BOSS CL-50 Compressor Limiter

Introduction

Thank you for choosing the BOSS CL-50 Compressor Limiter. To ensure you fully enjoy its capabilities and achieve lasting satisfaction, please read this Owner's Manual thoroughly before use.

Features

• The CL-50 is a high-performance dynamic processor offering compressor, limiter, and gate functions.
• It features a superior VCA for excellent SN ratio and low distortion, ensuring high sound quality.
• Gain Reduction Indicators provide clear visual feedback on operating status and settings.
• Equipped with a Detector In Jack for signal-correlated control and a Stereo Link Jack for synchronizing two CL-50 units.
• Optional RAD-50 Rack Mount Adaptor allows two units to be mounted in a standard 19-inch rack.

Important Notes

Power Supply

• Use only the manufacturer-supplied AC adaptor (BOSS BRA Series). Using other adaptors may cause damage, malfunction, or electric shock.
• Always turn off all equipment power before making connections to prevent damage or malfunction.
• Avoid using the unit on the same power circuit as devices that generate line noise (e.g., motors, variable lighting systems).
• Ensure your installation's line voltage matches the unit's requirement as indicated on the nameplate.
• Protect the power cord from damage; do not step on it or place heavy objects on it.
• When disconnecting the AC adaptor, grasp the plug, not the cord.
• Unplug the power cord if the unit will be unused for an extended period.

Placement

• Avoid temperature extremes (e.g., direct sunlight in a vehicle).
• Do not use or store in dusty, humid, or high-vibration areas.
• Using the unit near power amplifiers or equipment with large transformers may induce hum.
• The unit may interfere with radio and television reception; do not use it near such receivers.

Maintenance

• For daily cleaning, wipe with a soft, dry cloth. For slightly damp cleaning, use a slightly water-dampened cloth.
• For stubborn dirt, use a mild neutral detergent, then wipe thoroughly with a dry cloth.
• Never use benzene, thinners, alcohol, or solvents, as they can cause discoloration or deformation.

Additional Precautions

• Protect the unit from strong impact.
• Do not allow objects or liquids to penetrate the unit. If this occurs, discontinue use and contact qualified service personnel immediately.
• Never strike or apply strong pressure to the display.
• Before using the unit in a foreign country, consult with qualified service personnel.
• If a malfunction occurs or is suspected, discontinue use immediately and contact qualified service personnel.

What the CL-50 Can Do

The CL-50 integrates three essential audio processing functions: Compressor, Limiter, and Gate. Understanding their principles is key to effective use.

Compressor/Limiter

Both functions compress the input signal, differing in their application and parameters like Threshold Level and Ratio.

Compressor: Averages signals to create a more controlled and consistent amplitude.

Limiter: Protects equipment from excessively powerful input signals and prevents distortion.

Threshold Level

This is the signal level at which the Compressor/Limiter begins to operate. Signals below this level are output without compression.

Ratio

The Ratio defines the degree of compression applied to signals exceeding the Threshold Level. For example, a 2:1 ratio means that for every 2 dB the input signal exceeds the threshold, the output signal increases by only 1 dB.

Diagram Description: A graph showing Input Level (dBm) on the x-axis and Output Level (dBm) on the y-axis. A diagonal line represents the normal signal path. When the signal exceeds the Threshold Level, the line flattens to a slope determined by the Ratio (e.g., 'a' to 'b' represents a 2:1 ratio). Attack Time and Release Time are indicated on the time axis.

Attack Time

The time it takes for the compressor to reach its set compression value after the input signal surpasses the Threshold Level.

Release Time

The time it takes for the compression to be released and the signal to return to normal after it drops below the Threshold Level.

Diagram Description: A graph showing signal level over time. The input signal rises above the Threshold Level, triggering compression. The signal is then compressed for a duration (Attack Time) and released (Release Time) as the signal drops below the Threshold Level.

Gate

The Gate function mutes signals that fall below a specified Threshold Level, useful for eliminating noise during silent passages or muting unwanted sounds.

Gate Threshold Level

The signal level at which the Gate begins to operate. Signals below this level are attenuated.

Decay Time

The time it takes for the sound to be completely muted after the input signal drops below the Threshold Level. This is also referred to as the attenuating time.

Making Connections

The CL-50 offers versatile connection options for various audio setups.

Diagram Description: A diagram illustrating typical connections. An AC adaptor connects to the unit. A foot switch (optional) can be connected for remote control. Input signals from Guitar, Bass Guitar, or Keyboard are connected to the Input jack. The output can go to a Guitar Amplifier, Power Amplifier, or Tape Recorder. A stereo setup shows two CL-50s linked via Stereo Link jacks, connected to a mixer and audio signal distributor.

• AC Adaptor Jack: Connects to the supplied BOSS BRA Series AC Adaptor (120, 220, 240V).
• Comp Remote Jack: Connects to an optional foot switch (e.g., FS-5L) for remote control of the Comp/Gate switch. Set the front panel switch to "In" (▶️) when using a foot switch.
• Gate: Stereo Link Jack: Connects to the corresponding jack on another CL-50 for synchronized Gate operation in stereo.
• Comp: Stereo Link Jack: Connects to the corresponding jack on another CL-50 for synchronized Compressor/Limiter operation in stereo.
• Detector In Jack: Allows external signals to control the Compressor/Limiter/Gate functions.
• Output Jack: Provides the processed audio output.
• Level Switch: Selects the rated input/output level (-10dBm or +4dBm). For most instruments like guitars, set to "-10dBm". Changing this switch may affect Threshold Level settings.
• Input Jack: Receives the input signal.

Diagram Description: An illustration showing how to attach rubber feet to the unit if the optional Rack Mount Adaptor is not used.

Panel Descriptions

Front Panel

Diagram Description: An illustration of the CL-50's front panel with numbered controls and indicators.

1. Overload Indicator: Lights when the input signal is too high. It illuminates 6dB before the clipping point where distortion begins.
2. Input Level Knob: Adjusts the input signal level. Typically set to "0". If the Overload Indicator lights frequently, reduce the input level by turning this knob counterclockwise (◀️) until the indicator only lights on input peaks. Adjusting this knob after setting Limiter/Gate Thresholds will change the effective levels.
3. Output Level Knob: Sets the final output signal level.
4. Gain Reduction Indicators: Display the amount of compression (in dB) applied by the Compressor/Limiter.
5. Limiter: Threshold Knob: Adjusts the Threshold Level for the Compressor/Limiter. Turning counterclockwise (◀️) lowers the threshold and increases the effect.
6. Limiter: Ratio Knob: Sets the compression ratio. A setting of "1:1" bypasses the Compressor/Limiter effect. The ratio determines how much compression is applied to signals above the threshold.
7. Limiter: Attack Knob: Adjusts the Attack Time. Clockwise rotation (▶️) increases the Attack Time.
8. Limiter: Release Knob: Adjusts the Release Time. Clockwise rotation (▶️) increases the Release Time.
9. Gate Indicator: Lights when the input signal is below the Gate Threshold Level.
10. Gate: Threshold Knob: Adjusts the Threshold Level for the Gate. Clockwise rotation (▶️) increases the threshold. Setting to "OFF" disables the Gate.
11. Gate: Decay Knob: Adjusts the time it takes for the sound to decay after the signal drops below the Gate Threshold. Clockwise rotation (▶️) increases the Decay Time.
12. Comp Indicator: Lights when the Comp/Gate switch is set to "In" (▶️), indicating the effect is active.
13. Comp/Gate Switch: Selects whether the Compressor/Limiter/Gate is active ("In" ▶️) or bypassed ("Out" ◀️). When bypassed, the signal passes directly to the output.
14. Power Indicator: Lights when the Power Switch is turned on, indicating the unit is ready for operation.
15. Power Switch: Turns the unit's power on or off. When "On" (▶️), the Power Indicator lights up. Ensure your amplifier's volume is set to "0" before turning on the unit. A brief muting circuit is active for a few seconds after power-on.

Rear Panel

Diagram Description: An illustration of the CL-50's rear panel with numbered jacks.

16. Adaptor Jack: For connecting the AC adaptor.
17. Comp Remote Jack: For connecting an optional foot switch to control the Comp/Gate function.
18. Gate: Stereo Link Jack: For stereo linking of the Gate function with another CL-50.
19. Comp: Stereo Link Jack: For stereo linking of the Compressor/Limiter function with another CL-50.
20. Detector In Jack: For connecting an external signal to control processing.
21. Output Jack: For audio output.
22. Level Switch: Selects output level (-10dBm or +4dBm). Set to "-10dBm" for instruments like guitars.
23. Input Jack: For audio input.

Setup Examples

The CL-50 can be used in various configurations to enhance your audio.

• Limiter Applications: Connect before a tape deck for clear, distortion-free recordings, or before an amplifier to protect it from excessive input levels.
• Compressor with Vocals: Use to achieve clear, distortion-free vocal recordings with increased perceived level, especially for vocals with wide dynamic range.
• With Guitar or Bass: Creates a crisp, uniform sound for rhythm guitar playing. For bass, it can suppress peaks when using techniques like "slap" for a more balanced output.
• Use as a Noise Gate: Positioned at the end of an effects chain, it can eliminate unwanted noise generated by multiple effects units, particularly during silent moments.
• Use as a Signal Gate: Can eliminate lingering sounds from instruments like bass drums for a tighter sound, or remove stray sounds when recording with microphones for cleaner results.

Diagram Description: Front panel settings are shown for Limiter Applications, Compressor with Vocals, Guitar/Bass use, Noise Gate, and Signal Gate.

Further Applications for the CL-50

Leveraging the Detector In and Stereo Link jacks enables advanced applications.

• Use as a De-esser with Vocals: To increase vocal clarity and reduce harshness, the Limiter can be applied specifically to a frequency band (e.g., around 6 kHz). This targets abrasive sounds without sacrificing overall clarity.
• Use in Stereo as a Limiter: Two CL-50 units can be linked via their "Comp" Stereo Link jacks to provide identical limiting for both left and right channels in a stereo setup.

Diagram Description: A setup for de-essing vocals shows a microphone connected to a pre-amplifier/mixer, which then feeds into a graphic equalizer and an audio signal distributor. The CL-50 is placed in the signal path, likely after the equalizer, with its Detector In jack potentially used for frequency-specific control. The output goes to a mixer. Another diagram illustrates a stereo limiting setup where two CL-50 units are connected in tandem via their stereo link jacks, feeding into a mixer and then a power amplifier.

Block Diagram

Diagram Description: A detailed block diagram illustrates the internal signal flow of the CL-50. The input signal enters and is processed through stages including level adjustment, a VCA (Voltage Controlled Amplifier) for compression/limiting, and a noise gate. Envelope followers process signal dynamics to control these stages. A detector circuit receives input signals (possibly from the Detector In jack) to influence the processing. Indicators like Overload, Gain Reduction, and Gate status are shown. Stereo Link and Remote jacks are also depicted. The output stage includes level adjustment and amplification before reaching the output jack.

Specifications

Controls

• Input Level
• Output Level
• Compressor/Limiter: Threshold, Ratio, Attack, Release
• Gate: Threshold, Decay

Switches

• Power
• Comp/Gate In/Out
• Level Switch

Indicators

• Power
• Comp IN/Out
• Overload
• Gain Reduction
• Gate

Jacks

• Input
• Output
• Detector In
• Stereo Link (Comp)
• Stereo Link (Gate)
• Remote
• AC Adaptor

General

• Rated Input/Output Level: -10dBm / +4dBm
• Input Impedance: 1MΩ
• Output Impedance: 600Ω
• Frequency Response: 20Hz to 35kHz (-3dB)
• Residual Noise: Less than -95dBm (A-type) (Level Switch: -10dBm)
• Total Harmonic Distortion: Less than 0.005%
• Input Gain: -40 to +12dB
• Output Gain: -40 to +12dB
• Compressor/Limiter Threshold: -40 to +10dBm (Level Switch: -10dBm)
• Compressor/Limiter Ratio: 1:1 to 10:1
• Attack Time: 0.5ms to 20ms
• Release Time: 70ms to 1s
• Gate Threshold: -40 to +10dBm (Level Switch: -10dBm)
• Gate Decay Time: 25ms to 20s
• Power: 12V AC (BOSS BRA-120, 220, 240)
• Current Draw: 450mA
• Dimensions: 210(W) x 44(H) x 205(D) mm (8-3/8"(W) x 1-3/4"(H) x 8-1/16"(D))
• Weight: 1.4kg / 3lb 2oz
• Accessories: AC Adaptor (BOSS BRA-120, 220, 240), Foot Rubber x4
• Options: Rack Mount Adaptor RAD-50 (Not attachable to Rack Mount Adaptor RAD-50), Foot Switch FS-5L

Information

For repair service, please contact your local Roland Service Station or authorized Roland distributor.

Contact information for Roland service stations and distributors in various countries including U.S.A., Canada, West Germany, Spain, Hungary, Belgium/Holland/Luxembourg, Denmark, Sweden, Norway, Finland, Italy, Switzerland, France, Austria, Greece, Portugal, Brazil, Australia, New Zealand, and United Kingdom is provided. This information was current as of July 11, 1990.