Re: need help choosing between line level cables

"Serge Auckland" <sergeauckland@[EMAIL PROTECTED]
> wrote in
message news:W5WdnfxZpN4XP5nVnZ2dnUVZ8tOmnZ2d@[EMAIL PROTECTED]
> If I were doing what the OP is doing, I would wire my
> house with CAT5/6 cable which is really cheap these days,
> then use equipment with balanced I/O.

Sounds like a plan.

>  As already
> mentioned, CAT5/6 can carry 4 balanced audio signals, so
> you either get 2 stereos or a send and return stereo pair
> in each cable. Crosstalk isn't an issue with balanced
> operation.

Well, far less of an issue. Low impedance operation also favor low 
crosstalk.

> If suitable balanced equipment isn't
> available, then there are some alternatives. Transformers
> are definitely one, and they have the advantage of
> fully-floating operation and galvanic insulation.

Agreed.

> However, good transformers are expensive, although it's
> not necessary these days to have transformers which will
> drive 600 ohm lines, 10k-10k transformers are somewhat
> cheaper.

I did some tests on the pair of transformers that RS is selling as a
ground 
isolator, for the princely sum of $16.99 or so. They turned out to be very

good, especially if you keep their secondaries loaded with a few K.

http://www.radioshack.com/sm-buy-the-ground-loop-isolator-on-http-wwwradioshackcom--pi-2062214.html

I tested Radio Shack's "Ground Isolator" 270-054 using
test signals that maxed out around 2.5 v RMS. ZSource = 150 ohms, ZLoad = 
10K ohms.

All IM, THD, and noise artifacts were at least 80 dB down with most in
the -100 dB range or better. Frequency response showed a 2 dB peak at 20
Hz
and then 10 dB down at 10 Hz. There was a 3 dB peak at about 51 KHz
falling
to about 10 dB down around 100 KHz. +0.5 dB at 20 KHz.  A little more 
resistive loading tames both peaks.