Metric Halo 2882 operating guide - Manual (Page 23)

Mobile I/O User’s Guide
15
other devices that support the ADAT® Optical communication protocol. The
ADAT Optical standard allows a device to transmit 8 channels of 24-bit
audio at up to 50kHz along with digital audio clock information.
After the original 8 channel specification was finalized, Alesis and other
third parties extended the standard to support 4 channels of 24-bit audio at
2x sample rates. This extension of the standard is commonly referred to as
SMUX. Mobile I/O automatically supports SMUX transport over the ADAT
Optical connections when the box is in 2x mode (either 88.2k or 96k sam-
pling frequency). While operating in SMUX mode, the audio data for each of
the first four “ADAT” channels is placed on pairs of optical channels. ADAT
1 is placed on optical channels 1 and 2. Each optical channel continues to
transmit data at 1x speeds, and both devices are required to multiplex and
demultiplex the audio into and out of the optical channel pairs.
When Mobile I/O is receiving audio over the ADAT optical input, you will
generally get the best results when you have selected ADAT as the audio
clock source for Mobile I/O. You may find that other clocking combinations
work reliably, but the reliability of the the ADAT input will depend on the
details of the external device’s clocking circuitry.
Since Mobile I/O provides direct routing within the box, you can easily con-
figure the unit to work as an ADAT based 8 channel A/D/A. Refer to the
chapter on MIO Console for information about configuring the patchbay
router.
C LOCK S YNC
Clock sync is a serious consideration in any digital audio system.
If you are recording analog sources with Mobile I/O, you can simply use the
unit’s high-quality internal clock source to drive the converters. This is the
easiest case to deal with.
If you need to interface with other devices digitally or ensure sample accu-
rate sync with video sources, the extensive clock synchronization capabili-
ties of Mobile I/O will prove to be more reliable (and better sounding) than
most higher priced alternatives.