-48V telco power supply for Aleph? - diyAudio
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Old 21st May 2006, 08:30 PM   #1
jwb is offline jwb  United States
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Default -48V telco power supply for Aleph?

I had a very successful dumpster diving trip the other day, and came up with two wonderful telco power supplies, in perfect working condition. They are Power Conversion Products PS-19 TwinPack supplies, as seen here:


Each rack unit contains two power supplies, capable of -48V/12A output. In other words, 2400W of passively-cooled regulated DC power. Now I just need a really good idea for what to do with such a beast.

I'm thinking: four power supplies, four amplifiers in a stereo biamplified setup. Why not try to convert my +12V/-12V Aleph-X amps to run on -48V regulated supply? Has anyone built an Aleph-X with a regulated supply?
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Old 21st May 2006, 09:05 PM   #2
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Such units are typically resonant mode devices which have high efficiency and at that power level probably not all that high switching frequency.

I think you will have great success, particularly if you filter the output. One problem you probably will run into if you are using split supplies (i.e +-48V) is that you will likely see noise on the ground. Thus you should filter before combining the + terminal on one with the - terminal of the other (I am sure they are floating supplies ....).

Now, if you go the outer route and set up a balanced amp that does not require a ground connection, you can create your own floating ground as the mindpoint between the two, the amplifier will reject more of any type of noise found on the output.

If it were me, I would try to use a couple of LC filters where there was L in both phases and short out as much crap as possible between phases. There will likely be common mode crap on there too, but I am very concerned about connecting stuff to signal ground so try to avoid that if you can at all get around it.

The final thing you could try if you need lower voltages is to modify the supplies. However, I think it would probably be more fun to build a higher power amplifier.

Good luck and congratulations with this massive gear!


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Old 21st May 2006, 09:33 PM   #3
jwb is offline jwb  United States
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Actually, to my surprise, these are not ferroresonant designs. They are high frequency switchers, they only weight a few pounds each, and their output noise is specified from DC to 100MHz (!).

That's why I'm excited! Thanks for your ideas!
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Old 22nd May 2006, 03:52 PM   #4
anatech is offline anatech  Canada
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Moved to the Pass forum, since this is directed to powering one of these designs.

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Old 22nd May 2006, 06:00 PM   #5
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Let us know how it works out. I have a bunch of model P4850TC's and P24N100TC's I'd like to put to use.

Cheers, Casey Walsh
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