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Another source of turn on/off thump in lower cost SS amps is the output capacitor. When you turn on, the cap is discharged to 0V. The amplifier notes that its side of the output cap HAS to be at half its power supply, and does its manliest best to make it so. The current has to go/come from somewhere to charge that cap, and the only available path is the speaker. THUMP!
This is a problem mainly of single-power-supply amps, as bipolar amps usually don't have this issue because (1) they don't use an output cap; or if they do, (2) the DC voltage across it is nearly always near 0V, and as long as the bipolar power supplies rise mostly symmetrically, the thump doesn't happen.
Some amps go into a frenzy of oscillation at some lower-than-normal power supply voltage, so they put out a big GRATZ of oscillation that sounds like a thump and then goes away as the power stabilizes.
This is a problem mainly of single-power-supply amps, as bipolar amps usually don't have this issue because (1) they don't use an output cap; or if they do, (2) the DC voltage across it is nearly always near 0V, and as long as the bipolar power supplies rise mostly symmetrically, the thump doesn't happen.
Some amps go into a frenzy of oscillation at some lower-than-normal power supply voltage, so they put out a big GRATZ of oscillation that sounds like a thump and then goes away as the power stabilizes.
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