GX-A3001 - JBL Car Audio Service Manual (repair manual). Page 6

E

ng

lis

h

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.