Re: Balanced Audio

[Nigel Orr <nigel.orr@xxxxxxx>]

At 11:30 24/02/00 -0000, you wrote:
>The new location presents me with some problems the biggest of which is
the
>HiFi, to keep the HiFi in the attic room would mean long speaker cable
runs
>about 35ft perhaps a little more. If the HiFi goes in the lounge then I
>would need long phono cables, or balanced audio.
>
>What should I do ?

Either- it's only 35ft :-)

Best to extend the speaker cable.  It's high signal levels and low
impedance, so it's hard for noise to 'get in'.  Run a single 2.5mm^2 'Three
and Earth (3+E) cable and bob's your father's brother.

>Is 35ft to far with speaker cable ?

Not unless it is a _truly_ rubbish amplifier.  And I mean really really
really truly rubbishy...=20

>if I increased the length to about 40ft I could keep the wire well
away=
from
>mains would that be ok?

Yup.  Denon and the like of decent domestic amps are often used in
commercial audio with speaker runs over 100ft.

>what wire should I use (I am not a nerd (my CD's have never been in the
>freezer) but do want a good quality sound)

Ordinary mains cable is fine.  It's so cheap you might as well go for
2.5mm- bigger is only really necessary for long runs or high power (eg
>100m, >1kW), 2.5 is reasonably sized, and 1.5 isn't much cheaper.  2
runs
of twin and earth might be cheaper than one run of 3+E.  For a 15m run, x2,
T&E should be under a tenner.

>If I use balanced audio what will it cost ? any url's for equipment ?

As much as you want to pay.  You could get 4 reasonably decent balancing
transformers (OEP, Neutrik are a couple of lowish priced decent brands) for
about =A315 each, and put one at each end of each cable.  If you are going
that route, try it first with no transformers, if it doesn't buzz, and
sounds OK, it will probably work just fine.  We once ran a simple A/B test
through a 15m twin phono-phono cable at work (no, I've no idea where it
came from!)- there was definitely some loss of quality (a drop in treble),
but it wasn't significant...=20

If it does buzz, and it probably will, add a 1:1 transformer at one end,
and that should solve it.  If there is noticable rolloff of treble, add a
step-down transformer at each end so the cable run is lower impedance, say
a 5:1 or less transformer, with the '1' connected to the cable at each end,
and the '5' to the equipment.

As a guide, at home, I've got one 10m run of cat-5 with no balancing, from
a Denon amp to an old and truly dreadful PA amplifier, and it buzzes very
slightly. =20

>how much loss in quality would I get ?

Depends :-)

A =A3100 transformer will probably be unnoticable, A good transformer will
b=
e
hardly noticable, a 15 quid one will probably be just fine for a good
system and average listeners, and if you spend <=A35, it might sound
just
fine to you, or it might not...

In summary, run 2 lengths of T&E, and a length of cat-5, and then
fiddle
with different arrangements till it works acceptably.  You'll probably find
another use for the unused cable anyway...

HTH,

Nigel


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