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Twisted Sister RCA page
Whats the deal with Unshielded Twisted
Pair RCA leads(UTP)
For years we have been told shielded leads are the way to go
and yet this was basically due to them working well in the domestic AC enviroment.
In our specific 12 volt DC envioroment(the car) the fact is they didnt actually
prevent noise from entering our signal leads(RCA) and so we tried triple shielding
and even disconnecting the shield at one end(directional leads but with no sucsess.
Then unshielded twisted pair leads enter the scene courtesy of Richard Clarke
and David Navone. Now these 2 guys know a thing or 2 about our 12 volt DC enviroment,
and the leads they pioneered actually work.
The cablemakers persisted in selling us shielded leads and
its still common to see twisted pair leads that are sheilded. The fact remains
that shielding doesnt work in a car but that doesnt seem to stop many respected
brands still selling shielded leads at very high prices and although these leads
look good and can be fitted without causing induced noise issues, the fact remains
we are basically paying for the looks and will often still end up with induced
noise.
Unshielded Twisted Pair leads or UTP for short are actually
the best option in our noisy electrical situation.
Why Doesnt Shielding Work and Why Does UTP Work
Coaxial cable has more conductors in the shield than it does
in the centre conductor. This combined with the fact the shield is always
closer to the radiating noise source. This results in the coaxial cable will
always present a noise amplitude difference to the signal recieving device.
This amplitude difference is seen by the signal recieving device as an audio
signal and is then passed through.
By twisting equal sized conductors, we expose each lead
in the pair to exactly the same amplitude of the radiated noise, we find in
our automotive enviroment, and the conductors are effectively the same distance
from the radiated noise source. The noise is not passed through, only the
voltage difference between each side of the signal path is passed through.
This means if we have zero difference in amplitude in this arrangement, we
also have zero noise.
So get twisted already :)
Copyright ©cyberpunky 1997©
Last revised: August 01, 2001.