Listening directly to DC Power Supplies

[discrete]

Originally Posted by Dr.H

Hi everyone, I am thinking of listening to DC power supplies to judge their quality/noise levels.

A few questions:
1. Any tried this (with a DC blocking cap of course)?
2. Is there any merit in this approach?-can it really be used to differentiate between say a bog standard lm317 and a good say SALAS shunt regulator?
3. Links to any other results based on the same approach?

Thanks
Ryan

This works, but you have to use headphones with high sensitivity, e.g. the 16 ohm ear canal type like Sennheiser Cx series or similar.

Same as Andrew, I cannot see it on the scope.
But I do hear it with the headphones and a +12dB headphone amplifier.

And yes, I can hear an LM317, but not a good shunt circuit.

Best way though is with a sound card and some FFT software like ARTA.

Be careful with the transient through the cap when hooking up to the DC.

[Dr.H]

Thanks guys

[curryman]

Listening to (besides analysing/scoping) the power supply sounds interesting to me!
However you will only hear noise within audio frequency band. What about high frequency isues (EMI, RFI) in the power supply that could be rectified in the audio circuits and influence the performance of the audio circuit?

[discrete]

Originally Posted by discrete

Best way though is with a sound card and some FFT software like ARTA.

[Dr.H]

Hi Discrete, where is that pic from?

Do you have something similar for:
1. zener with and without CCS
2. ALW
3. Teddyreg
4. etc

Perhaps more to the point. Can you hear the difference that the charts suggest exist?

[discrete]

Originally Posted by Dr.H

Hi Discrete, where is that pic from?

Do you have something similar for:
1. zener with and without CCS
2. ALW
3. Teddyreg
4. etc

Perhaps more to the point. Can you hear the difference that the charts suggest exist?

I took those screenshots from Spectraplus software, using an Emu model 0204 usb DAC.

Unfortunately I do not have other types of regulators measured.

No audible difference (for me anyway) on the audio of the pre-amps they are used in.
But you can hear the noise using a portable headphone amp (4x gain) and the test suggested above.