D Basson wrote:
> Dear Robert
> I am (unfortunately?) using a CRT monitor...
I read the expert solutions offered and am reminded of "It was six men
of Indostan" - The Blind Men and the Elephant. The exception in this
case is that one of the solutions is probably correct: it is grounding;
it is radiation; it is conduction; or it is something else.
Before grabbing for one solution or another, it's worth a bit of effort
to find out what the problem is. Get a good sample of the noise and
analyze it. If largely ~15 KHz, it's likely to be from your monitor. If
multiples of the line frequency (60 or 50 Hz), it's likely to be hum
with the source identifiable from the mix of harmonics. If it's related
to audio level, it probably comes from analogue problems, presumably in
the sound card.
Solutions follow identification. You can do it the other way 'round if
you're lucky, but that can be slow and costly.
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