P 4020 - JBL Car Audio User Guide / Operation Manual. Page 2

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• 4-, 3- or 2-channel operation (P-4040)

2- or 1-channel operation (P-4020)

• Simultaneous stereo and mono

operation

• Built-in 12dB/oct electronic crossover
• Balanced differential input 
• Pre-amp outputs (filtered on P-4040)
• Oversized Floating Rail Mosfet Power

Supply

• Universal Interface
• Common Sense turn-on
• Variable input sensitivity (250mV–4V)
• Fully complementary, direct coupled

discrete power amplifier circuitry

• Gold-plated power, input and output

connectors

• 2-Ohm stable (stereo)
• JBL badge lights when amp is operat-

ing and flashes when protection circuit
is activated

• Made in USA

To attain maximum amplifier perfor-
mance, we encourage you to read the
remaining pages before installing and
operating your new JBL Power Series
amplifier. Especially review the
Applications section for ideas on design-
ing and expanding your system. Also,
save these instructions for future refer-
ence. Important: Installation of automo-
tive stereo components can require
extensive experience in performing a
variety of electrical and mechanical pro-
cedures. Although these instructions
explain how to install a JBL Power Series
amplifier in a general sense, they do not
show the exact installation methods for
your particular vehicle. If you do not
have the experience necessary, do not
attempt the installation yourself; instead
ask your Authorized JBL Car-Audio Dealer
about professional installation options.

• The JBL P-4020 (or P-4040) has five

levels of circuit protection that monitor
the amplifier and will shut it down if
the electrical system voltage drops
below 5Vdc or exceeds 18Vdc, temper-
atures are above 194° F (90° C), short
circuits occur, or current draw exceeds
product specifications. For best perfor-
mance, check the intended mounting
site to make sure the operating envi-
ronment does not create conditions
that will trigger the protection circuit.

• Prior to installation, turn off all audio

systems and other electrical devices.
Also disconnect the (–) negative lead
from the vehicle’s battery.

• At the installation site, locate and make

a note of all fuel lines, hydraulic brake
lines and electrical wiring. Use extreme
caution when cutting or drilling in and
around these areas.

• Check clearances on both sides of a

planned mounting surface before
drilling any holes or installing any
screws. Remember that mounting
screws can extend behind the mount-
ing surface. 

for purchasing your new

JBL Power Series™ amplifier. Power
Series amplifiers feature the latest
advances in discrete-circuit topology,
ensuring low distortion and superbly
clean and clear sound quality. In addition
to RCA-type pre-amp inputs, Power
Series amplifiers feature Universal
Interface™, designed to facilitate integra-
tion with factory-installed audio systems
for distortion-free performance that rivals
conventional pre-amp connections.
Included in the Universal Interface circuit
is Common Sense™ turn-on. Common
Sense turn-on senses the common-mode
voltage present on the speaker outputs of
factory and aftermarket radios, turning on
the amplifier without a separate remote
wire. All Power Series amplifiers feature
built-in electronic crossovers and pre-amp
outputs for easy system expansion with-
out requiring outboard processors.

P-4020/4040 OM.  7/14/98 11:42 AM  Page 2