400-watt, four-channel, Class D amplifier

Sold from 2010 until now

Predecessor Product: GRAND TOURING GTO 1004
Made in: China

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Product Specifications

MS Series
Input Sensitivity
Remote Bass-Level Control Included
Not Included
1-Ohm Power Output
400-watt, four-channel amplifier, dual speaker outputs
Signal-to-Noise Ratio
80dB referenced to 1 watt, 90dB referenced to rated rated power
Frequency Response
(3dB) 10Hz-27kHz
4-Ohm Power Output
Proprietary DSP technology
2-Ohm Power Output
Connects to any analog signal
Width (mm)
Weight (lb)
Height (in)
Width (in)
Depth (in)
Weight (kg)
Depth (mm)
Height (mm)

Harness the DSP control and Class D power

The JBL® MS-A1004 digital amplifier refines the pursuit of powerful sound in your car without compromising space or performance. Through leading-edge electronic and industrial design, JBL engineers have created an iconic-looking, small-footprint, full-range, Class D amplifier featuring a digital input mixer that provides precise audio-signal control by leveraging the power of an onboard digital signal processing (DSP) engine. The DSP controls all output levels and active crossover attributes (including relative channel levels, slope, filter point and bandwidth) to exacting tolerances. The unit’s CEA®-2006 rated power is delivered at 4 x 100 watts into 4 ohms (2 x 200 watts into 2 ohms) through easy-connect speaker-output terminals accepting up to 10AWG wire. There are pass-through RCA audio outputs to connect additional amplifiers such as the companion MS-A5001 mono block. Professional-quality amplifier configuration and setup is easily completed with the included CD, the intuitive user controls and the bright, easy-to-read display on the top of the amplifier.

The MS-A1004 is an efficient, full-range, premium Class D car audio amplifier. Since the MS-A1004 offers a frequency response of 10Hz – 27kHz (–3 decibels), it doesn’t compromise on audio quality. Its Class D topology means lower current draw and operating temperatures, which translate into greater efficiency in delivering high-quality sound.
The MS-A1004 is a four-channel amplifier that can easily bridge channel pairs to deliver 2 x 200 watts into 2 ohms, which allows flexible configuration of one or more subwoofers, including a dual voice-coil (DVC) subwoofer. You can configure this full-range amplifier as a more powerful two-channel amplifier for premium front-component speakers or those in dedicated bandwidths such as midbass, midrange or high frequencies.
The MS-A1004 leverages the power of digital signal processing (DSP) with its unique input mixer. All output-level settings, channel assignments and active crossover functions are handled through this powerful DSP engine to highly accurate tolerances. Should power be disconnected or lost, the unit will retain all of your settings in a non-volatile memory. And DSP technology, found in many high-end signal processors, is built right in.
The MS-A1004 provides top-panel control via a combination LED display and rotary-encoder control with just two navigation buttons. All necessary setup processes are aided with a menu-driven CD that’s included with the unit. Once you set up the unit, you need never worry about the controls being pushed or tweaked, since all settings remain in the unit’s memory even when the power is disconnected.
The MS-A1004’s digital input mixer features 97 individual crossover settings between 20Hz and 20kHz, for either low- or high-pass configuration, to match the needs of speakers and system configuration precisely. In addition, the unit lets you select three different orders of response (roll-off): 6, 12 or 24 decibels/octave.
JBL engineers have built the MS-A1004 for complete compatibility with any OEM (original-equipment manufacturer) audio system. The unit accepts input-signal voltages of up to 20 volts. (Speaker-wire-to-RCA adapters are included.) It can turn on with a wired input ranging from +5 volts DC to the standard +12 volts DC, allowing more flexibility with low-voltage turn-on circuits. If there is no turn-on circuit, programmable signal sensing can turn the unit on whenever an audio signal is present.
Setting and matching the input levels of the MS-A1004 is an easy and precise exercise with the help of the included setup CD. After you connect and configure the inputs, simply feed the amplifier an input signal and raise the signal source level to its maximum (undistorted) output volume. Then adjust the input controls until the checkmark icon is displayed to indicate that the unit has reached its optimum setting.
The MS-A1004 includes a set of pass-through, pre-amp level RCA outputs that are unaffected by the input mixer so that you can add amplifiers without using splitters or Y-adapters. It’s an efficient way to provide system expansion flexibility without having to run additional cables or make any additional connections.
The MS-A1004 amplifier features robust connection terminals for power, ground, remote turn-on and speakers. The power/ground terminals accept up to 4AWG wire. (We recommend a minimum of 8AWG.) Speaker terminals for each channel pair accept up to 10AWG wire, making it easy to connect to either factory-installed or aftermarket speaker wiring.
The MS-A1004 amplifier has a modest footprint that allows you to install the unit just about anywhere. At 7-3/16 x 8-1/4 inches (183 x 210 millimetres), the mounting area is small enough to work in any vehicle without compromising space. With a height of only 2-3/4 inches (70 millimetres), the amplifier has plenty of clearance to fit under seats, behind panels or in other locations.

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