GX Series
Professional Power Amplifiers
GX3 | GX5
GX Series amplifiers are ideal for professional entertainers who require maximum performance
and portability on a limited budget. QSC designers, headed by Pat Quilter, have optimized
output and appearance while reducing raw material cost and weight. It’s all here – dramatic
styling, easy hookup and adjustments, excellent audio quality and QSC reliability.
GX amplifiers deliver just the right amount of power to the most popular speakers used by
entertainers. Most loudspeaker manufacturers recommend an amplifier with power output
equal to the speaker’s “Program (Music) Power” rating or two times (2 x) the “Continuous
(RMS) Power” rating.
The GX3 is ideal for speakers in the 300 watt (Program) range, while the GX5 provides
full performance for 500 watt (Program) speakers. Both models supply maximum possible
power to 4 ohm and 8 ohm loads. Owners of popular 4 ohm loudspeakers (dual-woofer,
two-way models and many subwoofers) will find the 700 watt (4 ohm) power of the GX5
an ideal match.
Technical Notes
The GX3 uses the latest evolution of the QSC Grounded Collector output system, for optimum
cooling of the critical power transistors. A true Class B biasing system combines maximum
thermal efficiency with excellent audio performance.
The GX5 uses a Class H system, based on key elements of the PLX Series, almost doubling
power in the same size and weight. QSC design expertise allows the output devices to shift
from low-power to high-power rails in less than a millionth of a second, ensuring that the
output power is always right where it needs to be without excess loss.
Both amplifiers use premium toroidal power transformers for reliable “mid-weight” performance.
A variable-speed fan moves air crosswise through the amplifier, drawing cool air in over the
power transformer, through the fan, and then over the heat sink. This keeps the transformer
cool and allows a full size heat sink to fit in a down-sized chassis. As always, the amplifiers are
fully protected from the usual hazards of the trade, ensuring stable performance and long life.
GuardRail™
GuardRail protection delivers full peak power while preventing detrimental overloads. During
excessive clipping, or extreme overheating, GuardRail reduces gain just enough to preserve
the integrity of the music, protect the speakers and keep the audience excited, without
unprofessional distortion levels or shutdowns.
Subwoofer/Satellite Crossover
A subwoofer reduces strain on the full-range speaker, allowing it to play louder, or letting a
smaller speaker do the same job. The GX Series supports this mode with a Crossover switch
that splits the full-range input entering Ch 1, sending 20 Hz -100 Hz to the sub (Ch 1) and
100 Hz - 20 kHz to the top box (Ch 2). The front panel gain controls balance the sub and
top box, while GuardRail optimizes peak power into the sub and top individually, for greater
musical impact and dynamic range.
Features
• Power levels matched to the most popular
speakers used by entertainers
• Optimized for maximum real-world
headroom into 4Ω and 8Ω speaker systems
• Inputs: XLR, 1/4" TRS and phono input
connectors for compatibility with any source
• Outputs: Speakon® combo accepts, 1/4"
(TS) plugs or Speakon 2-pole and 4-pole
plugs (connects 2 poles only). Binding posts
support all other speaker wiring systems.
• Minimum depth chassis (10.1"/257 mm)
fits in compact, inexpensive effects racks
• Lightweight – less than 26 lbs (12.5 kg)
• Detented gain controls for precise setting
and matching of sensitivity
• GuardRail™ automatically protects the
amplifier and loudspeakers from damage
due to temperature rise or overdrive without
shutting down the show
• Front panel LEDs monitor Power, Signal
and Clipping
• Subwoofer/Satellite crossover built-in
Your Speaker's Power Rating
Model
GX3 For 8Ω speakers: 250 W - 350 W (program)*
GX5 For 8Ω speakers: 400 W - 600 W (program)**
*
For 4Ω speakers: 350 W - 500 W (program)
**
For 4Ω speakers: 550 W - 900 W (program)
GX Series
GX3 GX5
Stereo Mode
8Ω / both channels driven / 1 kHz*
8Ω / single channel driven / 1 kHz*
4Ω / both channels driven / 1 kHz*
4Ω / single channel driven / 1 kHz*
Distortion (typical)
20 Hz - 20 kHz: 1 dB below rated power 8Ω: less than 0.05% / 4Ω: less than 0.1%
Signal to Noise (20 Hz - 20 kHz) 100 dB
Input Sensitivity 1.2 Vrms
Voltage Gain (8Ω) 32.2 dB 34.4 dB
Output Circuitry Class B 2-tier Class H
Power Requirements (1/8 power, pink noise at 4Ω, 120 V) 6.3A 6A
Frequency Response 20 Hz - 20 kHz, +0, 1 dB
Dynamic Headroom (4Ω) 2 dB
Damping Factor 100
Input Impedance (Ω) Greater than 20k (balanced)
Maximum Input Level +24 dB (16 Vrms)
Input Connectors (each channel) 3-pin XLR and 1/4" TRS, balanced, parallel
Output Connectors (each channel) Speakon®, 1/4", Binding Posts
Amplifier and Load Protection Short circuit, open circuit, thermal, RF protection
Front Panel Controls and Indicators Gain controls, 21 detents
Rear Panel Controls Full Range / Crossover switch
Dimensions (HWD) 3.5" (2RU) x 19" x 10.1" (89 mm x 483 mm x 257 mm)
Weight - Shipping / Net 30 (13.5 kg) / 25 lbs (11.5 kg) 31 (14 kg) / 26 lbs (12 kg)
Agency Approvals UL, CE, RoHS/WEEE compliant
* At onset of clipping
300 W
350 W
425 W
500 W
Phono, unbalanced
Load protected against DC faults
Red Clip LEDs, proportional, 0.1% THD threshold
Green Signal LEDs, threshold -35 dB
Blue Power LED, AC on
100 Hz, 3rd order LP (sub), 2nd order HP (top)
Preliminary Specifications
500 W
600 W
700 W
850 W
Inputs
XLR, 1/4" TRS and phono input connectors
for compatibility with any source
All specifications are subject to change without notice.
QSC and the QSC logo are registered trademarks of QSC Audio Products LLC in the U.S. Patent and Trademark office and other countries. GuardRail is a trademark of
QSC Audio Products, LLC. Speakon is a trademark of Neutrik. All other trademarks are the property of their respective owners. US patent pending. Other patents may apply.
1675 MacArthur Boulevard • Costa Mesa, CA 92626 • Ph: 800/854-4079 or 714/957-7100 • Fax: 714/754-6174
GX Spec Sheet 02/15/08
Crossover
Subwoofer/Satellite crossover built-in
Outputs to Speakers
Speakon® combo output connector
accepts 1/4" or Speakon 2 wire connectors
Binding post output for compatibility
with any loudspeaker wiring scheme
qscaudio.com