[linux-audio-user] Feasibility of Crestron like Linux BasedWhole
House Audio System - Multisource / Multizone Capable????
A.Kuckartz at ping.de
Wed Jan 5 16:43:03 EST 2005
Florin Andrei wrote:
> But it might be ok, though, to run high-
> amplitude analog signal over lengthy cables. I.e., speaker signal.
> At those amplitudes and impedances, there's only a very low risk of
> picking up noise.
You do not pick up noise but the longer the speaker cables the higher their
capacitance and their resistance. There also are other strange distortions
happening due to cables. All of this can influence the sound:
"Speaker cable needs to have a very low electrical resistance, so it needs to be
fairly hefty and made from a pure material, such as oxygen-free copper (OFC).
Impure material can introduce nonlinearities (the oxidised copper actually
behaves as a semiconductor) that manifest themselves as increased distortion at
low signal levels. There are many cables that qualify, including 30A 'cooker'
mains cable, but a sensibly priced, heavy-duty speaker cable is easier to use
and looks nicer. If the cable resistance is more than a tiny fraction of an Ohm,
the amplifier's damping factor is compromised and also the loudspeaker's
frequency response can be affected. The reason for this is that a loudspeaker's
impedance varies with frequency, but if this impedance is placed in series with
a significant fixed cable resistance it acts as a potential divider, and the
power delivered to the loudspeaker at different frequencies will be altered
(It might be difficult to convince people who intend to buy expensive golden
speaker cables to use Linux and a little bit of digital hardware instead but one
could try :-)
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