On Thu, 8 May 2014 19:30:48 +0000
Jonathan E Brickman wrote:
> Last night I came to at least a working resolution of a really weird problem. I'm hoping others can tell me what is really going on here, and what best to do about it. I am not an electrical engineer or electrician or anything like that, I just learned a lot from my dad and friends and trial and error.
To me, a high pitched sound like this suggests that something (or a combination
of somethings) is marginally stable and different signal chains and earth loops
can set it off unpredictably. If there is a lot of gain in the system it can even
be something like speaker wires close to something not completely screened.
Usually, TRS is used for balanced signals but there can sometimes be benefit in
using it for unbalanced lines, in that the screening is separate from the return
path - mind you, in some cases that can actually cause RF interference problems!
All in all, I'd suggest going right back to first principles and connecting just
the absolute minimum system (even if that means listening on headphones),
ensuring you are free of the problem, then carefully adding bits. Do keep in
mind that if the problem re-appears it is not necessarily the last bit you
added that is at fault. It might just be completing a loop that triggers the
Will J Godfrey
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
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