SMPS power amps

[laverda]

I've been thinking about this for some time and see little on the subject.

In short Switch Mode Power Supply's used for power amps, commercially this has/is the norm for many companies for many years.

This cobbled together set up works a treat....two SMPS PS units set up for + - 55v feeding a NCC220 power amp. Each Meanwell LRS-200-48 SMPS is rated at 4.4amps at 48VDC, which is a regulated supply voltage. They cost less than £20 each, I think I got these for £15 each some time ago and forgot about this project but was a bit bored one evening this past week.

I was (to say the least) a little taken aback at just how good it is...(sounds) Early days and further measurements and listening tests to come but very good.

Anyone have any input?

 

[davidsrsb]

In pro audio weight and efficiency matters, so smps are popular.
HiFi reviewers like weight and traditional designers like to cast doubt on anything but a big transformer

 

[chartz]

Yes some people have even done that with 405 boards here in France, and seem happy. I believe the first company to do that was Sony in the early 80's.

 

[davidsrsb]

In the early 80s smps ran at far too low switching frequency to be good for power amplifier use - output impedance and noise issues.
In the UK Linn were the first major user.

 

[Arkless Electronics]

.... or maybe Chord.

 

[davidsrsb]

A class AB power amplifier is a challenging load for a smps.
Half wave current pulses at >10 kHz can find non-linearities in the power supply control loop.
The power supply rejection of most amplifiers falls badly at higher frequencies and the designer probably assumed that the power was coming from a bulk capacitor of low impedance

 

[JimmyB]

I did just this with this supply types while waiting for transformers to arrive in a nap160 build. It sounded great but I just used it for basic 'get it running' and when the transformers arrived I never did a comparison.
Interested in what you hear and whether it's worth using them in a permanent setup (not that I need another amp!)

 

[davidsrsb]

A good smps can sound different as you have a rock solid regulated bass, where a conventional power supply is rippling at 100Hz, sometimes generating intermodulation. There is a reason distortion is always quoted at 1kHz.
One thing to watch is that some amplifiers depend on voltage sag when running hard for output SOA protection- The NAD "feature"

 

[Bad Parameter]

In pro audio weight and efficiency matters, so smps are popular. HiFi reviewers like weight and traditional designers like to cast doubt on anything but a big transformer

Ain't that the truth! Much Hifi equals big toys for big boys, look out the window and there's the BMW K1600GT and Cadillac Escalade in the driveway.