MTX Audio TA7402 Stereo Amplifier User Manual


 
The gauge of the power and ground wire is often an overlooked aspect of amplifier installation. The more
power the amplifier receives, the more power it will produce. Power cables have a natural resistance, and
will lose voltage by the time the power makes its way to the amplifier. The larger gauge (diameter) wire will
hold more voltage over longer runs. Also, by having a larger diameter ground wire, the amplifier can run
more efficiently. MTX recommends using a minimum of 4 gauge power and ground cables to get the best
performance.
REM: This connection turns the amplifier on and off and needs to be connected to a remote turn-on wire
from your source unit if you are using a low level input connection.
Note: When numerous amplifiers are used in the same system, look into using a relay with a separate power wire
connected to an alternative power source to take the strain off the source unit. Normal source units can only
keep a constant 12 volts to 2 or possibly 3 amps. This wire should also be run away from the RCA cables.
CAP+: This 8 gauge terminal is internally wired in parallel with the +12V on the StreetWires Power
connector. It is the ideal connection point for the positive side of a capacitor to increase the amplifier’s
performance.
CAP-: This 8 gauge terminal is internally wired in parallel with the GND on the StreetWires Power
connector. It is the ideal connection point for the negative side of the capacitor to increase the amplifier’s
performance.
Double check all the previous connection installation steps, in particular the speaker and power wiring.
Securely mount the amplifier. If everything is in order, reconnect the vehicle’s negative battery connection and
begin following the feature setup and adjustment steps.
Feature Setup and Adjustments
1. Selecting the Input Sensitivity Range – Before you turn on your system, you must select the proper input
sensitivity range on your amp using the button labeled INPUT SENS located in the GAIN CONTROL section of
the control panel.
Setting for Aftermarket Source Units: Refer to your aftermarket owner’s manual for line level output
specification. If the specification is not available, please follow the instructions listed below.
X1 POSITION: 100mV–1V (Typically for RCA Input)
Setting for Factory (OEM) Source Units: To check the amount of voltage that is present from the source
unit, take a multi meter, or a volt/ohm meter, on the AC setting, (range from 100mV up to 10V) attach the
positive and negative leads directly to any exposed speaker. It will not matter if the polarity is correct, it will
read the same amount of voltage.
X10 POSITION: 1V–10V (Typically for Speaker Level Input)
Note: It is important not to have the amp set up to receive a low voltage signal and give it a high voltage signal.
Doing this can cause damage to the amp.
2. Adjusting the Gain Control – Before you start setting your amp gains, be sure to defeat all EQs (“off” position).
You want to set the gain levels properly BEFORE applying any equalization.
Start with the source unit’s volume around ¾ of the way up, and the gain on the amp all the way down
(counter-clockwise). Slowly increase the gain clockwise until the speaker starts to distort. Immediately
decrease gain until the distortion goes away. This will be a good reference point on the volume control to
where the signal starts to distort. Remember every CD will be different; use common sense and constantly
listen for obvious distortion and adjust volume the accordingly. The gain on the amp has nothing to do with
how much power the amp can produce, just how fast the amp puts out max power. Just like in an automobile,
full throttle is very rarely needed.
3. Adjusting the Hi, 12dB / Low, 24dB Mono @ 40Hz–350Hz Variable X-over Frequency Controls –
Setting for Subwoofers: First enable the electronic crossover by selecting the “ON” position of the X-
OVER switch, and then select the “L-PASS” (low pass) position on the L-PASS/H-PASS switch. Next, using
“L-PASS FREQ” you have control over what frequency you want your amp to start crossing over your signal.
By turning this control all the way counter-clockwise you are crossing the signal over at 40Hz (the range is
counter-clockwise 40Hz to clockwise 350Hz). This means that the amp will send the woofers frequencies from
20Hz to 40Hz and then start to taper down as the frequencies go over 40Hz (24dB/octave roll off). The industry