Our Product Research Team
At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere.
That's because we have our own in-house Product Research team — they open the box,
verify contents, check the owner's manual, and record dimensions, features and specs.
We stay on top of new products and technologies to help people make informed choices.
Power Output: The JBL GX-A604 Class AB 4-channel amplifier
delivers the following power output (RMS Power Output @ 1% THD+N, 14.4 VDC):
- 60 watts x 4 @ 4 ohms
- 85 watts x 4 @ 2 ohms
- 170 watts x 2 bridged into 4 ohms
Protection Circuitry: The amplifier features protection
circuitry for thermal overload, over- or under-voltage (<9V or >16V), and short circuits. The LED on the
end of the amp glows red if the amp goes into protection mode.
Input Level: The GX-A604's rotary gain control let you match the
amp's input sensitivity to the output of the source unit. There are independent
input level controls for the front and rear channels. The input sensitivity
range of the amplifier is continuously variable between 200mV and 12V. A small
screwdriver (not included) is required to set the gain.
Input Mode: The amp's 4 channels can be driven by input
signals from 4 channels. If you only have 2 channels of input, the Input Mode
can be switched to "2CH" and all four channels will receive audio signal from
the two connected inputs. The switch should remain at "4CH" if there are 4
Crossover: The amp features separate crossovers for the
front and rear channels. For the front, there is a selectable 80Hz high-pass
filter with an On/Off switch. The rear channels feature a 32Hz to 320Hz variable
crossover. A 3-way switch lets you configure the crossover for high-pass or low-pass
operation, or switched to "flat" to defeat the crossover.
Bass Boost: The GX-A604 has a switchable 12dB bass boost,
centered at 45Hz, for the rear channels. This is useful when using the rear
channels of the amplifier in bridged mode to power a subwoofer.
Terminals: The JBL GX-A604 uses screw
terminals for the +12V power, ground, turn-on (remote) lead, and speaker
outputs. The screws can be tightened/loosened with a Phillips-head or flat-head
screwdriver (not provided).
Power/Ground: The +12V Power and Ground terminals will
accept spade connectors up to 1/2" wide. It is recommended that you use an
8 AWG power wire to the battery, with an in-line 50A fuse installed no more than
18" from the battery terminal. An 8 AWG ground wire (minimum) should be used, and
attached to a metal area close to the amplifier.
Remote Turn-On: The Remote screw terminal will accept a
spade connector up to 3/8" wide. Typically, an 18 AWG turn-on lead is included in an amplifier
Speaker-Level Input: The amp includes two Speaker Level
Input harnesses for connecting the amp to a factory radio or aftermarket head
unit without preamp outputs. You should splice left and right speaker wires from
the head unit to each harness and plug the harnesses into the amp.
Line-Level Inputs: The amplifier is equipped with two pairs
of RCA inputs for connecting stereo RCA patch cables from the head unit to the
amp. If you are bridging the amplifier's rear channels and have only one input
for the rear channel, a "Y"-adapter will be needed to connect the left and right
rear RCA inputs.
Speaker Outputs: The amp features screw terminals for connecting speakers in
4-channel, 3-channel, or 2-channel configurations. In 3-channel mode, the front
channels are connected in stereo and the rear channels are bridged (using Left + and the
Right - terminals). For 2-channel mode, both pairs of speaker terminals are
bridged. The terminals will accept a spade
connector up to 3/8" wide.