Audio probs boil down to this
Hiss in audio & maybe its weak = audio IF
Buzz or ticking that changes with scene changes = audio detector
Hums, distortion etc = audio amp & out
How the volume control effects it is very important. A signal
detector is a nice thing to have for probs like this.
Test SPKR can be almost anything. Keep in mind almost all schematics, flow charts & block diagrams go from left to right. ( L input, R output ).
Dont go nuts changing stuff, we can help you narrow it down to a stage
and a few parts.
enuf fer now Zeno
LFOD !