🚀 go-pugleaf

francis@cs.adelaide.edu.au (Francis Vaughan) writes:

> A curious question has been nagging me.  When one looks at a
> HiFi system the signal levels are as a rule fairly low,
> certainly domestic equipment is designed with levels
> significanlty lower than professional equpiment, and a
> domestic system is very rarely run with the volume knob
> wound up all the way.
> 
You can't use a high gain pre-amp & power amp with negative feedback on 
the combined stages.
a
The reason you haven't seen it is that it won't work. You can't treat the 
pre-amp and power amp as an OPAMP and use negative feedback. The are too 
many stages and your circuit would be unstable.  Neg feeback is limited 
to power amps or preamps, but cannot be applied easily to both combined, 
with reactive non linear loads (speakers).
Better Amps use ganged pots to control attenutation of 2 stages, that 
power noise level is reduced at low levels.


dino@inqmind.bison.mb.ca
The Inquiring Mind BBS, Winnipeg, Manitoba  204 488-1607