Hi all. I run a professional amplifier service shop. I've seen most
different topologies used for high power audio amplification. But, this
Peavey amp really confuses me. It's a Peavey PV-1.3k massive 4U high
stereo power amp. It came into my shop with one channel badly blown,
looked like a disaster. 10pcs of blown output-devices, generally all
emitter-resistors were open, pcb traces exploded, driver-board severly
damaged. Customer refused repair and let me keep the unit for scrapping
parts. As I really enjoy audio power amps I decided to repair it just
for fun, in case I some day need 1000W per channel into 2 ohms. ;-)
Said and done, all defective parts replaced, but I can't figure out how
the stereo output-stage is configured. I'll try to explain it.
The power-supply has dual centertapped secondaries, each channel uses
its own supply of +/- 90V rails. The rails are applied to the output
stage collectors like a standard emitter-follower output stage. Now the
hocus pocus begins. Each output-device has its own pair of
emitter-resistors connected to a COMMON rail on the output-board. This
rail is actually used by both channels, so appearently both channels
are in parallel. And this rail is connected to chassis ground. This
rail is also connected to one side of the speaker output jacks.
I haven't seen anything like this before. The other side of speaker
output jacks goes straight to the centertap of the transformer.
(channel power ground) These centertaps are not connected together.
Most preferably, I would like to see the schematics for this amp,
secondly, if anyone could tell me what's going on in this hocus pocus
output stage.

Best regards
Stefan