6
Initially set the crossover-frequency control
midway. While listening to music, adjust the
crossover for the least perceived distortion from
the speakers, allowing them to reproduce as
much bass as possible.
Systems using a separate subwoofer set the
crossover mode to HP (high-pass) for your
full-range speakers. Adjust the crossover
frequency to limit bass, and provide increased
system volume with less distortion.
For subwoofers, choose the highest frequency
that removes vocal information from the sound
of the subwoofer.
If using the 7521a or 7541a to drive a subwoofer(s),
set the crossover mode to LP (low-pass).
NOTE:
The 311a, 611a, 1211a and the subwoofer
output of the 5761a are low-pass only and do not
have a crossover-mode switch.
SETTING THE CROSSOVER(S)
Determine your system plans and set the
crossover-mode switch accordingly. If your
system design does not include a subwoofer,
set the crossover mode to FLAT and skip to
“Setting Input Sensitivity.”
MODE SWITCH
Flat:
Allows a full-range signal through to the
speakers; can be used with larger full-range
speakers such as 6" x 9"s.
HP:
Allows a high-pass signal through to
the speakers; should be used with most
loudspeakers (can protect your full-range
speakers from being overdriven with low
frequencies, one cause of speaker damage).
LP:
Allows bass to pass through to the speakers;
should be selected when powering subwoofers.
Figure 13.
Control end panel.
SETTING INPUT SENSITIVITY
1. Initially turn the INPUT LEVEL control(s) to
minimum (counterclockwise).
2. Reconnect the (–) negative lead to the vehi-
cle’s battery. Apply power to the audio system
and play a dynamic music track.
3. On the source unit, increase the volume
control to 3/4 volume. Slowly increase the
INPUT LEVEL control(s) toward three o’clock
until you hear slight distortion in the music.
Then reduce the INPUT LEVEL slightly until
distortion is no longer heard.
NOTE:
After the source unit is on, blue LEDs (on
the top panel) will light, indicating the amplifier
is on. If not, check the wiring, especially the
remote connection from the source unit. Also
refer to “Troubleshooting” on page 7.
I
NSTALLATION AND
S
ETUP
311a/611a/1211a
7541a
7521a
5761a
REMOTE LEVEL CONTROL (OPTIONAL)
All three Reference subwoofer amplifiers and
the 5761a amplifier have inputs for an optional
remote level control (100rc). This will allow the
subwoofer level to be adjusted from the listening
position. Connect the optional remote level
control using the RJ-11 jack on the side of the
amplifier. Install the control module in the front
of the vehicle within easy reach of the driver.
Both the underside of the dash and the center
console are suitable locations. Refer to the
mounting instructions accompanying the 100rc.
SETTING THE BASS BOOST
The 7521a, 7541a and 5761a are all equipped
with a bass-boost control. This allows you to
enhance the bass output of your system at
50Hz up to 12dB.
NOTE:
Only rear channels of the 7541a are
affected by the bass boost control.
AUX OUTPUT
Reference amplifiers (except 5761a) are equipped
with full-range outputs that can be used to
connect additional amplifiers.
NOTE:
When using the low- or high-level inputs,
the AUX outputs can be used to pass a full-range
line-level signal to another amplifier.
