QSC GX3 User manual

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 – GX3 and GX5 less than 26 lbs
(12.5 kg). GX7 only 15.5 lbs (7 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
* 230V 16.5 lbs (7.5 kg)
GX Series amplifiers are ideal for professional entertainers who require maximum performance
and portability on a limited budget. The hallmarks of the QSC brand – professional audio quality,
meticulous engineering, precision manufacturing and long-term reliability - are all intrinsic to GX. Add
contemporary styling, multiple input/output options, light weight, and advanced protection circuitry,
and the GX Series clearly represents real value – something everyone can use.
GX amplifiers deliver just the right amount of power to the most popular speakers used by
entertainers. Typically, 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. The GX7 outputs 725 watts into an 8 ohm load.
Owners of popular 4 ohm loudspeakers (such as dual-woofer, two-way models) will find the 700
watt (4 ohm) power of the GX5 an ideal match while the GX7 1000 watts will very capably power
many of today’s popular subwoofers or two typical 8 ohm speakers per channel.
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 PL Series, (PLX, PL3, CX, DCA)
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.
The GX7 adds the road-proven PowerLight supply to the Class H output section, for more overall
output power and additional weight savings. The result is one of the highest power-to-weight ratios
in the industry. A low-noise variable-speed fan with rear-to-front airflow keeps amplifiers and
racks cool.
As always, GX Series 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. GuardRail
optimizes peak power into the sub and top individually, for greater musical impact and dynamic range.
Choose the right GX amp for your speakers
Model
GX3 For 8Ωspeakers: 250 W –350 W (program)a
GX5 For 8Ωspeakers: 400 W –600 W (program)b
GX7 For 8Ωspeakers: 650 W –800 W (program)c
GX Series
Professional Power Amplifiers
GX3 | GX5 | GX7
a) For 4Ωspeakers: 350 W –500 W (program)
b) For 4Ωspeakers: 550 W –900 W (program)
c) For 4Ωspeakers: 900 W –1250 W (program)

GX Series Preliminary Specifications
qscaudio.com
All specifications are subject to change without notice.
1675 MacArthur Boulevard • Costa Mesa, CA 92626 • Ph: 800/854-4079 or 714/957-7100 • Fax: [phone]
GX Spec Sheet 11/09/10
©2010 QSC Audio Products, LLC. All rights reserved. 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.
GX3 GX5 GX7 GX7 (230V Only)
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*
300 W
350 W
425 W
500 W
500 W
600 W
700 W
850 W
725 W
800 W
1000 W
1200 W
Distortion (typical)
1 kHz: 1 dB below rated power 8Ω: less than 0.02% / 4Ω: less than 0.05%
Signal to Noise (20 Hz –20 kHz) 100 dB
Input Sensitivity 1.2 Vrms
Voltage Gain (8Ω) 32.2 dB 34.4 dB 36.1 dB
Output Circuitry Class B 2-tier Class H 2-tier Class H
Power Requirements (1/8 power, pink noise at 4Ω, 120 V) 6.3 A 6 A 10.1 A
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
Phono, unbalanced
Output Connectors (each channel) Speakon®, 1/4", Binding Posts
Amplifier and Load Protection Short circuit, open circuit, thermal, RF protection
Load protected against DC faults
Front Panel Controls and Indicators Gain controls, 21 detents
Red Clip LEDs, proportional, 0.1% THD threshold
Green Signal LEDs, threshold -35 dB
Blue Power LED, AC on
Rear Panel Controls Full Range / Crossover switch
100 Hz, 3rd order LP (sub), 2nd order HP (top)
Dimensions (HWD) 3.5" (2 RU) x 19" x 10.1" (89 mm x 483 mm x 257 mm)
Weight - Net 27 lb (12.1 kg) 28 lb (12.6 kg) 15.5 lbs (7 kg) 16.5 lbs (7.5 kg)
Weight - Shipping 31 lb (14.1 kg) 32 lb (14.6 kg) 20.5 (9.3 kg) 21.5 (9.75 kg)
Agency Approvals UL, CE, RoHS/WEEE compliant
* At onset of clipping
Inputs
XLR, 1/4" TRS and phono input connectors
for compatibility with any source
Crossover
Subwoofer/Satellite crossover built-in Speakon®combo output connector
accepts 1/4" or Speakon 2 wire connectors
Binding post output for compatibility
with any loudspeaker wiring scheme
Outputs to Speakers
please recycle