Anyone know what the recommended bias...

renegader

renegader

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Joined: Tue, Dec 29, 2015 1:23pm
Posts: 9
Anyone know what the recommended bias is for both el34s and 5881s on the pre-roctron mica tol 100? Had one long ago but had to sell. Now she's coming home. Not sure what compliment I want to run her with yet.
 
renegader":2g464xlm said:
Joined: Tue, Dec 29, 2015 1:23pm
Posts: 9
Anyone know what the recommended bias is for both el34s and 5881s on the pre-roctron mica tol 100? Had one long ago but had to sell. Now she's coming home. Not sure what compliment I want to run her with yet.
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Depends on the plate voltage, measure that, pick your tube and stick it in here - you want to run between 60-70% dissipation.

http://ax84.com/biascalc.html

So if your plate is say 450V then 6L6 should be 25-30ma, EL34's 30-35ma etc.

EDIT:

Calculation is explained here:

https://www.eurotubes.com/store/pc/bias probe instructions.htm
 
Hi and thanks. I get all that. I'm looking for Bruce's recommendation (if he has one that anyone knows about). Mostly what voltage to never go above. I usually tune to taste but like to know if there is a danger zone to keep out of, so to speak.
 
renegader":2l98w4qp said:
Hi and thanks. I get all that. I'm looking for Bruce's recommendation (if he has one that anyone knows about). Mostly what voltage to never go above. I usually tune to taste but like to know if there is a danger zone to keep out of, so to speak.
Click to expand...

Ah cool I get where you're coming from - email Bruce directly is what I'd recommend - think he's at NAMM - but his email is begnater (at) aol (dot) com
 
I can only tell you about the Rocktron-TOLs but maybe it is helpful anyway; Bruce once told me that "35 to 40 is good for those tubes" and mine was equipped with EL34.
 
Pretty sure the roctron ones are the same circuit and going with el34s I've settled on 38 as the magic number. Much appreciated.
 
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