Balanced sends, Aes digital audio, Clock sync – Metric Halo Mobile I/O User Manual
Page 91: Firewire, Power
LIO-8 Users Guide
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Balanced Sends
The LIO-8 has eight balanced sends; these mirror the analog signal present at the Line input. This allows you
to use the sends as a splitter to feed a mixing console, recorder or other equipment.
You cannot route signal from a DAW channel to the balanced sends; to route signals from your computer to
the D/A converters, you must use the Line/Monitor outputs.
AES Digital Audio
The LIO-8 supports 8 channels of digital audio over copper-based connections. The native format of the LIO-8
is AES, but can be converted to SPDIF or optical using third-party adapters. The LIO-8 operates in single-wire
mode, providing 8 channels of digital audio at all sample rates. The LIO-8’s digital I/O connections are made
using industry standard Tascam/Digidesign pinout DB25 cables.
Wiring details for this connector can be found in the
appendix.
Clock Sync
Clock sync is a serious consideration in any digital audio system.
If you are recording analog sources with LIO-8, 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 accurate sync with video sources, the
extensive clock synchronization capabilities of LIO-8 will prove to be more reliable (and better sounding) than
most higher priced alternatives.
There are three different ways to get external clock information into the unit:
1. Sending a 1x word clock signal into the WC Input BNC.
2. Sending a 256x word clock signal into the WC Input BNC.
3. Sending an AES signal into the Digital input.
The BNC word clock input port is a 75 Ohm terminated coaxial input. It should be driven by a 75 Ohm source
driver and interconnected with 75 Ohm coaxial cable. If you do not use proper cabling and source drive, you
will introduce reflections on the word clock cable which will propagate jitter into the recovered word clock.
This is true whether you use the port as a 1x WC input or a 256x WC input, but becomes more important
when the clock signal is 256x.
1x is generally appropriate for use with devices that provide a word clock output. If your device provides
a 256x output, you may find that you get better results using that clock signal. The Digidesign® line of Pro
Tools® products use 256x as their “ SuperClock™” clocking signal.
The AES recommended procedure for distributing clock is to use an AES clock signal. The AES clock signal is
an AES digital audio signal with no audio activity. The LIO-8 only uses the AES preambles for clock recovery,
so it is immune to data dependent jitter effects. This means you can reliably use the Digital Input as a clock
source with or without audio data.
FireWire
Detailed information on FireWire implementation can be found in the
appendix.
Power
One of LIO-8’s great strengths is the flexibility of its power system. The LIO-8 can be powered from any DC
source in the range of 14V to 28V as long as it provides 32 Watts of power. The DC inputs on the LIO-8
are a 2.1mm coaxial power connector, center positive and a 4-pin XLR connector Pin 4 Hot. So if you are
powering the unit with a third party power source and it supplies 14V, the power source will have to provide
2.3 amps of current. If you are powering the unit with 24V, the power source will have to provide 1.3 amps
of current, and so on.