Shure SCM268 4-Channel Microphone Mixer User Manual

1. Introduction

This manual provides comprehensive instructions for the setup, operation, and maintenance of your Shure SCM268 4-Channel Microphone Mixer. The SCM268 is designed for professional audio applications requiring reliable microphone mixing with essential features.

Figure 1: Front view of the Shure SCM268 Microphone Mixer. This image shows the compact design suitable for half-rack spaces.

2. Safety Information

Please read and understand these safety instructions before operating the device. Keep this manual for future reference.

• Power Source: Connect the unit only to the specified power supply type indicated on the device.
• Ventilation: Ensure proper ventilation. Do not block ventilation openings.
• Water and Moisture: Do not expose the unit to rain or moisture. Do not use near water.
• Servicing: Refer all servicing to qualified service personnel. Do not attempt to service this product yourself.
• Cleaning: Clean only with a dry cloth.

3. Package Contents

Verify that all items are present in the package:

• Shure SCM268 4-Channel Microphone Mixer
• 6 Transformers
• IEC Power Cord Connector
• Rack mounting hardware

4. Key Features

The Shure SCM268 offers the following features:

• Four transformer-balanced microphone inputs.
• 12V phantom power for condenser microphones.
• Built-in low-cut filters on microphone inputs.
• Five unbalanced auxiliary level inputs (Phono connectors).
• One unbalanced auxiliary level output (Phono connector).
• One transformer-balanced microphone/line level output (XLR connector).
• Juke Box Muting function: Mutes background audio when a connected jukebox is active.
• Paging with Ducking function: Allows the SCM268 to function as a paging mixer, automatically reducing background audio during announcements.
• Half-rack space design with included rack mounting hardware.

5. Controls and Connectors

Familiarize yourself with the input and output connections and controls on the SCM268.

Figure 2: Rear panel of the Shure SCM268. This image details the power input, microphone inputs, auxiliary inputs/outputs, and main output.

Rear Panel Overview:

• IEC Power Connector: For connecting the AC power cord.
• MIC/LINE OUT (XLR): Main balanced output, with a switch to select between microphone and line level. A red LED indicates signal presence.
• AUX OUT (Phono): Unbalanced auxiliary output.
• AUX LEVEL INPUTS (Phono): Five unbalanced auxiliary inputs (labeled AUX IN, 1, 2, 3, 4).
• MIC LEVEL INPUTS (XLR): Four balanced microphone inputs (labeled 1, 2, 3, 4).
• 12V PHANTOM Switch: Activates 12V phantom power for condenser microphones on inputs 1-4.
• OFF/ON Switch: Power switch for the unit.

6. Setup

6.1 Power Connection

1. Ensure the SCM268 is switched OFF.
2. Connect the supplied IEC power cord to the IEC Power Connector on the rear panel.
3. Plug the other end of the power cord into a suitable AC power outlet.

6.2 Microphone Connections

1. Connect your microphones to the MIC LEVEL INPUTS (XLR) 1-4 on the rear panel.
2. If using condenser microphones requiring phantom power, set the 12V PHANTOM switch to ON. For dynamic microphones, ensure this switch is OFF.

6.3 Auxiliary Device Connections

1. Connect line-level audio sources (e.g., CD players, media players) to the AUX LEVEL INPUTS (Phono).
2. Use the AUX IN for general auxiliary input, or inputs 1-4 for dedicated sources.

6.4 Output Connection

1. Connect the MIC/LINE OUT (XLR) to your amplifier, powered speakers, or recording device.
2. Ensure the MIC/LINE switch next to the XLR output is set to the appropriate level (MIC for microphone-level input on the receiving device, LINE for line-level input).
3. The AUX OUT (Phono) can be used for an additional unbalanced line-level output, such as for monitoring or connecting to another auxiliary input.

7. Operating Instructions

7.1 Powering On

After all connections are made, switch the OFF/ON switch to ON. The power indicator LED will illuminate.

7.2 Adjusting Levels

The SCM268 is designed for set-and-forget operation. Input levels are automatically managed. Ensure your source devices (microphones, auxiliary players) are providing appropriate signal levels.

7.3 Low-Cut Filters

The built-in low-cut filters on the microphone inputs help reduce unwanted low-frequency noise (e.g., rumble, handling noise). These are always active.

7.4 Juke Box Muting Function

To utilize the Juke Box Muting feature, connect the control output from a compatible jukebox to a designated auxiliary input. When the jukebox is active, the SCM268 will automatically mute other background audio sources connected to its auxiliary inputs.

7.5 Paging with Ducking Function

For paging applications, connect the paging microphone to one of the MIC LEVEL INPUTS. When audio is detected from the paging microphone, the SCM268 will automatically reduce (duck) the level of other audio sources, allowing the page to be heard clearly. The background audio will return to its normal level once the paging announcement concludes.

8. Maintenance

The Shure SCM268 requires minimal maintenance.

• Cleaning: Disconnect the unit from power before cleaning. Use a soft, dry cloth to wipe the exterior. Do not use liquid cleaners or solvents.
• Storage: Store the unit in a cool, dry place away from direct sunlight and extreme temperatures.
• Inspection: Periodically check all cables for damage and ensure connections are secure.

9. Troubleshooting

10. Specifications

11. Warranty and Support

11.1 Warranty Information

The Shure SCM268 is covered by a 1-year limited warranty from the date of purchase. For full warranty terms and conditions, please refer to the official warranty document available on the Shure website or included with your product. A PDF version of the warranty can be found here.

11.2 Customer Support

For technical assistance, service, or further information, please visit the official Shure website or contact Shure customer support. You can find more information at the Shure Store on Amazon.

12. Product Video

Watch the official Shure brand video for an overview of Shure's commitment to sound quality.