[Audio Empire]

On Thu, 1 Sep 2011 16:27:56 -0700, Robert Peirce wrote
(in article ):

In article ,
Audio Empire wrote:

On Wed, 31 Aug 2011 07:02:39 -0700, Arny Krueger wrote
(in article ):

"Robert Peirce" wrote in message
...
I am coming to the conclusion that a simple optical line from my MacBook
Pro to my DAC might be the best way to go. The problem is it would
probably be about 25'. Does anybody have any experience with optical
lines of that length?

Long ago I bought a fairly typical pice of Toslink cable that was 30'
long.
It seemed to work the same as shorter cables.



It does, and it it should. No surprises there.

I am pleased that it does, but my question was based on wondering why it
should.

I think light through fiber is more efficient than electricity through
wire (although I might be wrong), but it seems to me both must suffer if
pushed over unreasonable distances. I believe even long fiber optic
lines use repeaters or amplifiers to boost the signal.

True. At some length, fiber requires in-line repeaters, but 30 feet is NOT
that length. Fiber. like everthing else, is lossy. Light leaks out the sides
of the cable, there are internal reflections that can cancel or otherwise
compromise signal integrity, Mainly optical's strengths are much wider
bandwidth (an optical signal can carry much more information than wire
without nearly as much loss because light is a much higher frequency than an
electrical signal). Optical is also electrically isolatory and can isolate
one electrical structure from another while still transmitting data between
them. In the case of digital audio, optical has easy duty. The amount of
data is not so great (7 or 8 channels of audio at most) and the frequency is
fairly low. For the most part, there is really little difference in the
quality of a coaxial digital connection and an optical one.

I am also not sure about how light behaves in long lines perhaps going
around corners. I can imagine (again perhaps wrongly) that there might
be some loss of energy or disruption of signal in going around corners.

There is, but over short domestic runs, it's inconsequential.

What I got from this response was that 30' is not an unreasonable length
in the real world, which was all that really mattered.

Neither would 50 ft or even 100 ft.