Yamaha DME32 DME32 Owners Manual - Page 233

228 Chapter 13-Wordclocks 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. Synchronization 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 synchronization 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 applications, 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 information. 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 indicator 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. DME32-Owner's Manual