Hello everybody. So I have an issue I need help with. Every time I turn it off there is a thumb in my speakers. What could that be caused by? Thx very much in advance Peter
Possibly that is the output capacitor discharging.
If possible, turn down the preamp's volume control completely first
before switching the phono off.
Otherwise, I would turn off the power amp first, and wait until it is completely off
before switching the preamp off.
When powering on, turn on the phono first.
If possible, turn down the preamp's volume control completely first
before switching the phono off.
Otherwise, I would turn off the power amp first, and wait until it is completely off
before switching the preamp off.
When powering on, turn on the phono first.
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It needs a relay to short the preamp outputs to ground for 30 seconds upon turn-on,
and to short them immediately to ground upon turn-off. There have been boards available
to add this function, or you can build one.
There's no other way to eliminate the thump, due to the topology of the circuit.
Something like this could work, but with a larger timing capacitor, a 10uF low leakage type.
Preamp Muting Circuit | audioXpress
and to short them immediately to ground upon turn-off. There have been boards available
to add this function, or you can build one.
There's no other way to eliminate the thump, due to the topology of the circuit.
Something like this could work, but with a larger timing capacitor, a 10uF low leakage type.
Preamp Muting Circuit | audioXpress
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Of course, you could instead use a simple manually operated shorting switch to ground instead,
if you can always remember to use it before turning the preamp off. Or use a switch on the preamp
that will turn off the phono audio outputs, such as the selector switch, or the tape monitor switch.
if you can always remember to use it before turning the preamp off. Or use a switch on the preamp
that will turn off the phono audio outputs, such as the selector switch, or the tape monitor switch.
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