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Features
Controls
Connections
Features
Multi-Channel Design: The JBL GTO-504EZ is a 4-channel
amplifier, basically two independent 2-channel amplifiers built into one
chassis. Either half can be bridged so it can be used as a 4-channel, 3-channel,
or 2-channel amplifier. The amplifier is stable to 2-ohms in stereo, and 4-ohms
when bridged.
CEA 2006 Compliant: The power ratings are measured according
to the Consumer Electronics Association CEA-2006 standards. These standards
allow you to accurately compare the rated power output of all CEA 2006-compliant
amplifiers, even different brands. Manufacturers who adhere to the standards can
display the CEA 2006 logo on their products and packaging. The power output is
measured from 20 Hz to 20 kHz, using a 14.4 volt power supply, and with no more than
1% THD+N:
- 4-Channel (4-ohm): 50 watts x 4-channels
into 4-ohms
- 4-Channel (2-ohm): 75 watts x 4-channels
into 2-ohms (2-ohms minimum)
- 2-Channel (Bridged): 150 watts x 2-channels
into 4-ohms (4-ohms minimum)
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-504EZ has a signal sensing automatic
turn-on circuit; it will turn on whenever an audio signal is present at any of
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: There are independent crossovers for the front
and rear channels built-in. Each crossover can be set to high-pass, low-pass,
or full range (bypassed). The crossover points are continuously variable from
40 Hz to 220 Hz and adjusted independently. The slope of both crossovers 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.
Line Level Output: The amplifier has a pair of RCA line
level outputs to feed a full-range stereo signal to another amplifier. The
GTO-504EZ's crossovers have no effect on the line output signal.
Routing Switch: The signal for the front and rear amplifier
channels can be supplied from the separate front and rear inputs (two pair of
stereo RCAs), or from just the front channel inputs (stereo RCAs). Set the switch
to F&R (front and rear) or F (front).
Bass Boost: A bass boost circuit, centered at 45 Hz, can be
applied to the rear channels. The boost is variable from zero to +12 dB. JBL
recommends only using bass boost when the rear channels are bridged to power a
subwoofer.
Controls
Top:
- Front channels:
- Crossover selector: three position
switch; high-pass, full range, low-pass
- Crossover Frequency: rotary knob;
continuously variable from 40 Hz to 220 Hz
- Input Gain: rotary knob (the gain
LEDs are above the knob)
- Rear channels:
- Crossover selector: three position
switch; high-pass, full range, low-pass
- Crossover Frequency: rotary knob;
continuously variable from 40 Hz to 220 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)
- Routing Switch: F (front)/F&R (front
and rear)
- Gain LEDs: on/off
Bottom:
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 10 gauge minimum. The recommended
accessory list for the GTO-504EZ includes wiring kits
with 10 gauge wire and either a 25 or 30 amp fuse, but
the amp has two 20 amp fuses (40 amps total), so if one
of these kits is used a replacement fuse must also be
added (at least 40 amps). If an 8 gauge wiring kit is
used no additional fuse is necessary.
- Remote Turn-on Terminal: set screw
terminal; accepts up to 8 gauge bare wire
- Speaker terminal: four pair of set
screw terminals (for front left, front right, rear left,
and rear right); accept up to 8 gauge bare wire
- Fuses: two ports for 20-amp ATO
fuses (fuses are factory installed)
Right Side:
- Audio Input: four female RCA jacks
(front left, front right, rear left, and rear right);
compatible with speaker level signals using the included
adapters
- Audio Output: two female RCA jacks
(left and right)
