QSC RMX850 Power Amplifier User Manual

Introduction

This manual provides essential information for the safe and efficient operation of your QSC RMX850 Power Amplifier. The RMX Series amplifiers are designed to deliver clean, dynamic power with the renowned QSC sound quality and reliability. Please read this manual thoroughly before operating the amplifier to ensure proper setup and performance.

Figure 1: Front view of the QSC RMX850 Power Amplifier, showing the QSC logo, RMX 850 model name, power switch, power indicator, and channel gain controls with clip/signal indicators.

Safety Information

Always observe the following safety precautions to prevent electric shock, fire, or damage to the unit:

• Power Source: Connect the amplifier only to the type of power source indicated on the unit. Ensure the voltage is correct for your region.
• Grounding: Always use a grounded power cord. Do not defeat the grounding plug.
• Ventilation: Ensure adequate ventilation. Do not block ventilation openings. Maintain at least 2 inches (5 cm) of clear space around the amplifier for airflow.
• Moisture: Do not expose the amplifier to rain or moisture. Do not place objects filled with liquids on the amplifier.
• Servicing: Do not attempt to service this unit yourself. Refer all servicing to qualified service personnel.
• Overload: Avoid operating the amplifier at excessive volume levels for extended periods, which can cause hearing damage or damage to connected speakers.

Key Features

The QSC RMX850 Power Amplifier offers a robust set of features for professional audio applications:

• Compact Size: Designed for efficient use of rack space.
• Versatile Inputs: Features 1/4" (6.3mm) TRS, XLR, and barrier strip balanced inputs for broad compatibility.
• Flexible Outputs: Equipped with binding post and Neutrik Speakon outputs.
• Front-Mounted Controls: Gain controls are conveniently located on the front panel for easy access and adjustment.
• Selectable Low-Frequency Filters: Includes 30 Hz or 50 Hz low-frequency filters to protect speakers and increase headroom.

Setup

1. Unpacking and Inspection

Carefully remove the amplifier from its packaging. Inspect the unit for any signs of damage that may have occurred during shipping. If damage is found, contact your dealer immediately.

2. Placement and Mounting

The RMX850 is designed for standard 19-inch rack mounting. Ensure the rack provides adequate ventilation. If not rack-mounted, place the amplifier on a stable, level surface, ensuring that the ventilation grilles are not obstructed.

Figure 2: Multiple QSC RMX series amplifiers, including the RMX850, shown stacked, illustrating typical rack mounting configuration and the importance of ventilation.

3. Connections

Before making any connections, ensure the amplifier is powered off and unplugged from the AC outlet.

Figure 3: Rear view of the QSC RMX850 Power Amplifier, highlighting the input (XLR, TRS, barrier strip) and output (Speakon, binding post) connectors, along with the fan and power inlet.

• Input Connections: Connect your audio source (mixer, preamplifier) to the amplifier's input jacks. The RMX850 provides XLR, 1/4" TRS, and barrier strip connectors for balanced input signals. Use high-quality shielded cables.
• Output Connections: Connect your speakers to the amplifier's output terminals. The RMX850 features both Neutrik Speakon and binding post outputs. Ensure correct polarity (+ to + and - to -) for all speaker connections. Verify that your speakers' impedance matches the amplifier's specifications (e.g., 4 ohms or 8 ohms per channel).
• Power Connection: Once all audio connections are made, connect the supplied AC power cord to the amplifier's power inlet and then to a grounded AC outlet.

4. DIP Switch Settings (Rear Panel)

The RMX850 features DIP switches on the rear panel to configure various settings, including low-frequency filters and operating modes (stereo, parallel, bridge). Consult the detailed diagram on the amplifier's rear panel or a more comprehensive technical manual for specific configurations. Ensure these are set correctly for your application before powering on.

Operating the Amplifier

1. Powering On

After all connections are secure and verified, turn the gain controls on the front panel fully counter-clockwise (minimum). Then, press the power switch to turn on the amplifier. The power indicator LED will illuminate.

2. Adjusting Gain

Slowly turn the gain controls clockwise for each channel until the desired volume level is achieved. Monitor the signal and clip indicator LEDs:

• SIGNAL LED: Illuminates when an audio signal is present.
• CLIP LED: Illuminates when the amplifier output is clipping (distorting). Reduce the gain immediately if this LED lights up frequently or stays on. Occasional, brief flashes on dynamic peaks are acceptable, but continuous illumination indicates severe clipping and potential damage to speakers.

3. Low-Frequency Filters

The selectable low-frequency filters (30 Hz or 50 Hz) help protect speakers from damaging sub-sonic frequencies and improve overall system headroom. Engage these filters via the DIP switches on the rear panel as needed for your speaker system.

Maintenance

The QSC RMX850 Power Amplifier is designed for reliable operation with minimal maintenance. However, regular care will ensure its longevity:

• Cleaning: Use a soft, dry cloth to clean the exterior of the amplifier. Do not use abrasive cleaners or solvents.
• Ventilation: Periodically check that the ventilation grilles are free from dust and debris. Use a soft brush or vacuum cleaner to remove any accumulation.
• Connections: Occasionally check all input and output connections to ensure they are secure.

Troubleshooting

If the problem persists after attempting these solutions, please contact QSC customer support or a qualified service technician.

Specifications

Warranty and Support

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

QSC Official Website: www.qsc.com