QSC CMX300Va (Factory Re-Certified)

  • $549.99

The New CMXa Series is an economical and rugged power amplifier designed to meet the needs of system integrators. It is based upon the proven, rock-solid, reliable performance found in the award winning RMX Series. The CMXa feature sets are designed for wide-ranging application in facilities such as performance halls, houses of worship, sports clubs, gymnasiums, dance venues, pubs, and FGM/BGM systems. The CMXa Series provides unmatched performance, the right power for the job and an affordable price point

Proven and Reliable Power Plant 

CMXa amplifiers incorporate everything QSC has learned in more than forty years of striving to deliver worry-free operations without failures. The design of these amplifiers starts with our world-class power supplies. The CMXa uses a powerful, high-current toroidal transformer and filtering to ensure generous energy reserves. This allows the amplifiers to effortlessly handle high-level transients, even when driving abusive 2 ohm speaker loads. 

The amplifier output sections feature rugged class AB and class H architecture depending on power level. Efficient class H output sections on the CMX 800Va and CMX 2000Va reduce AC current draw and cut down on waste heat. 

All CMXa amplifiers are protected from damage from shorted outputs. Automatic current limiting protects the amplifier from damage until the short is corrected. 

CMXa amplifiers also feature DC protection systems to prevent loudspeaker damage in the unlikely event of an output transistor failure. DC voltage from the power supply is never passed directly to your speakers, even in the event of an output circuit failure.

Superior Performance

The CMXa amplifiers deliver true and accurate studio-quality sound. A full complementary output circuit using high-grade linear output devices generates accurate, flat-frequency response with low distortion. SMT (Surface Mount Technology) triples small-signal component density, enabling high power output in a 2 rack unit chassis (3 RU for the CMX 2000Va). Unlike other designs, CMXa output devices are directly mounted to the heat sink for optimum thermal coupling and cooling.

The CMXa Series is available in four models. Three 2-rackspace models range in power from 300 to 800 watts per channel at 4 ohms. One 3-rackspace model provides 2500 watts per channel at 2 ohms. All four models feature a compact chassis less than 16” deep. 

The V in the model name designates the ability to directly drive 70-volt and/or 100-volt distributed loudspeakers. The CMX 300Va and CMX 500Va must be configured for bridgedmono operation in order to directly drive high-impedance systems while the CMX 800Va and 2000Va may be used in either stereo or mono mode

For installations requiring a transformer isolated output, the CMX has optional accessories to cover your needs.


  • ”Flex-Use” loading options allows CMX Series amps to drive low-impedance loads down to 2 ohms, and certain models can direct-drive (no output transformer) 70V and 100V distributed loudspeaker systems
  • ”Flex-Use” input connectivity choices including actively balanced barrier strip, XLR, or ¼" TRS
  • ”Flex-Use” output connectivity choices include NL4 Speakon™ and detachable terminal block.
  • Rack mountable with chassis less than 16" (40.6 mm) deep
  • 1-dB recessed, detented gain controls for fast, accurate, and repeatable settings
  • Tamper-proof security cover for gain controls
  • Low-noise variable-speed fans with rear-to-front airflow help keep amplifiers and racks cool

Stereo Mode (both channels driven)

FTC: 20 Hz–20 kHz after preconditioning

EIA: 1 kHz

8Ω FTC 0.1% THD 185 W
8Ω EIA 0.1% THD 200 W
4Ω FTC 0.1% THD 280 W
4Ω EIA 0.5% THD 300 W
2Ω EIA 1% THD 430 W

Bridge Mono Mode

FTC: 20 Hz–20 kHz after preconditioning; both channels driven simultaneously

EIA: 1 kHz

8Ω FTC, 0.1% THD 530 W
8Ω EIA, 0.1% THD 600 W
4Ω EIA, 1% THD 830 W
Signal to Noise (20 Hz–20 kHz, 8Ω) > 100 dB
Input Sensitivity into 8Ω 1.15 V (+3.4 dBu)
Max Voltage Gain 31.6× (30 dB)
Max Voltage Gain 31.6× (30 dB)
Output Circuitry Class AB
Current Draw (pink noise program)
Typical, 1/8 power 4Ω, 120 V 4.4 A
Severe, 1/3 power 4Ω, 120 V 6.6 A
Distortion (SMPTE-IM) < 0.02%
Distortion (typical)

20 Hz–20 kHz: 10 dB below rated power - < 0.03% THD / 4Ω and 8Ω

1.0 kHz and below: full rated power - < 0.03% THD / 4Ω and 8Ω

Frequency Response 20 Hz–20 kHz: ±1 dB; -3 dB points: 5 Hz and 50 kHz
Input Impedance 10 kΩ unbalanced, 20 kΩ balanced
Input Clipping 10 V rms (+22 dBu)
Cooling Continuously variable-speed fan, rear-to-front air flow
Connectors (each channel)

Input: Active balanced; barrier strip, XLR and ¼" (6.3 mm) – TRS tip and XLR pin 2 positive

Output: Detachable terminal block and Neutrik™ Speakon™


Front: AC switch, Channels 1 & 2 gain knobs

Rear: 10-position DIP switch

Indicators Power-on: Green LED / Signal: Green LED (1 per channel) / Clip: Red LED (1 per channel)
Amplifier Protection Stable into reactive or mismatched loads
Load Protection On/off muting, AC coupling (CMX 300Va and CMX 500Va), triac crowbar (CMX 800Va and CMX 2000Va on each channel)
Power Requirements On/off muting, AC coupling (CMX 300Va and CMX 500Va), triac crowbar (CMX 800Va and CMX 2000Va on each channel)
Dimensions (HWD) 2 RU models 3.5" (8.9 cm) 2 rack spaces x 19" (48.3 cm) rack mounting x 15.9" (40 cm) deep to rear support ears
Weight - Shipping 41 Lb

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