MXR M87 Bass Compressor Pedal Instruction Manual

1. Introduction

The MXR M87 Bass Compressor is designed to bring studio-quality compression to your bass rig. This pedal offers a comprehensive set of controls to fine-tune your sound, from subtle dynamic control to pronounced compression effects. Featuring CHT™ Constant Headroom Technology, it ensures clear performance and ample headroom. The transparent compression allows your full dynamic range to pass through until the signal reaches the compression threshold, which is visually indicated by ten bright gain-reduction status LEDs. Encased in a durable, lightweight aluminum housing, the M87 is built for the road.

Key Features:

• CHT™ Constant Headroom Technology for clear, clean performance.
• True bypass circuitry for uncolored tone when disengaged.
• Ten highly visible gain-reduction status LEDs for precise visual feedback.
• Transparent compression that preserves dynamic range until threshold.
• Durable, lightweight aluminum housing.

2. Controls and Features Overview

The MXR M87 Bass Compressor features a complete array of controls to shape your bass tone effectively.

Figure 1: Top view of the MXR M87 Bass Compressor, showing the control knobs and footswitch.

Control Knobs:

• ATTACK: Adjusts how quickly the compressor reacts to the input signal. Higher settings result in a slower attack, allowing more of the initial transient to pass through.
• RELEASE: Controls how quickly the compressor returns to its uncompressed state after the signal drops below the threshold. Higher settings result in a slower release.
• RATIO: Determines the amount of compression applied once the signal exceeds the threshold. Higher ratios mean more aggressive compression.
• INPUT: Sets the input level of your bass signal into the compressor. This control also affects when the compression threshold is met.
• OUTPUT: Adjusts the overall output volume of the pedal.

LED Indicators:

• GAIN REDUCTION LEDs: Ten bright LEDs provide visual feedback on the amount of gain reduction being applied in real-time. This helps in precisely setting the compression.
• STATUS LED: Indicates whether the pedal is engaged (on) or in true bypass mode (off).

Jacks and Footswitch:

Figure 2: Side view of the MXR M87 Bass Compressor, highlighting the input and output jacks.

• INPUT Jack: Connect your bass guitar or the output of another pedal to this 1/4-inch input.
• OUTPUT Jack: Connect this 1/4-inch output to your amplifier or the input of the next pedal in your signal chain.
• POWER Jack: Connect a 9V DC power adapter (not included) to this jack.
• BYPASS Footswitch: Toggles the effect on and off. The pedal features true bypass, ensuring your tone remains unaffected when the pedal is disengaged.

3. Setup

Follow these steps to set up your MXR M87 Bass Compressor:

1. Connect your bass guitar to the INPUT jack of the M87 using a standard 1/4-inch instrument cable.
2. Connect the OUTPUT jack of the M87 to your amplifier or the next pedal in your signal chain using another 1/4-inch instrument cable.
3. Connect a 9V DC power adapter (not included) to the POWER jack on the side of the pedal. Ensure the power supply meets the pedal's requirements (9V DC, center-negative).
4. Turn on your amplifier and adjust its volume to a suitable level.

4. Operating Instructions

The MXR M87 Bass Compressor is designed for intuitive operation. Experiment with the controls to find the perfect compression for your playing style and musical context.

Basic Operation:

1. Engage the pedal by pressing the BYPASS Footswitch. The STATUS LED will illuminate.
2. Start with all control knobs (ATTACK, RELEASE, RATIO, INPUT, OUTPUT) at their 12 o'clock positions.
3. Play your bass and adjust the INPUT knob until the GAIN REDUCTION LEDs show consistent activity, indicating that the compressor is engaging.
4. Adjust the RATIO knob to control the intensity of the compression. Lower ratios provide subtle smoothing, while higher ratios create a more pronounced, squashed effect.
5. Fine-tune the ATTACK and RELEASE knobs to shape the transient response and sustain characteristics. Faster attack settings will compress the initial pluck more, while slower attacks allow more punch. Faster release settings will return to uncompressed sound quickly, while slower releases provide longer sustain.
6. Use the OUTPUT knob to match the volume of the compressed signal to your bypassed signal, or to provide a boost if desired.

Tips for Tone Shaping:

• For subtle peak limiting and dynamic control, use a lower RATIO setting (e.g., 2:1 or 4:1) with moderate INPUT.
• To achieve a more sustained and punchy tone, increase the RATIO and adjust ATTACK to be slightly slower, allowing the initial transient to cut through before compression engages.
• The GAIN REDUCTION LEDs are crucial for understanding how the compressor is reacting to your playing. Aim for consistent, but not excessive, gain reduction for natural-sounding compression.

5. Specifications

6. Maintenance

To ensure the longevity and optimal performance of your MXR M87 Bass Compressor, follow these maintenance guidelines:

• Cleaning: Use a soft, dry cloth to clean the pedal's exterior. Avoid abrasive cleaners or solvents, as they may damage the finish.
• Storage: Store the pedal in a cool, dry place away from direct sunlight and extreme temperatures. If storing for an extended period, remove any batteries to prevent leakage.
• Connections: Periodically check all input/output jacks and power connections for any signs of wear or corrosion. Ensure cables are securely plugged in during use.
• Power Supply: Always use a regulated 9V DC, center-negative power supply to prevent damage to the pedal.

7. Troubleshooting

If you encounter issues with your MXR M87 Bass Compressor, refer to the following common troubleshooting steps:

• No Sound:
  • Check all cable connections (instrument, amplifier, power).
  • Ensure the power supply is correctly connected and functioning.
  • Verify that your instrument and amplifier are working correctly by bypassing the pedal.
  • Check the OUTPUT knob setting; ensure it is not turned down completely.
• Unwanted Noise/Hum:
  • Ensure you are using a high-quality, isolated power supply.
  • Check for faulty cables.
  • Try the pedal in a different location to rule out electrical interference.
  • Adjust the INPUT and OUTPUT knobs to avoid overdriving your amplifier or other pedals.
• Compression Not Engaging:
  • Increase the INPUT knob setting. The GAIN REDUCTION LEDs should light up when compression is active.
  • Ensure the RATIO knob is set above its minimum value.

8. What's in the Box

Your MXR M87 Bass Compressor package includes:

• MXR Bass Compressor Pedal

9. Warranty and Support

For warranty information and technical support, please refer to the official MXR website or contact your authorized dealer. Keep your proof of purchase for any warranty claims.