Using 2 x Meanwell SMPS to get +ve 0v -ve

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I need +40 -0v -40v at about 4amps per rail.

Instead of using a traditional 500VA 30-0-30 toroidal transformer, rectifier and psu caps, can anyone think of any problems using 2 x Meanwell 36V 350W smps ? The smps have 10% adjustment on the Vout.

Wired as +40v 0v....40v 0v


to give +40 -0v -40v ?

I know it should work in theory, does it hold true in practice?

Thanks
fs
 
Hi Ben
Thanks for the confirmation. Do you know if I can operate these in constant current mode, so that for instance I can draw 350w into a low R situation and not trip the over current protection?

Also do you have any experience in making the psu quieter for audio applications?

Thanks
 
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I've not use these to power an audio amplifier.

That page you pointed to earlier apparently discusses using it in current mode, but I don't know how current mode would apply to running an audio power amplifier.

As far as noise, not sure which you mean. there's acoustic noise - these things have cooling fans, but I doubt it would come on unless you play a modern hypercompressed "brickwalled" CD at full volume, and then you won't be able to hear the fan running anyway.

There's without a doubt a lot of electical noise in the outputs of these things. It's the kind of thing that's hard to eliminate, but some high-frequency L-C filtering should help. I could only guess at a first-approximation circuit and component values, maybe someone with more experience at that can help.
 
That page you pointed to earlier apparently discusses using it in current mode, but I don't know how current mode would apply to running an audio power amplifier.

My rationale for operating it in constant current mode would be to allow it to work at Imax into low Rload where it doesn't suddenly shutdown when the design current is breached, such as sizeable reservoir capacitors. I am hoping in conjunction with smoothing capacitors, the psu is able to supply considerably higher current peaks.

Thanks for your input.
 
How much idle power does your amp draw? If that is not much more than 100W then I can highly recommend the following part: http://www.google.de/url?sa=t&sourc...fI7MFyyTQ&sig2=d11ts5QhgglMll8ZM-Jgtg&cad=rja

That one has been designed for ultra low EMI, passive cooling up to 100W continuous output (very high efficiency), and provides +-47V that should suit your amp. It has been designed to be immune against power pumping (that your intended solution may be vulnerable of). It can not only supply but also sink current, so it is not possible to have over voltage due to power pumping. There may be two disadvantages: 1) it has no PFC 2) it is not regulated, it rather has to be seen as a transformer replacement. For me this is no problem as I run it together with digital amps that have a ripple rejection of > 60db, and I have large capacitors on the rails (< 5V pkpk ripple at full load of 600W).
 
... if I can operate these in constant current mode...

Please tell us what model you intend to use. For example, the Meanwell Power Supply Products has a current-limiting scheme to manage overload. That would be just what you need for an amp. However the output noise and ripple is very high, 200mV. You can use a common mode choke to absorb the noise energy.
 
Hi Tatus,
The hypex psu looks interesting, I guess it was designed for their class d modules.
The amp is biased at 1.9 amps at 40v per channel (bipolar). I am considering the S350-36, which has a Vout adjustment of 32v to 40v at 350w. I was thinking getting two of these and putting them in series to get a +40v 0v -40v. If it works well then I'll probably get another pair. My main concerns are that it won't work correctly in this application.

I'll check out the hypex psu to see if it is fit for purpose.


Thanks for your suggestion.

Fs
 
My SMPS +/- power supply solution

Hello,

Don't know if anybody still follows this tread but this is what I did to get an absolutely silent amp. It's a gain clone so PSRR is quite high which helps a lot.
 

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