Re: video cables

[mjmahon@aol.com (Michael J. Mahon)]

Simon Williams wrote:

> I've finally decided to get rid of all the spliced-together dollar store
> audio cables that I've been using for my A2 monitors... looking at the
> selection of more robust cables available, I've noticed a wide variation
> in pricing for cables depending on whether they are intended for
> composite video, audio or component video (even though all are the same
> brand and appear identical). Anyone know if there is really a difference
> or is this just marketing???

The answer, unfortunately, is _both_.

The _real_ difference is in quality and electrical characteristics of
the cable itself.  The shielding can be more complete, more flexible;
the internal (coaxial) insulation can be lower dielectric constant; the
outer sheath can be tougher and more flexible.  The bottom line for
video applications is that the cable can have a lower capacitance per
foot, reducing high frequency rolloff when not driven and terminated
as a transmission line (which is the case with Apple monitors).

The cost difference between a "fair" audio cable with medium capacitance
per foot and "good" shielding and a "good" video cable with low capacitance
and "good" shielding should be less than a factor of two.  A typical _cost_
for such a cable in the US would be about $3, with a typical _price_ of up
to $10 (for a typical 6-foot cable).  There is no advantage for an Apple
user to use a more expensive cable.  Such a "median" cable is shielded
better than the Apple II or the monitor is.  ;-)

If video bandwidth is a real concern, using a shorter cable is the best
way to reduce capacitive loading, though going under 3 feet is not going
to make a perceptible difference if the video driver is properly designed.

Now for the "marketing" difference.  Several years ago, someone found out
that the typical high-end audio consumer is quite ignorant about physics
and electronics, but fancies themselves knowledgable.  They found that
they could market cables using fancy terminology (oxygen-feee copper) and
irrelevant technology (Litz wire conductors) to appeal to this class of
consumers, who had money and a desire for perfection, but little technical
understanding of how to achieve it.

These folks were so successful in selling good cables, with costs perhaps
twice those of "median" cables, for prices up to ten times median prices!
That, my friend, is called "margin", and their profits went through the
roof--even after marketing costs.

This tactic has polluted the cable environment with meaningless hype, and
will probably continue to do so until consumers start taking science classes
and start caring more about how their system performs than how much they
can tell others it cost (or about how much they paid for some visible but
insignificant part of their system).

Ah, well--flame off.  ;-)

Just about any inexpensive cable intended for video and not too long
will work as well as any cable in existence for your application.

-michael

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Home page:  http://members.aol.com/MJMahon/