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Vintage threads from the first ten years
Plate voltage/cathode-bias?
 2/20/2000 2:29 PM |
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lion | Plate voltage/cathode-bias? I’ve been thinking about converting a fixed-bias amp (2x6L6) to cathode-bias for a rounder and mellower tone. (I know it also mean a little less power.) But, are there any limits voltage wise – my plate voltage is some 470V – would that be OK? How do I calculate the cathode resistor(s)? The schem for the low-powered tweed twin (5D8) shows a 250R/10W with a 25mF bypass cap – but there’s no voltage indikations. I guess the voltage is much lower than 470V. The formula for a bypass cap is: f = 1/(2pi * Ck * Rk) – right? Maybe I’m wrong, but I seem to remember something about mixed cathode and fixed bias - what is that - best of both worlds. Anyone had any experience with this setup? Huh - a lot of questions! How come I allways seems to end up in this situation every time I open one of my amps;-Q Any info, comments or help otherwise will be appreciated. Regards Lion |
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| Replies: |
| Ken Gilbert q{But, are there any limits voltage... -- 2/20/2000 6:22 PM Bruce 470vdc is a bit high for this but r... -- 2/20/2000 9:43 PM |