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payitforwardeddie 16th February 2013 08:25 PM

REQUEST FOR OPINIONS
 
I'm considering building a Stereo Tube Amp, 100watts per channel with SMPS supplying all power needs. E.G. Buy Embedded Switch Mode Power Supplies (SMPS) SMPSU,Encapsulated,PCB mount,393V,720W Astec AIT02ZPFC-01NL online from RS
Other SMPS would be used for bias and heater supplies. The intention is to sell these. Any opinions from you all will be welcome, positive and negative. If the overall response seems negative, I won't bother.

The amp will be totally tube.

LinuksGuru 16th February 2013 08:34 PM

As I see from the description/data sheet, this PFC (power factor correction module), and not stabilized power supply.

You will need forward DC-DC converter like HyperTFS in order to get finished stabilized power supply.
Sorry to disappoint you.

tomchr 16th February 2013 08:37 PM

Nice! One thing to be aware of is that many switchers require a minimum load in order to regulate the output voltage. It doesn't say in the datasheet for the Astec you found, though, there's a hint in the "Vout = 393 V @ 0.1 A" spec. Whether 0.1 A is the minimum or not would be a question for the applications engineer at Astec. It would also be nice to know the switching frequency, though, it's probably safe to assume that it's outside the audio band. Output ripple voltage would be nice to know as well.

The writing on the module itself labels it as a "PFC Module" i.e. Power Factor Correction Module. This explains the somewhat odd output voltage and why the output ripple isn't specified. I bet this module is intended to be used with a voltage regulator after the module to regulate to the final output voltage. This module only ensures that the power factor is as close to 1.0 as possible, it doesn't actually provide tight regulation of the output voltage. You could probably use a linear regulator after this module and have a quite good power supply, though. But that's a guess.

Also, beware that even with 90+ % efficiency, some 70 W will still be dissipated in the module. You'll need to get rid of this somehow, so a heatsink is definitely needed.

~Tom

payitforwardeddie 16th February 2013 08:44 PM

I would be putting all the SMPS in a separate box underneath the amp chassis with an integral fan like in a desktop PC. Connection would be with a suitable Anderson Connector.

LinuksGuru 16th February 2013 08:54 PM

Quote:

Originally Posted by payitforwardeddie (Post 3372685)
I would be putting all the SMPS in a separate box underneath the amp chassis with an integral fan like in a desktop PC. Connection would be with a suitable Anderson Connector.

PFC (power factor correction module) is NOT stabilized power supply, its an add-on for DC-DC converter, its purpose is to make load circuitry to appear as resistive.

PFC module must be accomplished with DC-DC converters like the ones listed at the Astec Emerson Power web site:

Emerson | Embedded Power | High Voltage DC-DC Converters

Magz 17th February 2013 03:07 AM

Or, if you want Really High Voltage, the DC-DC converters from Ultravolt...

High Voltage High Power Capacitor-Charging Supply - UltraVolt

smoking-amp 17th February 2013 03:48 AM

The biggest problem with these PFC units (in general) is that they lack isolation from power line input to output. (they are just a boost converter, which is an inductor from input to output, plus a switch after the L to the other polarity side) Check the datasheets given for this unit, under I/O isolation it says "none". They also lack energy storage on the input side for the zero crossing times of the AC input, so they have significant line ripple when loaded.

payitforwardeddie 17th February 2013 03:37 PM

Quote:

Originally Posted by smoking-amp (Post 3372995)
The biggest problem with these PFC units (in general) is that they lack isolation from power line input to output. (they are just a boost converter, which is an inductor from input to output, plus a switch after the L to the other polarity side) Check the datasheets given for this unit, under I/O isolation it says "none". They also lack energy storage on the input side for the zero crossing times of the AC input, so they have significant line ripple when loaded.

Oops, didn't see that. Back to the search. :cool:

DavesNotHere 18th February 2013 03:30 AM

well there ok but the one thing I have encountered with them is heavy emi filtering is needed on the input. It seems better to run the normal complement of capacitors plus putting some .01 across the caps to help clean up the noisy DC. I just get a good transformer because its a little less expensive after spending more $$ in supplemental components.
plus its surface mount technology, which means it probably last only 3-5 years.


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