MB Quart NA3-1000.5 5-Channel Waterproof Marine Amplifier

The MB Quart NA3-1000.5 is a five-channel marine amplifier designed to power a complete boat, powersports, or outdoor audio system from one weather-resistant chassis. It combines four full-range channels for speakers with a dedicated fifth channel for a subwoofer. This layout helps simplify system design when upgrading factory or aftermarket marine audio.

Channels 1 through 4 are intended for full-range speakers, while the dedicated Channel 5 subwoofer section provides low-frequency support. The amplifier is rated at 4 x 60 watts plus 1 x 350 watts RMS at 4 ohms, with the four full-range channels rated at 120 watts each at 2 ohms. Channel 5 is stable to 1 ohm for subwoofer applications.

The NA3-1000.5 uses MB Quart Class SQ circuitry for its multi-channel section and a Class Q1 mono design for Channel 5. Adjustable input sensitivity, electronic crossovers, and bass EQ allow the amplifier to be matched to compatible speakers, subwoofers, and source units. Its Q-Stasis preamplifier stage is designed to accept low-voltage source signals with minimal added distortion.

Marine-focused construction makes this amplifier suitable for installations exposed to water, dust, vibration, and changing outdoor conditions. It carries an IPX67 rating and uses marine-specific connectors. The gloss-white housing and concealed top-mounted control panel support a clean installation while keeping tuning controls protected.

This amplifier is a practical fit for systems using four cabin, tower, or deck speakers plus one subwoofer. RCA inputs are provided for source units with preamp outputs, while high-level input capability and DC-sense turn-on support integration with compatible source units that do not provide RCA outputs. A bass remote is included for convenient adjustment of the subwoofer channel level.

Key Features

• Five-Channel Layout: Powers four full-range speakers and one subwoofer from one amplifier.
• IPX67 Protection: Supports use in waterproof and dustproof marine-oriented installations.
• Dedicated Subwoofer Channel: Channel 5 is stable to 1 ohm and includes bass remote support.
• Variable Crossovers: Lets you set high-pass and low-pass filtering for appropriate speakers.
• Q-Stasis Preamplifier: Helps process low-voltage source signals with minimal distortion.
• Selectable Turn-On Methods: Supports remote-wire turn-on or DC-sense activation.

Design & Installation

The NA3-1000.5 has a gloss-white marine chassis with a top-mounted control panel concealed beneath a removable faceplate. Its marine-specific connectors, IPX67 rating, and protected control arrangement are intended for marine and powersports environments. LED protection diagnostics provide amplifier status feedback.

Install the amplifier on a secure surface with adequate airflow and do not mount it upside down. Use high-quality 10 AWG power and ground cable, connect the power lead through a fuse within 18 inches of the battery, and make the ground connection to clean bare metal near the amplifier. Use the front and rear high-pass filters for full-range speakers and the Channel 5 low-pass filter for a compatible subwoofer.