> Q: even at high cost some cables use braided copper shield & some
> use braided aluminium shield. Does anyone know what the actual
> difference is between the two in a practical sense ?
Jez,
Aluminium is cheaper. If there is a slight difference in conductivity,
this should still be well within the cable impedance spec.
The cable to avoid with long runs is helical screened which can puch
up RF interference from medium wave transmitters etc. That is the
reason for braiding.
I've got 100 and 150 metre cables and I went for cable designed for
permanent installations which was foil screened with a copper
conductor. This cable is not designed to be flexed frequently but I
use it in long semi-permanant runs into woodland.
The only problem I have had with my long cables was when I had two
double runs in opposite directions during a storm. My 11,000 volt
electricity supply line was arcing over, and I got fizzle when both
lines were plugged into my mixer, but that was extreme conditions.
I've also used conductive plastic screened cable for short cables but
have doubts about using it where flexibillty is not a requirrement,
but it works. The doubts are mainly financal. :-)
The other cable parameter is microphony but it is rarely given. Try
tapping cables without an input and at high gain. Conductive plastic
screening can be bad, but most helical screened types are quite low.
Microphony is not important with studio or music work but with
wildlife recording, if movement is involved, it could be a problem.
Sorry to waffle but avoid helical and go for cheap cable. :-)
PS. My cable drums are garden hose drums which are light and cheap and
I screwed in clips for the XLR's. They easily take 300 metres of the
foil screened cable. I use coloured heatshrink to identfy plugs.
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
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