Biamp MXA Series, Operation Manual

Page: 5 / 14

3
FRONT & REAR PANEL FEATURES
Remote Level Control: These two terminals (plus the adjacent
"
d
" terminal) provide remote volume control of the master level.
An internal voltage controlled amplifier (VCA) allows remote
control from up to 2000 feet away, using any 5k~50k
Ω
linear taper
potentiometer and/or switch to provide adjustment and/or muting of
the master level. Potentiometers are wired with high-side to
(+10V), low-side to (
d ), and wiper to (C). Mute switches simply
connect (C) to (
d
), with no (+10V) connection required.
Music On Hold Level:
This control adjusts the volume level of a
Music On Hold output (see below). To turn the output off
completely, set this control to the counter-clockwise position (min).
Music On Hold Output:
These three terminals provide a
balanced line-level output as a source for phone systems. This
signal is derived from input channel 6. For unbalanced output,
wire high to (+) and ground to (
d
)
, leaving (-) unconnected.
Pre Out & EQ In:
These two RCA jacks provide pre-tone patching
for external equipment. When used as an 'insert point' for external
signal processors, set the associated Link switch to the (off)
position. When using Pre Out for recording and/or EQ In for
stacking, the Link switch may remain in the (on) position.
Line Out & Amp In : These two RCA jacks provide post-master
patching for external equipment. When used as an 'insert point' for
external signal processors, set the associated Link switch to the
(off) position. When using Line Out for external amps and/or Amp
In for stacking, the Link switch may remain in the (on) position.
Low Cut:
This switch controls a low-cut filter (12dB/octave @
125Hz) at the amplifier input. CAUTION: To avoid output fault
conditions, Low Cut must be used when driving 25/70/100 Volt
speaker systems (see Installation Instructions on pg. 4). Also, any
other system equalization affecting frequencies below 125Hz
should remain flat or be used as cut-only. This also precludes
boosting of the Bass control (see above) in these applications.
DIP Switches: The five DIP switches above each input are used
to assign specific functions to those individual channels. Phantom
Pwr a48 Volts DC phantom power to the channel input, for
powering condenser microphones.
CAUTION: To avoid damage
to equipment, assign phantom power only on channels being used
as inputs for conderser microphones.
Priority assigns a channel to
priority. When signal is present in a priority channel, any non-
priority channels which are assigned to Auto Mute will be muted by
their selected amounts (see below).
NOTE: A priority channel
cannot be auto muted by another priority channel, but a priority
channel can be manually muted (see below).
Auto Mute assigns a
(non-priority) channel to be muted whenever signal is present in
any priority channel. Manual Mute assigns a channel to be muted
whenever the Mute/Chime terminal is shorted to ground via a
switch or contact closure. Mute Level assigns the amount of
muting (-80dB or -20dB) which is applied to a channel, when
triggered by either Auto Mute or Manual Mute.
NOTE: -80dB is
effectively complete muting (off), whereas -20dB is audible
attenuation (ducking).
Peak:
These red LEDs will light whenever channel signal levels
reach +10dB (8dB below clipping). Use this feature to aid in
proper adjustment of Trim (see below).
Trim:
These screw-driver controls set the channel gain (0~60dB)
to compensate for different input signal levels (mic or line). Adjust
these controls so the channel Peak indictors flash only on
occasional peaks.
Mic/Line or Tel Switch (Channel 1 only): This switch selects the
proper impedance and gain for either mic/line input signals or input
from 600 ohm sources. The input for Channel 1 includes an
isolation transformer, which allows connection to most telephone
system audio ports.
Inputs: These plug-in barrier strips provide a balanced input
connection for each channel. For unbalanced input, wire high to
(+) and ground to both (-) & (
d
). The input for Channel 1 includes
an isolation transformer.