The QSC RMX 850 Power Amplifier is a robust, reliable, and efficient piece of audio equipment designed to deliver high-quality sound reinforcement.

It is part of QSC’s RMX Series, which is known for combining professional audio performance with reliability and affordability.

This amplifier is well-suited for a variety of applications, including live sound reinforcement, installations, and studio work. Its features, design, and performance capabilities make it a versatile choice for audio professionals and enthusiasts alike.

Power and Performance

• Power Output: The RMX 850 provides 200 watts per channel into 8 ohms, 300 watts per channel into 4 ohms, and 430 watts per channel into 2 ohms. In bridged mono mode, it delivers 600 watts into 8 ohms and 830 watts into 4 ohms.
• High Current Capacity: The amplifier is capable of delivering high current to drive even the most demanding speaker loads without distortion.
• Class AB+B Topology: This design combines the efficiency of Class B with the linearity of Class AB, ensuring high-quality audio reproduction with minimal crossover distortion.

Build Quality and Reliability

• Rugged Construction: The RMX 850 features a robust chassis made from high-quality materials, ensuring durability and longevity even in harsh environments.
• Efficient Cooling: The amplifier is equipped with a rear-to-front airflow system and variable-speed fan, which help maintain optimal operating temperatures and prevent overheating.
• Protection Mechanisms: It includes comprehensive protection circuitry against DC, infrasonic, thermal overload, and short circuits, ensuring safe operation and longevity of the unit.

• Balanced XLR and 1/4″ TRS Inputs: These inputs provide versatile connectivity options, allowing the amplifier to interface with a wide range of audio sources.
• Binding Post and SpeakON Outputs: These outputs offer secure and reliable connections to speakers, with SpeakON connectors ensuring a robust connection that can handle high power levels.
• User-Friendly Controls: The front panel features detented gain controls for precise adjustment, along with signal and clip LED indicators for easy monitoring of performance and status.

Additional Features

• Low-Frequency Filter: Selectable 30 Hz and 50 Hz low-cut filters help remove unwanted low-frequency rumble and protect speakers from over-excursion.
• Slew Rate and Damping Factor: The amplifier boasts a high slew rate for rapid signal response and a high damping factor for tight, controlled bass performance.

Power Ratings

• Stereo Mode (per channel):
  • 8 ohms: 200 watts
  • 4 ohms: 300 watts
  • 2 ohms: 430 watts
• Bridged Mono Mode:
  • 8 ohms: 600 watts
  • 4 ohms: 830 watts

Frequency Response

• 20 Hz to 20 kHz: ±0.5 dB

Signal-to-Noise Ratio

• 100 dB: Below rated output (20 Hz to 20 kHz, unweighted)

Total Harmonic Distortion (THD)

• <0.05%: (20 Hz to 20 kHz, 10 dB below rated output)

Damping Factor

• >200: (20 Hz to 400 Hz)

Input Sensitivity and Impedance

• 1.15V RMS: for 8 ohms
• 10 kΩ: balanced
• 5 kΩ: unbalanced

Slew Rate

• 30 V/μs

Exterior Design

The QSC RMX 850 Power Amplifier features a sleek and professional exterior design, with a rugged metal chassis that is built to withstand the rigors of both road use and permanent installations. The front panel includes user-friendly controls and indicators, while the rear panel provides all necessary connectivity options.

Front Panel

• Power Switch: Located on the left side for easy access.
• Gain Controls: Detented knobs for each channel, allowing precise adjustment of input levels.
• LED Indicators: Signal, clip, and protect indicators for each channel, providing at-a-glance monitoring of the amplifier’s status.

Rear Panel

• Input Connectors: Balanced XLR and 1/4″ TRS inputs for flexible connectivity.
• Output Connectors: Binding posts and SpeakON connectors for secure speaker connections.
• Mode Switches: Stereo, parallel, and bridged mono mode selection.
• Low-Frequency Filter Switches: Selectable 30 Hz and 50 Hz low-cut filters

Live Sound Reinforcement

The QSC RMX 850 is an excellent choice for live sound reinforcement applications, thanks to its high power output and robust design. It can drive a wide range of speaker systems, making it suitable for small to medium-sized venues, such as clubs, houses of worship, and outdoor events.

Permanent Installations

For permanent installations, the RMX 850 offers reliable performance and long-term durability. Its efficient cooling system ensures stable operation even in environments with limited ventilation, and its protection circuitry provides peace of mind by safeguarding against common issues such as thermal overload and short circuits.

Studio Use

In the studio, the RMX 850 excels in providing clean, high-fidelity amplification for monitoring systems. Its low total harmonic distortion and high signal-to-noise ratio ensure accurate audio reproduction, making it a valuable tool for mixing and mastering engineers.

Initial Setup

Setting up the QSC RMX 850 is straightforward. Begin by connecting the amplifier to your audio source using either the balanced XLR or 1/4″ TRS inputs. Next, connect your speakers using the binding post or SpeakON outputs. Ensure that the amplifier is set to the appropriate mode (stereo, parallel, or bridged mono) and that the low-frequency filters are configured as needed.

Powering On and Adjustments

Once all connections are secure, power on the amplifier using the front panel switch. Use the gain controls to adjust the input levels, monitoring the signal and clip LED indicators to ensure optimal performance without distortion. If necessary, engage the low-frequency filters to remove unwanted low-end rumble.

Monitoring and Maintenance

Regularly check the amplifier’s performance by observing the front panel indicators and listening for any signs of distortion or anomalies. Periodic maintenance, such as cleaning the fan and vents, will help ensure long-term reliability and performance.

High-Quality Sound

The RMX 850’s Class AB+B topology and high slew rate contribute to its excellent sound quality, characterized by clear highs, detailed mids, and tight, controlled bass. Its low total harmonic distortion ensures that your audio remains clean and accurate, even at high power levels.

Reliability and Durability

With its rugged construction and comprehensive protection circuitry, the RMX 850 is built to last. Whether used in a mobile rig or a permanent installation, it delivers consistent performance and can withstand the demands of professional use.

Versatility

The RMX 850’s versatile connectivity options, mode selection, and low-frequency filters make it suitable for a wide range of applications. From live sound and installations to studio monitoring, this amplifier can handle diverse audio needs with ease.

Cost-Effective

Despite its professional-grade features and performance, the RMX 850 is priced competitively, offering excellent value for money. It provides high-end audio quality and reliability at a fraction of the cost of some other professional amplifiers.

The QSC RMX 850 Power Amplifier is a powerful, reliable, and versatile tool for audio professionals. Its combination of high power output, robust construction, and superior sound quality make it an excellent choice for live sound reinforcement, permanent installations, and studio use. With its user-friendly controls, efficient cooling system, and comprehensive protection circuitry, the RMX 850 ensures both outstanding performance and peace of mind. Whether you’re a sound engineer, a musician, or an installation professional, this amplifier is designed to meet and exceed your audio amplification needs.