JBL MA5055 5-Channel Marine Amplifier

The JBL MA5055 is a five-channel marine amplifier designed to power four cabin or tower speakers plus a dedicated subwoofer from one compact chassis. It helps simplify a boat-audio upgrade by combining full-range and bass amplification in a single unit. RCA preamp inputs and speaker-level inputs provide connection options for both aftermarket marine stereos and factory-installed systems.

This amplifier is suited to boat owners building a complete amplified system without adding separate multi-channel and mono amplifiers. Its front and rear channels can run full-range speakers, while the dedicated subwoofer channel handles bass reinforcement. The design also supports 4-ohm bridged operation on the front or rear channel pairs when a system layout calls for it.

At 14.4 volts, the MA5055 is rated for 50 watts RMS x 4 plus 320 watts RMS x 1 at 4 ohms, or 75 watts RMS x 4 plus 500 watts RMS x 1 at 2 ohms. Variable high-pass and low-pass filters let the speaker channels be tailored to the system, while the subwoofer channel has its own low-pass filter. A selectable subwoofer phase setting and adjustable bass boost provide additional bass-system tuning control.

JBL uses a Class AB+D amplifier design and Balanced Differential Inputs in the MA5055. The differential input design is intended to reduce noise and distortion and help resist radiated engine noise in a marine installation. Adjustable input sensitivity accommodates both line-level and speaker-level source signals.

The MA5055 can serve as the foundation of a five-channel marine audio upgrade, with direct outputs for front speakers, rear speakers, and one subwoofer. An included wired remote bass controller gives the user convenient adjustment of the subwoofer level from the helm area. Built-in protection circuitry monitors for shorts, high temperature, overvoltage, and undervoltage conditions, with an LED status indicator.

Key Features

• Five-Channel Configuration: Powers four full-range speakers and one subwoofer from a single amplifier.
• Class AB+D Design: Combines JBL's specified AB+D amplifier architecture in a compact marine amplifier.
• High- and Low-Level Inputs: Connects to RCA-equipped aftermarket receivers or speaker-level factory-system outputs.
• Variable Crossovers: Lets you set high-pass, low-pass, or full-range operation for front and rear channels.
• Subwoofer Tuning Controls: Provides low-pass filtering, 0-12 dB bass boost, and 0/180-degree phase selection.
• Wired Bass Remote Included: Allows convenient adjustment of subwoofer output level from the listening position.

Design & Installation

The MA5055 uses a low-profile chassis measuring 14-3/16 inches wide, 2-1/16 inches high, and 7-1/8 inches deep. Its control panel is protected by a removable cover, helping keep gain, crossover, phase, and bass-boost settings organized after setup. JBL specifies a 3.98 kg (8.77 lb) amplifier weight and a maximum operating temperature of 45°C.

Make wiring connections before permanently mounting the amplifier, then choose a secure location with adequate air circulation. JBL recommends 4-gauge power and ground cable; wiring and power-distribution hardware are not included. Do not mount the heat sink facing downward, and keep wiring clear of the vessel hull, fuel lines, moving cargo, and other boat systems.