less hum: switching power supply?

[René Schmitz]

Hi Christo, and welcome on this list!

At 12:20 02.06.00 -0400, chris wrote:
>   in a quest to totally eliminate the hum in the audio circuits...
>   i've decided that switching power supply is the way to go to get rid of 
>the big 60-cycle EMF.

Well you'd trade hum against noise or ripple in the kHzs. 
Switchers can be used for audio, but its best when you use 
a linear post-regulator. 

Then again, a good linear PSU can give you lots of hum rejection. 

Most opamps do have the better rejection at lower frequencies, thus the
high frequency ripple of a switcher could pose a problem.

Are you sure that the hum in your circuits is injected by the PSU?
I'd rather suspect stray-fields, ground loops and/or missing shielding.

Bye,
 René

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