100% sure, so I better ask.

Cheers

I'm looking to buy some of Dave Slagle's AVCs but the Intact Audio website seems to have been down for some days - does anyone know what might be going on?

Thanks

Hi all!

I am looking to make a 8" subwoofer and amplifier.

I have a 200W audio amplifier, which I was looking for advice on in this thread 200W amplifier design .

Does anyone have any good speaker companies? So far, I'm leaning towards skaraudio.com daytonaudio.
I'm thinking of getting their 8" 300W subwoofer.

When I have a 100W amp for a subwoofer, is a 300W subwoofer good? Would a 500W subwoofer sound better even though the amplifier is only 100W?

Thanks in advance!

There is to observe an unwanted looping of the tape instead a correct tension across the head.
First idea was to replace the belt by a new one.
After done this the unwanted looping wasn't gone - check out the image.
The left capstan rotates a bit faster than the right one - so as if the capstans had been swapped.

What is therefore the reason ?
Is it a typical effect on this model ?

post #1098 under
https://www.diyaudio.com/community/threads/what-did-you-last-repair.313739/page-55describes in general, what mechanism is it exactly, that maintains the exact proper tape tension across the heads in such cassette drives with dual capstan

This thread don't provide the wanted information:
http://www.hifi-forum.de/viewthread-185-4462.html
Maybe one of the member knows more - thank you very much for an advice.

So i bought these beautiful locally crafted 8" transmission line speakers. The company is now extinct sadly. (but i got them for an amazing price because of that.)
The cabinets are stunning and very inert. Made out of Plywood with a native real wood veneer.



Tweeter is a Dai-ichi DT-81 https://mega.nz/file/kQBQTDoS#qX3DtvMSzE9EnrmaVq-fWHBuMZocYfgWJGqBjSZi4M8
Mid - Response CW2192
Woffer - Response CW2196

Picture of the crossover for the mid and tweeter. Woofer just has a 9mH inductor in series.
https://mega.nz/file/sYQhWQRT#mv9-vGMiIxP4TJ5KTRLhibM3HcwISKbt7qlCMhEtpf8

Link to way-back machine achieve of Pure-sound websight.
https://web.archive.org/web/20160801014151/http://puresound.co.nz/?page_id=204
Unfortunately the High's somehow sound veiled, and also a bit fatiguing as well?

Because i got them for such good price, and the cabinets are so nice, i think upgrading them would be a good option.

Is this just a case of Finding a new tweeter that will physically fit, has a similar sensitivity, and desirable frequency response?

Any thought welcome.
Skyfire

Same issue as this thread only I dont think this one was ever solved: https://www.diyaudio.com/community/threads/kicker-dx500-1.270379/

Amp takes about ~8 seconds to fully power up.
During that time, theres only 1.2vDC across speaker terminals.
After 8 seconds, 12.8vDC across speaker terminals.
Amp rail voltage is 56vDC. I know this is a
I know there should always be about 27vDC on speaker terminals referencing ground, but one of the terminals is only at 14vDC. That terminal with only 14v on it; fets of this side are getting just every-so slightly warm to the touch.
Amp idles at 0.5A.

I've found R273/R274 underneath looking to have gotten hot but still measuring correctly at 8.8ohms as they're paralleled.

This amp is using two IRS20957S in the output stage. The partial service manuals on file for DX300/DX700 show HIP4080 as they're different amps.


Any help with why I may be seeing DC on speaker terminals.?

I've had a Behringer Xenyx 1002FX for a few years, but never really got into using it. Now I want to use it as a preamp for a condenser mike. However, whatever is selected on the fx knob seems to either have intense effects or has an unusable amount of reverb, and low sound quality (eg. 0 selected with the selector knob). It has always been like this, and I bought it new, but I even wonder whether it is faulty. Anyone know about this, before I chuck it out or take a hammer to it?

Hi All,

I've had recent problems with the laser for my Pioneer PD-91 CD Player and it got me thinking:

Lasers for old transports like mine are becoming harder and harder to find, with some models almost impossible to source any longer.

It would be a travesty to allow some of these players to die out because for the most part they are built and designed extremely well, (not to mention great sounding in their own way).

I know that for older gaming consoles there have been a number of successful recent implementations of 'Optical Drive Emulators' (Sega Saturn, Playstation etc..) allowing the user to replace the CD transport all together with a PCB board and hard-drive - this got me wondering of how hard it would be to implement something similar for vintage CD players.

The idea would be that this 'Emulation Board' could replace the CD transport with a SD Memory card or hard-drive and simulates the process of playing a CD allowing your player's DAC and output stage to still be put to good use.

Of course, this would be a shame for a lot of really well built transports (like in my Pioneer PD-91), however, in a world without suitable replacement lasers, what other options would you have to keep these players alive?

My hunch is that something like this must be possible, given that it works with gaming consoles (which have the added hurdle of anti-piracy protection)..

Thoughts?

Fish

In my quest to stay away from DSP and keep it all analog, I was thinking whether it would be possible to do a large array (25 pcs) of TC9FD18-08 and EQ it with a passive network instead of DSP?

I really want to avoid a A-D / D-A conversion in the signal path and keep it all analog (lots of vinyl listening). Active analog filtering is an option as well, but only with a higher end diy EQ, not the cheap noisy graphic EQs you find in the pro audio world. Of course I'd use a pair of dedicated subs to augment the low end.

What kind of EQ curves are you guys with TC9 arrays running?

Hello all,

I have decided to try and design my first PCB, so I thought I'd start with something simple; rectification plus caps. This is planned for a phono preamp. Any suggestions for improvements?

Thanks in advance

I have a pair of old Gallo Nucleus Solo speakers and one of the original Dynaudio woofers is going out (intermittent open). I just can't throw these speakers out -- must save! I am looking for ideas on a midbass driver that I can use as a replacement in the spherical enclosure (roughly 0.35 ft^3 with a 5" x 1.5" port). I'm thinking I will handle driver blending actively with one of the miniDSP units. Any suggestions appreciated!

I'll be surprised if posting images works on my first try, but here we go:



I've been working on this forever! and it's finally cosmetically "put together". It is a 2 way with a radian 475 in a 375 hz tractrix (the first few inches are actually a 6 degree conical to match the exit angle of the radian, then tractrix after that). Horn is cast in a mold from plaster, so I can easily cast duplicates. It is thick and heavy. Mated to a 12" dayton hf crossed at 500hz. The enclosure is ported, but i prefer to plug the ports with sewer plugs and run it sealed.

measures well, with woofer, equalized at listening position but measured at 1 meter in room:



tweeter/horn only unequalized, horizontal polar response



tweeter/horn only csd in room, floor reflection shows up early but it is very clean up to that:




The directivity falls quickly at 700hz, could be smoother there, but that also means that the directivity matches the woofer by 500hz. Polar response could be smoother, but a 2 way that plays 20-20k at insane levels with a SET from 500hz up, and huge solid state power below that has been a nice solution.

I've been to several RMAF shows and have heard a lot of gear over the years. I have not heard anything that can better this setup (partnered with a SET) when it comes to voices. They are haunting. Raising the crossover frequency destroys the charm. Resolution and imaging are also top notch.

It does require equalization, I use a minidsp 2x4hd with 48db/octave LR. I am of the opinion that the advantages of using a high resolution dsp far outweigh the disadvantage of the A to D, D to A conversion. Please chime in with any advice. Thanks, Craig Spieker

my last name is german, it's pronounced "speaker"

Hello Folks,

for an active Speaker project I am (re)using VFET Power Amp Modules and Transformer from old Speakers (let's leave the reasoning for that off topic here 😉). The Power Modules need +/-50V for the Driving Stages and +/-42V for the Power Stages.

I want to use LT4320 based active rectification (have the madules already), the toroid transformer's windings are shown in the principle schematic on the left. The My question is: Which of the LT4320 based detail circuits A or B on the right will work (if any)? If both should work, which one is better for a Power Amp?


(Circuits A and B show positive half of supply only, the negative half would be designed like "mirror image")


Thanks a lot for suggestions and explanations!
Winfried

Please forget about a full time splitter. I wasted hours to learn it does not work.

My Samsung TV only allows one signal at a time feeding any of its 4 HDMI inputs.

One input. Two outputs. I want it to route the signal to my TV in the “Off” position. In the “on” position, I want it to route the signal to my Surround Sound processor (SSP).

When I turn “on” my SSP, it sends a trigger voltage, either 5V 12V to turn “on” the HDMI switch.

I hope this makes sense. No suggestions of a splitter, please. One possibility that will work is, the trigger “turns off” one of the outputs.

I have a very simple, cheap, ($11), easy to access HDMI switch - one input; 2 outputs. Switching controlled by a simple button. But that too complicated for some of the people in my house.

This “upgrade” must remain inexpensive- as in “well south” of $100. I prefer to avoid adding another remote to the collection.

1000 thanks in advance. Tony

There are a lot of modern audio components with such kind of cd drive unit (e. g. Tivoli, SONORO, BOSE etc) - mainly are such cd slot loaders in use on lap tops resp. notebooks.
Nevertheless image series and repair resp. replacement advice are very rar on the web, unfortunately.

Here any few URL's I found:
http://muzso.hu/2008/08/17/how-to-c...ading-optical-drive-a-macbook-pros-superdrive Login to view embedded media Login to view embedded media
I want to know mainly descriptions concerning complete dismantling and refurbishing (cleaning/replacing the parts for draw-in and serve out the disc).
Thank you very much for posting some URL's.

Very recently i purchased 6 CDIL 2n3055 transistors from a reputable indian online store (diyaudiocart). After receiving i took a multimeter/diode test & believe me among 6 transistors three is faulty. All new & genuine 3055. So as per my experience beware of second source like CDIL. Always buy world class transistors like from Onsemi, St & Toshiba.

Hi, i want to start winding some transformers from 100VA to 600VA.

want to know where can i get info about how many windings i need to use and the thickness of the copper, i want to know that because i want to purchase an machine to do the job, but need to know the thickness of the copper and the amount of turns first 🙂

Regards

Hi All,

In the image below I present two kinds of local feedback typically seen on pentode output stages. I am currently using cathode feedback with great results, but the Schade Feedback intrigues me. What are the pros and cons of each method?

Many thanks,

Greg

Over the years I have tried many types of output transformers, Double C core EI core , Hashimoto, Amorphous NPA ,Electra Print, Tamura, Audiofeast/ Noguchi Finemet , but had read so much about Permalloy / Nickel being very nice I went in search of some .
I tried the small Sony / Tamradio Nickel 5K transformers , they were very nice but lacked frequency extension at each end.

Tamura 7000 @ 38% Nickel - Permalloy series are no longer made and silly prices on ebay .

Nickel Permalloy has become my new go to for cores .

I have partially got an RPi semi running over the last few days. I hit many dead ends and re-formatted the SD card many times. I have got to the point where I have it working and I would like to get it to stream through the Dac Hat.

I have tried flashing Volumio to the SD card having downloaded a Windows version on my laptop. This results in the RPi booting up, opening Volumio and then freezing. It won't then do anything else. After removing Volumio it powers on OK.

Should I be using the RPi and not Windows to install Volumio?

Closed.

I have a couple tube projects in mind, including a build of the Valve Wizard's phono stage. I'll be designing toward powering that circuit, first, but would like to have the power supply stand-alone in a separate chassis, so I might recycle at a later date, for another project.

I've repaired several tube amps, radios, an oscilloscope, but never designed anything myself, other than to tinker with coupling capacitor values in my amp (http://seancorron.com/blog/2020/01/30/my-latest-project/).

I've got a salvaged tube transformer from an RCA WO-88 oscilloscope (had an "average power consumption of 40 watts"). It seems to have two 6.3v windings (one center tapped, so 12.6v available I think?) various HT taps, and a shield. Schematic and photos of the transformer attached.

Would this transformer be good for this?

Can anyone recommend a power supply circuit? Other than copying the power supply section from the 'scope and modifying for the voltages I desire, what other things might I want to consider?

Is a rectified heater supply always preferred?

Thanks for any tips you might be able to provide!
Sean

Hey guys,

I'm looking for a software that EQ DSD & PCM files to save the equalized files, I don't know if exist, the purpose it's to EQ for HD600 headphones.

TIA
Felipe

Anyone tried this UK output transformer manufacturer? Stats look good! I'm interested in the single ended models.

https://primarywindings.com/shop/

I am in the process of building yet another LS3/5 'work-a-like' and I found images of the Rogers L35b woofer and XA75 crossover, which in conjunction with an LS3/5 makes the Rogers "reference system" or something.

Anyone have some hint as to the crossover point/slope of the XA75? Of course a schematic would be neat, but I doubt that exists. Searching around only hints at an old for sale add from a fellow in japan?



The Unofficial LS3/5A Support Site was where I initially spotted this image, so if they don't have more (that I can see) I'm thinking this is a long shot...

Hi, recently my sony str av320 receivers' speakers were not outputting anything, and protect mode was turned on, so I checked the mainboard and one current detection transistor in the protection section was faulty. Do I replaced it and the protect mode was gone, but still no sound from the speakers. So it looks like the power amplifier chip which it uses ie STK 4192II was no more working.

When I checked locally there are no original ones available now, and all of them in the market were low-quality Chinese clones.

I was looking for a replacement power amp that has a low THD and good performance, can you guys please help me find one?

Hi,

Been lurking this forum for many years, its a great resource. This is my first post though. I was hoping you could help me figure out what I am missing trying to fix my Yamaha RX-V3800:



I picked the amp up for a song from a film studio, who were selling off about 10 of them at once (I would have bought more if I had the room to store them). The problem listed was that the amp was not powering on – I was hoping that a power supply capacitor was blown, which is a very common problem for these RX series Yamaha amps. I’ve got another one that had exactly this problem.

Unfortunately, this is not the case, instead the amp powers on, and then shuts off after three seconds. I managed to get my hands on the service manual, which tell me that this is the protection circuitry cutting in, shutting off the amp.



Fortunately you can override the protection circuity by pressing a series of keys on the front panel together:



This brings up a diagnostic test, and also allows you to power on the amp (protection circuitry disabled obviously). The fault displayed is : Diagnostic DC PRT : 057. Consulting the service manual tells me that this indicates a DC voltage across the output.....



Bingo! 39V across the Right Rear Surround channel. All the other channels seem fine and have around 10mv of DC offset. My first thought was blown output transistors slamming the output into one of the power rails. I spent the next few hours pulling the amp apart to get to the main amp board (of course you have to pull literally every other board out to get to it):



Here my problem; all the output transistors seem fine. No short circuits, and responded appropriately in diode test mode. I even found the schematics for the channels and started checking all the ICs in the circuit:



All the ICs Ive ticked above are good; I was going to start testing all the passives, and even start desoldering and testing out of circuit, but thought I would check here first, in case I am missing something obvious.

The other thing that is causing confusion is that i checked the primary supply rails, and they are 60v +- rails, not 39V. My understanding is that a shorted output transistor would leave a 60v DC offset on the speaker terminals, not 39V.

So my question is, what am I missing? Is there something obvious that would put a 2/3 of the rail voltage on the speaker outputs, without damaging the output transistors (as far as I can tell)?

Thanks for any suggestions!!!

Hi All

I am currently looking at a refurb/ fix of an old (but immaculate conditiomn) magnum ai170 amplifier.

in short it sounds great , but occassionally has a bit of furry distortion on both channels -but one channel more than the other
- not being driven hard-
given its age - I wonder if it may be in need of recapping..

via a process of elimination the preamp appears ok - (tested via feeding tap outputs into another power amp) and bypassing the output stage (feeding outpuit transistors-(TIP 35C's) on the amp via their own power supply does not remove the "distortion""-- so i wonder if the issue is in the main power amp stage prior to output transistors..

Most listening has been via some old B&W DM4's or Stax electrostat headphones.
interstingly the power supply toroid after rectification and filtering putting out about 49.5 v on pos and neg rails
but
Main filter caps are rated at 50v... (!!)
at the very least i will be uprating the main supply caps to something above 60v or so......

i am seeking some schematics etc - despite trawling the net - i have been unable to find anything much on the amp.

far far too nice sounding to ignore.....any ideas out there...?

btw - internal construction is very nice 🙂


many thanks in advance

Cheers

Looking for a working pair of used FaitalPro HF201 tweeters. EU preffered.

Thanks,

Anyone know the Bias voltage to Monolith panels? I know the smaller Aerius use around 1800vdc, I have a pair of questionable mono panels and am wondering if I can power them off the Aerius Supply to test them.

I have an old Kenwood KA-88 amplifier...
It works fine...I just wanted to know the specifications of it? I can't find them anywhere...i even went to the kenwood site..

And I wanted to know if there's any way I can modify it for better

Does anyone have a schematic or manual for this unit? Previous owner removed parts from board and played with the wiring. I've already checked all of the usual places; can't find a thing. It seems to be a pretty rare piece. ANY help would be greatly appreciated.

I was given an old piece of "medical equipment" that was tube driven. Aside from some 6SN7's and power tubes, it also had this beast in it. I can not find any information on this type of UTC transformer. From a continuity standpoint:

Center 1A/2A are a coil.
4/3 another
2/1 another
10/8 are?

Any help is most appreciated.

Clearance season!
For sale a Nakamichi T-100 Stereo Audio Analyser

The Nakamichi T-100 Audio Analyzer is a powerful diagnostic instrument which enables you to get the optimum performance from your audio system.

Originally conceived as a tool for the serious recordist, the Analyzer also provides valuable information about preamplifiers, amplifiers, turntables, phonograph cartridges, loudspeakers, and microphones.

The T-100 incorporates the functions of an oscillator, a vacuum tube volt meter, a distortion meter, and a wow & flutter meter in a compact, portable form.
By connecting the Analyzer in parallel with your speakers, you can avoid amplifier/speaker overload when you play back.

Still in good shape as can be seen. Although it hasn't been serviced, it is in good working condition.

There are just a few of them on sale and it's very difficult to set a price for this.
Please, send your offer and I will consider it.

Greetings, dear friends!
I became the owner of a Jeff Rowland Capri S preamplifier. As I know, this preamplifier had an option - a built-in phono stage, which was placed on two boards and inserted into the preamplifier. And somewhere I saw information that these phono amplifier boards can be made by yourself, and there was even a circuit board on the site.
I did not find such a scheme on the site. I wrote to the contacts listed on the site, and did not receive an answer either.
I decided to write to you, you always help me out, for which I am immensely grateful to you.
Maybe this time I will be lucky and someone will have this scheme, or a finished product? 🙂
I look forward to hearing from you.

Hi all
Anyone with Experience with Precision devices PD.1845. IN
and the B&C 18SW115 ?

18SW115 LF Drivers - B&C Speakers

PD. 1845. IN
PD.1845-1N | Precision Devices Loudspeakers

Both drivers are Neo.

A friend is looking to upgrade ... the sub is horn loaded.

Just curious on the output of the drivers ... yeah I know the B&C is well respected !!

Cheers
Martin.

Bought the wrong relays

$25 shipped for 12 units

Sadly I have to inform you the passing away of Jan-Peter, owner and founder of Hypex.

Cant find a local shop to fix an amp I have... Looking for local help to solder in a relay on my amp board.

I'm located in the South Bay of LA... Willing to ship if needed

Searching on this forum and others , the vast majority of recommendations for placement of the port with respect to the driver say that within a quarter wave of the tuning frequency anywhere is pretty much the same.

However , in this thread it was noted by several members that where there were multiple identical drivers with one placed closer to the port than the other , the closer driver showed visibly greater excursion. However, the thread didn't appear to come up with an explanation for it , though one poster suggested that the closer driver starts to behave as if it were on an open baffle.

So the question is, is there such a thing as too close? and if so , where would the threshold be? Just asking if there is a known minimum safe distance from the driver for planning an upcoming build.

Thanks very much ! ! !

Hi Guys.

I was a big fan of Sketchup, - until it became an online-tool. I cannot get the online-thing to work properly (UI, shortcuts, mouse... feels wrong).

Whats the free alternatives? 3D preferred, 2D could be acceptable.

I'll be using it to design speakers, boxes and the odd house-renovation once in a while.

Kind regards TroelsM

I connected my 2 monoblocks v1.8 aca to monoblock parallel as per build instruction. I checked the ACA V1.6 operation modes table, Is my connection correct to follow the parallel input operation mode? i like to evaluate the highest damping factor 20 in my normal bedroom listening level at 8w (8 ohms) as compared to single ended bridge mono. Pls let me know. thank you.

Hello,

I hope I am in the right place.

I have some mic preamps with no power supply. The stock PSU is a linear supply +/-15V @ 1.2A and +48V @ 200mA (phantom power).

I would like to build a linear supply that can meet these specs. Off the shelf options like this guy seem too expensive. And I don't like the idea of shoving something on it's own chassis into my chassis.

Is there a generic power supply available that would supply the necessary quiet power? Possibly just as a PCB?

I have an electronics shop, mostly do repair. Should be easy to put something together but hoping for a somewhat off the shelf solution, not looking to design my own board. Hoping a generic PCB supply exists and I can just grab a chassis and toroidal PT and put it all together.

I did see the DIY Audio Universal Power Supply but the board is out of stock and not sure if it's the best option.

I figure I will probably have to use a separate board for phantom power.

Thanks in advance for any input.

I just got a new batch of Pete Millet's Korg 6P1 NuTube preamp module PCBs in. These fit the Yarra preamp motherboard or the M2X amplifier bolt pattern. This is a valve SE triode design using a compact NuTube vacuum tube design by Korg. The Pete Millet design is used with permission - thank you, Pete! And thank you, JPS64 for a super layout!

More info in the Yarra thread, here.

Here is the new green PCB:


Schematic:


Stuffing Guide:


FFT with VHEX+ amp 2.83vrms and 1.55v grid voltage:


Assembled preamp unit:


Mounted on Yarra motherboard:


The PCBs can be found in my shop here:
Korg 6P1 Preamp for Yarra | Etsy

The BOM in Excel xlsx format is below as .asc file. Rename as .xlsx to open as spreadsheet.

First, I struggled with choosing the correct section for this. I chose the tube section because I believe the cd, dac, and op-amp section of the cd player is ok. Anyway, happy to move it, have it moved for me, or re-post if I chose the wrong section...

Now, to my issue. The left channel rca (and headphone) output is about half to 1/3rd volume of the right channel. I've checked the signal on an oscilliscope and I see a balanced signal on the output of the op-amps as it enters the tube stage. Post tube and output stage the left channel is lower than the right channel. Digital outputs sound fine through an external dac.

I've swapped tube positions, checked every resistor I can find (a lot of surface mount here), pulled the big wima cap and a couple others, checked some other caps in-line, everything seems good.

I'm new to debugging tube amps, but I checked dc voltage of each pin of each tube and I don't know if they're correct but they at least match on the two sides. The filament voltage is 6.3V as labeled on the pcb. The +33V and -33V as printed on the board is correct as well.

In desperation I used the solder pads to set the right channel to 1.25V output voltage while leaving the left channel at 2.5V. This actually did balance the output (as far as I can hear) but is obviously a hack.

Any ideas about what else could be going wrong? As far as I know a schematic was never released publically. Is it possible that even though both tubes are good, the circuit, power supply, etc are unable to drive both and the left somehow suffers?

I know it's a long shot, there is basically zero info on these on the web (surprising). Also, I do realize there may be better cd players out there or that I should just use a transport and a tube buffer/preamp. It's a challenge now though, I just want to fix the thing.

Edit : I've long suspected the relays could be the problem as on my solid-state amps they are almost always culprits with channel imbalance. However, the board has two relays. I believe one is for the headphone and one for rca output and both have the same problem. I can't believe the relays both failed in exactly the same way. However, it could be that one relay is partially pulling down the left signal and it cascades around through the rest of the amp.

i recently downloaded ARTA to use in conjunction with REW to measure tweak my system, but i've noticed a strong rolloff on the HF spectrum, see attached image of an IMD test i was trying out. we see at ~8khz there is significant rolloff, and after testing frequencies above 10khz, ARTA appears to be gathering no data above that point. evidently i have a noisy room/measuring system, as evidenced by the lower frequency range, but i was expecting more bandwidth than that.

ARTA was set to 48khz sample rate, so we shouldn't have any issues on that front. apart from that, i do get full bandwidth response on REW, which measures as expected out to 20khz. i'm on windows, using standard motherboard audio on my desktop. the mic is a USB minidsp umik-1.

I'm looking for input and possible schematics, boards etc. to build a higher power class A amp. In particular though, I want to use the output transistors that I have an abundant supply of MJ15024/25. These are NOS and from the same lot code. I have about 150 of each. I currently have a Pass labs designed A-40 and F5. I would like to have something in the 100W/CH range and have the heatsinks from industrial drives that can support that. I can go with mono's or possible stereo chassis w/fan cooling. I love the sound of the A-40 and it would be great if that front end could be expanded to drive a different output stage to handle higher power. I realize that it is a darlington config but I did read somewhere where Pass was saying it would be simple to convert to a convential BJT with driver. I know that just about all the Pass stuff now is driven with MOSFETs and not the BJTs that I'm wanting to use. Any way interested in what people have to say on this.

Looking to buy a cheap, small and compact amp for some computer/desktop speakers I've purchased.

LM4780, LM3886, gainclones, AB or Tripath would be ideal.

Ideally integrated amp with USB DAC, but no problems if not.

If anyone has anything like this up for grabs in the UK let me know!

Thanks

I would like to know if using 12v 1625s instead of the 6v 807s would cause any issues besides using 2 of the 6.3v filaments in series for the 12.6v tubes.

http://pmillett.com/HV_bench_supply.htm

I bought a Yamaha CA-2010 integrated amplifier from 1977 with a balance control which doesn't work. Opening the device, the problem is immediately apparent: a technician has disabled balance control. See picture.

Why would such a thing be necessary? I am asking here before I restore it to stock condition.