Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: AmberB on September 24, 2020, 10:34:20 pm
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This has probably been asked before, but, When wiring up a volume control to the grid of the next stage in a preamp, does it matter which connection you use, between the top of the resistance, or the wiper?
I was looking at the wiring in a couple of my amps and I got to thinking, if the triode only has the volume control as it's grid resistor, shouldn't the grid be wired so that it sees the full resistance of the pot no matter where the wiper is?
Probably a simple question, but still...
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if the triode only has the volume control as it's grid resistor, shouldn't the grid be wired so that it sees the full resistance of the pot no matter where the wiper is?
The grid doesn't care. There were some older 1950s amps (ex. 5E3 Deluxe) that had the top of the pot connected to the grid. But that "backward" pot wiring gave way to the more common wiper to grid wiring.
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Feeding the wiper, when full-down, the source is shorted-out.
That may not be a problem in small audio. A guitar pickup or small triode will not burn itself out driving a short.
It also affects choice of coupling cap. Those backward-pot Tweeds sometimes have 0.1uFd caps where a forward pot could use a 0.02u cap.
It depends. But if you don't know any better, the "normal" scheme with load on wiper is probably the better bet.
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Thanks for the info. I hadn't really thought about the effect on the previous stage...