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Audio Transmission Line Optimization



Knowing that many hams are also interested in high performance audio 
systems, I thought that I should pass on this important technical 
advice offering suggestions on how to optimize your loudspeaker wires. 
Some of this advice is no doubt applicable to RF transmission lines 
also......

Dan Schultz N8FGV
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                        Wizardry With Wire

At least for the present, we still need wire to connect up most audio 
equipment. Here are a few application tips on selecting and getting
the best performance from wire.

Check any good handbook of physical constants and you will find that 
silver has much lower resistivity than copper. In fact silver has the 
lowest resistivity of anything which is solid at room temperature and 
is thus suitable for making wires. However, from a cost perspective, 
the practical solution is to use thicker copper wire. Still, to avoid 
the debilitating nature of skin effects, the best solution is to use 
silver plated copper wire. Of course, not to be overlooked is the fact 
that copper is reddish, and so will tend to brighten or warm up the 
sound; while silver, being white, will tend towards a neutral 
presentation, which can be tweaked towards brightness by selective 
use of gold-plated jacks and plugs.

The type of wire insulation used can grossly affect sound quality. 
For example, rubber-type insulations act as shock absorbers that dampen 
dynamic peaks (such as turning the crack of a rim shot into something 
more like a thud). They also have a high coefficient of friction which 
slows the passage of sound through the wire causing the musical pitch 
to be lower. To counteract this effect, musical groups have to tune to 
a concert A as high as 450 Hz in order to for the correct musical pitch 
to be reproduced through the sound system. The best wire insulation is 
Teflon which is a very firm material with a very low coefficient of 
friction. This allows the sound to slide easily through the wires 
without dampening the peaks or slowing it down.

The colors of wire insulation should be selected according to light 
spectrum wavelengths and absorption. Generally bright colors are 
reflective. Therefore bright colored insulation will reduce high frequency 
loses by reflecting HF audio back into the wires thus maintaining clarity 
and brightness. Dark, absorptive colors should be used for low frequency 
wire insulation. By absorbing and carrying some of the low frequency energy 
dark colored insulation actually increases the effective diameter of the 
conductor - a good thing for improving the high current flow needed at low 
frequencies.

You should also rack your signal sources above your amplifiers, and rack 
the amplifiers higher than the loudspeakers. This is so that the electrons 
don't have to struggle uphill through the wires to get the sound out. You'd 
be amazed at the difference that can make. Also, both speakers should be 
off to the same side of the amp, so that the loudspeaker cables are subject 
to the same Coriolis forces owing to the earth's rotation; failure to 
observe this can result in truly nasty phase shifts.

Dr. Sam Gidren




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