computer power supply?

[bostonswoop]

Where can i find info on possibly using a old computer power pack for a chip amp? Or is this a bad idea?

I have lots (more like to much) old computer parts and i have HP pavilion case that im taking the board out of and was thinking of using the power supply from it...... possibly and using the case , moded of course, for my chip amp.

I like the idea of using the switch on the power pack and the power cable and block and the grounding on it already.

What parts can you salvage out of old computers to use in DIY of this sort anyway?

Im new to DIY Audio but i really enjoy the concept before this i mostly worked on peoples computers and that is so straight forward its silly. But inturn ended up with people leftovers from upgrades. (read total computers mostly due to building new ones for them.


Thanks
Sam

Need stuff i might have?
lol

[mr-mac]

Surely a switching PSU which most computer ones have been for ages are a bad idea in any sort of audio????

John

[bostonswoop]

so thats a No???? sorry i wasnt sure what you ment with your ? marks....

[mr-mac]

I mean as far as I am concered switching PSU = Bad in audio but not any experience of a chip amp so maybe someone will know 100%

[bostonswoop]

I see, im not up on my electical at all, but i thought i read somewhere that people had used computer power supplys for amps or maybe it was somthing else.
Im easily confused.

[xstephanx]

if youre talking abtou the sonic impact t amp, they susually mean the outboard transformers for laptops.

[Zero One]

Well actually I am running a gainclone on a pair of computer smps supplies and it is utterly wonderful, 2 LM1875 based clone modules and it puts out enough watts to drive my full range system very loud. I have work to do as the supplies only put out 1 amp on the -12V and 8 on the +12V, there are ways around this, but I haven't fixed that yet.

In fact my Pre-amp is also running SMPS as well.

I have heard that you would hear switching noise etc, well my speaker system is very very revealing and I can't hear anything odd at all, just beautiful music. I have done comparisions with my regular torroid supplies and frankly I wouldn't use the torroids again in this application, the sound is grainy and loose by comparison.

Now having said the above, you will need two supplies and it is a fiddle to get them working and tidy them up and to get a good high amp supply for both + and - rails is a fiddle, you have to isolate the boards from the ground and re box the whole set-up so as not to electrocute yourself etc, so this is not a good first DIY task. BUT ultimately I think either this appraoch or battery power are the way to really turn a gainclone into a music maker of excellence.

Oh and heres the really great bit, these SMPS cost me just $2.00 each from a 2nd hand shop and I have a mate who can give me a few as well, he's a computer repair guy and smps's get upgraded all the time.

Food for thought.

[raromachine]

I guess the way to look at it would be to figure out what the ripple in the SMPS is and how that compares to the ripple your Gainclone (or other) chip will reject. Probably easier said than done though?

[Zero One]

I imagine the ripple will vary from one type of supply to another and I don't know how it would all be factored in, but I don't think that I have read of anyone who has tried SMPS for their clones saying they are going to go back to the conventional supply despite the fact that the power output is far less.

I have heard of some who are using batteries though and have used SMPS as well.

It is definitely worth a try, but I feel anyone new to cloning should get a std clone up and running well first, if for no other reason than to have a reference point to work from.

BTW computer supplies would need to be pretty well engineered in the first place as computers are pretty sensitive to power supply problems, I'm not sure though how they compare to the industrial type supplies that are now commonly available. None of those have plus and minus rails, but you can get around that.

[lndm]

SMPS's are getting used now more than before. I believe it is possible to build one that performs highly, even though that wouldn't have been believed once. I still prefer to avoid them.

That said, what makes a high quality SMPS may not be what you find in a computer power supply, and they are very different depending on who made it and when.

Importantly, a chip amp has a fair power supply rejection ratio. On any other amp, you mightn't be so lucky. My amp has a fairly poor power supply rejection ratio for example, and noise would be more obvious.

Depending on what you choose, a computer power supply is a good source of switches, IEC sockets, fuse holders etc. but also high voltage caps.