[Niteshade]

These things are neat!

http://www.picoelectronics.com/dcdclow/peQP.htm

Would be nifty to make a preamp out of one or something like a SEP 6V6 or EL84 circuit.  It would be too costly to gang them up for more current- but I still believe it's a fantastic device for the DIY'er.

[JoshK]

I see you have been perusing the competition.     Yeah, I pretty much suspected the same.  I've seen a number of dc-dc converter chips, but I didn't pay enough attention at the time.  Not really a solution I care to explore.

[Niteshade]

I would like to see switching power supplies that operated on AC and provided 300+ volts DC at around 500ma. Guess it's time to go hunting again. Switching power supplies & DC-DC converters are a good way to eliminate filtration issues in preamps, especially phono preamps- wouldn't you think?

[Audiovista]

I make my living designing switching power supplies, but I'm still on the fence regarding audio applications. Hi-Fi apps, to be more specific - PA systems and instrument amplifiers are something else.

Typical problems that I encounter are complexity, cost and noise (conducted and radiated), and efficiency improvements are negligible in low power applications. Heat management too, but that is less of a problem in audio due to low average power.

Another possible issue, related to audio, is that regulation loop operates within audio bandwidth (0.5-2kHz typically for off-line power supplies). It can be made slower, but then output capacitors alone handle peak load and situation is identical to line frequency rectification (no savings in capacitors, moreover, they need to be able to handle 120Hz AND high frequency ripple). Unfortunately the feedback loop cannot be made much faster - well above 20kHz would be nice....

Oh, by the way - I know the guys who design power supplies at Pico. Nice people. Many Newcastle Brown Ale went down in their fine little town.

[Niteshade]

Hi Boris,

I have used an Astron SS-30 (30 Amp, 18.8v) switching power supply for my amateur radios and it worked great! There was no AF or RF noise on any of the bands.

I see your point about the issues and understand why they can be expensive, but I believe it is a good idea. I have one application where one of these would be most welcome. You will have to try one out for yourself in an audio application.

Blair

[Audiovista]

Hi Blair,

You don't have to try to convince me that switchmode power supplies are great.  But they are noisier and slower than their linear counterparts.

Yes, all the issues can be addressed at a cost of increased complexity and price (and require serious equipment). I'm just not sure about their advantages in low power audio applications 

Best,
Boris

[Niteshade]

Low power- Oh no!

The tiny DC-DC converters may be good for that if one wants to go that route. I was thinking about 400v @ 2 amps and 12.6 volts @ 20 amps.

[Audiovista]