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QSC RMX 4050a Power Amplifier

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Item#: RMX4050A
UPC: 684284062864
Ships in 1-3 days
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About This Product

QSC RMX 4050a Power Amplifier

The RMXa Series is an update on a proven line of amplifiers line of amplifiers combining legendary QSC reliability, audio performance and affordability. Entertainers and touring users can continue to rely on the RMXa as one of the leading amplifier series in the world. For mid-power applications, the 2RU models offer 4Ω power ratings from 300 to 800 watts per channel. For premium loudspeaker systems with extremely high power capacity the 3RU models (RMX 4050a and RMX 5050a) are unchallenged.

The RMXa Series amplifiers from QSC offer true professional-quality performance at an affordable price.

Three 2-rackspace models range in power from 430 to 1200 watts per channel at 2 ohms. Two 3-rackspace models provide 2000 to 2500 watts per channel at 2 ohms. All five models feature a compact chassis less than 16” deep.

RMXa amplifiers include a comprehensive set of features including XLR and 1/4” balanced inputs, Speakon and binding post outposts for convenient connectivity. User-defeatable clip limiters and selectable low-frequency filters optimize sonic performance.

The RMX 4050a is a “heavy duty” model designed to work as hard into 2 ohm loads as most competing amplifiers will at 4 ohms.

Both the RMX 5050a and RMX 4050a feature a three-tier, Class H design that is extremely efficient at real world power levels. Less AC current is wasted and more available current goes into producing useful audio power. 120 volt versions of the RMX4050a accomplish all this with a standard 15 amp plug.

RMX 4050a Features:

  • Compact size — up to 2500 watts in two rack spaces, or 5000 watts in three rack spaces.
  • High-current toroidal transformers, for greater 2-ohm power and low noise.
  • Independent user-defeatable clip limiters reduce distortion.
  • Selectable low-frequency filters (30 Hz or 50 Hz) protect speakers and increase headroom.
  • The 4000-watt RMX4050a operates on a standard 15 amp plug (120V).
  • Both the RMX4050a and the RMX5050a feature a dual mono, high-current power supply for increased reliability and performance.
  • The RMX4050a's particularly exceptional combination of cooling capacity and electrical efficiency provides robust thermal performance suitable for high continuous power in 2-ohm stereo or 4-ohm bridged applications.
  • Balanced 1/4” (6.3 mm) TRS, XLR, and barrier strip inputs.
  • Touch-proof binding post and Neutrik Speakon outputs.
  • Front mounted gain controls for easy access.
  • Signal and clip LED indicators for monitoring performance.
  • Independent DC and thermal overload protection on each channel automatically protects amplifier and speakers.
  • 3-year warranty plus optional 3-year extended service contract.
QSC RMX 4050a Specifications
 Model RMX 850a RMX 1450a RMX 2450a RMX 4050a RMX 5050a
Power per Channel, Stereo Mode (both channels driven)
8Ω, FTC 20 Hz–20 kHz, 0.1% tdD 185 W 260 W 450 W 800 (650**) W 1050 W
8Ω, EIA 1 kHz, 0.1% tdD 200 W 300 W 500 W 850 W 1100 W
4Ω, FTC 20 Hz–20 kHz, 0.1% tdD 280 W 400 W 650 W 1300 W 1600 W
4Ω, EIA 1 kHz, 0.1% tdD 300 W 500 W (0.5% tdD) 800 W 1400 W 1800 W
2Ω, FTC 20 Hz–20 kHz, 1% tdD 1600 W 2000 W
2Ω, EIA 1 kHz, 1% tdD 430 W 700 W 1200 W 2000 W 2500 W
Power, Bridge-Mono Mode
8Ω, FTC 20 Hz–20 kHz, 0.1% tdD 530 W 800 W 1300 W 2600 W 3200 W
8Ω, EIA 1 kHz, 0.1% tdD 600 W 900 W 1500 W 2800 W 3600 W
4Ω, EIA 1 kHz, 1% tdD 830 W 1400 W 2400 W 4000 W 5000 W
Signal to Noise (20 Hz–20 kHz) -100 dB
Distortion (SMPTE-IM) < 0.01% < 0.02%
Input Sensitivity at 8Ω 1.15V (+3.4dBu) 1.23V
(+4.0 dBu)
1.42V (+5.3 dBu)
Voltage Gain 31.6x (30 dB) 40x (32 dB) 50x (34 dB) 64x (36 dB)
Output Circuitry Class AB 2-tier Class H 3-tier Class H
Current Draw (120 V AC)
Typical, 1/8 power pink noise at 4Ω*
Severe, 1/3 power pink noise at 4Ω*

4.5 A
6.6 A

6.0 A
9.6 A

6.3 A
15.6 A

10.0 A
20.1 A

13.9 A
26.9 A
AC Mains Plug
NEMA 5-15

NEMA 5-20

35 lb (15.9 kg)
41 lb (18.6 kg)

40 lb (18.2 kg)
46 lb (20.9 kg)

44.5 lb (20.2 kg)
50.5 lb (23 kg)

68 lb (30.8 kg)
77 lb (34.9 kg)

75 lb (33.1 kg)
87 lb (37.2 kg)
Distortion (typical)
20 Hz–20 kHz, 10 dB below rated power
1 kHz and below, full rated power

< 0.03% tdD, 4Ω and 8Ω
< 0.03% tdD, 4Ω and 8Ω

< 0.02% tdD, 4Ω and 8Ω
< 0.02% tdD, 4Ω and 8Ω
Frequency Response 20 Hz–20 kHz: +0/-1 dB -3 dB points: 5 Hz and 50 kHz (LF filter bybassed, 8Ω)
Damping Factor (1 kHz and below) > 300 at 8Ω > 250 at 8Ω
Input Impedance 10 kΩ unbalanced; 20 kΩ balanced
Input Stage Clipping 10 V rms (+22 dBu) 6.4 V rms (+18 dBu)
Cooling Continuously variable speed fan, back-to-front air flow
Connectors (each channel) Input: Active balanced; 3-pin Euro-style detachable terminal block and XLR (pin 2+)
Output: Touch-proof binding posts; Neutrik Speakon®
Controls Front: AC switch; Channel 1 & 2 gain knobs
Rear: 10-position DIP switch
LED Indicators Power on: Green; Signal: Yellow (1 per channel); Clip/Protect: Red (1 per channel)
Amplifier Protection Full short circuit, open circuit, tdermal, ultrasonic, RF protection. Stable into reactive or mismatched loads
Load Protection Turn-on/off muting; AC coupling (850, 1450); Triac crowbar (1850HD, 2450, 4050HD, 5050) on each channel
Dimensions 3.5” (8.9 cm) tall; 2 rack spaces 5.25” (13.3 cm) tall; 3 rack spaces
Power Requirements 100, 120, 230 V AC (factory configured), 50–60 Hz
The RMX 4050a Box Includes:

(1) QSC RMX 4050a Power Amplifier
(1) Quick Start Guide
(1) Adhesive Rubber Feet Kit (For non rack-mount applications)
(1) Rear Rack Ear Mounting Kit
(1) IEC Detachable Power Cord

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