Where to find PowerSupplies

[MotoMan_Yz400]

I'm working on a nice little gain clone. It's going to need 40-0-40 to drive it and mostlikely needing a 400-550VA power capability. I been looking at SMPS and Linear power supplies. If I can with a linear design, where can I find the toroids needed, but at a cheap price (for here in eastern America). I would rather a SMPS just for it's smaller form factor, but does anyone know of a source for them cheap? I'm going to have a supply for each channel, so I'm going to need to of everything. Could anyone point me in the right direction?

[jackinnj]

For linear supplies I have used the transformers from John at www.antekinc.com -- they've just started advertising in AX. Most of John's stuff goes for CNC machines so they may be over-rated for our audio purposes.

For switching supplies -- the telecom 48VDC switchers show up fairly often on EBay. I have used one of these (an old Sorensen Raytheon) on a single ended GC type amplifier. There are Power-One open frame supplies 120/220VAC in 48VDC out on EBay at the moment. (Don't make the mistake of purchasing 48VDC DC-DC converter, however.)

[danielwritesbac]

Originally posted by MotoMan_Yz400
I'm working on a nice little gain clone. It's going to need 40-0-40 to drive it and mostlikely needing a 400-550VA power capability. I been looking at SMPS and Linear power supplies. If I can with a linear design, where can I find the toroids needed, but at a cheap price (for here in eastern America). I would rather a SMPS just for it's smaller form factor, but does anyone know of a source for them cheap? I'm going to have a supply for each channel, so I'm going to need to of everything. Could anyone point me in the right direction?

That voltage would overheat most of the usual gainclone amps. They do top about 38+38 DC before there's no heatsink large enough. Even at that voltage, its pretty warm. And the usual VA rating need only be 100. In the highest quality center tap transformer (less noise than torroid), that's about $30 or so.

So, what's the application?

[MotoMan_Yz400]

I'm trying a design for a high output gain clone array. It's going to have a total of 6 clones per channel arrange in a bridged/parallel config. They say more you have in parallel, the more heat you can dissipate. With this design I should get around 300-400RMS into 4 ohms, and be fairly good. I'll have to have some massive heat sinks with fans, but I think I should be able to make it work.

But danielwritesbac, from everything I heard the toroid design produces ALOT less EMF noise. A regular transformer has problems with leaking EMF that can get into the electronics, reasoning behind why they use a toroid. I maybe wrong, but thats what I've heard.

[danielwritesbac]

Well, to answer the original question, howabout http://www.alliedelec.com There's power suppies aplenty and also bulk heatsink channel.

On the noise part, EI are available in a wide range of qualities. Perhaps considering 10 to 12 amps, a torroid eliminates the guesswork.

Over at newegg.com, you can find Artic Ceramique (most effective thermal paste) and CoolerMaster fans (very quiet). The larger, slower fans are almost inaudiable. Most DC fans run nicely from power resistors to control their speed.

At the local hardware store, you can find a simple bimetallic line thermostat made for attic fans. These are somewhat adjustable, fairly cheap, and easy to mod. I think that you could use one to switch on the fans based on operating temperature.

That's about all the help I can be, because your project is pretty far over my head. I think its great and really fascinating too.

[danielwritesbac]

One pair 28v can be wired for 56vct, which is 39.5+39.5 volts DC, what you asked for, and still too hot for chip amps.

However, this:
http://www.alliedelec.com/Search/Pro...A8F8803DD9617F
has plenty of strength.

Otherwise, 56vct audio grade EI core can be found at goodwill, thrift, salvation army, ebay, curbside, in old transistor amps that have probably gotten hot enough to melt the solder right off the output transistors.

[gootee]

Originally posted by MotoMan_Yz400
I'm trying a design for a high output gain clone array. It's going to have a total of 6 clones per channel arrange in a bridged/parallel config. They say more you have in parallel, the more heat you can dissipate. With this design I should get around 300-400RMS into 4 ohms, and be fairly good. I'll have to have some massive heat sinks with fans, but I think I should be able to make it work.

But danielwritesbac, from everything I heard the toroid design produces ALOT less EMF noise. A regular transformer has problems with leaking EMF that can get into the electronics, reasoning behind why they use a toroid. I maybe wrong, but thats what I've heard.

Toroidals do radiate less. But EIs filter the AC mains better. Take your pick. :-)

[Nordic]

The only trouble with EI, is fitting a medium power (250VA+) into a standard case... The height requires a high (more expensive) case...

[danielwritesbac]

Originally posted by gootee
Toroidals do radiate less. But EIs filter the AC mains better. Take your pick. :-)

I was sure that I couldn't explain that.
Thank you so much!!

Normally, one can find a 105c temp rated EI core and it will put out much better amperage than advertised, if you don't operate it at really hot temperatures.
However, with his 40+40dc, that's already a furnace, so I didn't know how to select the va versus temp criteria.

Do you think that LM3875T on Mica sheet and foot-long heatsinks, clamp bars, and steel rails, could withstand that voltage "fanless" on 4 ohm loads?

[Nordic]

yes, .... for all of 30 seconds..

Once you reach a certain heatsink size, increasing it, makes no diffirence.... the ultimate thermal bottlenecks lies before you even get the heat out to the sink....

As you may know, the recommended voltage is 28VDC for 4 ohm loads.