GTO-804EZ - JBL Car Audio Service Manual (repair manual). Page 7

When you’re using the amplifier’s rear channels to power a subwoofer, the Bass Boost control can provide up to 12dB 
of bass boost at 45Hz. Set this control according to your personal taste, but be careful not to set the control at a high 
enough level to cause audible distortion or bottoming of your subwoofer. CAUTION: Only use the Bass Boost control 
if you’ve configured the rear channels to power a subwoofer. Using the Bass Boost control with full-range speakers 
can damage the speakers.

The GTO amplifier Power/Protection LED’s color indicates the amplifier’s operational status:

• LED is orange: Normal operation (power is on)

• LED is off: Amplifier is in standby mode

• LED is red: Amplifier is in protect mode

If the amplifier is in the protect mode (the LED is red), see Troubleshooting, on page 11.

IMPORTANT: Disconnect the vehicle’s negative (–) battery terminal before beginning the installation.

If you have not already done so, remove the two end caps that cover the amplifier’s connectors as explained in 
Mounting the Amplifier, above. This will provide easier access to all of the amplifier’s connectors.

No remote turn-on connection is necessary because GTO amplifiers include signal-sensing turn-on, which will turn 
the amplifier on when it receives an audio signal at any of its input connectors. The amplifier will automatically turn off 
approximately five minutes after the input signal ceases. 

If your audio system’s source unit includes a remote turn-on wire and you would prefer to use it, the amplifier 
will sense that you’ve used a remote turn-on wire and that connection will override the signal-sensing turn-on. If 
necessary, you can defeat the signal-sensing turn-on circuit by moving the Auto Turn-On switch to the “Off” position.

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