External Synchronization - RME Audio OctaMic User Manual

7.2 External Synchronization

The inputs of the ADC Module are used for external synchronization only. In case the clock
shall not be generated internally (operation mode Master), an external synchronization (opera-
tion mode Slave) is available via word clock or AES (SPDIF).
SteadyClock, integrated into the ADC Module, guarantess exceptional performance in all clock
modes. Thanks to a highly efficient jitter suppression, the AD-conversion always operates on
highest sonic level, being completely independent from the quality of the incoming clock signal.
And even in an error state SteadyClock will help: when the current word clock source fails, the
last valid sample rate will be held automatically.
Wordclock - BNC
The transformer balanced, ground-free word clock input is activated by DIP switches 1 and 2.
Both switches must be set to their lower position.
The word clock input is shipped as high impedance type (not terminated). A push switch allows
to activate internal termination (75 Ohms). The switch is found beside the BNC socket. Use a
small pencil or similar and carefully push the blue switch so that it snaps into its lock position.
Another push will release it again and de-activate the termination.
Thanks to RME's Signal Adaptation Circuit, the word clock input still works correctly even with
heavily mis-shaped, dc-prone, too small or overshoot-prone signals. Thanks to automatic signal
centering, 300 mV (0.3V) input level are sufficient in principle. An additional hysteresis reduces
sensitivity to 1.0 V, so that over- and undershoots and high frequency disturbances don't cause
a wrong trigger.
Due to the ADC Module's outstanding clock control a synchronization of the output signal to the
input signal is not only possible at identical sample rates, but also at half, quarter, double and
quad sample rates!
Example 1: DIP switch 3/4/5 in upper position results in a sample rate of 44.1 kHz. The exter-
nal synchronization source (word clock or AES) can now be 44.1 kHz, 88.2 kHz or 176.4 kHz.
Example 2: DIP switch 3/5 in lower position results in a sample rate of 192 kHz. The external
synchronization (word clock or AES) source can now be 48 kHz, 96 kHz or 192 kHz.
AES – D-sub
Using the D-sub connector, an AES, AES/EBU or SPDIF signal can be used for synchroniza-
tion. For this to work, DIP switch 1 has to be set to the upper position, DIP switch 2 to lower
position.
The D-sub connector uses the widely known and often found pinout of the Tascam recorders
(TEAC). Therefore multicores D-sub to XLR can be ordered easily. These cable have 4 XLR
outputs male and 4 XLR inputs female. The ADC Module's synchronization input uses AES 1
(see chapter 8.1, AES D-sub). The input is transformer balanced and ground-free. Thanks to a
highly sensitive input stage, also SPDIF signals can be processed by using a simple cable
adapter (RCA/XLR).
User's Guide OctaMic © RME
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