Creative 0404 owner manual Word Clock In/Out, House Sync Generator, Digital Device Digital Device

6 - Appendix

Word Clock In/Out

Word Clock In/Out

Word clock provides a standardized means of synchronizing multiple digital audio devices so that data can be transferred digitally. In order to digitally transfer from one device to another, the two devices MUST be synchronized. Clicks and pops in the audio will result when transferring digital audio which is not synchronized.

The E-MU 0404 PCI card can be externally clocked from the S/PDIF input (either optical or electrical) or from the Sync Daughter card (if installed). In a digital studio, all digital devices in the system should run off the same master Word Clock.

To Synchronize PatchMix DSP to an External Clock Source:

1.Make sure an external clock source is connected to the E-MU Digital Audio System hardware via the word clock or S/PDIF input.

2.Open the Session Settings dialog box.

3.Under the System tab, select External Source, then select either Word Clock or S/PDIF.

4.Press OK to close the dialog box.

5.Check the Sync section of PatchMix DSP to verify that the Locked indicator is illuminated.

Devices can be connected in daisy chain fashion (word clock out connected to the next unit’s word clock in) or in parallel for one or two devices, but professional digital studios normally use a master word clock generator or “House Sync” with a distribution system so that each device receives a phase-coherent and jitter-free word clock.

fWord clock and S/PDIF synchronize at the sample rate and are used to transfer digital data between machines.

House Sync

Generator

Digital

Device 1

Digital

Device 2

Digital

Device 3

Digital

Device 4

A master word clock generator is preferable for larger digital setups.

Word Clock In: Receives word clock (sample clock) from another digital device such as a digital video deck, digital recorder or digital mixer.

Word Clock Out: Sends word clock (sample clock) to another digital recorder. Word clock is always output, whether it is generated by the internal clock or passed through from the word clock input.

75Ω On/Off: Termination for the word clock input can be switched on or off in the Sync Card menu of the PatchMix DSP application. Normally word clock termination should be left on. If you have problems with a weak word clock signal, try turning termi- nation off. See Word Clock Termination.

The diagram below shows the proper way to connect and terminate a serial word clock chain. Using a BNC “T” connector ensures that word clock is precisely in phase for both devices. The middle device has termination turned Off and the last device in the word clock chain has termination turned On.

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