D Basson wrote:
> Dear Rod, Mike, Lou, Richard, Joe, etc.
> Thank you very much for your advice!
> I've disconnected the monitor and recorded "silence", but the buzz (like 
> a shaver) was still present.  I've removed the I/O box from the PC case 
> and everything sounded much better.  One thinks of upgrading one's 
> system (in need of speed) just to encounter new problems slowing you 
> down again!
> Kind regards,
> Diederick Basson

I'm sure the others agree that you are most welcome.

Now to gripe again: Please measure the noise; a description helps, but 
semi-quantitative information helps more. Simply run a spectrum - 
CoolEdit / Audition offers it and it's likely to be in your preferred 
audio editor as well. Since the razor buzz makes it sound like a 
power-line noise and I gather you have 50-Hz power, look for harmonics 
of 50 Hz. Any substantial 50-Hz component means one sort of ground 
problem; substantial 100-Hz means filter problems on a full-wave power 
supply; low components there but large ones at higher harmonics makes it 
likely that radiation is the culprit rather than conduction.

Card sensitivity to conduction and to radiation varies substantially and 
the above is a simplification.

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