[Scott Dorsey]

Chris Hornbeck wrote:

It's an interesting problem because most modern amplifier
failures are catastrophic (brimstone and treacle). Failures
that don't cause a China Syndrome Meltdown are rare and
interesting.

My guess is that this amp has a whole bunch of paralleled output
transistors, and that one or more of them have failed on one leg, so
it's unbalanced. The feedback is keeping the thing DC stable, sort of.

My other guess is that if you keep operating the amp like this
for long, it will have a catastrophic failure and take out the rest
of the output stage.

Since you really need to go in and replace all the output transistors
if one is bad anyway, this is not as bad as it might sound.

Generic advice (from me): if it works at all, it's well
worth repairing. My personal experience of bass amps is
of tragic underdesign and terminal cheap-assedness. Just
a taste of modern life, really. Find somebody who cares
enough to fix the one you've got; better may not be easily
buyable, is my point.

If this is too harsh an advice and a real picker out there
knows of something current and solid, speak! I'd love to be
wrong, fersure.

A lot of older ones are pretty awful too. I have... I think... a Precision
BB-15 here that I can't find docs on... if anyone has a schematic I would
love to see it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."