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octal tube preamp ideas wanted...


 
4/12/2004 12:51 AM
Ian Anderson
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octal tube preamp ideas wanted...
I'm wanting to build a new amp with some octal preamp tubes - just something different. Want medium 'rock' type gain (2203 type would be enough) and a master volume. Anyone have experiences, tips or schematics they'd care to share?  
 
Cheers... Ian :)
 
4/12/2004 1:58 AM
Enzo
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You can be different and also pretty much the same. 6SN7 and 6SL7 are common dual triodes in octal. Use them essentially like a 12AU7 and a 12AX7. The circuit around them would be about the same. Use any 12AX7 type preamp circuits you like but build with the larger tubes.  
 
Look near the rear of the RCA book for a section called Resistance coupled amplifiers. There are charts of common tube types and typical component values used in the circuits.
 
 
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4/12/2004 1:24 PM
Ian Anderson
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So I can use these octal preamp tubes with the exact same circuit as say, a JTM45?  
 
... Ian :)
 
4/12/2004 9:25 PM
Trace - Voodoo Amps
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I've built many amps using octal tubes and have experimented a lot. The best octals I've found for what you are looking to build would be the RCA black base 6SL7. They sound great and handle gain better than most. You can only squeeze so much gain out of them before you get noise issues though.  
 
Good luck & have fun! :)  
Trace
 
4/12/2004 9:49 PM
Ian Anderson
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Cheers Trace, you da man!!! :D  
 
... Ian :)
 
4/12/2004 10:46 PM
Trace - Voodoo Amps
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[b]Cheers Trace, you da man!!! ... Ian [/b]  
 
I appreciate the kind words my friend but I'm certainly not the man! (ha, ha) I'm glad I was able to be helpful though.  
 
 
Have a good time building!  
Trace
 
4/14/2004 6:21 PM
anonymous
Trace,  
 
A couple of years ago I found a nice deal locally on some NOS GE short bottle, silver top 6SL7s; I haven't had a chance to build anything with them yet but I did test about 10 of them (of 20) in a 1953 Sano (essentially an Ampeg BassAmp w/tremolo) and found that a few were microphonic, a few were noisy, and most were fine.  
 
Have you had any expereince with the GE 6SL7's?  
 
Thanks,  
Craig
 
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