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gaetan8888 9th June 2007 02:54 PM

Switching power supply for a power amp ?

Do switching power supply can be use for an audiophile power amp ?

Or it's still to noisy ?

Wen I say noise it's can also be low hf noise who can trigher the transistor of the power amp.

Is there a web site who show some good schema of noiseless switching power supply ?



unclejed613 10th June 2007 06:38 PM

actually, in pro-audio there are now many amplifiers doing that, both with class AB and class D amplifiers. when i worked at Apt in the '80s, we were designing the Apt-2 amplifier, which would have been a class AB amp with a switching supply.... actually, since the power supply was going to follow the envelope of the audio, it would have been a class H design... a class AB with variable power supply rails.

the pro-audio amps that use this type of technology are known as "ultralight" amps.

gaetan8888 10th June 2007 08:07 PM


Do you know any 70 volt ct switching power supply schematics that can be use in an home audiophile power amp ?



jaycee 10th June 2007 11:14 PM

By switching I assume you mean SMPS.

To be really effective, such an SMPS would have to be an off-line circuit. These are hazardrous and as such, outside the scope of many DIYers. For example, one of the many factors is radiated emission, something usually tested in a Faraday cage.

You'd also have to have a pretty high switching frequency to stop the noise getting onto the audio band.

Dr_EM 10th June 2007 11:19 PM

Probably best off buying a module such as this:

gaetan8888 10th June 2007 11:38 PM


How about this schematic ?



Leolabs 11th June 2007 02:24 AM

Need to add some filtering at the input and output.

Jonathan Bright 11th June 2007 07:21 AM

Ben Duncan did a piece for "E&WW" several years ago which was specifically looking at bass response and he quoted some work on power amps with SMPS and said that subjectively he thought they were really worth pursuing.

analog_guy 12th June 2007 06:06 AM

I agree with the previous thread that recommended buying an off the shelf supply. Switchmode power supplies are complex things that in most cases will involve designing and building your own transformers and/or inductors. Take a look at the SMPS in a typical PC and you will find over 50 components, and this is a design that has had every last possible component squeezed out of it.

Additionally, the voltages/currents on the rectifier and primary side are large enough to be lethal. Unless you have experience in designing and building high voltage electronics, I strongly suggest buying rather than building such a supply.

CeramicMan 12th June 2007 06:59 AM

What I like to do is go on manufacturer websites such as ON Semi and look at evaluation boards/development kits designed around their ICs. That could be one way to start things off. I don't see much point re-inventing the wheel every time you want to get something done.

At the moment (in addition to all the other things I'm doing) I'm designing a power factor controller input stage, based on the "NCP165148VEVB" evaluation board. It would take me months or maybe even longer to do something like that from scratch.


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