In article , Dave Plowman (News)
wrote:
Pretty basic MOSFET power amp.

I'm used to it thumping at switch on. No speaker relay in this basic
design.

But one of them as taken to thumping at switch off. Not always, which
makes fault finding more tricky.

Most likely cause?

Circuit diagram might help diagnosis. I'm also not clear if the "switch
off" thump is at the instant you switch off, or a short time later.

My first guess is that something is adding a dc offset that now causes the
thump as the amp bias collapses and it is abruptly removed. However I can
only guess due to lack of detailed info.

Jim

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