Car amp to guitar amp conversion

[mojo_hand]

I think maybe you're attaching undue weight to the noise issue.  Many thousands of guitarists plug directly into a sound card that's a few inches away from a 400 watt switching supply, and most seem to think it sounds pretty good.

My personal suspicion is that switching supplies get badmouthed a lot, not so much because they're hopelessly noisy, as because they have inverse mojo.

[earthtonesaudio]

I think maybe you're attaching undue weight to the noise issue.  Many thousands of guitarists plug directly into a sound card that's a few inches away from a 400 watt switching supply, and most seem to think it sounds pretty good.

My personal suspicion is that switching supplies get badmouthed a lot, not so much because they're hopelessly noisy, as because they have inverse mojo.

Well, I guess it's either the SMPS radiating RF energy, or a heavy, inefficient transformer radiating EM energy... take your pick.  Filtering the noise from a SMPS does seem pretty straightforward though.  I have a hunch that getting rid of EM energy is a lot harder unless you start with a toroidal transformer.

Based on replies so far, I think I'm gonna go for some sort of re-used PSU from a junk PC.  Based on expense, performance, and ease of adaptation, it looks like the winner.

[mojo_hand]

Just remember to show a VERY healthy respect for the voltages inside the PS case.  Contrary to popular belief, the use of rectified line voltage is not dead, it lives on in the first stage of every computer PS.  So if you're ever going to open it up, it MUST be unplugged, and the capacitors discharged with great care; the stuff in there can kill you every bit as easily as a tube amp could.

[earthtonesaudio]

+1 on the don't die advice.

I've been checking out some of the PSUs that are lying around the shop at work, and there's quite a bit of variation out there.  Not just +/- 12 and 5 volts, but +/-3 sometimes also.  And tons of amperage, especially for the lower voltages.  I saw one that had 23A for the +5V output.  That is enough to make me cautious.