Acoustic 123 huge thump when turned on or off

[lepercon]

Guys-
I have a nice thump through the speaker when this amp is turned on/off whether the volume is turned all the way down or not. I am thinking this is power supply cap issue?
Help!
Mike

[J M Fahey]

No, it's normal, don't worry.

[joecool85]

It's probably normal, how loud is the thump?  If it is very loud then it could be an issue, if it is only as loud as someone talking or so then it's not a problem (other than annoying).

[LJN]

Joe is right. Myself, I couldn't tell you the cause, but I know that I've had a few amps that did that. Usually, it's not a problem. If you hear any noise like a loud hum, or buzzing sound, that's something to worry about.