Hi, wondering if someone can help solve a problem with the TU-8200 (earlier version).

About a year back I tried the 6P3S-e and while they sounded fine, the amp clearly was not pleased. Everything got really hot and ended up with weird buzzing noise. I replaced the mosfets Q1-Q4 and some of the problem went away.

Now, I have the strangest problem - even with the amp switched OFF I hear a slight buzz. The speakers are Altec with a fair bit of efficiency, but none of my other DIY amps have a similar problem. The buzz remains when playing music and gets louder with the volume control turned up. When switched off, the buzz is at a constant level and the volume control has no change. Any ideas would be really helpful, this thing is driving me NUTS.

Since THAT experiment I've stuck with G.E 6L6GC (tested on another amp). The only way to get rid of the buzz is unplugging the mains cord.

thanks,
Sunil

I have a pair of One-Electron UBT-3 output transformers, 3000 to 4/8/16. These are new with full leads.

Located in St. Louis, Missouri, USA. $220.00 for the pair plus shipping.

I've had the opportunity to pick up a few pairs of vintage speakers recently, Dynaco A-35s and Akai SW-180s. I'm enjoying them on my SS amps that I own now but I'm interested in trying speakers with some tubes. I currently have a DarkVoice for my headphones which I love but I'd like to try a stereo tube speaker amp. I've seen a number of kits out there for DIY tube amps but I'm not sure which one would be best for my application and price point. I'd like to use this with my record player and with my phone via either Bluetooth or RCA and I'd like the best kit I can buy for $300 or less shipped to the US. I don't need a headphone output for this amp and I don't need any crazy high wattages to drive these speakers.

SOLD

Asking $179 per driver or $295 for both.

The drivers look new. They came out from REL T5 subwoofers that their amps didn’t power on. The amps have leaked caps and bad resistors. The amps are also for sale if you are interested.

I have two woofers/drivers for sale.

You get what you see in the photos.

No returns.

8in., 200 mm long-throw, steel chassis

P.S. If you look at the photos TOO CLOSELY, you see some stuff; they are FUZZ! I think from the carpet. There is ZERO scratch or anything like it on the driver itself.

Hi all,
I would like some advice on which excellent spray product to use to protect the soldering side PCBs after having cleaned, degreased and removed the original protection applied by manufacturers on old pcb's.
I don't want to leave the pcb without any protection.
Thanks

Hello.
Its strange problem of protect mode on TECHNICS SU 8600 Amplifier.
If I desoldered TR506 relay click,and Amplifier works fine.
With TR506 relay not click.
All voltages are ok.
No DC voltage on speakers terminals.
Amplifier works fine without TR506....
THANKS

Hi,

I've been given a Digidesign 442 audio interface box - the Nubus Mac and controller card is long gone.

Rather than put this into landfill as toxic waste, I was wondering whether anyone has any experience of getting these units to 'free-run' as DAC boxes - taking S/PDIF from the RCA input jack and putting the analog audio out of the XLR connectors.

The S/PDIF decoder is the Crystal Semi CS8412

The DAC/filter pair is AD1860/NPC SM5813

I've found datasheets for the CS8412 and AD186x - no luck at NPC.co.jp for the digital filter, sadly.

I've tried feeding 2-channel 44kHz PCM from my CD player into the S/PDIF input to see if the box has any autonomous capability - but it stays stuck on AES/EBU 48kHz :-(

Opinions about the practicality of this project welcome !

SOLD

Set of 3 various power supply boards from an overseas supplier. All can be used for various Class A amplifier needs.

Asking $20 including Continental USA shipping.

1) Dual Mono Single Rail board, 100 x 100mm, mounting holes look UMS compatible at 90mm x 90mm spacing. Diodes mount to board.

2) Pass type PSU board. 145 x 127mm, not UMS compatible mounting

3) Red Dual Mono PSU, 150 x 145 mm, not UMS compatible.

Come as bare boards with schematics and BOMs as shown

Folks:

I have a decent supply of project boards and a bunch of 2- and 3-position fixed terminal connectors. All are compatible with 5.08 mm spacing. Many of my fixed terminal connectors have mounting pins that are too large to fit into the holes on the project boards. Virtually all of the things I build on the project boards involve very low current, so I don't have a need for heavy duty terminal connectors. Drilling out the holes is annoying. Can anyone point me towards a supplier for fixed terminal connectors with very narrow pins (ideally smaller than 0.9 mm x 0.7 mm)?

Regards,
Scott

I'm building some HT speakers and wondering if I should buy a built sub and re house it or put one together from a raw driver and amp? I want something small that my wife won't protest too much. I'm on a very tight budget but I can stretch to about $500. Its going in a small room and we usually don't listen too loud. I'd like to hit f3 in the low 20s. Looking at the RSL Speedwoofer 10S MKII versus the Dayton Audio RSS265HO-44 10" Reference Series HO DVC Subwoofer with the Bash 500S Digital Subwoofer Plate Amplifier 500W RMS. If not one of these then what do you reccomend?

These are rendered concepts. The 10" sub box is 1.5 ft3 plus port.


I was going to go more budget with the 12" GRS 12SW-4HE and dayton 300 watt amp, but the cabinet ended up way too big to get the ok from the minister. Since we hope to live with this sub for many years I'm going to spend extra for the smaller size. These are some of the concepts I had played with.


In case you were wondering the plan is to cnc the cabinet parts and use lime plaster or microcement to coat the exterior. The baffle will be mdf with white oak veneer.

Empire 2000E/III with good stylus, very well balanced electrically $50
Sonic Sonus Silver needs stylus (aftermarket appears available from Japan.) $60
or both for $100 + shipping

I'm going to be placing a more in depth write up of a rebuilt./modification that I did to my speakers. What is the character limit & photo limit for a single post?

I'm happy to split the content into several posts in a new thread...is to original post followed by posts 2, 3, 4,.....just hate it when somebody manages to comment as a new post when I'm trying to "reserve" the next post...Had this happen on other forums..


Also as I can't see a separate "my build" section I presume the best section to place my "modification thread" is the "Multiway speaker" section......just I'm not asking questions just placing my "how I did it" as a reference guide...

In years past I used to build quite a few amplifier modules and sell them on ebay.
In more recent years the competition from China and very cheap vendors has just killed it.
The only one I am left selling is a JLH96 class A amp. There are plenty of JLH69 but not so many 96's.

I have had to move on to model railway electronics and USB scopes to continue selling.

I am working on restoring a vintage amp (a Heathkit, relevant schematic shown below). I believe I shorted Q707L collector to ground (silicon heatsink pads = bad, lesson learned, stick with mica). Q707L of course was bad, R741 literally burned up, as did Q709L so I replaced those components. I also replaced Q706L as it seemed to not be testing good. All of the surrounding components seem to be testing good, including the diodes, resistors, and other transistors like Q705 and Q703, as well as Q704 and Q708. I get sound at a decent volume from the channel but it is a bit distorted and phases in and out a little bit. Putting the other channel in place sounds good so I do not think it is the preamp section or anything upstream. I've exceeded my ability to interpret the circuit to diagnose the symptoms the channel is exhibiting - any thoughts on what could be suspect that would cause the amp to distort but not be dead? I appreciate any thoughts!

I need to replace the two 2A3 sockets on my Moth 2A3 amplifier. Any suggestions on what I should use and where I can obtain them?

Thank you.

Hello!

I pulled this little guy out of the FM module of a Fleetwood tube radio from the early '60s. It was causing intermittent problems due to a broken leg. When I tried testing it, it's other leg fell off too, but there was enough metal to try. I think it's a 'dog bone' resistor, but I've also seen photos of antique ceramic caps that look similar. I tested for resistance and capacitance and got nothing (open resistance). There are about 5 of these type of parts mixed in with normal looking carbon resistors and ceramic disc caps, so I'm not sure why they're needed (and only in the FM circuit). I pulled a couple similar parts out, but they also failed to test. Could they perhaps be tiny wire wound resistors that blew with a surge? Or maybe out of my meters range? I tried for hours to find a schematic, but could not.

Anyway, the main part in question is grey with a green dot on the left end, with 82 printed on the body. Grey would match up with the 8, and green could be the multiplier? So maybe a 8.2 Mega ohm resistor?

Any help or insight would be greatly appreciated.

Hey techies.🙂

I have a bass combo amp, swr superredhead, that has an issue that I cannot really tell if its a preamp issue or power amp / section issue.

Distortion at low volumes. If I turn the amp up, it gets almost as loud as it should, and its cleaner, but she aint "off the shelf" sounding yet. Here is what I have done so far.

1. replaced the only tube in the amp. a 12ax7. this does not solve the issue. ANd I have reason to believe that the preamp section is okay. Replaced some of the preamp caps and resistors. More of the tone im looking for, but the power still is lacking a little.

So, what would you check? Caps? Resistors? Power transistors? Those are 2SC3264's. 4 of them for a 350 to 450 watt ourput. I have the trannies on order, should show up this week.

Thanks for any input peeps.

Mike

TDA7850 CLASS AB HIFI DC12V
It can replace class D amplifier as hifi level performance improvement.

The TDA7850 is a breakthrough MOSFET
technology class AB audio power amplifier in
Flexiwatt 25 package designed for high power car
radio. The fully complementary P-Channel/NChannel output structure allows a rail to rail
output voltage swing which, combined with high
output current and minimized saturation losses
sets new power references in the car-radio field,
with unparalleled distortion performances.
The TDA7850 integrates a DC offset detector.
THD Distortion
Po = 4W 0.006%
Po = 15W; RL = 2R 0.0015%

Hi all. I've been given a Thorens TD160 turntable which has been in storage for sometime. It does turn after the belt is replaced. However, I noticed that a very thin nylon wire between the balance wheel and the tonearm is broken (attached two photos show the broken wire). Is the wire part of the anti-skate mechanism? How to repair? Appreciate advice. Thanks.

I have bought a Cyrus DAD3 CD player that has a fault with the tray*. When the 'eject' button or equivalent on a remote is pressed. the tray comes out fully then goes back in.
This is intermittent so the player is usable. I took the bottom plate off and cleaned off the grease on the tray rails - seemed to be quite a lot of it and put a small amount of lthin white lithium grease and after 50 eject cycles, the problem did not occur. This was done outside where it is quite warm.

When I brought it in indoors, the problem has returned. (possible theory is that the grease I piut on has thickened due to cooler temps)

I'm posting this on the off chance that someone may have had a similar problem. I haven't figure out the cause and comparing the tray with an identical model, I cannot see any difference nor can see a limit switch or any ajustment.

* In case anyone says it, the fault was known so returning is not an option; it's still usuable, just a bit annoying have to press ejecty until it behaves.

is it gorgeous?​

Looking for a quiet, good quality amp to power a 15w compression driver pair, used over 6khz.
pre-built, affordable, ugly box is ok.
PM me

I have a modulus86 and a parallel86 and both have an IEC module, mounted on the back panel, with a power switch so I have to reach around the back to turn on the power. I want to put an illuminated power switch on the front panel. My question should I use a 125VAC switch connected to the IEC module or a 36VDC switch connected to the PCBs?

Anyone have experience with this device? Has been getting some attention lately because of vinyl resurgence.

https://www.audionirvana.org/forum/...scales/89647-blast-from-the-past-from-ortofon

http://snvinyl.co.uk/WebRoot/Daily/...24/DE99/651C/0A0C/05BE/BF2F/Skjermbilde_m.jpg
https://www.audionirvana.org/filedata/fetch?id=166862&d=1652746332
https://www.audionirvana.org/filedata/fetch?id=166863&d=1652746381

I have just purchased a pair of Threshold SA/12e mono blocks. One of the power fuse holders broke in transit. Does anyone know where I can purchase the original parts? Maybe Nelson has a lead for me?
These amps are true monsters and I am looking forward to putting them to use 🙂

Nelson, how many SA/12e were produced? (approximately if you don't remember exactly) and how many were made in black versus natural finish?

Thanks,

Michael

A couple of years ago I found this forum in a Covid induced dive into the idea of building both DML speakers and a tube amp. At that point I was in Korea and working so after learning a bunch all project work was shelved. Now I'm back in the US and retired so projects are coming back out.

Current projects -
Spud amp just to get my feet wet with tubes
DML speakers
Get my cnc router set up and working (only tangential to this board although I have some plans for a nice front panel)

I have a Hafler se 120. I am just curious why one side the DC offset is 2MV and the other channel is 60MV when on for about ten minutes, no load attached. Is this something to worry about. also when i try to cool the high channel it actually goes higher which seems very strange. i check all the solder connections and no problems. Any troubleshooting would be appreciated. The electrolytic show no bfldgin or leaks. They are only 50vDC and the unit mains are 54V. I don't understand how Hafler makes this work.

I am salvaging some parts from a pair of these edifier bookshelf speakers and also a few parts I have which are two of these woofers and two of these tweeters . I was wondering what the best configuration would be given these parts (2-4 Ohm tweeters, 2 - 4 Ohm woofers, 2 - 8 Ohm tweeters, and 2 - 8ohm woofers)?

Should I make one enclosure full of 4ohm parts and one of 8ohm parts? Is there a crossover I can buy pre-made that can help with this? Should I wire them in parallel or series?

Hi, there!
Signed up just now...
Just picked a Carlsbro Cobra 90 Keyboard out of a dumpster. It is in good working order, with only a little bit of crackling from some of the pots. But since I am who I am, I was wondering if an Lansing Subwoofer Model 515-8G would fit inside. And would it give more omph? Salvaged the Lansing speaker from a wrecked cinemaspeaker years back, and it has been sitting on shelf ever since. It is in very good shape, so it's a shame not to find a use for it.

Hello everyone, I've joined this community few days ago, I've found a lot of interesting thread here 🙂 Can anyone explain me how I can be enabled to send a PM another member?

Thanks
Stefano

I am choosing a midrange for a 3 way rebuild project. The mid has a 2.5L sealed enclosure all to itself within the cabinet that cannot be changed. I have narrowed it down to a choice of 3 drivers:

seas MU10RB-SL
scanspeak 10F/4424G00
SB satori MR13P-4

running the specs through a box volume calculator the seas and satori look fine, flat down to 200Hz but the scanspeak starts rolling off from 1kHz and is 2db down at 200Hz. I was a little surprised to see this as the seas and satori are such different drivers but model so similar, and the scanspeak is quite like the seas in construction and size, yet appears to behave differently.

I'm intending to cross over the mid/bass at about 400-600Hz so this just might not make any difference at all, but i'm wondering if this rolloff signifies something else going on that might make the scanspeak an unsuitable choice.

if it matters, mid/tweeter crossover will be about 4kHz

Hi, I was wondering if anyone knew of any detailed troubleshooting tips on the Philips CDM3 CD unit..or is it available in a service manual? I've got one with some intermittant problems, mostly on the side of not working at all...but sometimes it surprises me and works for a few minutes.

Just curious what normally goes bad on these or what I should perhaps be looking at, since I saw some previous posts about them being 'repairable'...

Any help is appreciated! Thanks!

Pete

I'm sitting here reading the latest Highfidelity (nordic Hifi-magazine) and they have tested the Synthesis Magnum 100 with great results.

It's a tube-buffered LM3886-based integrated amplifier using apparently 2 LM3886 in parallel/channel, each buffered with a ECC88/6DJ8-tube.

Some comments by the author of the article:

Magnum 100 showed it's self directly to be a very musical amplifier with a rich and warm mid-register.

The bas is rapid and rhythmic...

Above all the orchestral depiction sounded homogeneous and realistic...

Contrabass and cello felt solid and present...

Realistic representation of the piano sound is always difficult, even this did Magnum 100 with bravura...

The continued listening was done with regular CDs and confirmed the picture of the Magnum 100 as a very balanced and musical amplifier with a rich, warm midrange, an unstrained treble reproduction and a solid, well-detailed bas.


And on and on...

Overall they are very happy about the amplifier and I think its great fun to see a Hifi-paper test a chipamp-based amplifier without once mention anything negative (or for that positive) about the fact that it's build with chip-amps.

Have anyone here listen to the Synthesis Magnum 100 (or the 50, a smaller version with only one LM3886/channel I guess) and if so, how was it?

Hi,

I built an MTH-30 sub for our little ska/ reggae band and we are delighted with how well it works. Loaded with precision devices 12 running off crown amp. Kick sounds great.

I have 2 HK tops (old!) called "HK Compact." Replaced (! piezo) tweeters with APT150 and fitted 12 inch fane 250TC drivers to replace the fitted eminence 12LTA. Sounded much better. Also fitted new crossovers- tried a 2.5 and also 5 KHZ crossover. Not sure if they were a good idea...

Honestly - a stupid question - we like the tops as they are small, and that is very important in the small venues we play but they are a tiny bit harsh, ? at 5 KHz? maybe running the crossover too high, I think we can get a better sound. Not sure if the triple cone speaker should be allowed to run all the way as high as it can go and just have a HP on the tweeter instead?

I'm thinking of either replacing the tweeters/crossover - space is limited in the cab so would like a tweeter that could run a bit lower and also fit the APT150's plastic horn... Or maybe replace the speakers entirely with maybe something like a SLA Pro - some sort of column design or maybe Omintop 8 (with compression drivers not piezos!) - I'm very concerned at having ports on the side of the cab though as seems like a recipe for feedback??We would need a cab to do down to about 120Hz to meet the MTH-30 I think?

Probably stupid questions but if it was you and you had to build as narrow a cab as possible to match an MTH-30 sub to take full band (kick, keys, vox, bass) what would you do? We need horizontal and definitely NOT vertical dispersion where we play - low ceiling pubs in UK! Should I be looking at or 10's , 12's or maybe a column speaker/horn speaker of some sort. Not really up for a commercial powered cab as I like making speakers and after MTH-30 feel we can get good sound from DIY cab. We have another 1400w amp available. Any advice please? Great forum by the way!

https://www.erinsaudiocorner.com/loudspeakers/linkwitz_lx_mini/


No set of measurements completely describe how a speaker sounds - it’s a visual translation of an auditory event- but Erin does it better than anyone else who is publishing measurements.

exhibit A:




@bikinpunk Thank you Erin, for listening work and descriptive comments before your measurements. Your methodology, experience and interpretation is advancing our understanding.

For dipoles, I must say the CTA2034A isn’t all that helpful- I went straight to the Youtube review to hear what you had to say about this speaker.

Hi folks,

20 year Mac user here so a little short on PC knowledge. I've had a 2011 Mac Mini (High Sierra) boot camped with Win 7 32 for probably 6 years. It's been solid but the drive is dying and my kids are claiming the Mac Mini so I need to start over.

I'll do a Bootcamped Mac again, likely used with a clean install of Catalina. What Windows version should I get?

My use case is pretty narrow - Prism dScope, maybe an Audio Precision in the mid term (likely older), simulation software (LTspice etc), Kicad, some speaker simulation stuff. All day to day Audio work is done on my Macs.

Should I buy Win 10? If so which version would you suggest? Or just go with Win 7 32 that I already own?

Thanks!
Ruairi

Windows 10 generates a 13dB increase in noise & distortion when going from Windows output level 99 to 100. I am posting Audio Precision APx555B analyses to illustrate.

This anomaly was verified in two ways: 1) USB to I2S to APx555B DSIO digital input, 2) USB to ASIO to Yamaha A-S801 headphone out to unbalanced APx555B analog input. The latter is illustrated.

THD+N (ratio) goes from -94dB @Windows 99 level out to -81dB @Windows 100 level out.

This bug is likely to be encountered, even by Audio professionals, because it is well known that audio quality is optimized by generating maximal digital levels out of a PC; i.e, controlling volume on a downstream analog audio amplifier.

Hello,

As the title suggests, I am looking for any general or specific recommendations or referrals. While I do have some clue (and am a trained EE), I am certain some people here just have much more knowledge about what's available and what's best. I am open to new or used, bench or portable, etc.

I am sort of a repair hobbyist, I work on particular older car audio equipment, sometimes with the help of Mr. Babin or other distinguished contributors. This is for personal use or small jobs for friends or acquaintances.

I don't want to break the bank, but I do have a reasonable budget and may pay more if it's right.

Thank you for any suggestions or feedback!

Hi Guys,

I've recently build a reel to reel playback tape head tube preamp. I have followed the Tandberg 64x tube preamp schematic however something is not adding up and maybe someone can clarify if this is normal behavior. I have checked the build and everything is as per schematic.

Tandberg doc specifies that the cathode follower output is 1.5V. Mine is 12.2mV which is a huge difference. I have traced the signal and the values can be seen in the attached schematics. Also, the plate and cathode voltages are correct in my build as specified in the Tandberg doc. I also removed the entire EQ part and the results are the same.

Did I do something wrong or the values measured look right to you?

Thanks

I have these Eminence 15" speaker special run speakers with the following specs......could someone inform me
what would be the smallest box volume ported and If these speakers are usable as a home woofer use??? Thanks
These are old left over new speakers 109oz 4"VC 300watt
Fre Resp 50-1500 hz
FS 28hz
vas 10.33
qts.28
qms 9.4
qts..28

I have several used Dale NH-100 4-ohm, 100W, non-inductive resistors. Theye are the aluminum housed, chassis mount ones that are great for dummy loads. I have at least a couple dozen. These were mounted on heatsinks, which I might have access to (in storage) in the coming week.

These will ship from Encinitas, California. Asking $15 each, plus shipping. Local pick-up is also fine.

Click on images for proper resolution.






Cheers,
-Casey

Hello,
If I have a 3" voice coil that is 70cm long. How long and wide would the Faraday ring need to be to use it efficiently? Okay, I imagine it needs to be at least 3 inches but there are still more to consider?And where would be the best place to put it?

Hi. I am building a boombox for my father in law as a birthday present and need to calculate the port size and length. I’m using aura ns3 8a drivers and my box volume is .11 cu ft. I used to use winisd but our household has been taken over by Apple. Hope someone can help?

I'd like to buy some genuine OPA1656 and OPA1655.
PM me if you have them 4 sale.
Thanks!

Like a lot of you I have a lot of old projects laying around unused so I decided to make a deck bluetooth boom box out of some decent but unused old stuff. Inspiration came from an old picnic set that I ran across in a thrift shop. I stuffed an old MRefC chip amp, a Subbu DAC, a Kookabarra preamp, and an ebay bluetooth gismo into the case and added power. Easy to transport and sounds great. Using Mark Audio full range speakers.

This turntable has been used by people who were careless, drugged, or drunk. 😢
It has the AS system pin broken in a very difficult place to remove and replace with a new one. Luckily they didn't throw the balance weight.
It is very difficult to work with the arm installed, would it be necessary to make a small well-centered hole and get an extractor...so small? Or drill everything and make a new supermeasure thread.
Or extract the arm from the chassis and take it to a microturning specialist... All of that would take a lot of effort and money.
So you can see my solution. In a few hours it was ready, the hardest part was getting a new bolt of the exact size. So I had to file down a threaded screw until it worked smoothly, with just the right amount of clearance.
The result is satisfactory, the AS works perfectly.
Now the arm lock on his seat needs to be repaired, but that will take time, I'll have to make the piece out of copper plate. I have done this work before on a capsule holder spindle and it turned out very well. For now, I leave you the photo show.
The secret was to make a small cavity above the new bolt to match the tiny bolt rest protruding from the main body.
That put him in his correct position. And the cable gland secured it in place.

I've been using the LNR2A473MSE 47kuF 100V 63mm dia electrolytic as upgrade to the original 20kuF caps until recently.
I have another DH500 to upgrade this week, but all three suppliers show this as now being non stock item with min order of 25 pieces.

Does anyone know a source where this part is in stock?

I'm wondering if anyone knows the minimum loading that a Hypex SMPS400 may need on both the +/- main outputs as well as the +/- aux outputs for doing some basic go/no-go functional checks. I didn't see it on the Hypex data sheet but I could have just read right past it. The context for my question is the local high school has a commercially sold powered loudspeaker that the music department uses. It is based on the SMPS400 for the power supply, a custom pre-amp board and then 3 hypex amplifier modules (1 for the tweeter, 2 in bridge config for the bass/mid). There is a logo that is supposed to light up on the front of the unit but instead it flashes with a quick flash ever few seconds and there is no audio. I'd like to break the problem in half and decide if it is or is not the power supply which is what lead to my question about minimum load. Or can this unit handle running with no load? When the unit is fully connected (i.e. power supply, pre-amp, amp boards all connected normally), the supply main outputs are definitely not right (+ very low, - even closer to ground).

Regarding lab capability, I have access to various DMM, decent soldering equipment that is sufficient for the SMT stuff on the hypex boards, scope, microscope, and the usual sort of electronics bench hand tools. Regarding my experience, I'm an IC designer by trade but mostly not related to power electronics. That said, I've serviced tube amps as a hobby and in a previous life designed an offline flyback converter so I'm not totally without experience keeping my fingers and tools away from mains. For anything beyond a really light load I'll have to obtain something that can handle a bit more power.

FWIW, last year I fixed the other one of these units that the school has but in that case it was a linear regulator on the pre-amp board made out of discretes. That was a bit easier to track down even if the manufacturer did put a lot of goop on the components.

Anyone have a decent schematic for these supplies?

Thanks so much in advance.

-Dan

SOLD
These beauties test practically NOS on calibrated lo mile TV-2 tester as follows:
delta 7E2 90,95
delta 5L1 100,105
delta 7D2 102, 110
delta 7D2 93,93
delta 5L1 93,95
$75/all

Hey ya,
Just wondering where is the best place to get music these days? I try to get music on cd for the sound quality as it beats downloading mp3s :O
Is there any website out there where I can purchase and download individual songs from that are at least cd quality? wav preferably?
Cheers

Hi!
Usually everyone wants to get the most out of this tube, e.g. 16W.
But what would be the ideal operating parameters for just a 8W version?
Greets:
Tyimo

For your possible interest.

I have this amp on my bench for repair. The lady who brought it to me says it was her grandpa's Harmonica Amp and would like restored. Did a circuit trace. Very interesting tone control, treble boost/cut by feedback around the output tube. I looked up the tone control in RDH to find that the entire design is a 1942 W.N. Williamson design, Yep same Williamson who did the famous (well certainly the most copied) HiFi Amp design. Could have saved the circuit trace effort if I had know that up front.
6J7 triode mode to 6J7 pentode mode to 6V6 with an 80 rectifier. Lamp in standby switch line as a HT fuse.

Cheers,
Ian

A while ago I saw this post by DIY perks.
video here Login to view embedded media and resources here https://diyperks.com/project_31_high-quality-usb-c-microphone/

I was fairly intrigued so I bought the mic capsules. well they've been sitting on my shelf for a while and I was going to build the rest of it, but looking at his amp circuit i'm not really happy with what I see. it's ac coupled in 3 places. I also see that it doesn't have any negative feedback.


Then I did a bit of digging and found the "alice" electret amp circuit

https://www.instructables.com/OPA-Based-Alice-Microphones-a-Cardioid-and-a-Figur/



Now from a bit of digging I've heard this one is supposed to sound a bit better, but I see it's still AC coupled on the outputs, and it's for XLR while I want to use my sound blaster's 3.5mm microphone input. for power I'll probably use usb, and if I need to boost levels / get negative voltages I can use the NMA0515Sc from the first schematic. I would probably add some LC filters after the power regulator though.

Now onto my questions. Does anyone have a better circuit, maybe something dc coupled that would work for this situation. I'm also really unclear about what voltage levels the microphone input on my soundcard uses and I'm afraid to blow it out.

Also would bootstrapping the opamp be applicable at all?

Thanks

hi

looking for some parts (probably like everyone else right now).
i'd like to finish STARKRIMSON amps and my needs are as per below list:
TI SN74LVC2G17DCKR 6pcs (minimum)
TPS7A4700RGWR 5pcs (minimum)
TPS7A3301RGWR 3pcs (minimum)
7G31A-100M 5pcs
7G23B-100M 10pcs

i was holding back with my order for to long and now sending rfq's everywhere i can 🙂
mouser shows availability dates close to nov.2022...

thanks!

hi all,

here http://www.emissionlabs.com/Article...2-Circuit-Topology-for-Tube-Power-Supply.html

you can find the following statement :



" Circuit 5: This is how to connect a double coil Choke, such as the Lundahl LL1673 or similar products. Beware the polarity of the connections. (the dots in the circuit diagram here). The importance of this circuit is very high. We have complete inductive separation of the transformer from the amplifier. Definitely, the transformer capacitance from primary to secondary can not inject an AC hum current into the amplifier any more.
Design Quality of Circuit 5: Five Stars ***** "

in another word, this is the best possible connection with Lundahl chokes according to datasheet.

The question:

can I use this Circuit 5 connection not in CLC (capacitor input) mode but in LC (choke) mode?

as shown in the diagram below

Hello, Trying to repair the left channel on this Sony ES amp and not having much luck. Suppose to be getting 45 vdc +- on the left side but only getting around 32vdc +-, also getting around 5 vdc on the speaker +-outputs of that channel which isn't good and causing speaker to pop. Any help on this would be greatly appreciated.
Thanks

50VA R core transformer with 2x0-18V secondary windings.

Asking £ 35 with UK delivery.

Want to buy
PPY`s ReClocker for BeagleBone


Please pm

400VA Canterbury Windings Toroidal transformer with 2x0-22V secondary windings; interwinding screen and Goss band.

Asking £75 delivered UK only.

Hey everybody!

Since I just ordered a Behringer iNuke 3000DSP for my subwoofer, I thought I'd look at my options for an amplifier for my fronts. I stumbled across the KM1700 because I know that it's basically like Class A/B but with a variable and dynamic voltage rail. Correct me if I'm wrong!

They're slightly (and that's a mild expression) overpowered at 2x500w into 8Ohms. My speakers are barely 90 Watts RMS (if they're set as fullrange. They can take slightly more when not in fullrange, I suppose. Or less? Less movement is less cooling hmmmmm.)

Since I'm not very good with the specification-sheet reading, what would your opinion be? I can't actually find a specsheet. 🙁

Any input is greatly appreciated.

Cheers,
Anna

https://www.amazon.com/Behringer-KM1700-BEHRINGER/dp/B01MAY7S7W

Has anyone listened to the Behringer KM750 or know if it is ok for sub duty ? It is cheaper than the INUKE NU1000 but i don't know if the KM750 is quiet.

I just got done building one channel of my monoblock and have been listening to both of my speakers fed from that with mono mixes. And i find that native mono mixes (from youtube) sounds excellent.

But some music downmixed to mono (either digitaly or with a switch) sounds horrible. The frequency balance is way off. So much so that it makes the amp sound as tho its broken.

Why is there such a discrepency and whats the science of it?

Thanks and regards

Er der nogen som har erfaring med at erstatte ensretterrøret 5AR4 med en 8 pin solid state rectifier RT 515i en Tubelab simple SE power forstærker med El 34 monteret. Jeg har rørt 5AR4 monteret i 8 pin octal sokkel for tiden, men ønsker at prøve med solid state rectifier i 8 pin octal sokkel hvor rør normalt sidder. Jeg har ikke loddet dioder i printet og har kun 8 pin octal løsningen tilrådighed.

Can someone tell me a good way to obtain h3 and only h3?

Hi im trying to reformat my preamp to smt format through jlcpcb. Its a mono mono double bridge config, each channel 18 0 18 0 ac input and up to 500ma bias output at +-15vdc rails.

Until now ive been using uf4004 diodes and now since looking into smt schottkys im overwhelmed by the number of choices thats at jlcpcb.

Anybody have a good recommendation on them? What are some user favorites? Thanks

Hello,

My old CD player has small EI transformer which is starting to hum badly so try to replace with a quality one.

When I measure the voltage of primary and secondary windings of existing transformer, I got below readings.

Primary: 52.8 Ohm, 245V
Secondary: 5 ohm, 30.3v

Dimension is 55mm L x 20mm D x 45mm H.

I am aware of that I need to get 230v primary voltage rating transformer but not sure,

(a) if I need to get 28V or 30V secondary voltage rating since actual AC feeding to it from main is 240~250v.
(b) what power rating transformer should be given the dimension of the transformer mentioned above.
(c) And, which company's EI transformers are reliable? I am thinking to get either Triad or Hammond from Mouser. Are they good enough?

Thank you so much for guidance and help on this.

Hi,
I need to draw up some speaker level passive crossovers.
Can you recommend free software that will work for this?

I've recently finished my third and fourth B1 boards (bought from the official source, with the JFETs). The two boards were built identically (for balanced operation, eventually), with extra-high quality parts (e.g., Z-Foil resistors in the signal path).
One of them is working perfectly, but the other is giving me problems. I'm guessing it is because, when first testing it, I hooked up the power supply backwards. Presumably, that could have damaged (or worse) the filter caps. Before I swap those out, though, I thought I'd ask here, and see if anyone had other ideas.
The symptom is bad distortion in both channels, and what seems like low volume, as well. I used to hear something similar when using batteries with my other B1, when they would start to die. But voltage measures OK at e.g. the gate of Q100.
I'll attach a photo of the board in my test enclosure, though I don't know if that will be much help.

Hello guys,

I would like to ask something about my ka-8011 which is same as kenwood ka-801. I don't have the amplifier for long time and it is working lets say normally.

It was surprise for me when I opened bottom cover and saw this.. Path to Q1 collector burnt. What can cause this and how it is possible that it can still working with burnt path ?

Thanks a lot

Dear all,

I've ventured into building a crossover for a two-way speaker system. I acquired capacitors and inductors from Mundorf, but now I'm scratching my head with the task of soldering all together. The inductors are made out of something that look like copper foil and I have never soldered something like this. Is there are right way of doing it? Do I need to somehow fix the foil before soldering? Or it should hang free off the inductor?

Folks:

My wife and I had the opportunity to tour the HiFi2000 factory in July, and it seemed appropriate to post a brief write-up about the experience. Gianluca (the principal contact for HiFi2000 and a regular contributor here at diyAudio) and I were trading PMs a few months ago when I mentioned an impending vacation in Italy that included a few days in Bologna. His response: “why don’t you come for a tour?” I immediately agreed.

It turns out HiFi2000 is a tiny, family-owned business that was started in 1977 by Gianluca’s parents. They’re ostensibly retired, though the day we visited they were hard at work helping to fill orders. Gianluca now runs the business, which is located close to Bologna’s airport in an industrial park and consists of a few offices, a design studio, two CNC systems in a workshop area (where panels and heat sinks are drilled, threaded and customized), a digital printing station, inventory storage and management systems and an order fulfillment area. I believe Gianluca said there was a staff of 7 or 8 people, including his parents and himself.

The operation struck us as incredibly efficient (though for all my wife and I know it may be the norm these days). There was a person in the front office, someone in the design studio and someone operating the CNC systems; everyone else was busy gathering parts and/or putting orders together. Gianluca was very proud of the fact that HiFi2000’s products are 100% Italian – for example, the aluminum for their panels is smeltered in Northern Italy and cut to size by a vendor in the Bologna area. Anodizing is outsourced to a nearby shop. Most of the other components are also locally sourced. Gianluca was passionate about customer satisfaction, HiFi2000’s efforts to accelerate deliveries to customers and supporting their market generally. It was rewarding listening to someone who is deeply invested in what he does.

Hanging out with Gianluca for an hour was a pleasure. I did a rough count and it seems I’ve purchased (or directed people I was helping with projects to purchase) about 19 chassis from HiFi2000 over the past 15 years or so (naturally, there are plenty more projects in the works). It was fun seeing how it all comes together. There are a lot of ways to spend your time in Bologna, and for me the tour was a far better experience then watching sausage being made.

Regards to all!

Hello,
I’m curious the concensus on loading mechanisms on CD players. Front load is much more common but top load just seems a better mechanism. More accurate and less to go wrong. What do you think?
Thanks

Hey everyone!

This past week I purchased a used Yamamoto A-08s amplifier. This came after months of research and careful decision making. It's also my first foray into the tube world, after owning solid state gear for decades. As such, I'm sorry for any silly or irrelevant points I may bring up, as they will be extensions of my very basic understanding of valves and their circuits (I'm learning experientially).

Here's the situation. After a very careful unboxing and clean-up, I'm happy that the amp is visually in mint condition. I finally got to the point of powering it up last night, and immediately the rectifier tube (80) began to arc and flicker. I did a few hours of research, and it appears to me that it was not what people call 'tube flash', but rather arcing, or 'cathode stripping'. I let it go for about 3 seconds to see if it would stop, but then made the quick decision to power it back down... then immediately started researching.

From what I gathered, it seems that this is caused by the tube being 'overtaxed' from two factors -- first, on a cold startup, it is only able to operate at a fraction of it's 'warmed up' ability. Second, and compounding the issue, is that the tubes highest demand period is right at startup, when it need to charge a large 'empty' capacitor. Again, I'm sure this assessment is begging for corrections or clarifications.

In addition to any general advice people may have, I have a few specific questions:

1. What are the chances that this compromised or damaged any other component in the amp? From what I gather, some people just let the tube arc at startup and let it subside after it warms up, but I'm not so brave myself... so hopefully this means that it is 'safe' for everything else in the amp.

2. Could this issue have anything to do with the fact that I'm powering it through a Furman "IT-Ref 20i" isolation transformer? I know that each AC leg is split to carry 60v each in this design, as opposed to the 'regular' 120v + neutral... It just had me thinking, what if there is an incompatibility there somehow?

3. Could this be actually be a normal occurrence for a healthy tube that hasn't been powered on for some time? I don't know when it was last used / powered up... but if it's been years, perhaps time has some relevant effect. If this is the case, should I keep using the tube, or is it dead?

I turned to this community first because you guys seem like you really know your stuff -- thank you for any and all help!

Hello guys

pleas who can help me i want to make toroidal transformer for inverter

my inverter is 5kw 48v

and the dimensions of the core is
ODd:-30cm
IDd:-12cm
H:-10cm

thanks for helping

For sale are 4 lot 1Z26XX TOKIN 2SK180 SIT's. Never used NOS and selling as a lot for $240 US + shipping.

Sorry but I'm limiting sale to CAD and US only due to unknown logistical shipping issues elsewhere. - Thanks

I need help identifying missing part number please.

I thought I'd tidy up my portable sound system. I had to do something as the subwoofer channel was becoming intermittent. I thought go for the bluetooth version - why not?

What did I buy? Why doesn't it need a heat-sink?

https://www.ebay.co.uk/itm/394022243115

I'm designing a 100W class D amplifier, with discrete components (IRF8707 and IRS2011 gate drivers), running at about 350kHz. There's a lot of energy moving on this thing, so I'd like a good starting point. (Assume good PCB design practices have been used.)

What's the best practice for filtering the DC power input?

1. Common-mode choke between the DC input and power amp? (Between the applied voltage/gnd and the internal applied voltage/gnd)
2. Series inductor or ferrites on input? (At 24V supply, this would be several amps but possibly)
3. Combined one of the above with copious capacitor bypass of course.

The line inputs are referenced to the "true ground" - PCB ground plane, circuit ground, shield, which could be slightly isolated by the CM choke if I used it.

I'm of course going to test all this, but I wanted to get a sense of a good starting point.