Dave wrote:
wrote in message
ps.com...

Well, the good news is the sooner you get onto another piece of kit the
sooner you're going to have a result.
Plus you can use your TIPs to make a nice big power amp.
Coincidentally, you've even got the psu, case & preamp all already
there.

The pre-amp/amp are *heavily* integrated, same PSU. I'd have to look pretty
hard to find a point to break into the circuit at pre-out. I think I'll
just build myself a 20-150Hz variable low-pass filter and 50W push/pull amp
for the subwoofer with the TIPs. I can cut the board off (the PSU is well
isolated off by itself) and use the relatively large empty space for my new
amp. Conveniently, the 4-channel audio processor chip which provides input
switching btween three sets of input jacks (even a high-gain set!) are all
on the PSU end of the board.

I'm disappointed I can't get it working fully as it *potentially* does
exactly what I want.

IIUC all you've lost is your power amps, the rest works. I'm not clear
what you mean by pre and main being integrated, I've not seen anything
like that since the valve days. Same pcb sure, same psu of course, but
circuit intertwined? I cant think how it would be.

Simple no frills power amp modules are quite easy to make. Use a fast
opamp and you can do away with output bias circuits altogether. Forget
about all the nonessential points and you can get some very simple
power amps done. If you cant get them into the case any way, they can
always sit outside it on their own, using the main units psu.

Anyway, It ounds like you'll get something out of it one way or
another.


NT