Re: Behaving like undervoltage?

apa wrote: 
I went into my studio last night to find a dim overhead light and my 4
RNC's buzzing like a vibrating cellphone in a pile of bottlecaps.

It has a bypass relay that comes on when you power it up.
Under low supply voltage, the power supply regulator will drop out of regulation and the ripple will appear on the power rails, hence the relay chatter (most likely guess anyway).

and the sound stops. Then I notice that many of the peak lights are on
on the board. The record light has come on on the tape deck (it usually
doesn't light unless the transport is engaged). There is a hum through
the monitors and the only other piece of gear that's powered up (an
Orban 642) is peaking on one channel and peaking about once a second on
the other channel.

The control logic will get into all sorts of funny states if its power supply has big ripple and sub-spec level because of lack of regulation.

Same with analog audio circuits - when the rails drop out of regulation that ripple will find its way into the audio chain.

Anahata
.