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Setting the 121m’s Low Pass crossover
The 121m comes with an on-board, low pass
crossover. This type of electronic crossover is needed
when playing most subwoofer systems. The crossover
is a 12 dB per octave “Butterworth” configuration with a
fixed crossover frequency of 90 Hz.
The amplifier is shipped with the low pass crossover active.
To turn-off the crossover, simply move the crossover bypass
jumper (see page 6 and below) from the “XOVR” position to
the “BYPASS” position.
Crossover Jumper settings
Using the Service JUmper
All M Series amplifiers are equipped with a “service
jumper” (see page 6, 7 & 8 and below). This jumper pro-
vides a simple means of turning the amplifier on or off at
the amplifier.
The “service jumper’s” position will either pass or interrupt
the remote turn-on voltage being sent from your source unit to
trigger the amplifier’s turn-on circuitry. With the amplifier playing,
simply move this jumper to the “Disable” position to temporarily
turn-off the amplifier. Move the jumper to the “Enable” position
to turn the amplifier back-on. Here are a few examples of when
to use the “service jumper”:
• adjusting input sensitivity
• adding an accessory module
• adjusting an accessory module
service Jumper settings
“XOVR”
With the jumper in
this position, the
crossover is active
“BYPASS”
With the jumper in
this position, the
crossover is not active
“DISABLE”
With the jumper in
this position, the
remote turn-on lead
is not connected
“ENABLE”
With the jumper in
this position, the
remote turn-on lead
is connected