4
REAR PANEL
Input: These plug-in barrier strips provide the balanced line-level
inputs to the channels. For balanced connection, wire high (+),
low (-), and ground (
d
). For unbalanced connection, wire high (+)
and ground to both (
d
) & (-). NOTE: When using a pair of
channels in 'bridged' mode (see Bridge below), input signal must
be connected to the odd numbered channel.
Level: These screw-driver adjustable controls determine the level
of input signals allowed into the channels. Level provides a gain
range from 'off' (min.) to 'unity' (max.). The Level control is factory
set for -24dB of gain, which will produce maximum output power
with input signal peaks of +24dBu. For best performance, first
adjust the source signals for optimum (maximum) levels, then
adjust the MCA Series Level controls for the desired volume.
Signal / Peak Indicators: These 2-color LEDs indicate the signal
level for each channel. When an LED is green, that channel has
signal (above -30dB). When an LED is red, that channel signal is
clipping (max. power). CAUTION: Signal levels should be
adjusted to avoid clipping. Clipping can cause severe distortion,
over-temperature conditions, and even loudspeaker damage.
NOTE: Signal / Peak indicators will turn off during Temp / Fault
condition (see Temp / Fault Indicators on pg. 3).
HPF: These DIP switches provide High-Pass Filters for the input
channels. High-Pass Filters are used to eliminate unnecessary
lower frequencies (12dB/octave @ 125Hz) for speech and
distributed speaker applications. From the factory, the High-Pass
Filters are bypassed (switches up). To assign a High-Pass Filter
on an input channel, move the switch to the down position.
CAUTION: To avoid output fault conditions, High-Pass Filters
must be assigned on channels driving 25/70/100 Volt speaker
systems (see Output below). Also, any other system equalization
affecting frequencies below 125 Hz should remain flat or be used
as cut-only.
Bridge: These DIP switches allow adjacent channels to Bridge
together in pairs, for a higher, combined output power (see
Bridging on pg. 6). Bridge disables the even numbered input, and
applies the odd numbered input signal to both amplifier channels.
From the factory, Bridge is bypassed (switches up). To assign
Bridge to a pair of channels, move the switch to the down position.
Output: These screw terminals provide the speaker outputs from
the channels. Connect the positive speaker line to the (+) terminal
and the negative speaker line to the (-) terminal of the channel
being used. The minimum speaker load on an individual channel
is 4 ohms. NOTE: When using a pair of channels in 'bridged'
mode (see Bridge above), connect the positive speaker line to the
(+) terminal of the odd numbered channel and the negative
speaker line to the (+) terminal of the even numbered channel.
The minimum speaker load for a bridged output is 8 ohms. Output
transformers for 25/70/100 Volt speaker systems are available as
an option (installation instructions are included with the output
transformers). Transformers (by model) are as follows:
TDT50 = MCA 8050 individual channels (50 Watts)
TDT100 = MCA 8050 bridged channels (100 Watts)
TDT150 = MCA 8150 individual channels (150 Watts)
TDT300 = MCA 8150 bridged channels (300 Watts)
Remote Control: This 15-pin Sub-D (female) connector provides
remote level & muting control of the input channels (see Remote
Control on pg. 9). NOTE: When using a pair of channels in
'bridged' mode (see Bridge above), apply Remote Control only to
the odd numbered input channel.
AC Power Entrance: The switch applies AC power to the unit.
The receptacle accepts the detachable AC Power Cord. The AC
Power Cord is for connection to three-prong grounded AC outlets.
CAUTION: Do not remove or defeat the ground prong on the AC
Power Cord, as this constitutes a shock hazard.
Line Voltage Selector Switch: Set this switch to "115" for
nominal line voltages of 110-120 VAC. Set this switch to "230" for
nominal line voltages of 220-240 VAC. Make sure that the
appropriate fuse is installed when changing voltage selections.
Fuse: Replace Fuse with same type and value only.
MCA 8050 @ 115VAC Fuse = F 10 A H 250 V
MCA 8050 @ 230VAC Fuse = T 4 A L 250 V
MCA 8150 @ 115VAC Fuse = F 15 A H 250 V
MCA 8150 @ 230VAC Fuse = T 6.3 A L 250 V
NOTE: If the Fuse continues to blow (even after checking for
proper output connections and speaker loads) the amplifier may
require service.
