Re: Preamp causes hum even when off



tomg@xxxxxxxxxxx wrote:

Can anyone shed some light on possible reasons that a tube-based
preamp could cause the main power amplifier to produce hum, even when
the preamp is not powered?

Well .. when a signal source (such as a preamp) is TURNED OFF the output
becomes high impedance and it's really quite likely that hum will result
if other equipment further down the signal chain is switched ON.

I came acroso this only earlier this evening with a pro-audio sound
reinforcement setup because I'd forghotten to turn the damn mixing
console ON ! Had me going for a few minutes ! :-(

Why are you worried about hum in this scenario ? Does it also hum too
much when the preamp is ON ?


Graham

.

Relevant Pages

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