Operating Elements And In/Outputs; Loudspeaker Connections; Setting The Input Sensitivity; Low-Pass Filter With Adjustable Cross-Over Frequency - MAC Audio MPX 4000 Owner's Manual

4.3 LOUDSPEAKER CONNECTIONS

· In normal operating mode (i.e. one loudspeaker on each individual amplifier channel), the lowest terminal
resistance is 2 ohm per channel.
· In bridging mode (two amplifier outputs combined) the lowest terminal resistance doubles to 4 ohm.
· The impedance in tri-mode may not fall below 2 ohm per channel.
· Never connect the loudspeakers' minus terminals to the vehicle chassis.
· Never connect the +12 V supply voltage to a loudspeaker output as this would destroy the amplifier final
stage.
If the amplifier is operated with lower terminal resistances or incorrectly used as described above, both
the amplifier and the loudspeakers may be damaged. The warranty becomes void in such cases.
5.

OPERATING ELEMENTS AND IN/OUTPUTS

5.1 SETTING THE INPUT SENSITIVITY

The input sensitivity may be adapted to any car radio or tape deck. Turn the volume control of your radio to its
central position and then adjust the input-level controls (3) and (4) to produce an average medium volume. This
setting usually provides sufficient power reserves at optimum weighted noise voltage.
ATTENTION: only reproduce loud test noises briefly to prevent damaging the loudspeakers.

5.2 LOW-PASS FILTER WITH ADJUSTABLE CROSS-OVER FREQUENCY

If the amplifier is used as a subwoofer amplifier, set the switch (9)/(10) to "LPF". Set the desired cross-over
frequency using the control (7)/(8). This makes the filter adaptable to the installed woofer's sound requirements.
The filter's high edge steepness is responsible for the precision reduction of medium and high frequency ranges.
5.3 HIGH-PASS FILTER WITH ADJUSTABLE CROSS-OVER FREQUENCY
If the amplifier is to be used as an amplifier for satellite loudspeakers (mid-range/tweeter loudspeakers), set
switch (9)/(10) to "HPF". Set the desired cross-over frequency using the control (11)/(12). Only the frequencies
above the set cross-over frequency will then be amplified. This effectively minimizes distortions caused by
excessive membrane movement at low frequencies and small satellite loudspeakers without reducing the bass
level.
5.4 BASS-BOOST
The bass-boost function (5/6) is used to increase or equalize the lower bass frequencies.
5.5 OUTPUTS FOR CONNECTING ADDITIONAL AMPLIFIERS
The input signal of the LINE INPUT connections CH1, CH2, CH3, CH4 (1 and 2, Fig. 7) is accumulated and
forwarded directly to the LINE OUT (14) jacks. The LINE OUT connections allow the use of a subwoofer amplifier
without requiring additional T-plugs and cables.
FIG. 1 POWER SUPPLY / REMOTE SWITCH-ON CONNECTIONS
(1) GND terminal for the ground, to the battery's minus pole
(2) REM terminal for remote switch-on
(3) Terminal for + 12 V battery voltage
(4) Battery
(5) Cable fuse
(6) To your car radio's automatic aerial connection
If your car is not equipped with an automatic aerial connection, connect this cable's plus pole (+) to the
ignition lock. An on/off switch should be inserted in this case. Make sure that this switch is switched off if
the amplifier is not used.
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