JL Audio MediaMaster MM55-HR Hidden Marine Source Unit, NMEA 2000 MFD Control, 10-16V DC, 25W x 4 @ 4 Ohm

Overview

The JL Audio 010-03372-00 is a hidden marine source unit that brings Bluetooth, radio, and USB audio into a three-zone boat system, with control handled through NMEA 2000. It runs on 12 V negative-ground power (10 V to 16 V input), includes a built-in 4-channel amplifier rated 25 W x 4 at 4 ohms, and uses a 15 A fuse.

This is meant to mount out of sight in a console or behind a panel, then get operated from a compatible NMEA 2000 control option at the helm and around the boat. The chassis measures 7.68 in x 2.28 in x 4.96 in (195 mm x 58 mm x 126 mm), which helps when you are planning a protected mounting spot with room for cabling and airflow.

Key features

• Hideaway receiver format for installs where you want the stereo brain tucked away and the dash kept for navigation and switches.
• NMEA 2000 connectivity with Micro-C connector and LEN 1 for integration on a vessel backbone.
• Three audio zones (Z1, Z2, Z3) with separate line-level outputs for left, right, and subwoofer per zone.
• Built-in 4-channel amplifier (25 W x 4 at 4 ohms) with 2 ohm minimum per channel support.
• Speaker-level outputs for Zone 1 and Zone 2, plus dedicated RCA outputs for all zones for systems that mix internal power and external amplifiers.
• Preamp output voltage up to 4 V RMS, with fixed output options selectable at 4 V, 2 V, or 1 V RMS.
• Bluetooth audio streaming supports SBC and Qualcomm aptX, with connection range up to 35 ft (11 m) in open space.
• AM and FM tuner with RDS, plus DAB+ tuning support and up to 18 presets across tuners.
• USB 2.0 input plays MP3, MP4, WAV, AAC, M4A, M4B files and provides up to 1 A device charging.
• Water-resistant construction for typical marine exposure; avoid submersion and high-pressure spray.

Compatibility and control

The unit needs a compatible NMEA 2000 control option to operate. Full functionality is available through a network controller, or through a compatible multifunction display when used with the appropriate MFD data interface. NMEA 2000 control compatibility depends on the entertainment PGNs supported by the display and may require software updates on the helm side.

Electrical and network integration

Power is for 12 V negative-ground systems only. Plan for a clean 10 V to 16 V DC supply, protect the circuit with a 15 A fuse, and keep grounding solid to avoid noise in the audio system. If your boat is 24 V, use a proper DC-DC converter that can handle peak current demand.

On the network side, the Micro-C NMEA 2000 connection drops onto your backbone like any other device, so you will want an open T-connector and correct termination in place. The three-zone layout is a practical fit for boats with separate listening areas such as cockpit, cabin, and bow seating, where each zone needs its own level and tone control.

Installation notes

Choose a dry, well-ventilated location and mount it securely so vibration and pounding do not stress the connectors. If the boat sees frequent washdowns, keep the unit away from direct spray and leave a drip loop on wiring where possible. When routing power, speaker, and RCA runs, keep them away from ignition wiring and high-current conductors, and use grommets and loom anywhere the harness passes through fiberglass or metal.

Who it suits on board

This setup fits boats where you want the head unit out of sight and you already have, or plan to add, networked control at the helm and around the vessel. It also makes sense for multi-zone systems that use internal amplification for a couple of areas while feeding external amps for larger zones.

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Returns may be requested within 30 days of receiving your order. Items must be unused, uninstalled, unaltered, and returned in their original packaging with all tags, packing materials, blank warranty cards, manuals, instructions, accessories, and included items. Certain products, including installed or used electronics, electrical components, lighting, consumables, custom or special-order items, cut-to-length products, safety equipment, and merchandise exposed to water or marine conditions, may not be eligible for return.

To request a return, sign in to your account and select the applicable order and items, and submit your request for review. Eligible unfulfilled items may also be submitted for cancellation within 1 hour of placing the order. Returns or cancellations are not considered approved until you receive confirmation from Apollo Lighting. Please do not ship or drop off merchandise before receiving return approval and instructions.

Customers are responsible for arranging and paying for return shipping unless the return is due to an error by Apollo Lighting or the item is verified as defective, damaged, or incorrect. Missing, damaged, defective, or incorrect items must be reported within 2 business days of delivery, and photos or other documentation may be required for review. If the issue is verified, Apollo Lighting may provide or reimburse return shipping and issue a replacement or refund depending on the circumstances. International customers are responsible for return shipping, duties, taxes, customs charges, brokerage fees, and other costs associated with an international return.

After your return is received and inspected, approved refunds are issued to the original payment method and may take 5-7 business days to appear after processing. Original shipping and handling charges are nonrefundable, and the value of any included free items that are not returned may be deducted from the refund. Apollo Lighting does not charge a standard restocking fee on eligible returns. Returns that are incomplete, damaged, installed, used, altered, improperly packaged, or otherwise do not meet the eligibility requirements may be refused. We recommend using a trackable and appropriately insured shipping service for all customer-arranged returns.

For assistance, contact info@apollolighting.com or call +1 (954) 375-0100.

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Many products sold by Apollo Lighting include a manufacturer's warranty covering defects in materials or workmanship. Warranty terms vary by brand, product category, and model, so eligibility, coverage duration, exclusions, and available remedies are determined by the applicable manufacturer. We recommend reviewing the warranty information provided with your product before installation or use, especially for marine electronics, navigation equipment, lighting, electrical systems, pumps, safety equipment, and other specialized marine products.

If you need warranty service, the claim must follow the process established by the manufacturer, authorized service center, or designated warranty provider. You may be asked for proof of purchase, a serial number, product registration, photos, maintenance or installation records, or other documentation. Apollo Lighting does not determine or modify a manufacturer's warranty coverage or final claim decision, but we are happy to help provide purchase information and direct you to the appropriate manufacturer or warranty resource.

Keep your receipt, product documentation, serial number information, and original packaging when practical. Damage caused by normal wear, misuse, improper installation, insufficient maintenance, corrosion, impact, unauthorized modifications, electrical issues, or operation outside the manufacturer's specifications may not be covered. Warranty claims are separate from standard returns, so a product that has been installed, used, or exposed to marine conditions may no longer qualify for return while still remaining eligible for evaluation under the manufacturer's applicable warranty.

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