Low cost high quality excellent performing LPSU for audio.

[Miska]

This is pretty good one! And doesn't cost much either.

 

https://www.meanwell-web.com/en-gb/ac-dc-medical-desktop-adaptor-output-5vdc-at-6a-ac-gsm60b05--p1j

 

[Miska]

17 minutes ago, Kal Rubinson said:

But not an LPSU?  Manual says "Adaptor is a kind of external switching power supply....."

 

Yeah, it is SMPS. Why would it need to be LPSU?

 

Thing is that you don't need to have 50/60 Hz transformer to have good PSU. Or even LPSU. You can also have LPSU with transformers running for example at 50/60 kHz instead. Most would call latter one "SMPS" and first one "LPSU". But it is not that black and white.

 

[Miska]

21 hours ago, One and a half said:

For audio use it's clear to use a linear power supply over an SMPS. The EMI at 60 kHz to 200 kHz is not acceptable, being responsible for high leakage currents from an SMPS which screw up DAC imaging plus a host of other reprehensible artifacts. It is that black and white.

 

It is not so clear.

 

Medical grade PSUs, like the one I referred to, have been specifically designed to have very low leakage currents, in µA range.

 

Even with standard SMPS wall-warts, it is entirely possible to design very low noise analog devices. I have measured enough many DACs running from SMPS that I know it is more about the design than the type of PSU. Overall, 60/200 kHz is much easier to filter out than 50/60/100/120 Hz. Especially since the fundamental and it's harmonics are outside of audio band.

 

[Miska]

17 hours ago, Superdad said:

100 milliVolts p-p DC output noise? No thanks.  (Just to give the lay folk perspective, the output noise of the Linear Technology LT3045 is a few microVolts; 100 milliVolts = 100,000 microVolts.)

 

For example powering a cheap Pro-Ject Pre Box S2 Digital DAC through it's USB interface, from an UP Board NAA powered by the said medical SMPS PSU gives less than 8 µV of output noise from the DAC analog outputs.  While powering the DAC from the supplied wall-wart through the separate power connector instead doubles this noise. to about 17 µV.

 

 

This given that the said UP Board NAA is running an open PCB without any casing. Highest noise components also in this case are 50 Hz harmonics.

 

So yeah, I continue happily powering my NAAs with that SMPS PSU.

 

Or at least I want to see some DAC analog output measurement data.

 

[Miska]

8 minutes ago, jabbr said:

I power my NAA (NUC) via an "el cheapo" LPS. One could compare that to the SMPS and see if there is any difference.

 

NUC takes in 19V by default and runs it through it's switching regulators to produce for example the USB VBUS. One reason I prefer NAA boards that take in 5V and feed it through to the USB only through the current limiter chip (sorta mandatory part of USB).

 

[Miska]

6 hours ago, asdf1000 said:

Another great thing about 5Vdc endpoints is they can be powered by USB powerbank!

 

This completely removes the biggest issue of SMPS - leakage current / ground current / ground loop etc.

 

A bigger issue than their output ripple (depending which DAC designer you talk to).

 

Well, the medical PSU I'm using doesn't have leakage currents and since it's floating it doesn't have that ground current.

 

That ripple is left-over from the switching DC/DC converter. Usually it is higher frequency than the 50/60 Hz mains hum and thus easier and cheaper to smooth out.

 

One challenge with the LPSUs is to find ones with high enough current output. The medical SMPS I'm using outputs 5V 6A (30W). Which is of course still very low power, compared to the switching PSUs for example for CPUs and GPUs that can put out 100+A at 1.2V supply voltage...

 

[Miska]

On 1/31/2021 at 9:09 PM, Superdad said:

If the PS that is the source of the leakage has an electrical path to something that is grounded (such as a DAC, preamp, poweramp etc), maybe an interconnect, USB cable, Ethernet cable etc, the leakage current will create a voltage across the impedance of the cable, frequently the "ground wire" or shield of the cable.

 

By the way, if your ethernet cable is grounded, you are certainly doing it wrong!

 

[Miska]

10 minutes ago, asdf1000 said:

It has low leakage, not no leakage currents. So you will still have (low) dirty ground currents / ground RF...

 

Well, it doesn't have ground leakage because it doesn't have ground!