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Vintage threads from the first ten years

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previous: Randall Aiken Dave, how well did this work? I wa... -- 3/26/1999 7:13 PM View Thread

Re: "Screen grid" MV

3/31/1999 9:30 AM
J FletcherRe: "Screen grid" MV
For what it's worth, I tried something similar once. I was experimenting with the idea of a 1/2 power switch that dropped the screen voltage 100 volts. I used 100 volt zeners in series with the screens. There didn't seem to be any change in power output, but I had to lower the bias voltage from about -42 to -36 volts and use the 8 ohm transformer tap instead of the 4 ohm tap to get full power. Still, power output remained at 40 watts in this particular amp.Lately I saw a 1/2 power mod that switched a 25K resistor in series with the choke in a Fender Showman. Did that ever look wierd when scoping the output at clipping. Rounded off tops of the waveform with little "pips" on top that would grow as you went farther into clipping. The owner said it sounded ok though....Jerry

 
Replies:
Steve A. JF:    ... -- 3/31/1999 9:35 PM