206 Chapter
About Wordclocks
Unlike analog audio equipment, digital audio equipment must be synchronized when digital audio is transferred from one device to another. Otherwise, the digital audio might not be read 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 words in an audio system. Note that wordclocks are not the same as SMPTE or MIDI timecode, which are used to synchronize audio recorders, 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 acts as the wordclock master and the other devices act as wordclock slaves that synchronize to the master wordclock signal. If the 01V is the only digital audio device in your system, no special wordclock settings are required and the 01V synchronizes to its own internal wordclock. Add a DAT recorder or digital multitrack recorder, however, and you must decide which device to use as wordclock master and which devices to use as slaves. Even when you’ve done this and configured your system, it may be necessary to change the wordclock settings in certain situations, such as when recording from a DAT or CD player.
The wordclock signal runs at the same frequency as the sampling rate. The 01V generates its own wordclock at 44.1 kHz (the
Wordclock signals can be distributed via dedicated cables or derived from standard digital audio connections, as shown below. With AES/EBU and Coaxial digital audio con- nections, a wordclock signal is transmitted even when no audio signal is present.
Wordclock slave | Wordclock slave | ||
| Wordclock In |
| Digital Audio In |
| Wordclock Out | Digital Audio Out |
|
|
| Wordclock |
|
| Digital Audio Out | master |
|
| Wordclock Out |
| |
| Digital Audio In |
| Wordclock In |
00.00.00.00 | DAT | 00.00.00.00 | DAT |
Wordclock slave | Wordclock slave | ||
In a system where all devices share a common wordclock, it’s important that all devices be turned on even when 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 commencing with a recording session, make sure that all wordclock slaves are synchronized to the master wordclock. Some devices have front panel indicators to show when they are wordclock synchronized. Refer to the instructions for each device.
The following system examples show three typical wordclock setups with the 01V. For detailed system examples with specific equipment, see “System Examples” on page 241.