[PLUG] Buzzing speakers

[Michael Barnes]

Not really Linux related, but very strange. I have a real nice set of Altec
Lansing computer speakers hooked up to one of my Linux Mint machines. This
is a three piece set with two desktop speakers and a large subwoofer on the
floor. I've had these speakers for at least ten years and they have always
worked and sounded good.  I hooked them up to this computer about a month
ago. After a couple weeks, they started making a very loud low frequency
beep/buzz every thirty minutes. It is about a one second burst. I turned
them off with the on/off switch on the volume control, and the beep
persisted. At exactly :29 and :59. I unplugged the audio input from the
computer speaker jack and the beep continued. There is no kind of logic
circuitry in this thing. Just an audio amplifier and related electronics.
The only way to stop it is to unplug it. When plugged in it is like
clockwork at exactly :29 and :59, regardless of whether it is connected to
the computer or not. I hooked up another set of speakers to the computer
and they do not do this. Sad, because these are a great sounding set of
speakers.

Anyone run into something weird like this?

Michael