Owner`s manual

74 Chapter 8—Wordclocks
SREV1—Owner’s Manual
Wordclocks & the SREV1
Unlike analog audio equipment, digital audio equipment must be synchronized when
digital audio signals are transferred from one device to another, otherwise, signals may
not be received correctly and audible noise, glitches, or clicks may occur. Synchroniza-
tion is achieved using what’s called a wordclock, which is a clock signal for synchronizing
all the digital audio signals in a system. Note that wordclocks are not the same as
SMPTE/EBU timecode or MIDI timecode, which are typically used to synchronize tape
machines, MIDI sequencers, and so on. Wordclock synchronization refers to the syn-
chronization of the digital audio processing circuits inside each digital audio device.
In a typical digital audio system, one device operates as the wordclock master, and the
other devices operate as wordclock slaves, synchronizing to the wordclock master.
Wordclock signals can be distributed via dedicated cables, typically BNC cables, or
derived from digital audio connections, such as AES/EBU.
If you’re connecting to the SREV1 using only analog inputs and outputs, no special
wordclock settings are required, and the SREV1 can be set to use its own internally gen-
erated wordclock. If you’re connecting other equipment digitally, however, you must
decide which device to use as the wordclock master and which devices to use as slaves.
The SREV1 can be used as a 48 kHz wordclock master, or slaved to an external word-
clock source of 44.1 kHz or 48 kHz. It can receive an external wordclock signal via an
AES/EBU input, SLOT input, or the BNC WORD CLOCK IN connector.
In a system where all devices share a common wordclock, it’s important that all devices
be turned on even if they’re not being used. Turn on the wordclock master first, and
then the slaves. When shutting down the system, turn off the slaves first, and then the
master. Before use, make sure that the wordclock slaves are correctly locked to the
wordclock master. Most devices have front panel indicators, similar to the FS LOCK
indicators on the SREV1, to show when they are wordclock locked. Refer to the relevant
owner’s manuals for more information.
When the wordclock source is changed, lower the volume of your system just in case a
device becomes unlocked and outputs any unpleasant noises.
Wordclock Connections
The WORD CLOCK IN BNC connector is used to
receive wordclock signals from other digital audio
equipment. When the wordclock source is set to
WCLK IN, the SREV1 locks to the wordclock sig-
nal received at the WORD CLOCK IN connector.
See “Wordclock Hookup Examples” on page 78 for
more information.
The WORD CLOCK IN is auto-terminating.
WORD CLOCK IN
An external wordclock can
also be sourced from an
AES/EBU input or the slot
input of a digital I/O card.