Wordclocks & The D24 - Yamaha D24 Owner's Manual

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Chapter 11—Wordclocks
Wordclocks & the D24
Unlike analog audio equipment, digital audio equipment must be synchronized when
digital audio signals are transferred from one device to another, otherwise, the signal
may not be read correctly and audible noise, glitches, or clicks may occur. Synchroni-
zation is achieved using what's called a wordclock, which is a clock signal for synchro-
nizing 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, so
that signals can be transmitted and received correctly.
In a typical digital audio system, one device operates as the wordclock master, while the
other devices operate as wordclock slaves, synchronizing to the wordclock master. If
you're connecting to the D24 using only analog inputs and outputs, no special word-
clock settings are required, and the D24 can be set to use its own internally generated
wordclock. Add a digital mixer or DAT recorder, however, and you must decide which
device to use as the wordclock master and which devices to use as slaves. Normally, the
D24 should be used as the wordclock master. For certain applications, however, such as
recording a digital source via the COAXIAL STEREO DIGITAL INPUT, the D24 must
be configured as a wordclock slave.
Wordclock signals can be distributed via dedicated cables, typically BNC cables, or
derived from digital audio connections, which are synchronous and transmit a clock
signal regardless of whether any digital audio signals are present. The D24 can receive
an external wordclock signal via its BNC WORDCLOCK INPUT or derive an external
wordclock signal from the SLOT 1, SLOT 2, or COAXIAL STEREO DIGITAL INPUT
audio connection. In a multiple-unit system, wordclock signals can be distributed via
SYNC IN/OUT connections by setting the timecode source on each slave to REMOTE
IN. See "Selecting a Wordclock Source" on page 124 for more information.
The following block diagram shows three different methods of wordclock distribution.
The first via dedicated BNC wordclock cable, the second via S/PDIF coaxial cable, and
the third via AES/EBU, ADAT, or Tascam TDIF-1 multichannel YGDAI connection.
The D24 can be used as the wordclock master for an entire system, or slaved to an exter-
nal wordclock source of between 41.454 kHz and 50.88 kHz (44.1 kHz –6% to 48 kHz
+6%). With sampling rates of 44.1 kHz and 88.2 kHz, the frequency of the wordclock
signal and digital output signals is 44.1 kHz, and with sampling rates of 48 kHz and
96 kHz, it's 48 kHz. When using the higher sampling rates of 88.2 kHz and 96 kHz, the
D24 uses what's known as Dual AES/EBU mode, in which the wordclock frequency is
D24—Owner's Manual
Wordclock master
Source: Internal
BNC WC output
YGDAI slot Coaxial output
S/PDIF coaxial cable
Multichannel AES/EBU,
ADAT, or Tascam TDIF-1
BNC cable
BNC WC input
Coaxial input
YGDAI slot
Wordclock slave
Source: BNC input
Wordclock slave
Source: Coaxial input
Wordclock slave
Source: YGDAI slot