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If your amplifier isn’t performing the way you think is should, check to see if the problem is covered in this section before calling your dealer or 

contacting JBL customer service.

No sound (the amplifier’s Power LED is off)

• Check that the amplifier’s +12 V and GND connections have been properly made.
• Check if the fuse on the +12 V wire located near the battery is blown: If so, replace it with an

identical fuse.

• Check all amplifier fuses; if any are blown, replace them with identical fuses.
• If you are using the amplifier’s REM connection for turn-on, check that the wire is properly

connected to the audio system’s remote turn-on wire or to the vehicle’s ACC power terminal.

No sound (the amplifier’s Power LED is orange)

• Check that all amplifier input and speaker connections have been properly made.

• Check that the amplifier’s Level controls are not turned all the way down (counter-clockwise).
• Check that the vehicle audio system’s source unit’s volume control is not turned all the way

down.

No sound (the amplifier’s Protection LED is red)

• Confirm that the vehicle’s electrical system is supplying between 9 V and 16 V DC to the

amplifier. If the supply voltage is outside of this range, correct the condition before attempting to 

use the amplifier.

• If the amplifier has overheated, wait until it has cooled down before attempting to use it again.

• Disconnect all speakers from the amplifier and attempt to turn it on again:
 – If the amplifier turns on (the Power LED is orange), there is a short circuit in one or more of the

speaker wires. Correct all short circuits before reconnecting the speakers to the amplifier.

 – If the amplifier does not turn on (the Protection LED is still red and the Power LED is off),

contact your authorized JBL dealer for assistance.

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Sound only comes from some of the speakers 

connected to the amplifier

• Check that the vehicle audio system’s source unit’s balance and fader controls are set to their

center (midpoint) positions.

• (GX-A604): Check that the setting of the amplifier’s Mode Switch matches the input and speaker

connections made to the amplifier

Sound is too quiet, even with the vehicle audio 

system’s source unit volume all the way up

• Check that the amplifier’s Level controls are not turned too low. See Set The Input Level, on 

page 22, for information about setting the Level controls.

Sound in the front/rear speakers is distorted

• Make sure the amplifier’s Crossover Filter switch for the distorted channels is set to HP.
• Set the Crossover control for the distorted channels to a higher setting.
• Check that the distortion is not originating from the vehicle audio system’s source unit.

Sound in the subwoofer is distorted

• (GX-A604, GX-A602): Set the Bass Boost switch to "OFF".

• (GX-A3001): While listening to bass-heavy music, turn the Bass Boost control all the way down,

and then gradually increase it until the distortion begins to return. Reduce the Bass Boost 

control setting slightly to eliminate the distortion and leave it set there.

• Check that the distortion is not originating from the vehicle audio system’s source unit.

specificAtions

Max power (15.5 V, 1 kHz, 10% THD,

total ch, 2 ohms)

435 W

280 W

415W (15.5 V, 50 Hz, 10% THD,  

2 ohms)

Rated power output @ 4 ohms

60 W x 4

60 W x 2

200 W x 1

Bridged power output  

(4 ohms, 1% THD)

170 W x 2

170 W x 1

N/A

THD+N at rated power

<1%

<1%

<1%

Signal-to-noise (2 V @ 4 ohms)

>75 dB

>75 dB

>75 dB

Effective damping factor (4 ohms)

>50

>50

>50

Frequency response (–3 dB)

20 Hz – 20 kHz ±1 dB

20 Hz – 20 kHz ±1 dB

10 Hz – 320 Hz

Maximum input voltage

20 V

20 V

20 V

Maximum input sensitivity

200 mV

200 mV

200 mV

Fuse size

20 A x 2

25 A

20 A x 2

Dimensions (H x W x D)

2-1/16" x 11-13/16" x 8-1/8"  

(52 mm x 300 mm x 206 mm)

2-1/16" x 7-13/16" x 8-1/8"  

(52 mm x 198 mm x 206 mm)

2-1/16" x 11-7/16" x 8-1/8"  

(52 mm x 291 mm x 206 mm)

Weight

5.3 lb (2.4 kg)

3.8 lb (1.7 kg)

5.3 lb (2.4 kg)

1

2

3

4

5

6

7

8

A

B

C

D

8

7

6

5

4

3

2

1

D

C

B

power supply

1

2

3

GROUND

REM

+12V

bass boost

45Hz    0-12dB

power

P1

A5

FUSE

P2

HI-IN auto ON

A1

A2

PRT

INPUT SENS

0.1V-4V

A1

A3

A4

A6

SPK out
2Ω/4Ω

L input

Class AB Audio Power Amplifier

input selector

1

2

3

4

HI IN

Pitch 2.5mm

A2

R input

input selector

A1

A2

crossover

32/320Hz 12dB/ oct

HP/LP pass 

10Hz

32Hz

320Hz