I noticed my guitar pots scratching while playing through my recent 5E3 build. Checking the input jacks with a DMM revealed about .10 volts across the input jacks, not much but enough to cause my guitar pots to scratch.
I checked everything I could think off, solder connections, resistor values, changed tubes several times. No luck but I did see some volts on V1 and V2 grids while in stand by. The amp sounds excellent and is very quiet except for this issue. Does anyone have any ideas?
Thanks.
5e3 DC voltage on input jacks
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MadDitch
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Alexo
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I had the same issue on a recent build, I think this is "normal" in a lot of amps, particularly if the tube is running at a reduced plate voltage.
Looking at my somewhat illegible notes from my 5E3, it looks like V1 was at 122 on the plate - probably low enough to induce some scratchiness. .1 volts is actually pretty good, my recent build was at .45 at first, I was able to tame it down a lot by playing with the cathode resistor to find a good bias for the tube - one where the plate voltage was close to half the voltage on the power supply side of the plate resistor.
Could also just be a bum tube.
Looking at my somewhat illegible notes from my 5E3, it looks like V1 was at 122 on the plate - probably low enough to induce some scratchiness. .1 volts is actually pretty good, my recent build was at .45 at first, I was able to tame it down a lot by playing with the cathode resistor to find a good bias for the tube - one where the plate voltage was close to half the voltage on the power supply side of the plate resistor.
Could also just be a bum tube.
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