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Features
Controls
Connections

Features

Setup Disc: The included setup CD is used to optimize the input gain. A test tone is output from the disc and the Gain LEDs on the amp (green, yellow, red) guide you through adjusting the gain controls.

Note: The instructions in the first version of the manual indicate the radio should be at full volume when playing the setup disc; this is wrong and JBL is in the process of correcting the manual. The volume should actually be as high as possible without distorting the signal; this will be different for every radio, but approximately 3/4 volume is typical.

Auto Turn-on: The GTO-751EZ has a signal sensing automatic turn-on circuit; it will turn on whenever an audio signal is present at the RCA inputs. The amplifier will automatically turn off approximately five minutes after the input signal ceases. If you prefer to use the radio's remote lead, the auto turn-on feature can be turned off.

Crossovers: Because this is a subwoofer amplifier, the low-pass crossover cannot be bypassed. The crossover point is continuously variable from 40 Hz to 280 Hz and the crossover's slope is 12 dB/octave.

Audio Input: If your radio has no line-level outputs, use the included adapters to convert the speaker wires to RCA and plug them into the amplifier's inputs. The input level switch has a Hi2 position, used to present a speaker load to factory radios equipped with a circuit that turns the radio off when an amp is connected.

Controls

Top:

• Crossover Frequency: rotary knob; continuously variable from 40 Hz to 280 Hz
• Input Gain: rotary knob (the gain LEDs are above the knob)
• Bass Boost: rotary knob; continuously variable from 0 to +12 dB; boost centered at 45 Hz

Right Side:

• Input Level: three position switch; Low, Hi1, or Hi2 (used only with factory radios having a circuit that turns the radio off when it sees no speaker load)
• Gain LEDs: on/off

Bottom:

• Auto Turn-on: on/off

Connections

Left Side:

• Power and Ground Terminals: set screw terminals; accept up to 4 gauge bare wire
  • Note: JBL recommends the power and ground cables be 8 gauge minimum. However, because the GTO-751EZ has two 40 amp fuses (80 amps total), we recommend using 4 gauge power and ground wire.
• Remote Turn-on Terminal: set screw terminal; accepts up to 8 gauge bare wire
• Speaker terminals: one pair of set screw terminals; accepts up to 8 gauge bare wire
• Fuses: two ports for 40-amp ATO fuses (fuses are factory installed)

Right Side:

• Audio Input: left and right female RCA jacks; compatible with a speaker level signal using the included adapters
• Remote: RJ-25 jack (the wired remote is not yet available as of 2/21/12)