• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Help wanted to identify tubes / info on DIY amps

Sitandlisten

New Member
Hey all! I'm hoping to pick up these tube amps this weekend. Before I do, I was hoping to gather as much info on them as I can to make a fair offer on buying them all. Please review the photos I've attached and post any knowledge you may have on them! These are all DIY handmade amps and unfortunately the builder is deceased so I'm unable to ask for any info. Thanks all in advance!
 

Attachments

  • 465607353_1080729603580736_4241429930254830864_n.jpg
    465607353_1080729603580736_4241429930254830864_n.jpg
    108.2 KB · Views: 91
  • 465578175_8677585258962801_4052790345088667162_n.jpg
    465578175_8677585258962801_4052790345088667162_n.jpg
    105.6 KB · Views: 93
  • 465595788_2029425444161642_5751837708520713100_n.jpg
    465595788_2029425444161642_5751837708520713100_n.jpg
    80.6 KB · Views: 86
  • 465527793_1297369697945363_598351554623852306_n.jpg
    465527793_1297369697945363_598351554623852306_n.jpg
    109.6 KB · Views: 83
  • 465621361_759974699617372_3510500586642129556_n.jpg
    465621361_759974699617372_3510500586642129556_n.jpg
    116.8 KB · Views: 92
Register to hide this ad
Wow, there's some seriously neat stuff there. Shame the builder is gone. The first pic appears to be a line stage hooked up to a single ended amp, with maybe 6L6G outputs, maybe. The second pic looks like another single ended amp. The last pic looks like another line stage hooked up to a push-pull amp. That would be a huge score. :thumbsup:

jeff
 
Last edited:
In the 1st pic those 2 red tubes look to be Mullards possibly EF37A's

As for the amps themselves and what they're designed to do I suggest you hold tight as the knowledegable will be along soon to assist
 
Good luck with your potential purchase!
Agreed these are DIY equipment, and appears a bit esoteric.
I can offer some guesstimates, in order of your photos:
1. Good looking preamp hooked up to a unique stereo single-ended amp (good looking OPTs; James?). Looks like plug & play.
2. Looks like SET stereo amp; Darling Clementine?
3. Odd preamp. mono?
4. Mono amp
5. Unique preamp feeding stereo tube amp. Looks to be the most powerful & common design amp.

I don't do mono, so if the price is right, I could go for 1, 2 & 5. If I only get one, then #1.

All would be great to play with your Fortes & ST70 (I got both!). I also have a Darling Clementine, which is a nice alternative to the ST70.
Any of the equipment with top grid tubes is going to be 'unique', especially with a DIY build. Not crazy or $$, but not very common tube or probably circuit (e.g. vs ST70). It would take me a bit to blueprint these & check them out prior to adding to rotation. Some may be a PCB build, so that could answer some questions.
 
They look nice, but with the exception of the red chassis, they all look to be single ended.
Single ended amplifiers make low power and the power they make is bandwidth limited. People claim they sound really sweet on simple vocals or small combos.
Play something with a bass line and they tap out.
If you are looking for the single ended experience these may be just the ticket.
If you just want to experience a great sounding tube amplifier, I'd wait until something comes along which uses a push pull topology. A 6l6 push pull amplifier will handle all types of music, including sounding magical on small combos and female vocals but also will shake the floor when called upon to do so.

All that being said, if the price is low enough it would be a good buy just to flip em, provided that they work.
James transformers have a following amongst the SET cult and they are no longer making them...
 
They look nice, but with the exception of the red chassis, they all look to be single ended.
Single ended amplifiers make low power and the power they make is bandwidth limited. People claim they sound really sweet on simple vocals or small combos.
Play something with a bass line and they tap out.
If you are looking for the single ended experience these may be just the ticket.
If you just want to experience a great sounding tube amplifier, I'd wait until something comes along which uses a push pull topology. A 6l6 push pull amplifier will handle all types of music, including sounding magical on small combos and female vocals but also will shake the floor when called upon to do so.

All that being said, if the price is low enough it would be a good buy just to flip em, provided that they work.
James transformers have a following amongst the SET cult and they are no longer making them...

You are monomaniacal on push-pull topology. I've got PP and SET amps and my current choice of speakers means SET get much more play time lately.
 
There's plenty of people who go on and on about their SET amplifiers and who am I to criticize them? People seem to love them, and with bigger triodes you can make power. I heard one once at burninv amp using 211s that had both negative and positive feedback applied to it, and it delivered plenty of power and sounded darn good. The builder is a Mad Genius type.
It cost as much as a good car, you'll have 1kv+ power supply in your living room(kill you dead instantly level of dc voltage) you'll need a hand truck to move it, and good luck getting anyone besides the original builder to wrap their head around it (service it)
That's not what you have here.
What you have here is well under 10 watts, and given that nothing is known about the builder, they could be anything from brilliantly executed, rock solid designs, to a total nightmare of boutique capacitors, cold joints and ground loops.
From the outside they look carefully built, attractive and symmetrical.
Can't tell much else...
Can you enjoy Reggae through them?
I listen to all types of music and I love to crank it up loud and feel it in my chest, and for whatever it's worth, SET amplifiers in this power range simply aren't going to get the job done. For me personally, and I know I'm not alone, imagining the bass line doesn't cut it. So I give my perspective on the issue, others will give theirs. We can all have our opinions and preferences. If we all had the same opinions and preferences, it sure would get boring... If you want to read about people gushing over SE amplifiers, well there's enough of that online to keep you reading for years. My perspective, as someone who has built over a dozen tube amplifiers from scratch, differs...
 
Wow, a fun puzzle! I see:

1) Single ended 300B amp (the Sovtek 300B dates it back 20 years or more);
2) 6F8G preamp
3) Stereo SE 1626 "Darling" amplifier
4) Stereo SE 6L6 amplifier
5) single noval tube preamp--12AU7?

Most of the tubes are probably marked so you'll be able to identify them fairly easily, and figuring out the DIY circuits won't be hard from there. I'm betting most of the are fairly standard DIY designs.
 
Not to wade heavily into the land of opinion here, but I do have an SE amp that sounds good. I don't really use it because it doesn't quite make enough power to work well with my speakers. 4 watts needs more than 88db efficiency to really get the job done but it does bass better than you'd think within its limitations. I use it nearfield in a second system that is within arm's reach of the recliner I read books in. Don't need a lot of power when reading and the speakers are like 2 feet from my head.

anyway, the 6L6 if its in pentode mode is probably the high power amp here. Figure 8 watts or so of output, or about 5 in triode mode. At that power level to make serious sound levels you need efficient speakers. Just something to keep in mind if you're a shake the paint off the walls listening level kind of person.
 
Op.
When you get to the estate to check out the amplifiers, see if the builder left any test gear. Not only is good test gear often more valuable of a score than simple tube amplifiers, the presence of a signal generator, distortion measurement set and a dummy load would suggest that the builder tested verified his designs. Many do not. Early in my days playing with tube amplifiers I built a single ended 6sn7 power amp. I didn't own any test gear besides my ears, and I thought it sounded OK. Once I got my hands on some test gear i determined it could almost make 3/4 of a watt. I had fun building it, learned a few things and gave it away, because it's a debutante of an amplifier.

It's gorgeous, but it doesn't work.

The presence of test equipment in the estate would be the best indicator of weather or not the builder even had the capability of building a good amplifier.

I'll also repeat that if the price is low enough. You can try em for free. Plug em in, check em out and maybe you'll fall in love, or maybe you'll decide to move on.
If you decide to move on, please remember that these amplifiers represent an esoteric corner of the deep rabit hole of tube amplifier designs and are not anything like most of the successful commercial designs which kept bootys shaking prior to the widespread use of the transistor.
 
When you get to the estate to check out the amplifiers, see if the builder left any test gear. Not only is good test gear often more valuable of a score than simple tube amplifiers, the presence ... would suggest that the builder tested verified his designs.
Good observation & advice!
I can add the easy suggestions - consider getting the interconnects as 'part of the deal', and ask if they have any extra tubes!
Always ask the open-ended question 'anything else similar you were looking to sell? any other stereo equipment? speakers? LPs?'
 
That single tube preamp looks like it may be the Universal single gain stage preamp, or something similar?
I built one. It can use a 12AU7, 12AY7, 12AT7, 12AX7, 12AZ7, etc.
Although the 12AU7 and 12AY7 are all the gain you usually need.
 

Attachments

  • 20220607_112902.jpg
    20220607_112902.jpg
    126.6 KB · Views: 10
Thanks all for your comments above and sage advice. I picked them up and am slowly figuring out what they all seem to be. There was a binder full of messy schematics and notes about the tubes etc. - so that's encouraging. Very excited to dig in. I'll post more photos and details about these pieces when I can!
 
There's plenty of people who go on and on about their SET amplifiers and who am I to criticize them? People seem to love them, and with bigger triodes you can make power. I heard one once at burninv amp using 211s that had both negative and positive feedback applied to it, and it delivered plenty of power and sounded darn good. The builder is a Mad Genius type.
It cost as much as a good car, you'll have 1kv+ power supply in your living room(kill you dead instantly level of dc voltage) you'll need a hand truck to move it, and good luck getting anyone besides the original builder to wrap their head around it (service it)
I guess I qualify as described... In 1996, I built my first tube pre-amp followed by a pair of Williamson Ultralinear monobloc's. In 1999, my first 2A3 tube amps (mono again). Smitten by the triode sound, I plunged into a 211 amp design in 2000 (mono? Yes.) +1KvDC Ps and all.
 
Ok here's an update on one of the sets from the collection! It sounds fantastic through my Klipsch Forte's!

Details on tubes/components:
Pre line stage preamp - 1 GE JAN 6X4WA E202 Made in USA rectifier tube, 2 12AU7A Tubes, By RCA USA.
Power amp - 2 6V6G CV509 M2463 tubes British for RAF, 1 Cetron JAN-5R4WGB Rectifier Tube, 2 Mullard EF37A (red), James Audio JS-6113HS Single-Ended Power Output Transformers.
 

Attachments

  • image2 (1).jpeg
    image2 (1).jpeg
    69.6 KB · Views: 13
  • image1 (1).jpeg
    image1 (1).jpeg
    117.9 KB · Views: 13
  • image0 (1).jpeg
    image0 (1).jpeg
    65.6 KB · Views: 13
Ok here's an update on one of the sets from the collection! It sounds fantastic through my Klipsch Forte's!

Details on tubes/components:
Pre line stage preamp - 1 GE JAN 6X4WA E202 Made in USA rectifier tube, 2 12AU7A Tubes, By RCA USA.
Power amp - 2 6V6G CV509 M2463 tubes British for RAF, 1 Cetron JAN-5R4WGB Rectifier Tube, 2 Mullard EF37A (red), James Audio JS-6113HS Single-Ended Power Output Transformers.
Now you have seen the tip of the iceberg.
Get yourself in front of some high efficiency Altecs, EVs, or klipsch and a 6l6 or 6550 push pull amp and hear the rest of the music...
Seriously, if you like the SE sound you have experienced the first 10% of what is possible. Next step is to take it all the way.
 
Now you have seen the tip of the iceberg.
Get yourself in front of some high efficiency Altecs, EVs, or klipsch and a 6l6 or 6550 push pull amp and hear the rest of the music...
Seriously, if you like the SE sound you have experienced the first 10% of what is possible. Next step is to take it all the way.

I run a Dynaco ST70/Pas3 tube combo as well, and have some efficient Klipsch Forte's. I love what I'm hearing!
 
Back
Top Bottom