When starting up an amp for the first time, should all pots be at 0R or does it depend on circuit design? As in, for some topologies should you start with pots at max resistance? Thanks.
It depends on how the bias of that amp is generated. It is best to start with close to zero bias, which for most solid-state push-pull amplifiers (when the Vbe multiplier is properly designed) starting at maximum resistance. Reason for maximum resistance = low/zero bias is so that if the wiper disconnects you will not have destructive currents in the output stage.
For certain amplifiers the bias is set to zero when pots are set to zero (some of the Pass Labs amplifiers are like this, but they're not the only ones). For some, such as SE amplifiers which bias the input stage to provide the amplifier bias, it is best to start around the midpoint.
In short, it totally depends.
For certain amplifiers the bias is set to zero when pots are set to zero (some of the Pass Labs amplifiers are like this, but they're not the only ones). For some, such as SE amplifiers which bias the input stage to provide the amplifier bias, it is best to start around the midpoint.
In short, it totally depends.
The output offset voltage adjustment potentiometer on the M2x poweramp is "safest" (least likely to do damage) when set to the 50% point before powering-on.
The output stage bias current adjustment potentiometer on the F4 poweramp is "safest" when set to the max-resistance point before powering-on.
The output offset voltage adjustment potentiometer on the ACA poweramp is "safest" (least likely to do damage) when set to the min-resistance point before powering-on.
The output stage bias current adjustment potentiometer on the F4 poweramp is "safest" when set to the max-resistance point before powering-on.
The output offset voltage adjustment potentiometer on the ACA poweramp is "safest" (least likely to do damage) when set to the min-resistance point before powering-on.
Bear in mind that some amp pcbs have the bias pots connected to increase the bias current
when you turn the pot CCW. Who knows why, since the long time convention is that
CW rotation means increasing bias current. So always read the documentation carefully beforehand.
Never just assume it is a particular way.
when you turn the pot CCW. Who knows why, since the long time convention is that
CW rotation means increasing bias current. So always read the documentation carefully beforehand.
Never just assume it is a particular way.
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