• here. Bob Lee is from QSC and may weigh in

Why would they want to do this in home/pro audio amplifiers?
One reason is space. Since you are dealing with 50/60hz
transformers you need "big uns" to get some high powered amplifiers
plus "big uns" transformers are very ineffecient, alot of power
is lost to heat.

High frequency switching power supplies done correctly can
reduce size because they require a much smaller transformer
(toroidal typically), they are more effecient. The reduction
in size is because they switch the transformer on/off not
at 50/60 hz but perhaps anywhere from 20khz - 100khz depending
on who designed the circuit.

Some people may argue that switching noises may leak into the audio
signal path. Sure, if the amplifier is poorly designed. Plus,
can your ears hear this noise ?

I've done car audio for 10 years and didn't experience any leakage
noise problems, even with cheaper amplifiers.

Still not sure? go listen to one and be 100% sure.

Oh, the reason most home amplifier companies don't do this
is because of cost. It's cheaper to just buy a beefy 50 pound
transformer, add a bridge rectifier and some storage capacitors
and the power supply circuit is done and it's realiable.

Ask the same designer to convert to a high frequency switching
power supply and he will say "oh no, now I have to do some
real engineering work".

The reason is actually pretty simple, it's easier to work at higher voltage and lower current and it's also easier to filter HF than LF. The large coils and caps required to filter 100Hz or 120Hz (full wave rectified) power are more expensive, and the components required to channel higher currents are more expensive too. All the same reasons we distribute power at kilovolt potential and then transform it down to household current levels.

None of this really suggests which type is better, because there is no better type. Both can be made to perform very well. It's all the "same stuff" really, just "smooshed" into different forms.

Perhaps today that is the case since mosfet transistors are much
cheaper now than say 10-20 years ago. Plus, more people are actually
figuring out how to make them, designing one 20+ years ago was
considered a black art. hehe Most of those bipolar switchers weren't
that good, but they worked..

Still, most if not all home audio amplifiers are not going with
this method, not sure exactly why. I haven't seen any trend
toward switchers in home audio.

If I was designing a switcher vs. traditional methods the first thing
that comes to mind is this.

50/60hz toroidal transformers are much cheaper now, 10-15 years
ago getting one stock off the shelf was impossible that met
your requirements. Getting it custom made cost alot of money.
Last year I was researching this and more companies offer these
toroidals with voltage specifications tailored for amplifier use
standard in their catalogs, no need for custom ones anymore = much
cheaper. I think I priced a beefy one at $100-$150 each.
If I use one of these, I have to sacrifice real estate, it's
a big core.

What if I convert to a switcher that is able to run 1000W ?
I need more heatsink area to accomodate the mosfets, added cost.
I need mosfets, added cost. I need a smaller toroidal core.
Since switchers are "fly by design", can't really find a toroidal
"off the shelf" that meets my voltage, current and frequency
requirements? I can probably alter my design and work around
with given specs.

For a switcher I don't need as many large capacitors

*BUT*

you know how audiophiles are, they want a bank of 60kuf-120kuf
per rail or they are not happy. They want the extra energy
storage for transients and what not. It would be hard to
convince these people that they don't need as much. heheh

The last thing that comes to mind is reliability. That shouldn't
be a problem, but having a bank of switching mosfets is just
another failure mechanism, one shorts out and whole bank can be blown
which means that the amplifiers is coming back for repair - heheh
It's hard to punish a 50hz/60hz transformer and wall outlet
is a pretty reliable source of frequency.

So what do I do as an amplifier designer?
Use the traditional method or make a switcher?

What type of poison do I want to drink ?

hehehe

Car audio folks had no choice - hehehe

the part "fill a niche which has arisen" caught my eye. it implies that these are specialized solutions to specific issues, not "just another" p/s topology. Sam