Using PC PSU for Sure 4x100 amp board


2008-07-06 1:55 am
Hey folks,

I'm looking at this simple PC "booster" PSU to use in a modular DIY project using multiple of the Sure 4x100 amp boards, which recommends a 27V 350W regulated PSU (but according to docs will work with 12V). Here's the PSU:

Epower Technology - ePOWER EP-450CD 450W ATX12V / EPS12V Modular Power Supply - Power Supplies

Obviously attractive price...$20.

The above has two +12V DC legs each with *theoretical* individual max output of 20A...or 38A combined.

I would like to convert this to 24V DC. Yes, I know this is likely a crappy PSU for audio use, but bear with me...

So in theory I need to invert one of the +12V to -12V so that I get 24V total reference between the two.

Can I simply short the 0V of leg #1 with the 12V of leg #2, thereby giving me a total of 24V between the two? Or will this fry things?

If I can and do this, how do I hook up ground at the amp board, which would now be floating between the two? From the amp board's perspective, wouldn't ground now be the - of second leg? Is that safe?

Or, would I just be better off using the 12V hookup, and then in theory being able to drive two 4x100 amp boards per PSU. They are driving 6 or 8" ceiling speakers, 8ohm, and of average efficiency, and rated for 100w.

Or could I can hook up a voltage doubler circuit after each of these, which would still give me in theory 10A or so @ 24V, and the max draw for the board is 12A anyway.

If I can get a clean 40w RMS or so out of the amps, I think I will be happy with them. This is for background listening only, we'll never be cranking them except for the outdoor speakers, and those I'm going to put on a separate amp.

Thanks in advance for any thoughts on this...

- Rhino


2008-07-06 1:55 am
Decided to go with these instead:

Has remote sense (awesome), and enough power to run 3 boards / 6 zones at moderate levels.

I'll probably put two of these installed vertically and on the outer edges of a 3U chassis along with 6 Sure 4x100 boards also installed vertically between them for a total of 12 stereo zones in one 3U package.

I'll orient the Sure boards so that the heatsink finks are oriented vertically, and the top of the chassis over the amp boards will be vented, and the PSU's will have their active fans exhausting out the rear. I'll have to play with it but hopefully that will be enough cooling. The PSU's I bet are loud, but no biggie as this is going into the basement AV / Network room.

Each PSU will have it's own fused cord, as this PSU can suck 12A nominal / 30A inrush. This way I can plug them into separate 15A home circuits. I'm not sure if I can hook two of those up to a single 20A outlet

Any thoughts? Should be an interesting project. Going to be a tight fit lol...