DOWNLOAD JBL P 4040 (serv.man8) Service Manual ↓ Size: 916.77 KB | Pages: 8 in PDF or view online for FREE

5

4. In some systems it may be desirable

to have two sources play simultane-
ously 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 sim-
ple as turning the unused source off,
and the other on. (Note: you must con-
nect 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 above.)

Electronic Crossover
The electronic crossover in the P-4020 and
P-4040 should be used to route the appro-
priate signal to speakers intended to play
only bass, or only midrange and treble fre-
quencies. The crossover slope is 12dB/oct
and the frequency is fixed at 80Hz.
Pre-amp Outputs
Connect these to the input connectors of
other amplifiers or processors in your
system. Refer to the “Applications” sec-
tion 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 sensi-
tivity 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 (counterclock-
wise) 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 “Trouble-
shooting” on page 7.)

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) toward 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 maxi-
mum undistorted output level of your
system, and it should not be exceeded
during use.

3. After adjusting the level of the main

speakers in your system, you should
adjust the remaining channels (if you
are using a P-4040 or a multi-amp
system) for the desired system bal-
ance. You’ll find this easiest to do by
adjusting the channels in the following
order: 1) front speakers, 2) rear speak-
ers, 3) subwoofer. Elaborate, multi-
channel systems may be complex to
adjust. Your local JBL installation spe-
cialist is the best person to help with
such an adjustment. 

For your convenience, we’ve included
several application diagrams to help you
plan your own system installation.
Figures 1 through 3 show how to config-
ure the JBL P-4020 or P-4040 for stereo,
bridged-mono and tri-mode operation. 
For system expansion ideas, see Figures
4 and 5 on the next page. (Note: For sim-
plicity, Figures 1 through 5 do not show
power, remote and input connections.)

Many different system configurations are
possible using the crossovers and pre-
amp outputs featured in Power Series
amplifiers. If you are considering expand-
ing your system beyond what is shown
here, please consult your local JBL instal-
lation specialist, who is experienced in
designing complex mobile-audio systems. 

P-4020/4040 OM.  7/14/98 11:42 AM  Page 5

30

6

20

30

20

20

Figure 1. This wiring diagram shows
a JBL P-4020 amplifier set to stereo
to drive a pair of full-range speakers.

Figure 2. This wiring dia-
gram shows a JBL P-4020
amplifier set to bridge
mode (mono) to drive a 
single subwoofer.

Figure 3. This wiring diagram
shows a JBL P-4020 amplifier set
for tri-mode operation. For a
desired crossover frequency, use
the chart on page 4 to select an
inductor for the subwoofer, and
corresponding capacitors for left
and right speakers.

Figure 4. In this example system,
the front channels of a P-4040
drive a pair of 5-1/4" 2-way speak-
ers, and the rear channels are
bridged to drive a single 12"
woofer.

Figure 5. In this expanded system, a JBL P-4040 drives two pairs of 6-1/2" 2-way speakers.
The JBL P-4040’s pre-amp outputs feed a JBL P-4020 to drive a single 12" subwoofer in
bridge mode. 

20

P-4020/4040 OM.  7/14/98 11:42 AM  Page 6

7

No audio

Low/no remote on voltage

Check connections; turn-test turn-on voltage

Speakers are not connected or are blown

Check wiring; use VOM/DVM to measure speaker-coil 
resistance

Distorted audio

Input sensitivity is not set properly

See Setting Input Sensitivity on page 5

Audio lacks “punch”

Speakers are wired with wrong polarity

Check polarity of connections; refer to Applications

Audio cycles off and on;

A protection circuit is turning the 

Verify the following: off electrical system is

amber protection LED 

amplifier off and on

between 5 ~ 18Vdc; temperature is not 

(JBL badge on top panel)

over 194°F (90°C); there are no short circuits; speaker 

is flashing

loads are not less than 2 ohms (4 ohms in mono)

Audio cycles off and on;

GAIN is set too high

Set Input Sensitivity

amber protection LED

correctly (see page 5)

(on top panel) is flashing

Fuse blows

Incorrect wiring or short circuit

Check connections; refer to Applications 

Use the following guide to identify
symptoms and solve problems. Make
sure the vehicle’s electrical system is
working properly and power is reaching
the JBL P-4020 (or P-4040).

Declaration of Conformity

Kongevejen 194B 
DK-3460 Birkerød
DENMARK

declare in own responsibility, that the products  

  described

in this owner’s manual are in compliance with technical

 

standards:

EN
EN 

55013/A12/8.1994
55020/12.1994

Steen Michaelsen

Birkerød. DENMARK. 3/98

P-4020/4040 OM.  7/14/98 11:42 AM  Page 7

JBL Consumer Products
250 Crossways Park Drive

Woodbury, NY 11797

Part No. SH1122  
Made in USA

Power Output, 4 ohms:

2 x 40 watts

4 x 40 watts

Power Output, 2 ohms:

2 x 50 watts

4 x 50 watts

Power Output, Bridged 4 ohms:

100 watts

100 watts x 2

Frequency Response:

20Hz ~ 20kHz +0dB, –1dB

20Hz ~ 20kHz +0dB, –1dB

Input Sensitivity:

250mV ~ 4V

250mV ~ 4V

THD + Noise (4 ohms):

0.05 %

0.05 %

Signal-to-Noise:

>100dB

>100dB

Maximum Current Draw:

18A

40A

Dimensions (W x H x L):

7-5/8" x 2-1/4" x 8-3/4"  

13-5/8" x 2-1/4" x 8-3/4" 

194 x 58 x 223mm 

347 x 58 x 223mm 

P-4020/4040 OM.  7/14/98 11:42 AM  Page 8