Purchasing a switching dual power supply.

[beppe61]

Dear Friends,

I need your help.
I would like to try a off-the-shelf switching dual power supply with a power amp I am using as a work bench.
The requirements are:
+/- 45 V
400-500 VA
I cannot find a good source for this kind of PS.
Moreover I would need one suitable for audio purpose (low noise etc.).
On the basis of what I have read on the web switching power supplies have been improved very much lately.

Any suggestion on this topic would be very appreciated and valuable.

Kind regards,

beppe61

[beppe61]

This silence tells me that this kind of power supplies are not that common.
Am I wrong?

Regards,

beppe61

[Dirk67]

You can get those devices on www.digiamps.com wich is a spinoff of www.cadaudio.dk ...

[beppe61]

Originally posted by Dirk67
You can get those devices on www.digiamps.com wich is a spinoff of www.cadaudio.dk ...

Dear Mr. Dirk,

thank you so much for the very interesting link.
Do you have direct experience of these PS in audio applications (power amps) or do you have any link to reviews/testimonials?
I think that in the next future a lot of power amps will have a SMPS. they are just to convenient (space, costs, efficiency) to be overlooked.
I wonder why they are not so common.
In comparison for instance at the PC world.

Thank you again.

Kind regards,

beppe61

[Dirk67]

Originally posted by beppe61


Dear Mr. Dirk,

thank you so much for the very interesting link.
Do you have direct experience of these PS in audio applications (power amps) or do you have any link to reviews/testimonials?
I think that in the next future a lot of power amps will have a SMPS. they are just to convenient (space, costs, efficiency) to be overlooked.
I wonder why they are not so common.
In comparison for instance at the PC world.

Thank you again.

Kind regards,

beppe61

"I wonder why they are not so common.
In comparison for instance at the PC world."

It's always a problem to use regulated Power-supply (no matter if switched mode or not) within an audio application, because of some "over-swinging" of the ("too good"=too fast) feedback control (closed loop regulator).
in other words:
you can not take every "industrial" SMPS or linear regulated Power-Supply for Audio --> it has to be tuned and adapted carefully for audio puposes....
(e.g. make the regulation "slow" / choose suitable (not disturbing) switching frequency / reduce the noise dramatically at the outputs / and so on...)

The SMPS in the link above (cadaudio.dk) are designed to be used with their class-D amplifiers.
(you can sychronize the switching frequency of the SMPS with the switching frequency of the class D modules...)

You have to ask them if this SMPS are also suitable for an analog Amp.

I personally would not use them for a Class A Amp, because this topology is very sensitive to noise on the rails.
Class A/B may work very well, like some commercial solutions within the PA-Scene have already demonstrated....


by the way: a good linear regulated power supply (for Audio) is designed by Hartwig Thel .
He also noticed, that it has to be somehow "slow" regulated, to fit the needs for audio...
With this you can get almost "noisefree" supply rails for any class A odr A/B Amp.
(But it saves no energy like a SMPS does , but who cares of energy exept the PA guys... )

[beppe61]

Dear Mr. Dirk,

thank you so much for your extremely kind and valuable reply.
Let me please put some other questions.

Originally posted by Dirk67
"I wonder why they are not so common.
In comparison for instance at the PC world."

> It's always a problem to use regulated Power-supply (no matter if switched mode or not) within an audio application, because of some "over-swinging" of the ("too good"=too fast) feedback control (closed loop regulator).

This is clear also for me.

> in other words: you can not take every "industrial" SMPS or linear regulated Power-Supply for Audio --> it has to be tuned and adapted carefully for audio puposes....
(e.g. make the regulation "slow" / choose suitable (not disturbing) switching frequency / reduce the noise dramatically at the outputs / and so on...)

I suspected so.

> The SMPS in the link above (cadaudio.dk) are designed to be used with their class-D amplifiers.
(you can sychronize the switching frequency of the SMPS with the switching frequency of the class D modules...)
You have to ask them if this SMPS are also suitable for an analog Amp.

Maybe I am trivial here but a good PS should be good in general.
If they are good for their amps they could be fine also for analog ones. Maybe I am simplifying too much here, I do not know.

> I personally would not use them for a Class A Amp, because this topology is very sensitive to noise on the rails.

I did not know this. Thank you very much.
Another reason against class A amp, then.

> Class A/B may work very well, like some commercial solutions within the PA-Scene have already demonstrated....

I am for A/B amps as they can be made to be very well sounding.

> by the way: a good linear regulated power supply (for Audio) is designed by Hartwig Thel .
He also noticed, that it has to be somehow "slow" regulated, to fit the needs for audio...
With this you can get almost "noisefree" supply rails for any class A odr A/B Amp.
(But it saves no energy like a SMPS does , but who cares of energy exept the PA guys... )

Dear Dirk, thank you very much indeed for the extremely interesting link. Great stuff there indeed !
Have you built any of their kits?
They look really well designed.
Regarding the energy saving problem, it can be done with more efficient speakers?

Thank you very much for your very precious advice.
Kind regards,

beppe61
ITALY

[Dirk67]

Originally posted by beppe61
Dear Mr. Dirk,

thank you so much for your extremely kind and valuable reply.
Let me please put some other questions.



Dear Dirk, thank you very much indeed for the extremely interesting link. Great stuff there indeed !
Have you built any of their kits?
They look really well designed.
Regarding the energy saving problem, it can be done with more efficient speakers?

Thank you very much for your very precious advice.
Kind regards,

beppe61
ITALY

Yes I got two AccuSound 100 in a double Mono configurated Power-Amp.
It's very well designed.
Mr.Thel is a "fanatic" with great practical experience who drives each little detail to the top...

In my opinion you don't need to choose the "AccuSound 101" Version with the Welwyn-precision-resistors...

But I recommend instead the use of a seperate Power-Suply for the Gate drivers (as described) on the page.
You can even increase the gain then, so that you are able to use a fully "passive Pre-Amp" (that means a Poti and a switching matix only)...

Maybe I am trivial here but a good PS should be good in general.
If they are good for their amps they could be fine also for analog ones. Maybe I am simplifying too much here, I do not know.

Yes, you are simplifying too much here...
An analog amp is influenced by the Power-Supply Voltage in a completely different way, than a Class-D does...
And even amongst the Class-D's are so many different topologies -> some of them would surely not work at all with a SMPS -> for example the ClassD's from
lcaudio.dk sounds horrible when supplied with a SMPS...

As you can be read on http://www.cadaudio.dk/pwmaudio_whp_en.htm about the Power-Supplys for Class-D:

For most domestic applications a high quality linear power supply , a toroidal transformer, high speed diodes and low esr electrolytic capacitors + regulated power supply for input and driver circuitry will work just fine. For mobile applications or other low weight applications or small size you can choose a switch-mode power supply to power you class-d amplifier, here are a couple of pitfalls, as mentioned above some class-d amplifiers do not at all like being powered with a smps, some of the self-oscillating designs seem to pick up the clock from the SMPS and some of them counteract with the feedback loop of the SMPS giving a completely unstable system alltogether.

[peranders]

Originally posted by beppe61
The requirements are:
+/- 45 V
400-500 VA
I cannot find a good source for this kind of PS.
Moreover I would need one suitable for audio purpose (low noise etc.).

Ready made dual GOOD SMPS are very rare and if they do exist they are expensive. A SMPS which have to deliver an output current with a factor 1:100 with low noise, no major over or under shoots is rare. You can buy pretty good lab PS but they are also pretty expensive.

On the market you can find ICE modules with built-in SMPS, only for OEM customers I'm afraid.

www.icepower.dk

[beppe61]

Originally posted by Dirk67
Yes I got two AccuSound 100 in a double Mono configurated Power-Amp.
It's very well designed.
Mr.Thel is a "fanatic" with great practical experience who drives each little detail to the top... .......

Dear Dirk,

thank you so much for your extremely kind and valuable advice.
You have given me a university level lecture on power supply.
And stuff to study during the weekend eh, eh, eh.
Very interesting indeed.
Thank you sincerely.

Kind regards,

beppe61

[beppe61]

Originally posted by peranders

Ready made dual GOOD SMPS are very rare and if they do exist they are expensive. A SMPS which have to deliver an output current with a factor 1:100 with low noise, no major over or under shoots is rare. You can buy pretty good lab PS but they are also pretty expensive.
On the market you can find ICE modules with built-in SMPS, only for OEM customers I'm afraid.
www.icepower.dk

Dear Mr. Peranders,
thank you very much indeed for your always kind and extremely valuable advice.
I have read a lot about those ICE module.
What is your opinion about?
They are just convenient and efficient or they also sound good?
There is still some debate on this topic about them.

Kind regards,

beppe61