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Subject: Re: Cheap/good digital-audio Boston Acoustics BA735
From: LoveLearn (LoveLearn_at_iw.net)
Date: 2003-09-06


Sharing research results:

1984 standard S/PDIF is unbalanced .5 volt originally designed for
lengths up to 1 meter.
For long feeds, lots of vendors sell S/PDIF converters to produce 1985
AES/EBU (Audio Engineering Society/European Broadcast Union), a balanced
5 volt similar standard reportedly useful to 100 or 200 meters,
depending on which description you read.

From http://www.soundonsound.com/sos/Jun03/articles/qa0603.asp
"You can run S/PDIF up to a metre or two without any problems at all,
almost regardless of the type of cable, and if you use decent 75(omega)
coaxial cable (proper 'digital' cable or standard video coax) you can
run an S/PDIF signal several metres.
However, if you are intending to run an S/PDIF signal to a D-A converter
I would say keep the cable as short as you possibly can, because
cable-induced jitter will affect the decoder's clock in a detrimental
way. The D-A relies directly on the embedded clock signal and cable
jitter will mess this up. The longer the cable, the more capacitive it
is and the greater the jitter will become. Very few budget D-A
converters have decent jitter-rejection properties able to cope with the
effects of long cables. Jitter can be heard as a vagueness in the stereo
imaging and very flat, two dimensional sound stages on well-recorded
acoustic material."

Satisfied S/PDIF cable user reports seem to stop at about 12 feet. So
much for the cheap long runs pipe dream. I still don't know if a single
S/PDIF output can simultaneously drive two inputs using a simple in-line
splitter.

Here's an instructive S/PDIF site:
Andrew's S/PDIF Stuff
http://www.andrewkilpatrick.org/mind/spdif/



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