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Conference napalm::guitar

Title:GUITARnotes - Where Every Note has Emotion
Notice:Discussion of the finer stringed instruments
Moderator:KDX200::COOPER
Created:Thu Aug 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3280
Total number of notes:61432

2114.0. "playing with the bias?" by FSCORE::KAYE (where's my Kama Sutra pop-up book for zero-g) Mon Feb 18 1991 16:33

I did some work on my Fender Super Reverb on the weekend. I took a
look at the bias circuit and it only allows a range of -47V to -63V.
It has a 10k pot on top of a 27k resistor fed by -63V. They probably
did this to keep it in the AB class range. I have the schematic for
the CBS version of the amp with 6V6's instead of 6L6's and they show
the bias as -35V (they use a 10k resistor instead of 27k). Should i
play with this?? I was going to add a 2ohm 10W resistor between each
cathode and ground on the 6L6's to allow me to see what the bias is
doing to the plate current. What kind of voltage should i expect
across these resistors when things are setup properly?

 mark
T.RTitleUserPersonal
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2114.1Super biasingLEDS::BURATITue Feb 19 1991 22:505
    Most of the mid '60s supers use a bias of -52V to -55V. 
    I've never heard of a Super with 6V6 output stage. And I've
    seen a lot of Super Reverb schematics. Are you sure about this?
    
    --Ron
2114.2cleaned my glassesFSCORE::KAYEwhere's my Kama Sutra pop-up book for zero-gThu Feb 21 1991 14:218
>    I've never heard of a Super with 6V6 output stage. And I've
>    seen a lot of Super Reverb schematics. Are you sure about this?
    
After cleaning my glasses, the schematic is for a 'Deluxe Reverb'. 
Very close tho, a couple of resistor values and the output tubes 
are the only differences.

 mark