GT5-A402 (serv.man3) - JBL Car Audio Service Manual (repair manual). Page 5

Installation Warnings and Tips
• Disconnect the negative (–) lead from your vehicle’s

battery.

• At the installation sites, locate and make a note of

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

• Choose a safe mounting location away from moisture. 
• Make sure there is sufficient air circulation at the

mounting location for the amplifier to cool itself.

• Mount the amplifier, using the supplied hardware.

Specifications
• 40W RMS x 2 channels @ 4 ohms and 

≤1% THD + N*

• 60W RMS x 2 channels @ 2 ohms, 14.4V supply and

≤1% THD + N*

• 120W RMS x 1 channel @ 4 ohms, 14.4V supply and

≤1% THD + N*

• THD + N: 0.05% (rated power @ 4 ohms)*
• Signal-to-noise ratio: 85dBA 

(reference 1W into 4 ohms)*

• Signal-to-noise ratio: 101dBA 

(reference rated power into 4 ohms)

• Frequency response: 10Hz – 100kHz (–3dB)*
• Total peak power: 240 watts
* CEA-2006A-compliant

0 Speaker Output Connectors

• Connect the speakers to these terminals,

observing proper polarity.

• Two-channel operation: Connect the left

speaker to the L+ and L– terminals and the
right speaker to the R+ and R– terminals. 

• One-channel (bridged) operation: Connect the

single speaker to the R+ and L– terminals.

• Minimum speaker impedance for 2-channel 

operation is 2 ohms. Minimum speaker impedance
for 1-channel (bridged) operation is 4 ohms. 

1 Fuse

• Replace only with the same type and rating.

2 Power Input Connectors 

• +12V: Connect to the positive terminal of the

vehicle’s battery. 10 AWG wire is recommended.
Install an appropriate fuse holder and fuse (15A
minimum) within 18 inches of the battery. Make
sure the wire is not damaged or pinched during
installation. Install protective grommets when
routing wires through the firewall or other sheet
metal. 

• GND: Connect to the vehicle’s chassis. Refer to

the picture below.

• REM: Connect to the “Remote Out” lead from

the source unit or to a source of switched 
12V+ (ACC).

3 Input Connectors (RCA)

• Connect to the RCA outputs from the source unit 

or signal processor.

4 Input-Level Control

• Used to match the input level of the amplifier 

to the output level of the source unit.

• See A for the adjustment procedure.

5 Power On LED

• Illuminated when the amplifier is on.

6 Protect LED

• Illuminated under any of the following fault 

conditions: battery over/under voltage, short 
circuit in speaker wires, amplifier is too hot,
amplifier’s output circuit has failed (DC voltage
is present in the amplifier’s output).

7 Crossover-Frequency Control

• 12dB/octave crossover, variable from 

32Hz to 320Hz.

• See B for the adjustment procedure.

8 Crossover-Filter Selector

• LP: Select for subwoofer(s).
• FLAT: Select for full-range speakers when 

no subwoofer will be used in the system.

• HP: Select for midrange speakers or 

full-range speakers when a subwoofer is 
used in the system.

9 Bass-Boost Control

• Provides 6dB of boost at 50Hz. Set the Bass-

Boost control according to your preference,
being careful not to apply enough boost to 
damage the speaker(s). 

A Setting Input Level

A Turn Input-Level control counterclockwise to

6V (minimum).

B With a dynamic music track playing, turn the

head unit’s volume control to the 3/4 position.

C Turn Input-Level control clockwise until the

music is so loud that it no longer sounds clear
(distortion is present in the output).

D Turn Input-Level control counterclockwise

gradually, just until the music sounds clear,
once again.

E Input level is now adjusted correctly.

B Setting the Crossover

A Crossover setting for 5" or larger full-range

speakers when no subwoofer is included in 
the system.

B Crossover setting for midrange and/or 

full-range speakers when a subwoofer 
is included in the system.

C Crossover setting for subwoofers.
Note: Acceptable frequency ranges are indicated 
in gray.

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