User Manual

User's Guide Digiface USB © RME

15.3 Channel Count under Core Audio

The Digiface USB ADAT optical interface offers sample rates of up to 192 kHz. For this to work

single-channel data is spread to two or four ADAT channels using the Sample Multiplexing tech-

nique. Therefore the number of channels is reduced to 16 or 8 respectively.

It is not possible to change the number of Core Audio devices without a reboot of the computer.

Therefore whenever the Digiface USB changes into Double Speed (88.2/96 kHz) or Quad

Speed mode (176.4/192 kHz) all channels stay present, but become partly inactive.

Single Speed Double Speed Quad Speed

Digiface USB ADAT (1-8) Digiface USB ADAT (1-4) Digiface USB ADAT (1+2)

Digiface USB ADAT (9-16) Digiface USB ADAT (5-8) Digiface USB ADAT (3+4)

Digiface USB ADAT (17-24) Digiface USB ADAT (9-12) Digiface USB ADAT (5+6)

Digiface USB ADAT (25-32) Digiface USB ADAT (13-16) Digiface USB ADAT (7+8)

15.4 Various Information

The driver of the Digiface USB requires at least Mac OS 10.6.

Programs that don't support card or channel selection will use the device chosen as Input and

Output in the System Preferences – Sound panel.

Via Launchpad – Other – Audio MIDI Setup the Digiface USB can be configured for the sys-

tem wide usage in more detail.

Programs that don't support channel selection will always use channels 1/2, the first stereo pair.

To access other inputs, use the following workaround with TotalMix: route the desired input

signal to output channels 1/2. In the channel settings of outputs 1/2 activate Loopback. Result:

the desired input signal is now available at input channel 1/2, without further delay/latency.

Use Configure Speakers to freely configure the stereo or multichannel playback to any avail-

able channels.

16. Using more than one Digiface USB

OS X supports the usage of more than one audio device within an audio software. This is done

via the Core Audio function Aggregate Devices, which allows to combine several devices into

one. All units have to be in sync, i.e. have to receive valid sync information via a digital input

signal.

x If one of the devices is set to clock mode Master, all others have to be set to clock mode

Slave, and have to be synced from the master by feeding ADAT or SPDIF. The clock

modes of all units have to be set up correctly in their Settings dialog.

x If all units are fed with a synchronous clock, i.e. all units show Sync in their Settings dialog,

all channels can be used at once.

Note

: TotalMix is part of the hardware of each device. Up to three mixers are available, but

these are separated and can't interchange data. Therefore a global mixer for all units is not

possible.