Basic Conditions For Digital Audio Connection - Roland VM-7100 Connection Manual

Basic conditions for Digital Audio Connection

In this setting guide, the typical parameter settings for each respective equipment combination are introduced. There may be
other possible connections and parameter settings which work.
To transfer audio via digital connection between two devices, the following two conditions should basically be accomplished:
Condition #1: Consistent sampling frequency
The sampling frequency should be the same between the two devices so that the same sampling clock can be
shared.
Condition #2: Consistent phases
The phase of the sampling clock should be the same between the two devices.
To achieve these two conditions, the two devices should be in synchronization with the sampling clock which is transferred with
the digital audio signal. With word clock synchronization, only condition #1 (sampling frequency) is achieved.
Depending on the hardware structure of the device's digital input, both condition #1 and #2 (phase), or only condition #1, or none
of them need to be achieved.
• Case 1: Both Conditions #1 and #2 need to be achieved.
When using a digital input including R-BUS, TDIF or AES/EBU on the DAT
• Case 2: Condition #1 needs to be achieved.
If a buffer to absorb the phase inconsistency is provided in the digital input, the system will work with only condition #1, i.e.
word clock synchronization.
The AES/EBU input on the AE-7000 and the OPTICAL IN on the ADAT are equipped with this type of buffer.
• Case 3: None of the conditions #1 or #2 need to be achieved.
If a sampling rate converter is included in the digital input, digital audio can be transferred without achieving condition #1 or #2.
DIGITAL IN A and B on the VM-7200/7100 are equipped with sampling rate converters.
Even in this case, if the condition #1 (word clock synchronization) is achieved, the result is better due to precise synchronization
and minimum sampling rate conversion.
DIGITAL IN A and B on the VM-7200/7100 are equipped with sampling rate converters. So you do not have to change the
sampling clock of the VM-7200/7100 and the connected system even if the digital input source such as a DAT has a different
clock.
Terminology: Sampling Clock
In this setting guide, "sampling clock" is defined to be the clock for sampling and transferring the digital audio data, i.e. the clock
of one sample cycle. This is sometime called "word clock," but in this guide, we define "word clock" only as the signal which is
transferred via "word clock I/O" and "word sync I/O."
Other notes
• If a DIF-AT and an AE-7000 are connected to each other via R-BUS, they do not work. They are designed to work
independently with a VM mixer.
• If a DIF-AT and an ADA-7000 are connected to each other via R-BUS, they do not work. They are designed to work
independently with a VM mixer.
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