Jim Lesurf wrote:

Woody wrote:

I built a dual mono MOSFET power amp based on the Ambit boards
containing a Hitachi design. It was good and provided 110wpc without
difficulty. I then built the regulated supply designed by the late great
John Lindsey-Hood and fitted that - and the aural difference was
dramatic, and not least that it did 110W into 8R and 220W into 4R. The
PSU design also provides d.c. offset protection for the speakers. I
think I have a copy of the circuit of anyone wants it.

That isn't really a matter of changing to an actively regulated PSU. Just
one of ensuring the PSU has a low output impedance and ripple even when the
current demand is high. if the "aural difference was dramatic" then I'd
suspect something was wrong with the unregulated PSU you'd used.
Unregulated supplies can give the advantage of providing higher peak
transient powers. Given that music tends to have higher crest factors than
test sinewaves that can be quite useful. However the amp has to be built to
cope.

Even pro amps with SMPSs don't make any serious attempt to regulate the rails.

Graham