Introduction
Thank you for choosing the LEGACY LA978 1200 Watt 2 Channel Bridgeable Mosfet Amplifier. This manual provides detailed instructions for installation, operation, and maintenance to ensure optimal performance and longevity of your amplifier. Please read this manual thoroughly before attempting installation or operation.
Key Features
- 600 Watts x 2 Output (Stereo)
- 1200 Watts x 1 Bridged Output (Mono)
- Variable Hi/Lo Electronic Crossover Network
- Variable Bass Boost
- Variable Input Level (Gain) Control
- MOSFET PWM Power Supply
- Power ON LED Indicator
- LED Protection Indicator
- Remote Bass Boost Capability
- Hi/Lo Impedance Input
- Thermal / Overload / Short Circuit Protection
- Anti-Thump Turn-On Circuitry
Safety Information
Important Safety Instructions:
- Always disconnect the vehicle's battery negative terminal before starting any installation.
- Ensure proper grounding to prevent electrical hazards.
- Use appropriate gauge wiring for power and speaker connections to avoid overheating and damage.
- Mount the amplifier securely in a well-ventilated area, away from moisture and direct sunlight.
- Do not operate the amplifier if it has been exposed to water or sustained physical damage.
- Seek professional assistance if you are unsure about any installation steps.
Setup and Installation
Proper installation is crucial for the performance and safety of your amplifier. Refer to the diagrams below for connection details.
Mounting the Amplifier
Choose a mounting location that is dry, well-ventilated, and secure. Avoid mounting on carpet or in enclosed spaces that restrict airflow. Ensure sufficient space around the amplifier for heat dissipation.
Image: Top view of the Legacy LA978 amplifier, showing its compact design and heat sink fins. This image illustrates the overall physical appearance of the unit.
Power Connections
- +12V (Power): Connect directly to the positive terminal of the vehicle's battery using a fuse holder within 18 inches of the battery.
- GND (Ground): Connect to a clean, unpainted metal surface of the vehicle chassis. Ensure a solid connection.
- REM (Remote Turn-On): Connect to the remote output of your head unit. This wire turns the amplifier on and off with your car stereo.
Audio Input Connections
- RCA Inputs (Low-Level): Connect to the RCA pre-amp outputs of your head unit.
- High-Level Inputs: If your head unit does not have RCA outputs, use the high-level inputs by connecting them to your speaker wires.
Speaker Output Connections
- Stereo Mode (2-Channel): Connect one speaker to the left channel outputs (+ and -) and another speaker to the right channel outputs (+ and -).
- Bridged Mode (1-Channel Mono): For higher power output to a single subwoofer, bridge the amplifier. Connect the positive terminal of the speaker to the positive output of one channel and the negative terminal of the speaker to the negative output of the other channel (refer to specific bridging instructions on the amplifier or in a detailed wiring diagram). The LA978 offers 1200 Watts x 1 bridged output.
Operating Instructions
Once installed, adjust the amplifier settings for optimal sound performance.
Variable Input Level (Gain) Control
This control matches the amplifier's input sensitivity to the output of your head unit. Start with the gain control at minimum, then slowly increase it until you hear distortion, then back it off slightly. Do not use the gain control as a volume knob.
Variable Hi/Lo Electronic Crossover Network
Use the crossover controls to filter frequencies. A Low Pass Filter (LPF) allows only low frequencies to pass, ideal for subwoofers. A High Pass Filter (HPF) allows only high frequencies to pass, ideal for full-range speakers or tweeters. Adjust these settings to match your speakers' capabilities and desired sound.
Variable Bass Boost
This feature allows you to increase the bass output at a specific frequency. Use sparingly to avoid distortion and potential speaker damage. The amplifier also supports a Remote Bass Boost for convenient adjustment from the driver's seat (remote sold separately or included depending on package).
LED Indicators
- Power ON LED: Illuminates when the amplifier is receiving power and operating normally.
- Protection LED: Illuminates when the amplifier detects a fault (e.g., thermal overload, short circuit, low voltage). If this LED lights up, immediately turn off your audio system and troubleshoot the issue.
Maintenance
- Cleaning: Use a soft, dry cloth to clean the amplifier's exterior. Do not use harsh chemicals or abrasive cleaners.
- Ventilation: Ensure that the amplifier's cooling fins are free from dust and obstructions to maintain proper airflow and prevent overheating.
- Connections: Periodically check all power, ground, and speaker connections to ensure they are secure and free from corrosion.
Troubleshooting
If you experience issues with your amplifier, refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| No Power (Power LED Off) | Blown fuse, loose power/ground/remote wire, faulty head unit remote output. | Check fuse, verify all power connections, test remote wire for 12V. |
| Protection LED On | Short circuit in speaker wiring, amplifier overheating, low voltage. | Check speaker wires for shorts, ensure proper ventilation, verify battery voltage. Allow amplifier to cool down. |
| No Sound Output | Loose RCA cables, incorrect gain setting, speaker wires disconnected, head unit settings. | Check all audio connections, adjust gain, verify speaker connections, check head unit output. |
| Distorted Sound | Gain set too high, improper crossover settings, damaged speakers, poor ground connection. | Reduce gain, adjust crossover, inspect speakers, ensure solid ground connection. |
Specifications
| Feature | Detail |
|---|---|
| Model Number | LA978 |
| Output Power (Stereo) | 600 Watts x 2 Channels |
| Output Power (Bridged) | 1200 Watts x 1 Channel |
| Amplifier Class | MOSFET PWM Power Supply |
| Input Level Control | Variable Gain |
| Crossover Network | Variable Hi/Lo Electronic |
| Bass Boost | Variable, Remote Capable |
| Input Impedance | Hi/Lo Impedance Input |
| Protection Features | Thermal / Overload / Short Circuit |
| Turn-On Circuitry | Anti-Thump |
| Dimensions (H x W x L) | 2.09" H x 12.17" W x 13.50" L (Product Description) |
| Item Weight | 10.4 pounds |
| Product Dimensions | 19.29 x 13.9 x 4.53 inches (Packaging/Shipping) |
| ASIN | B000MCELBU |
| UPC | 068888880664 |
Warranty Information
The LEGACY LA978 amplifier comes with a 1-Year Limited Warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use. It does not cover damage resulting from improper installation, accident, misuse, abuse, neglect, unauthorized repair, or modification. Please retain your proof of purchase for warranty claims.
Support
For technical assistance, troubleshooting, or warranty inquiries, please contact LEGACY customer support. Refer to the official LEGACY website for the most current contact information.
Note: Product specifications and features are subject to change without notice.
