Re: connecting PC to TV

Gerard Bok wrote:

> Would a double balun with twisted-pair in between outperform a
> straight coax connection on TV-audio ?

Yes it will. Besides, in many cases a high(er) end audio equipment will
expect ALREADY BALANCED line level input, so you can drop the second balun
or else you have to provide one for your common mode coax signal.

> Actually, I doubt that.
> On audio frequencies and levels, a 'simple balun' requires a
> complete mu-metal encased transformer.
> Otherwise, just the transformers themself both would pick up as
> much noise as the twisted pair suppresses :-)
> And this arrangement would still suffer from rather huge losses,
> both in level and sound quality. My 2 cents :-)

It was a very good point but you had a wrong conclusion made. In ANY
balanced-signal transmission over any cable that's worth buying these
days, the active equipment will be MUCH more susceptible to EMI than the
cable. Besides, EMI can also (big times!) enter the active equipment via
its power cables. However, it should always be assumed that the active
device bears FCC or EC EMI compatibility approval label else just drop
that one and go buy the approved one. Therefore, you can let electronics
designers worry about EMI shielding INSIDE the boxes (what a daunting task
that is!) and concentrate on laying your cables away from apparent EMI
sources and installing it properly to avoid any physical damage that would
ruin the balance.

And, just to finish it off: in some cases baluns aren't too practical
given cost, reliability (can be torn off the patch cable), size or other
considerations. As a result we end up sending line level audio signals and
composite video via a CAT5E cable without ANY baluns (up to 100 feet), and
no visual picture or audible sound degradation can be found. I'm not
talking about concert halls, obviously, so, if you have "golden ears",
please DO take care of balancing the signals before sending them over UTP.

--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
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