F2 on an SMPS

[hacknet]

i was browzing through the F2's schematics this morning and the low voltage required gave me a silly idea.

is it even imaginable to run the F2's off a 24v SMPS? i think it would be pretty cheap and easy to get my hands on a pair of 24v ~8A SMPS. that would give a mile of current headroom and a pretty stiff 24v.

sonically would it be ludacrise to do something like that?


love to hear your ideas! happy new year guys!

[GRollins]

The idea comes up every month or two, usually spurred by the availability of surplus computer power supplies. Search the forums--you'll probably find a hundred similar threads.
Unfortunately, switching supplies generate a lot of RF. Some are less than stable when confronted with an amplifier as a load. What a computer regards as available current and what an amplifier thinks are different things. That said, it can be done, at least some of the time. If you can get them cheaply enough you're certainly welcome to try. I've done it once or twice, but always as a stopgap measure; went to a 'normal' power supply as soon as possible.

Grey

[Nelson Pass]

One advantage is that the F2 is literally constant current
draw, so you don't have to be concerned about audio
transients being greater than the rating of the supply -
if it runs at all, it should run great.

Also, with no feedback and low gain, the F2 is very resistant
to RF noise.

[flg]

Not to circumvent what Grey and nelson said But... I have taken your typical (42Volt Printer suply) and used it for my preamps a couple times now They work great, with the supply a few inches- a foot away, with a big low esr cap close to the amp, and a couple of film bypass'es. I was surprised myself...
I have a ciouple I want to use for a power amp soon...
Just my experience

[hacknet]

thanks for your replys guys! i just might get the project off the ground and give it a try.

i cant seem to find large VA 18v transformers locally thats why i am thinking of using SMPSes.

[GRollins]

I got peeved one afternoon because I didn't have any music down where I do my electronics stuff. Seemed unjust. Pulled out an old car radio and a 12V computer supply. It worked first time.
Newer supplies are better designed (hopefully more stable), but sometimes older ones would smoke when put into audio use. Knew a fellow who spent half an afternoon trying various power supplies, only to have a fair-sized pile of junk at the end of the day.
At least he managed to clear a lot of shelf space.
This is not to discourage you from trying--just be aware that there can be problems. If they're cheap enough, or better yet, free, then you'll be okay even if they pop. If they work, then you're ahead of the game.

Grey

[hacknet]

sounds good!

ive seen alot of these steel caged smps for sale at the electronics stores. i was just wondering if it was possible to use them. i will go do more snooping around to see if they are cost effective.

maybe it just might make sense to buy toroidals off farnel and build a simple power supply.