2 subminiature tube amps

Tube or solid-state, this section goes to eleven!
Post Reply
User avatar
jjs
Information
Posts: 3
Joined: 14 Aug 2007, 16:23

Post by jjs »

After some requests, here's a place to discuss about my subminiature tube amps.

Schematics and info can be found here:
http://www.jjs.at/electronic/

And here are two pics:
Image

Image

User avatar
DougH
Transistor Tuner
Information
Posts: 1087
Joined: 18 Aug 2007, 04:53
Has thanked: 4 times
Been thanked: 23 times

Post by DougH »

Man, you do beautiful work. Those are really pretty! I love the inside shot on your page.

User avatar
bajaman
Old Solderhand
Information
Posts: 4544
Joined: 26 Jun 2007, 21:18
Location: New Brighton, Christchurch, NZ
Has thanked: 593 times
Been thanked: 2049 times

Post by bajaman »

I saw these at DIYSTUMP and have your webpage marked in my favourites column - I love the clean white and black finish and well engineered design and in depth explanations given - top work, and thanks so much for sharing with us :D :D :wink:
bajaman

User avatar
bajaman
Old Solderhand
Information
Posts: 4544
Joined: 26 Jun 2007, 21:18
Location: New Brighton, Christchurch, NZ
Has thanked: 593 times
Been thanked: 2049 times

Post by bajaman »

ps; don't those knobs look HUGE :lol:

User avatar
oscarv77
Solder Soldier
Information
Posts: 181
Joined: 25 Aug 2007, 01:41
Has thanked: 11 times
Been thanked: 11 times

Post by oscarv77 »

Welcome JJS! :D

Those amps are a thing of beauty. Congrats!

User avatar
Papa_lazerous
Breadboard Brother
Information
Posts: 67
Joined: 25 Sep 2007, 22:33

Post by Papa_lazerous »

Hello jjs glad to see you here :wink:

User avatar
guisquil
Information
Posts: 28
Joined: 03 Sep 2007, 23:04
Location: USA

Post by guisquil »

WOW those are beautiful, do they sound as good as they look?

G

User avatar
Goop_buster
Solder Soldier
Information
Posts: 247
Joined: 22 Jul 2007, 22:31
Been thanked: 7 times

Post by Goop_buster »

Welcome jjs :D

Regarding the subminitube sockets which you solved with separate sockets. You may also use ready to go 8 pin TO-5 sockets if you just bend the first and last tube pin a bit. This is what I usually use.
You must be carefull to position the tubes right afterwards though :wink:

I also have a source for original NOS submini sockets but they are very limited supply and a bit large in heigth. PM me if you want any of those and I may perhaps be able to source some more of them in the future.

Also
"there was so much radiated EMI that digital TV reception through my room antenna was completely blocked out when the amp was on. "

Be very carefull with these types of supplies and tubes radiating. Not only your TV may be affected. Worst case you may fry your testicles, kidney, neighbours pace maker or whatever without even realizing it.

User avatar
jjs
Information
Posts: 3
Joined: 14 Aug 2007, 16:23

Post by jjs »

Thank you all for the warm welcome!

I have not recorded sound clips yet, but I will eventually.
As for noise, the single-ended amp has almost none, the push-pull one has some buzz from the rectified AC. The input is very close to the output tranformer secondary, which is directly connected after the bridge rectifier and the filter capacitor is several centimeters away. I think that is the problem.
For sound I like the AB amp better, though. It got a clearer tone and the low end is tighter (due to it being a push-pull amp and having a pentode output). Of course the James tonestack is nicer, too.

Thank you for the offer, Goop_buster, submini tube sockes are really scarce, especially 8-pin ones, but for the moment I will pass on it.
I'm not sure if I could mount them from the solder side and putting them on the component side would give some problems.
TO-5 sockets may be an alternative, I have no NOS tubes, though. So all my tubes where either already socketed or were soldered in and then (not very carefully) removed with pliers. All of them got only short leads, not sure if they can be bent enough to fit.

The EMI really got me thinking, yes. I'm glad I could tame it so that it does not seem to interfere with anything I got. Maybe the story sounds worse than it really was, my TV reception is not that good anyway and I had situations where the opened PC case caused some interference, too.
While I had the circuit on breadboard EMI was probably much worse. For some configurations it got so bad that my USB oscilloscope crashed everytime I only connected the probes ground lead to the amp.


Edit:
I have now recorded three short samples of the class AB amp in action. They can be found on the project page. Sound quality is not that great and my playing is crappy as usual :oops: .

I have also added a link to the suggested power supply on the class A page. The amp itself is currently disassembled and I'm trying out that new regulation method. That's also the reason why there are no samples of this amp yet.

Post Reply