Alpine S2-A120M S-Series Mono Subwoofer Amplifier and RUX-KNOB.2 Remote Bass Knob User Manual

1. Introduction

This manual provides comprehensive instructions for the Alpine S2-A120M S-Series Class-D Mono Subwoofer Amplifier and the Alpine RUX-KNOB.2 Remote Bass Knob. It covers essential information regarding product features, proper setup, operational guidelines, maintenance procedures, troubleshooting common issues, and detailed technical specifications. Please read this manual thoroughly before installation and operation to ensure correct usage and optimal performance.

2. Product Overview

2.1. Key Features

S2-A120M Amplifier: Class-D Mono Subwoofer Amplifier with 1200W RMS power output at 1 or 2 Ohms.
Features Alpine's Class D Amplifier Circuitry.
Designed with a two-sided terminal layout for efficient wiring.
Includes built-in selectable and adjustable crossovers.
Compatible with optional remote bass knobs (RUX-KNOB.2 or RUX-H01).
RUX-KNOB.2 Remote Bass Knob: Allows for convenient adjustment of amplifier bass gain from within the vehicle cabin.
Supports multiple amplifier control with telephone cord adapters.

2.2. Components

The product bundle includes the Alpine S2-A120M Mono Subwoofer Amplifier and the Alpine RUX-KNOB.2 Remote Bass Knob.

Alpine S2-A120M Amplifier and RUX-KNOB.2 Remote Bass Knob

Figure 1: Alpine S2-A120M S-Series Mono Subwoofer Amplifier and RUX-KNOB.2 Remote Bass Knob. This image displays the amplifier unit and the separate remote bass knob.

Figure 2: Top view of the Alpine S2-A120M Amplifier. The top panel features the Alpine logo and a central indicator light.

Close-up of Alpine RUX-KNOB.2 Remote Bass Knob

Figure 3: Close-up view of the Alpine RUX-KNOB.2 Remote Bass Knob. This image highlights the control knob and its mounting bracket.

3. Setup and Installation

Proper installation is crucial for the performance and longevity of your amplifier. It is recommended that installation be performed by a qualified professional.

3.1. Amplifier Placement

Choose a location that is dry, well-ventilated, and protected from direct sunlight or excessive heat.
Ensure adequate space around the amplifier for proper heat dissipation.
Mount the amplifier securely to prevent movement during vehicle operation.

3.2. Wiring Connections

The S2-A120M amplifier features a two-sided terminal layout for organized wiring.

Rear panel connections of Alpine S2-A120M Amplifier

Figure 4: Rear panel connections of the Alpine S2-A120M Amplifier. This view shows the power supply terminals (BATT, REM, GND) and speaker output terminals (SPK OUT).

Power Connection: Connect the main power cable from the vehicle battery to the BATT terminal. Ensure an appropriate fuse is installed close to the battery.
Ground Connection: Connect a short, heavy-gauge ground cable from the GND terminal to a clean, unpainted metal surface on the vehicle chassis.
Remote Turn-On: Connect a remote turn-on wire from your head unit to the REM terminal. This wire signals the amplifier to turn on and off with your audio system.
Audio Input: Connect RCA cables from your head unit's subwoofer output to the amplifier's input jacks (not explicitly shown in the provided image, but standard for amplifiers).
Speaker Output: Connect your subwoofer(s) to the SPK OUT terminals. Observe correct polarity (+ to + and - to -).

3.3. RUX-KNOB.2 Installation

The RUX-KNOB.2 remote bass knob connects to the amplifier via a telephone cord adapter. Install the knob in a convenient location within the vehicle cabin for easy access.

Mount the RUX-KNOB.2 using the provided bracket and screws.
Connect the telephone cord from the RUX-KNOB.2 to the designated remote bass knob port on the S2-A120M amplifier.

4. Operating Instructions

4.1. Initial Power-Up

After all connections are made, turn on your vehicle's ignition and audio system.
The amplifier's power indicator should illuminate.

4.2. Gain Adjustment

The gain control on the amplifier matches the output voltage of your head unit to the amplifier's input. Set the gain carefully to avoid distortion.

Start with the amplifier gain set to minimum.
Play a familiar music track with strong bass content.
Slowly increase the head unit volume until it reaches about 75-80% of its maximum.
Gradually increase the amplifier gain until you hear slight distortion, then back off slightly.

4.3. Crossover Settings

The S2-A120M features built-in selectable and adjustable crossovers to filter frequencies sent to your subwoofer.

Adjust the low-pass filter (LPF) to send only low frequencies to the subwoofer. A common starting point is 80-100 Hz.
Refer to your subwoofer's specifications for recommended crossover points.

4.4. Using the RUX-KNOB.2 Remote Bass Knob

The RUX-KNOB.2 allows for real-time adjustment of the subwoofer's bass level from the driver's seat.

Rotate the knob clockwise to increase bass output.
Rotate the knob counter-clockwise to decrease bass output.
This knob provides fine-tuning of the bass level without needing to access the amplifier directly.

5. Maintenance

Regular maintenance helps ensure the longevity and optimal performance of your Alpine amplifier and bass knob.

Cleaning: Periodically wipe the amplifier and bass knob with a soft, dry cloth to remove dust and debris. Avoid using harsh chemicals or abrasive cleaners.
Connection Check: Annually, inspect all wiring connections (power, ground, remote, RCA, speaker) to ensure they are secure and free from corrosion. Loose connections can lead to performance issues or damage.
Ventilation: Ensure that the amplifier's cooling fins are not obstructed to allow for proper heat dissipation.

6. Troubleshooting

If you encounter issues with your Alpine amplifier, refer to the following troubleshooting guide before seeking professional assistance.

Problem	Possible Cause	Solution
No Power / Amplifier Not Turning On	Blown fuse Loose power or ground connection Remote turn-on wire not connected or faulty	Check and replace fuses (battery and amplifier). Verify all power, ground, and remote connections are secure. Ensure head unit is providing a remote signal.
No Sound Output	Loose RCA input cables Incorrect speaker wiring Amplifier gain set too low Head unit volume too low or muted	Check RCA connections at both amplifier and head unit. Verify speaker wire polarity and connections. Adjust amplifier gain (refer to Section 4.2). Increase head unit volume.
Distorted Sound	Amplifier gain set too high Incorrect crossover settings Damaged speaker or subwoofer	Reduce amplifier gain (refer to Section 4.2). Adjust crossover settings (refer to Section 4.3). Inspect speakers/subwoofers for physical damage.
RUX-KNOB.2 Not Functioning	Loose or disconnected telephone cord Incompatible amplifier (though S2-A120M is compatible)	Ensure the telephone cord is securely connected at both ends. Verify the knob is connected to the correct port on the amplifier.

7. Specifications

7.1. Alpine S2-A120M Amplifier

Power Output (14.4V, <0.1% THD+N):
- 600W x 1 @ 4Ω
- 1200W x 1 @ 2Ω
- 1200W x 1 @ 1Ω
Signal-to-Noise Ratio (S/N Ratio): >85dB
Frequency Response: 20Hz – 400Hz
Damping Factor: >750
Dimensions (W x H x D): 13.1” x 2.25” x 8.25” (33.27 cm x 5.72 cm x 20.96 cm)
Weight: Approximately 8 lbs, 11 oz (3.94 kg)

7.2. Alpine RUX-KNOB.2 Remote Bass Knob

Function: Remote bass gain adjustment for compatible Alpine amplifiers.
Compatibility: Designed for use with S2-A120M and other compatible Alpine amplifiers (e.g., MRX-M50, MRX-M100, MRX-V60, PDX-M12, PDX-M6).
Connection: Via telephone cord adapter.

8. Warranty and Support

For warranty information and technical support, please refer to the official Alpine website or contact Alpine customer service directly. Keep your purchase receipt as proof of purchase for warranty claims.

Alpine Customer Support: Visit Alpine's Support Page

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Alpine S2-A120M