Somewhere on teh intarwebs Jim Lesurf wrote:
In article , ~misfit~
wrote:
Somewhere on teh intarwebs Arny Krueger wrote:


As time marched on, fairly inexpensive and modest-sized output
devices with excellent SOA and reasonble high frequency resposnse
made it relatively inexpensive to build very high powered audio
power amplifiers. Most of the money ended up in the heat sinks,
power supply transformers and filter capacitors. The former are
continuing to shrink as improved output devices improve their
reliabiity at higher operating temperatures and power supplies are
making greater use of switchmode technology. As power device speed
continues to improve, switchmode amplifier circuits operate at
higher and higher frequencies, which in turn makes filtering the
switching noise out of their outputs a more economic and effective
operation.

Thanks for elucidating Arny. Interesting what you say about
Switch-Mode Power Supplies (SMPSs). I've been dabbling in PC
building on-and-off for a decade and, when I last looked you could
get SMPSs that were outputting 1.2 KW. I asked a friend, who owns a
bunch of Perreaux gear and also builds his own amps using toroids
why he couldn't use a SMPS and he said "too noisy".

Considering the price he was paying for big toroids (and that he was
using a few large caps anyway) I wondered why not just filter better
and maybe make a split-system, with the SMPS in a seperate box,
perhaps on the floor....

I think this starts off with a situation where a 'new' approach simply
isn't up to the task and then slowly glides into one where people use
whichever approach they are more comfortable with.

So I tend to still prefer to design/think in terms of 'traditional'
transformer/rectifier/caps PSUs as I know how to get what I'd want
that way, and what the snags are.

However in terms of RF hash I do tend to feel there is a 'prevention
is better than cure' argument. Why put up with having to filter and
suppress it if an alternative that works well doesn't generate it.
But this may just be me being old fashioned. :-) I can see the
advantages of SM PSUs in terms of being efficient, small, etc.

Slainte,

Jim

Heh! Yeah, I see your point Jim. However, as Arny just said (essentially),
it seems to be the way of the future.

Cheers,
--
Shaun.

"Humans will have advanced a long, long, way when religious belief has a
cozy little classification in the DSM."
David Melville (in r.a.s.f1)