Inputs and Outputs Notes
Mono-Channel Subwoofer Amplifier: The JL Audio A1800 is a class D
monoblock subwoofer amplifier that is rated at 640 Watts RMS x 1-channel in
4 ohm at 20 to 250 Hz with a signal-to-noise-ratio of 95 dB and a total
harmonic distortion of 1% while receiving 14.4 Volts. The amplifier is rated at
1,000 Watt RMS x 1-channel in a 2 ohm load at 14.4 Volts. While receiving 12.5
Volts the amplifier is rated at 480 Watts RMS x 1-channel in 4 ohm with a total
harmonic distortion of 0.08% or 800 Watts RMS x 1-channel in 2 ohm. The JL Audio
subwoofer amplifier's frequency response is limited to the range of 10-250Hz and
is not designed for driving midrange speakers or tweeters. Every aspect of the
amplifier's operation has been optimized for low-frequency amplification.
Class D Circuitry: This JL Audio Class D subwoofer amplifier utilizes
a proprietary Class D circuit. JL Audio's Patented Class D output circuit
utilizes a discrete control section and a unique feedback loop design that
results in outstanding power regulation and a damping factor greater than 500 at
4 ohms (>250 at 2 ohms). This is vastly higher than other Class D designs and
also higher than most Class A/B amplifiers. The benefit of this exclusive JL
Audio technology is tight, clean bass reproduction with the efficiency advantage
of Class D amplification.
Simplified Gain Setting: The A-Series amplifier makes setting
the gain level of the amp via the input sensitivity control very simple. All you
need is Digital AC Voltmeter (142TK12V, sold separately) and a Test CD Disc
(503CD104, sold separately) with a sine-wave test-tone recorded at 0 dB
reference level in the frequency range to be amplified for that set of channels
(50 Hz for subwoofer channels).
Differential-Balance Inputs: The JL Audio amplifier features
differential-balanced input architecture to effectively control noise and ensure
compatibility with a wide variety of source units, including many OEM
systems. Without resorting to line output converters, you can directly connect
most OEM source units to the JL Audio amplifier without creating any noise or
compatibility issues. Unlike conventional single-ended inputs, the
differential-balanced design does not connect one side of the audio signal to
chassis ground. This eliminates any voltage sensitivity between one input
terminal and ground and greatly reduces the incidence of alternator whine in a
typical car audio installation. The A1800 amplifier provides range switching
on each of its inputs via the "Input Voltage" switch. This permits connection to
a wide range of source voltages while retaining excellent sensitivity setting
Note: You will need a speaker wire to RCA adaptor (136CLR2SW, sold
separately) to connect this amplifier to your headunit via speaker-level.
Preamp Outputs: The A-Series amplifier features on pair of preamp
outputs that make connecting multiple amplifiers simple. The preamp pass-through
outputs are configured in parallel with the amp inputs. The signal present at
these outputs is identical to the signal at the amp inputs and is unaffected by
any on-board processing.
Active Crossover: The active crossover sections of the A-Series
amplifier offer excellent flexibility and precise tuning. The A1800 features the
following crossover adjustments.
Low Pass Filter: You can select a 12 dB/octave Low Pass or 24
dB/octave Low Pass. You can also turn the amplifier's Low Pass crossover off
if you choose to use an external electronic crossover. In the Off mode the
amplifier has a frequency range up to 250 Hz.
Filter Frequency: The filter frequency for the 12dB/octave or
Pass crossover can be set from 40 to 200 Hz.
Bass Controls: The bass boost circuit of the A-Series amplifier offers
the following controls.
Bass Boost: The amplifier is equipped with a fixed +6dB, 48 Hz
Remote Bass Port: The amplifier is equipped with a connection for
a wired Remote Bass Control (136RBC1, sold separately) that allows fully
variable boost control (0-12dB) from the front of your vehicle.
Advanced Rollback Protection: Should an A-series amplifier ever
intelligent, unregulated power supply reacts by limiting available peak voltage
until the amplifier returns to a safe temperature range. Likewise, if an
impedance lower than optimal for the amplifier is present at the outputs, the
A-series amplifier will roll back peak voltage to protect itself without
Note: There is only one condition that will shut down the
A-Series amplifier completely and that is if the battery voltage of your
vehicle drops below 10 volts.
Protection Circuitry With Status Indicator Lights: There are two
status indicator lights on the right side of the amplifier.
Power (Green): This LED lights green to indicate that the
amplifier is turned on and operating normally.
Protect (Red): The Protection LED lights Red to indicate the
amplifier's protection circuitry has been activated to prevent product
failure due to a short-circuit or a dangerously low impedance connected to
the amplifier's outputs.
Inputs and Outputs Notes
Left Side Of Amplifier:
Power and Ground: The JL Audio amplifier's set-screw Power and Ground
connections are designed to accept 8 to 4 AWG power wire.
Remote Turn-On: The A-series amplifier's set-screw turn-on lead will
accept 18 to 12 AWG wire.
Speaker Outputs: The A1800 amplifier's set-screw speaker terminals
will accept 16 to 8 AWG speaker wire.
Right Side Of Amplifier:
Preamp Inputs: The amplifier features one set of differential-balanced
RCA jack inputs. The amplifier's input level can be set to Low (200mV-2V RMS)
when connecting the amplifier to a low-level preamp signal or set to High
(800mV-8V RMS) when connecting the amplifier to a high-level speaker signal.
Preamp Outputs: The amplifier also features one set of pass-through
preamp outputs so you can send an unaltered audio signal to another amplifier in
Remote Bass Port: The amplifier is equipped with a connection for a
wired Remote Bass Control (136RBC1, sold separately).
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 verify what’s in the box, 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.