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JandG 22nd December 2008 10:18 PM

2 stage IT coupled SE suggestions.?
I am wanting to try something differant than my IT coupled 12bh7/6l6g SE amp. I like fixed bias on outputs, but doesn't have to be, I can just convert. I have Hashimoto H-20-7U outputs that have 5k & 7k w/ g2 UL taps for both & O'Netics 1:1 IT's. Any suggestion would be great for me.
J & G

45 22nd December 2008 10:48 PM

Do you want to stick to those tubes or make another use of your trannies?
How does your previous amp "look"?


JandG 22nd December 2008 10:59 PM

I am wanting to try differant tubes . My previouse amp looked like cra...All test clipped, etc.. & huge , many PS's & just way to crazy & dangerouse ....*s*. This one is going into a chassis I swear......................................... I have a a hammond 193L so choke input supply is o.k., & many,many motor runs. I am very low on 2a3, no spare 300B, & also very low on 45,so they are out. I actually would like to stay away from those 3 if I can help it. I allready have a 45 SET & 300B PP amp & do not want another expesive output tube amp. Maybe differant driver for 6v6 or 6l6G..? Don't know no really I sure would like to stay with a 2 stage...on this amp.
J & G

Jaap 23rd December 2008 11:06 AM

I have a 5842 (or D3a or E810F) => IT => 300B amp. I am planning to rebuild this into a pse 807 amp (pentode connection + local feedback). I will use the same OPT (3,5K) and try mosfet regulated screensupply.

You can of course also use 6L6, EL34, KT66, KT88, etc.

Another idea is screendrive a parallel 6AV5 or other sweep tube.

FlaCharlie 23rd December 2008 02:43 PM

How About SEP?
Hey JANDG - As you know, I'm not a designer and I don't know if it would lend itself to your front end topology but . . . perhaps a 47 (SE pentode). I do know that the 7k primary of your OT is correct. Beyond that ??? Power out is a bit more than a 45. They're available and not too expensive.

. . . Charlie

JandG 24th December 2008 12:19 AM

Great idea. I might even have some 47, never thopught of trying those. Wonder what would be a good driver in a 2 stage would be..? Any idea's..? Certainly worth a try.
thanks J & G

45 24th December 2008 01:36 AM

47 driver, KT66 output. Both in triode connection.
Plus 6SN7 RC-coupled input.

KT66 at 400V/63mA/-38V.

The true replicas are Golden Dragon or Valve Art. Nice sound, IMO. :nod:
The russians look, work and sound more like smaller KT88's.......:dead:

Using 5K instead of 4.5K, you should still get 5.5W.
You could play a little bit with the operative conditions of 47 looking for both good sound and lower THD (harmonic cancellation).


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