JL Audio
JL Audio MM55-HR Hidden Marine Source Unit w/ 4-Channel Amp 010-03372-00 (99977)
JL Audio MM55-HR Hidden Marine Source Unit w/ 4-Channel Amp 010-03372-00 (99977)
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JL Audio MediaMaster MM55-HR is a premium hidden marine source unit with a built-in 4-channel amplifier and multi-zone control, designed for vessels where the “brain” of the system is tucked away and controlled from remote locations or an MFD. It delivers high-fidelity audio, full 3-zone management, and extensive connectivity while keeping the dash clean and focused on helm controls.
This hideaway receiver includes a 25W x 4 (100W total) built-in amplifier for Zones 1 and 2, plus nine channels of 4V preamp outputs across three audio zones, each with its own dedicated subwoofer output. With Bluetooth® streaming, global AM/FM tuner, USB audio, analog AUX input, and NMEA 2000® network connectivity, the MM55-HR is built to be the centralized audio hub for serious marine systems.
Key Features
- Premium hidden marine source unit with built-in 4-channel amplifier
- Up to three independent audio zones, each with its own subwoofer output
- Nine channels of 4V preamp outputs (front/rear/sub per zone)
- Integrated Bluetooth® audio streaming with high-fidelity codec support
- Global AM/FM tuner with preset storage
- Rear USB 2.0 input for music files and device charging
- Rear stereo AUX RCA input for external sources
- NMEA 2000® compatible for control via supported MFDs or JL network remotes
- IP67-rated water-resistant design for real marine environments
Technical Specifications
| Model | MediaMaster MM55-HR |
| Part Number | 010-03372-00 |
| Built-In Amplifier | 25W RMS x 4 @ 4Ω (Zones 1 & 2) |
| Preamp Outputs | 9 channels, 4V RMS (front/rear/sub for Zones 1–3) |
| Zones | 3 independent audio zones with dedicated sub outputs |
| Inputs | Bluetooth audio, AM/FM tuner, rear USB, rear stereo AUX RCA |
| Network | NMEA 2000® compliant (MFD and network remote control) |
| Preout Voltage | 4V RMS (selectable fixed output levels where applicable) |
| Operating Voltage | 10 – 16 VDC |
| Recommended Fuse | 15A |
| Standby Current Draw | Approx. 100 mA |
| Operating Temperature | -4°F to +149°F (-20°C to +65°C) |
| Water Resistance | IP67-rated marine construction |
| Physical Dimensions | Approx. 7.7" W × 5.0" D × 2.3" H |
Zone & Audio Management
- Three discrete audio zones with individual level control
- Dedicated subwoofer level control per zone
- Onboard crossovers per zone (selectable high-pass and low-pass points)
- Independent tone controls (bass, midrange, treble, balance)
- Zone naming for easy identification on compatible controllers
- Zone volume limits to cap maximum output in specific areas
Control & Integration
- Designed to be controlled via JL MediaMaster MMR-40 network controller (sold separately)
- Compatible with supported NMEA 2000® multifunction displays for on-screen audio control
- Works with JL Audio wired and wireless remote options (sold separately)
- MediaMaster Remote app support for smartphone-based control (where available)
Ideal Applications
- Premium multi-zone marine audio systems
- Center-console, cruiser, yacht, and pontoon installs needing a hidden source
- Systems built around MFD control instead of a traditional head unit on the dash
What’s in the Box
- JL Audio MediaMaster MM55-HR hidden source unit
- Power / speaker / preout harness
- Mounting hardware
- Documentation
Why Buy From MCOR Automotive
- Authorized JL Audio dealer
- Real-world marine and powersports system design experience
- Support for multi-zone, MFD-controlled audio architectures
- 20+ years in high-end 12-volt and marine integration
Fitment & Installation Help
Need help confirming fitment or installation parts? Use our Fit Guide or contact us through the chat button before ordering.
Authorized Retailer & Warranty
MCOR Automotive is an authorized JL Audio / Garmin retailer. Products purchased from MCOR include applicable manufacturer warranty coverage when installed and used according to manufacturer guidelines.
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