ART Pro Audio SyncGen - Word-Clock Generator - Manual (Page 7)

Connecting more than one device to an output
More than one digital audio unit can be connected to a single wordclock output by daisy chaining the
audio units together using either their Wordclock Thru jacks or by the use of BNC “T” adaptors.
ART products with Wordclock Thru jacks are NOT terminated internally, thereby allowing easy con-
nection of more than one device to a single SyncGen wordclock output. A 75 Ohm terminator will be
required on the last unit in the chain (furthest from the SyncGen).
NOTE: If you have a digital audio device with internal termination, it should ALWAYS be placed at the
end of the cable run. You should not use a BNC “T” Adaptor on a unit with internal termination as this
effectively places a termination at that point in the line. Terminations should always occur at the end
of a line.
Cable length
The delay through a high quality cable is a little over one nanosecond (1 x 10
-9 sec.) per foot. We
would recommend keeping cable lengths less than 15 feet (or 15 feet maximum length between all
different devices connected to the same SyncGen output), as this would represent about a one half of
one bit interval at 192KHz.
Jitter
Jitter is the variation in the timing of the sample rate. Imagine calling out each second as it ticks off
using the second hand of a watch. Now, imagine that the watch is shaking so much that you can
hardly see the precise position of the second hand. This inability to correctly read the second hand is
a source of signal error.
Digital systems need to do this millions of times a second since audio samples are broken up into 64
(bit) intervals per sample (44100 samples/sec. x 64 = 2.822 million bits/sec.) Both recording and
playback jitter will create audible errors, however jitter in the recording process is a permanent part of
the recording and cannot easily be corrected with standard playback gear. Therefore the SyncGen
can be a very useful recording tool.
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