P 7520 (serv.man3) - JBL Car Audio User Guide / Operation Manual. Page 5

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2. If you are connecting the amplifier to a

factory installed source unit, or to a
source unit that only has speaker level
outputs, connect the speaker outputs
of the source to the speaker inputs on
the amp observing the following color-
code:
Front Left+: White
Front Left-: White with black stripe
Front Right+: Gray
Front Right-: Gray with black stripe
Rear Left+: Green
Rear Left-: Green with black stripe
Rear Right+: Purple
Rear Right-: Purple with black stripe
(Note: When using the Universal
Interface Speaker Level Inputs and
speaker level outputs, the “rem”
terminal on the amplifier may be used
as a remote output connection, and
will provide power to turn on other
amplifiers and processors in the
system.)
(Note: The front and rear inputs on the
P-2510 are  summed to mono inside
the amp, and will provide constant
bass regardless of source unit balance
and fader controls)

3. If you are connecting your Power

Series amplifier to a source unit with
output voltage higher than 4V, connect
the output signal wires of the source
unit to the Universal Interface Speaker
Inputs. Because the inputs have an
impedance of 10K Ohms, this
connection will provide the best noise-
free performance posssible.

4. In some systems it may be desirable

to have two sources play
simultaneously through the audio
system . For instance, if you have a
factory installed radio in your car, and
you want to add an aftermarket CD
player, you may connect the CD player
to the RCA inputs of the amp, and the
factory radio to the Universal Interface
Speaker Inputs. Note: Front and rear
channels of the CD and radio must be
driven into the front and rear inputs of
the amplifier. Use Y adapters if
necessary. The Universal Interface
circuitry will isolate the two signals
from each other while allowing them
to drive the amp simultaneously.
Therefore switching from one source
to the other is as simple as turning the
unused source off, and the other on.
(Note: you must connect the remote
turn-on wire from the CD player to the
Rem terminal on the amp. Install a
diode in the remote line from the CD
player as shown in the diagram
below.)

Electronic Crossover
The electronic crossover in the P-7520, 
P-7540 and P-2510 should be used to
route the appropriate signal to speakers
intended to play only bass, midbass,
midrange or treble frequencies. The
crossover slope is 12dB/oct and the
frequency is variable from 32Hz - 320Hz. 

Pre-amp Outputs
Connect these to the input connectors of
other amplifiers or processors in your
system. 

The crossover selector switch determines
which filter will be assigned to the pre-
amp outputs. The pre-amp outputs may
be High Pass (switch set to HP), Low Pass
(switch set to LP), or unfiltered (switch set
to Flat). The crossover frequency is
determined by the crossover frequency
control, and will be the same frequency
as the amplifier channels affected by that
control.
Refer to the “Applications” section for
system expansion possibilities.

Setting Input Sensitivity
Proper input sensitivity control settings
on Power Series amplifiers are critical to
ensure optimum performance, low noise
levels and maximum system reliability.
As a general rule,  controls at the front
end of a system (source, equalizers, and
other processors) should be set as high
as possible with the amplifier input
sensitivity set as low as possible while
still providing adequate volume levels.
Using a high signal level and a low
sensitivity setting will help keep
background noise in the system to a
minimum.

Initially, turn the input sensitivity GAIN
control to its minimum (counter-
clockwise) position.
1. Reconnect the (–) negative lead to

your vehicle’s battery. Apply power to
the audio system and play a favorite
music track from CD or tape. 
NOTE: After the source unit is on, the
JBL badge (on the top panel) will
illuminate, indicating the amplifier is
on. If not, check the wiring, especially
the remote connection from the
source unit. Also refer to
“Troubleshooting” on the next page.

2. On the source unit, increase the

volume control until it is
approximately 3/4 of its maximum
output level. Slowly increase the Input
Sensitivity control (clockwise) towards
three o’clock and, at the same time,
listen to the quality of the reproduced
sound. At some point, you’ll hear
distortion on the music peaks. Stop
the adjustment and turn it back
slightly. This is the maximum
undistorted output level of your
system, and should not be exceeded
during use.