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Chapter 13—Wordclocks
DME32—Owner’s Manual
Wordclocks & the DME32
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. If
you’re connecting to the DME32 using only analog inputs and outputs, no special
wordclock settings are required, and the DME32 can be set to use its own internally
generated 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. Normally, the DME32 should be used as the wordclock master. For certain appli-
cations, however, you may need to use another device as the wordclock master, in which
case the DME32 must be configured as a wordclock slave.
Wordclock signals can be distributed via dedicated cables, typically BNC cables, or
derived from digital audio connections, such as AES/EBU, which are synchronous and
transmit a clock signal regardless of whether any digital audio is present.
The DME32 can be used as the 48 kHz wordclock master for an entire system, or slaved
to an external wordclock source of between 39.69 kHz and 50.88 kHz. It can receive an
external wordclock signal via its BNC WORDCLOCK IN or the input of a digital I/O
card. In a multiple-unit system, wordclock signals are distributed among DME32s via
the cascade connections. See “About Multiple DME32s” on page 236 for more informa-
tion.
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 LOCK indi-
cator on the DME32, 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.
