I was just tooling around on ebay looking for parts and I noticed you can get computer (PC) power supplies pretty cheaply.  I'm assuming they put out very clean well-regulated power, but I know absolutely nothing else about them (voltage output, current, etc.).  Has anyone played around with these things?  Do they have any value as a bench, amp, or pedalboard supply?

I'm not sure, but I too would be interested in knowing more about using PC power supplies (especially as amp power supply). Has anyone had experience with these?

well, I use one for this Crap heap amp I have(its .2% distortion). They have limited output (meaning two bipolar high current outputs( +5/-5 (so ten volts) and +12/-12 (so 24 volts)). The outputs are filtered pretty well. You can also just rip them apart for the fan, heatsink, and filter caps.

Since Computer PSUs are switchmode, all I've heard using them is this nasty high-pitched WHIIIIIIIIIIIIIIIIIIIII instead of nice clean power. So I don't use em. You wan't a linear PSU (AKA transformer and diode bridge) for audio.

When I put a second set of filter caps, It gave no whine in my SS amp. I guess it depends on the supply.

I built some synth-circuits using power I ripped out of and old Pentium90. Didn´t have a noticable problem with noise. And another good thing is that you get +/-15v AND +/-5v from them, so you can have a circuitry that needs high-power and also CMOS chips that require lower voltages
But the noise might be an issue when you don´t have a VCO sticking rail-to-rail all the time, but more quiet audio signal, like guitar which doesn´t even make sound all the time.. Haven´t tried that.
ch.

Quote from: sir_modulusI guess it depends on the supply.

You're right there

Ok, main problem is switching noise. It depends on the supply, but some of them switch at audio frequencies. This is no good.

Also, some of the cases don't provide much RF protection.

Another problem is that they are not true bipolar supplies. The one I have infront of me is +12V @ 5.5A, but it's -12V @ just 0.5A. Similar story with the ±5V rail.

Switch modes are often used for audio, but computer power supplies aren't always suited. Often, we electronic bagmen end up with the old tired ones, with filter caps that are drying out and other worn out bits and pieces...

old caps in ANY circuit are trouble.

Only one way to find out, suck it and see. You might have a good one!