User manual

AUDIO I/O AND SERIAL PORT WIRING ENG
Page 29
18 AUDIO I/O AND SERIAL PORT WIRING
Where possible use balanced connections for the audio inputs and outputs to minimise noise pick-up. Avoid running
audio cables near to mains or lighting cables or thyristor dimmer units, power supplies etc. These may cause audible
hum and buzz.
The use of low impedance sources significantly reduces interference pick-up. Check the cables for correct wiring to avoid
problems with phase reversal and unreliable connection.
XLR connector pin-out:
Pin 1 Gnd
Pin 2 Signal
Pin 3 Return
In case of unbalanced connections, please connect the cold pole (Pin 3) to the ground (Pin 1).
AES/EBU digital audio signals are transmitted at high, video-like frequencies (at around 6MHz) and should be handled
very differently than standard analog audio lines. Commonly used XLR-3 microphone cables have various impedance
ratings (30 ohm to 90 ohm typical) and exhibit poor digital transmission performance. The result is signal drop out and
reduced cable lengths due to severe impedance mis-matching (VSWR) between AES/EBU 110 ohm equipment. It is
important to use a balanced cable with an impedance rating of 110 ohms designed for transmission of digital audio.
18.1 ANALOG AUDIO INPUT
The processor features electronically balanced XLR female inputs.
An hardware bypass directly connect the two input XLRs to the output ones in the
event of power failure or processor switched off.
Factory preset input impedance is 10 kOhm. This impedance may also be set to 600
Ohm by moving the two internal jumpers on the analog I/O board (see last chapter on
hardware settings).
The input level – factory preset to 0 dB – can be adjusted via menu within the +/- 6
dB range. Attention: while enabled, the digital input excludes the analog one.
NOTE: in the case of connection to MONO sources, we recommend injecting the same signal on both channels (FM
version) or setting the processing mode to mono (ST and TV versions).
18.2 DIGITAL AUDIO INPUT *
The digital input (available only as an option - DG-IN) features two connectors: coaxial and
optic. Only one connector may be connected at a time
to avoid malfunctions (TOSLINK
optical connector should be kept covered while not used).
XLR female connector is designed for AES/EBU sources (“professional standard” interface),
while TOSLINK connector is designed to carry S/P DIF signals (“consumer standard”
interface).
The digital input automatically recognizes the digital format (AES, EBU, SPDIF, etc.), the type
of connection (optic or coaxial) and can seamlessly handle 32KHz, 44.1KHz, 48KHz and
96KHz sample rates.
Coaxial input (on XLR) is transformer balanced, and so highly immune from external disturbances and noise (EMI).
The Digital Input LED on the front panel indicates while the digital input is active.
Attention: while enabled, the digital input excludes the analog input.
* available as an option on all versions