Pairing computer power supply with amp

[JahJahBinks]

I just had this interesting thought. Since the quality of DC output from a power supply plays nontrivial role in getting the best sound from the amp, how would an ordinary computer power supply compare to any of the power supply made for headphone amps?

 

[Mindless]

First of all, they are not built in the same way, the PSU of a computer provides the computer with watt's, not volt's, as amplifiers. I've been speculating in taking a computer PSU and putting it into an amp, but frankly, I dont know if it would work, and I dont care very much. And a transformator in an amp probably plays the biggest role in the sound of an amp (ok, opamps and other things affect the sound too)

 

[00940]

Of course it would work. But you don't get a lot of interesting outputs. Typically there's a 12V@8A output you can use with a -12V@ 0.5A. It's ok for opamps-based headamps.

However, it's a switching power supply optimized to give quantity and not quality, that means that the rails are far from being clean enough for high end audio.

I've one open under my eyes right now (it's broken). There's a few interesting things for diy, like a pair of big diodes, 2 nice heatsinks for to220 packages, a few big film caps for main filtering, iec socket, TL431 shunt regulators.

 

[tangent]

The -12V lead from a PC power supply only goes to the motherboard, so you either have to splice into this lead, or be satisfied with the +5V and +12V you can get from the drive connectors. That either limits your chip choice and output voltage severely, or you require a DC-DC converter to bring the voltage up.

Through suitable filtering, you can clean up the noise from the power supply. You wouldn't want to plug it straight into an op-amp, but it wouldn't require heroic measures to get clean enough power to get reasonable sound quality. You'd be more worried about RFI pickup than power supply quality, I'd think.

If you add a high-quality DC-DC converter, you effectively get filtering "for free" -- the converter's job is to put out a stable, clean voltage as long as the inputs are within range. A good DC-DC converter will cost you about $20, though.

 

[Edwood]

If you can match up the voltages and output wattage, it should work fine.

Now good sound quality, that's another story altogether.

It would be best to look for a linear and/or regulated wall wart. Switching power supplies are notorious for being very noisy.

-Ed