1. Introduction
This manual provides detailed instructions for the proper installation, operation, and maintenance of your Memphis MJP822 MOJO Pro 8" Dual 2 Ohm Subwoofer. The MOJO Pro series subwoofers are engineered for high output and robust performance, designed to deliver powerful bass in various applications. Please read this manual thoroughly before attempting installation or operation to ensure optimal performance and safety.
2. Features
The Memphis MJP822 MOJO Pro Subwoofer incorporates advanced design elements for superior audio reproduction and durability:
- Specifically designed for high SPL (Sound Pressure Level) performance.
- DVVC (Direct Vent Voice Coil) Cooling system for enhanced thermal management.
- Equipped with a 2.5-inch Voice Coil for robust power handling.
- Cross-drilled front plate venting to further aid in cooling.
- Aluminum shorting ring for reduced inductance and improved linearity.
- Double-stitched foam surround for increased durability and excursion.
- Rigid paper cone for accurate and impactful bass reproduction.
- Progressive spider for controlled cone movement.
- Diecast basket for structural integrity and resonance reduction.
- Single-sided compression terminals for secure and convenient wiring.
3. Safety Information
Adhering to these safety guidelines is crucial for preventing damage to the subwoofer, your vehicle, and personal injury:
- Professional Installation Recommended: Due to the complexity of car audio systems, professional installation by a qualified technician is highly recommended.
- Power Handling: Do not exceed the rated RMS or peak power handling of the subwoofer. Overpowering can lead to permanent damage.
- Proper Enclosure: This subwoofer requires a properly designed and constructed enclosure for optimal performance and longevity. Consult a car audio professional or refer to recommended enclosure specifications.
- Wiring: Ensure all wiring is correctly connected, insulated, and secured to prevent short circuits and electrical hazards. Pay close attention to polarity.
- Volume Levels: Prolonged exposure to high sound pressure levels can cause permanent hearing damage. Exercise caution when adjusting volume.
- Vehicle Electrical System: Verify that your vehicle's electrical system can adequately support the power requirements of the subwoofer and amplifier. An upgraded alternator or battery may be necessary for high-power systems.
- Secure Mounting: Always ensure the subwoofer is securely mounted within its enclosure and the enclosure is securely fastened within the vehicle to prevent movement during driving or in the event of an accident.
4. Setup & Installation
Proper installation is critical for the performance and longevity of your MOJO Pro subwoofer. This subwoofer features a Dual Voice Coil (DVC) with a 2 Ohm impedance per coil, offering flexible wiring options.
4.1. Enclosure Requirements
The MJP822 is designed for use in custom-built enclosures. Consult a car audio specialist or refer to Memphis Audio's official resources for recommended sealed or ported enclosure volumes and tuning frequencies to match your specific application and desired sound characteristics.
- Mounting Depth: 5.6 inches
- Cut Out Diameter: 7.3 inches
4.2. Wiring Configurations (Dual 2 Ohm Voice Coils)
The MJP822 has two 2-ohm voice coils. Understanding how to wire these coils is essential to match the impedance requirements of your amplifier. Incorrect wiring can lead to amplifier damage or poor performance.
4.2.1. Parallel Wiring (1 Ohm Load)
Connecting the two 2-ohm voice coils in parallel will result in a 1-ohm total impedance load. This configuration draws more current and is suitable for amplifiers stable at 1 ohm.
- Connect the positive (+) terminal of Voice Coil 1 to the positive (+) terminal of Voice Coil 2.
- Connect the negative (-) terminal of Voice Coil 1 to the negative (-) terminal of Voice Coil 2.
- Connect the combined positive (+) terminals to the amplifier's positive (+) output.
- Connect the combined negative (-) terminals to the amplifier's negative (-) output.
4.2.2. Series Wiring (4 Ohm Load)
Connecting the two 2-ohm voice coils in series will result in a 4-ohm total impedance load. This configuration is less demanding on the amplifier and is often used for stability or when bridging amplifier channels.
- Connect the positive (+) terminal of Voice Coil 1 to the amplifier's positive (+) output.
- Connect the negative (-) terminal of Voice Coil 1 to the positive (+) terminal of Voice Coil 2.
- Connect the negative (-) terminal of Voice Coil 2 to the amplifier's negative (-) output.
4.3. Physical Installation
Once the enclosure is prepared and wiring is planned, carefully mount the subwoofer:
- Ensure the mounting surface is flat and free of obstructions.
- Carefully place the subwoofer into the cutout, aligning the mounting holes.
- Secure the subwoofer using appropriate screws, tightening them evenly to prevent warping the frame. Do not overtighten.
- Connect the speaker wires to the subwoofer's compression terminals, ensuring a tight and secure connection. Observe correct polarity.
- Secure the enclosure within the vehicle to prevent it from shifting during driving.
5. Operating Instructions
Once installed, follow these guidelines for optimal performance and longevity of your subwoofer:
- Break-in Period: Allow a break-in period of approximately 20-30 hours of normal listening before pushing the subwoofer to its limits. This allows the suspension components (surround and spider) to loosen up and reach their optimal compliance.
- Gain Setting: Properly set the gain on your amplifier. Do not use the gain control as a volume knob. It should be set to match the output voltage of your head unit to the amplifier's input sensitivity. Incorrect gain settings can lead to clipping and damage to the subwoofer.
- Crossover Settings: Utilize the low-pass filter (LPF) on your amplifier or head unit to send only low frequencies to the subwoofer. A typical LPF setting for an 8-inch subwoofer might be between 60Hz and 100Hz, depending on your system and preferences.
- Subsonic Filter: If your amplifier has a subsonic filter (HPF for the subwoofer channel), enable it and set it slightly below your enclosure's tuning frequency (for ported enclosures) or around 25-30Hz (for sealed enclosures) to protect the subwoofer from over-excursion at very low frequencies.
- Listen for Distortion: If you hear any distortion, rattling, or unpleasant sounds, immediately reduce the volume. Distortion indicates that the subwoofer or amplifier is being overdriven.
6. Maintenance
The Memphis MJP822 MOJO Pro subwoofer is designed for durability and requires minimal maintenance. However, periodic checks can help ensure its long-term performance:
- Cleaning: Gently wipe the cone and surround with a soft, dry cloth to remove dust and debris. Avoid using harsh chemicals or excessive moisture.
- Inspect Connections: Periodically check all wiring connections at the subwoofer and amplifier to ensure they remain tight and free of corrosion. Loose connections can lead to power loss or intermittent sound.
- Visual Inspection: Inspect the subwoofer's cone, surround, and spider for any signs of damage, tears, or fatigue. Address any issues promptly to prevent further damage.
- Enclosure Integrity: Ensure the subwoofer enclosure remains sealed and structurally sound. Air leaks or damaged enclosure panels can negatively impact performance.
7. Troubleshooting
If you experience issues with your MJP822 subwoofer, consult the following table for common problems and solutions. If the problem persists, contact a qualified car audio technician or Memphis Audio support.
| Problem | Possible Cause | Solution |
|---|---|---|
| No Sound from Subwoofer |
|
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| Distorted or Unclear Bass |
|
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| Subwoofer Overheating |
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8. Specifications
Key technical specifications for the Memphis MJP822 MOJO Pro 8" Dual 2 Ohm Subwoofer:
| Parameter | Value |
|---|---|
| Model Name | MJP822 |
| Speaker Size | 8 Inches |
| Voice Coil Configuration | Dual Voice Coil (DVC) 2 Ohm per coil |
| RMS Power Handling | 750 Watts |
| Peak Power Handling | 1500 Watts |
| Sensitivity (dB) | 82 dB |
| Magnet Size | 105 Oz |
| Voice Coil Diameter | 2.5 inches |
| Mounting Depth | 5.6 inches |
| Cut Out Diameter | 7.3 inches |
| Product Dimensions (D x W x H) | 8.5"D x 9.7"W x 9.8"H |
| Item Weight | 17.6 Pounds |
| Connectivity Technology | RCA (Implied for amplifier connection, not direct subwoofer connection) |
| Mounting Type | Flush Mount |
| UPC | 702588008323 |
9. Warranty & Support
Your Memphis MJP822 MOJO Pro Subwoofer comes with a Limited Warranty. The specific terms and duration of the warranty are subject to the policies of Memphis Audio and the retailer from whom the product was purchased. Please retain your proof of purchase for warranty claims.
For technical support, warranty inquiries, or service, please contact Memphis Audio directly or the authorized dealer where you purchased the product. You can find contact information on the official Memphis Audio website:
Visit Memphis Audio Official Website
Always refer to the official manufacturer's website for the most current warranty information and support resources.