"William Sommerwerck" wrote in message
...
Agreed, checking the supply rails is fundamental, and I guess
I should have, except there was no particular reason to on this
one, as it appeared to all be working except for this slightly
'raspy' buzz, that wasn't actually loud enough to be causing
a problem, but was annoying to the owner, as it shouldn't have
been there.

Did you say whether you found the source/cause of the buzz?


Yes, it was the 7815 that was short input to output, and shoving 28 volts up
that rail to the preamp opamps ...

Arfa