Gravity MGR-208BT Marine Stereo and Speaker System User Manual

1. Introduction and Overview

This manual provides detailed instructions for the installation, operation, and maintenance of your Gravity MGR-208BT Marine Stereo and Speaker System. Designed for marine environments, this system features a waterproof stereo receiver and 6.5-inch marine speakers with built-in LED lights, Bluetooth connectivity, and various audio playback options.

Image 1.1: The Gravity MGR-208BT Marine Stereo unit with two 6.5-inch marine speakers.

2. Safety Information

• Always disconnect the vehicle's battery before beginning any installation to prevent electrical shorts.
• Ensure all wiring connections are secure and properly insulated to prevent damage from moisture and vibration.
• Do not operate the stereo system at excessively high volumes for prolonged periods, as this may cause hearing damage.
• This product is designed for marine use with weather-resistant features. However, avoid direct high-pressure water jets on the unit.
• Consult a professional installer if you are unsure about any part of the installation process.

3. Package Contents

Please verify that all items listed below are included in your package:

• 1 x Gravity MGR-208BT Bluetooth Marine Receiver
• 2 x Gravity 6.5-inch Marine Speakers with LED Lights
• 1 x Wire Harness
• 2 x Stereo Removal Keys
• 1 x User Manual (this document)
• 1 x Remote Control

Image 3.1: The Gravity MGR-208BT Marine Stereo Receiver unit.

Image 3.2: Two Gravity 6.5-inch Marine Speakers featuring built-in blue LED illumination.

Image 3.3: The remote control for the Gravity MGR-208BT Marine Stereo.

4. Setup and Installation

4.1 Stereo Receiver Installation

1. Mounting Location: Choose a suitable location in your vessel that is protected from direct exposure to extreme weather conditions, although the unit is designed with a conformal-coated PCB for enhanced durability against moisture.
2. Power Connection: Connect the yellow wire (constant 12V) to a constant 12V power source, the red wire (accessory 12V) to a switched 12V source, and the black wire (ground) to a reliable chassis ground.
3. Speaker Connections: Connect the speaker wires from the stereo's wire harness to your marine speakers. Ensure correct polarity (+/-) for optimal sound performance. The MGR-208BT supports a 4-channel output.
4. Antenna: Connect your marine antenna to the designated input on the stereo.
5. Secure Unit: Slide the stereo into the mounting sleeve until it clicks into place.

4.2 Speaker Installation

The 6.5-inch marine speakers feature a low-profile design for easy integration into various marine watercrafts and off-road vehicles.

1. Mounting Location: Select a flat surface for mounting. Ensure there is sufficient depth behind the mounting surface for the speaker magnet.
2. Cut-out: Use the provided template (if applicable, or refer to specifications for cut-out dimensions) to cut a circular opening for each speaker.
3. Wiring: Connect the speaker wires from the stereo to the terminals on the back of each speaker. Observe correct polarity.
4. Secure Speakers: Mount the speakers using the supplied screws, ensuring a snug fit.

Image 4.1: Rear view of a Gravity MG680-LW marine speaker, showing wiring terminals and specifications.

5. Operating Instructions

5.1 Basic Operation

• Power On/Off: Press the PWR button to turn the unit on or off.
• Volume Control: Rotate the central knob to adjust the volume level.
• Source Selection: Press the MODE button to cycle through available sources: Radio (AM/FM), CD, USB, AUX, and Bluetooth.

5.2 Bluetooth Operation

1. Pairing: Select Bluetooth mode. On your mobile device, search for available Bluetooth devices and select "MGR-208BT". Enter "0000" if a passcode is required.
2. Audio Streaming: Once paired, you can stream audio from your Bluetooth-enabled device to the stereo. Use your device or the stereo controls for playback (play/pause, skip track).
3. Built-in Microphone: The stereo includes a built-in Bluetooth microphone for hands-free calling.

5.3 USB and AUX Input

• USB Playback: Insert a USB drive into the front USB port. The unit will automatically switch to USB mode and begin playing compatible audio files (MP3, WMA, AAC, WAV, FLAC).
• AUX Input: Connect an external audio device (e.g., MP3 player) to the front AUX input using a 3.5mm audio cable. Select AUX mode to play audio from the connected device.
• iPod/iPhone Connection: Direct connection for iPod/iPhone is supported with an optional cable.

5.4 CD Playback

• Insert a CD into the disc slot. The unit will automatically switch to CD mode and begin playback.
• The unit plays CDs, CD-Rs, and CD-RW discs, including those loaded with MP3, WMA, AAC, and WAV music files.

5.5 Audio Settings

• Tone Controls: Press the SEL button repeatedly to access Bass and Treble adjustments. Use the volume knob to adjust values (Bass: +/-10dB, Treble: +/-10dB).
• Drive EQs: Improves sound quality to compensate for exterior noise.
• Sound Reconstruction: Restores fullness to compressed digital files.
• Low-Pass Filter & Sub Level Control: Adjust these settings for optimal subwoofer performance, if connected.
• Speaker Setting Function: Optimize audio output for different sizes and types of speakers.

5.6 Display and Faceplate

• The unit features a glare-resistant white display with variable-color illumination (up to 5 different tones).
• The faceplate is removable for theft deterrence. To remove, press the release button and gently pull the faceplate off. Store it in the provided case.

Image 5.1: The Gravity MGR-208BT Marine Stereo with its removable faceplate detached.

Image 5.2: The removable faceplate of the Gravity MGR-208BT stored in its protective case.

6. Maintenance

• Cleaning: Use a soft, damp cloth to clean the stereo unit and speakers. Avoid abrasive cleaners or solvents.
• Faceplate Care: When removed, store the faceplate in its protective case to prevent scratches and damage.
• Connections: Periodically check all wiring connections for corrosion or looseness, especially in marine environments.
• Water Resistance: While the speakers are waterproof and the stereo has a conformal-coated PCB, ensure all covers (like USB/AUX input covers) are securely closed when not in use to maintain weather resistance.

7. Troubleshooting

8. Specifications

• Model: MGR-208BT
• Connectivity Technology: Bluetooth, USB
• Special Feature: Waterproof (speakers), Conformal-coated PCB (stereo)
• Compatible Devices: Smartphone, Speaker
• Connector Type: USB
• Audio Output Mode: Stereo
• Surround Sound Channel Configuration: 4 channel
• Amplifier: Built-in MOSFET amplifier (22 watts RMS/50 peak x 4 channels)
• Playback Formats: CDs, CD-Rs, CD-RWs, MP3, WMA, AAC, WAV (via CD/USB), FLAC (via USB)
• Display: Glare-resistant white display, variable-color illumination (up to 5 tones)
• Tone Controls: Bass +/-10dB, Treble +/-10dB
• Additional Audio Features: Drive EQs, Sound Reconstruction, Low-pass filter, Sub level control, Speaker Setting function
• Faceplate: Removable theft-deterrent faceplate
• Item Weight: Approximately 9.7 pounds (total package)
• Product Dimensions: Approximately 9 x 12 x 8 inches (package)

9. Warranty and Support

Your Gravity MGR-208BT Marine Stereo and Speaker System is covered by a manufacturer's warranty. Please refer to the warranty card included in your package for specific terms and conditions, including warranty duration and coverage details.

For technical support, troubleshooting assistance, or warranty claims, please contact your retailer or the manufacturer's customer service department. Contact information can typically be found on the product packaging or the manufacturer's official website.