TM
GX POWER AMPLIFIER SERIES
User Manual
GX3 300 watts per channel at 8 ohms
GX5 500 watts per channel at 8 ohms
EN
TD-000271-01 REV. A
*TD-000271-01*
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3
GX POWER AMPLIFIER SERIES
Professional Power Amplifiers
WELCOME
Thank you for purchasing a QSC Audio amplifier. The GX Series is
the latest in a long line of hard-working, low cost amplifiers, designed
to produce the best possible results for a wide range of users. In
most cases, you can plug and play with no surprises, but for best
results, we recommend you review the enclosed user guide.
UNPACKING
EN
Confirm that the amplifier has no visible shipping damage. Confirm
that amplifier has the correct AC cord and voltage rating for your
region (See rear panel, Serial Number plate). It is best to keep the
carton in case the amplifier needs to be returned, at least until it has
been tested.
FEATURES
Power levels matched to the most popular speakers used by
entertainers.
Optimized for maximum real-world headroom into 4Ω and
8Ω speaker systems.
SUPPORT AND SERVICE
Inputs: XLR, 1/4” TRS and phono input connectors for
compatibility with any source.
QSC Audio Products maintains a world-wide network of distributors
and service centers. These local agencies will be able to answer your
questions and take care of any problems.
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.
QSC WEBSITE
supported in multiple languages. Visit frequently for new
announcements, typical questions, and other user information.
Minimum depth chassis (only 10.1” / 257 mm) fits in
compact, inexpensive effects racks.
Light weight – less than 26 lbs (12.5 kg).
IMPORTANT SAFETY PRECAUTIONS
QSC products are designed for safe operation, and have been
certified by recognized product safety agencies to meet all normal
standards for this type of product. However, dangerous voltages
and power levels exist within the covers of this amplifier. The user
is requested to study the precautions in this manual. If the product
has been dropped, dented, soaked, or appears to have loose parts
inside, the risk of shock is increased. Unplug the AC cord, and take
the product to qualified service personnel for inspection and repairs.
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.
POWER RATINGS
Watts at 0.1% clipping, both channels driven
Model
GX3
8 ohms
300
4 ohms
4ꢀ5
ꢀ ohms*
ꢀ00
GX5
500
700
350
*NOTE: 2-ohm loading is not recommended for high power use.
To avoid protective limiting, use only at low levels.
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4
FRONT PANEL FEATURES
MODEL NUMBER
The GX3 and GX5 power
ratings are shown in the
Specifications page.
ON-OFF SWITCH
Move the rocker switch up to turn on the amplifier.
The blue PWR LED will turn on immediately.
The red CLIP LEDs may trigger for 1-2 seconds until the amp
has completed its turn-on cycle. If no lights come on, check the
power cord and the AC reset on the rear panel.
COOLING VENTS
The internal fan draws air in from the left side,
and exhausts on the right side. Keep vents clear.
The fan speeds up in response to heavy use.
EN
DIMENSIONS
10.1
Inches (cm)
(25.7)
17.0
(43.2)
9.0
(22.9)
19.0
(48.3)
3.5
(8.9)
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5
GAIN CONTROLS, CH1, CH2
The markings show attenuation in dB. For normal
use, keep the control in the upper half of its range
(less than 10 dB of attenuation). If set below half,
the source may overload before the amplifier
reaches full power.
RACK MOUNTING
Fits standard 19-inch rack, 2RU.
Accepts #10 or 6 mm screws,
as determined by the rack rails.
Add rear support to prevent
damage in portable rigs.
EN
RED CLIP LEDS
Red flashing indicates the amp is being overdriven. Heavy overdrive triggers internal gain
reduction, to reduce overload distortion. Normal gain will resume after the signal level returns to
normal. See Troubleshooting if the red LED remains on continuously.
GREEN SIGNAL LEDS
The green LED starts flashing on soft signals (-35 dB), and changes to steady green as the
signal level increases.
BLUE POWER LED
The blue PWR (POWER) LED indicates that the AC switch is on, and the amp is receiving
power. Within two seconds, it is ready to use.
ALTERNATE GAIN MARKING
When the CROSSOVER switch is active (see rear panel),
LF (CH 1) controls low frequencies (subwoofer),
HF (CH 2) controls the high frequencies (mid-high box).
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6
REAR PANEL FEATURES
CROSSOVER SWITCH
EXHAUST VENT
Keep vent clear. Install in
open-back rack.
CROSSOVER POSITION
Splits a full-range signal to drive a subwoofer and top box.
CH 1 receives the lows, from 20-100Hz, for the subwoofer.
CH 2 receives 100Hz to 20kHz, to power a full range speaker.
When using CROSSOVER mode, connect signal to CH 1 only.
Use the two Gain controls to balance the LF and HF signals
(see Front Panel).
FULL RANGE POSITION
For normal, 2-channel use with all inputs active.
The crossover is bypassed.
EN
REAR EAR MOUNTING
INPUT CONNECTIONS
Rear ears designed for protecting the
rear connector wire dressing and
supporting the amplifier in a rack. A rear
rack support mounting kit (model FG-
000031-00 pack of two) is available from
QSC Technical Services Group.
BALANCED XLR INPUTS
Pin 2 Positive, Pin 3 Negative, Pin 1 Shield (Ground).
Recommended for long or short runs, either fixed or
frequently changed. Each channel’s XLR and TRS jacks
are connected internally, and provide feed thru
to the other connector.
BALANCED 1/4-INCH TRS INPUTS
Tip positive, Ring Negative, Sleeve Shield (Ground).
Recommended for long or short runs that are frequently
changed.
UNBALANCED 1/4-INCH TS INPUTS
Accepts unbalanced 1/4-inch plugs for short runs.
Tip positive, Sleeve Shield (Ground).
UNBALANCED PHONO INPUTS
Tip Positive, Barrel Shield (Ground). Recommended
for semi-permanent connections to nearby sources,
within the same rack. NOTE: when using these
inputs, the TRS or XLR inputs should not be used.
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7
AC BREAKER RESET
If the amplifier shuts off after a long burst of power,
turn off the AC switch and check the circuit breaker.
The button can be pressed back in after a 30 second
cool-down period. If the breaker trips repeatedly,
the amplifier may need servicing.
SERIAL NUMBER AND RATINGS
The rated AC voltage and output power
is shown on the serial number plate.
Record the serial number in a safe place.
EN
AC INLET
SPEAKER CONNECTIONS
BINDING POSTS
Accepts banana plugs
(not permitted in CE regions).
Bare wires or terminals may be
inserted into the side holes.
1/4-INCH CONNECTORS
Insert plug into the center of
the Speakon-Combo jack.
Use only heavy duty speaker cables.
SPEAKON CABLES (2 wire type):
Insert and turn until the connector clicks.
Use the thumb latch or locking ring
to release the plug.
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8
SYSTEM HOOKUP EXAMPLES
INPUT CONNECTIONS
SPEAKER CONNECTIONS
8 OR 4 OHM
XLR
MIXER
SIGNAL LEVEL SOURCE
SPEAKON
SET TO FULL RANGE
SET TO FULL RANGE
SET TO FULL RANGE
¼
MIXER
EN
¼
SIGNAL LEVEL SOURCE
WIRE
PHONO
MIXER
SIGNAL LEVEL SOURCE
BANANA JACKS
One 4-OHM speaker, or two 8-OHMspeakers, may be connected to each channel.
If speakers have pass through jacks, do not put more than two in a chain.
CONNECTION MULTIPLE SPEAKERS
To connect two speakers to one amplifier channel,
connect one speaker with Speakon or 1/4 –inch jack,
and connect the other speaker with a banana plug
or wires to the binding posts.
8 OHM
8 OHM
8 OHM
8 OHM
It is also possible to use banana plug for one speaker,
and binding post wires for the other speaker.
Second speaker
First speaker
4 OHM
8 OHM
4 OHM
8 OHM
Speakon
and wires to
the binding posts.
Second speaker
1/4 –inch jack,
And wires to the
First speaker
4 OHM
binding posts.
4 OHM
4 OHM
4 OHM
Second speaker
First speaker
banana plug
and binding post
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ꢁ
SYSTEM HOOKUP EXAMPLES
SUBWOOFER AND TOP BOX
Move the CROSSOVER switch to
the CROSSOVER position.
Connect a single source, into the
Ch 1 input.
Connect a subwoofer to the
Ch 1 output and connect a
2-way to box to the Ch 2 output.
8 OR 4 OHM
INPUT
TOP
SET TO CROSSOVER
8 OR 4 OHM
SUB
8 OHM
8 OHM
POWERING HOUSE AND MONITOR SPEAKERS
MAIN
MAIN
EN
Set the CROSSOVER switch
to the FULL RANGE position.
Use a mixer with Main and
Monitor outputs. Connect cables
into Ch 1 and 2 respectively.
Connect Ch 1 output to
two large speakers.
Connect Ch 2 output to
two floor wedges.
SET TO FULL RANGE
4 OR
8 OHM
4 OR
8 OHM
STEREO PLAYBACK
OR
Set the CROSSOVER switch in the
FULL RANGE position. Connect a
Left / Right signal source to channel 1
and channel 2 respectively using
XLR, TRS or PHONO connectors.
Connect a speaker to each channel
using SPEAKON, ¼’ PHONE,
L
R
BANANA JACKS or WIRE.
SET TO FULL RANGE
L1
USING BOTH CHANNELS FOR THE SAME
L2
4 OR
4 OR
8 OHM
Move the CROSSOVER switch to the
FULL RANGE position. Hook up a single source
using Ch 1 XLR input. Install a RTS jumper
going between Ch1 and Ch2.
8 OHM
Connect a speaker to each channel.
Each speaker ahs its own gain
adjustment on the front panel.
DO NOT connect both channels
Into the same speaker.
SET TO FULL RANGE
FULL RANGE
DO NOT connect both
Channels to the same speaker.
RTS jumper
between
CH1 and CHꢀ
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10
TROUBLESHOOTING
NO POWER, NO LIGHTS, NO FAN
NO SOUND, WITH BLUE LED ONLY, NO GREEN OR
RED LED
Confirm that the Gain controls are turned up. Confirm that
the input cables are correctly installed at both ends. If using
1/4-inch speaker cables, do not confuse with input cables.
Confirm that the source is active. If necessary, try another
source, or connect another amplifier to the existing source.
Confirm that the AC cord is fully seated and connected to a
live outlet. Check the AC source by trying another device
such as a lamp. Check the BREAKER on the back of the
amplifier by pushing in the button. If the breaker trips off
quickly, the amplifier needs servicing.
AMPLIFIER LOSES VOLUME
If the amplifier is worked too hard, GuardRail™ will
reduce volume to prevent thermal muting. The fan should be
running at full speed. Reduce input signal somewhat and the
amp should return to normal gain within 1-2 minutes. If the
amp feels hot and the fan is not running, it needs to be
serviced.
NO SOUND, BUT THE GREEN LED IS RESPONDING
The green LED indicates the amp is producing a signal, so
sound should be heard if the speaker is connected. Check
the speaker connections at both ends, and try a different
speaker.
EN
NO SOUND, RED LED ON
CHANNEL 1 PRODUCES DEEP BASS ONLY.
Check the position of the CROSSOVER switch on the rear
panel. Set on FULL RANGE for normal, independent use of
each channel.
The amp mutes briefly when turned on and off to prevent
thumps. If the amp overheats severely, it will mute until it cools off.
The fan will be running at full speed, and sound should
resume in less than a minute. If the amp feels hot and the fan
is not running, it needs to be serviced.
CHANNEL ꢀ INPUT SEEMS DEAD.
Check the position of the CROSSOVER switch on the rear
panel. Set on FULL RANGE for normal, independent use of
each channel.
BACKGROUND HUM
Balanced XLR or TRS cables are better for long runs. Hum can be a
problem when connecting to TV-cable rigs, since the TV cable often
creates a ground conflict. Request or install a TV-cable isolator to
reduce this problem.
AMPLIFIER SOUNDS DISTORTED.
If the red CLIP LED is flashing, the amplifier is being played
beyond its normal rated power. GuardRail™ circuitry will reduce
volume somewhat to prevent severe overdrive, but if the input
signal is further increased, the limiter can be overridden, with
increased distortion.
Hum can also occur earlier in the signal chain, depending on the
types of connections. It often helps to plug everything into the same
AC strip, if the total power consumption is not excessive.
As a last resort, mild hum can sometimes be reduced by
lowering the amp gain, and increasing the source gain to
compensate, but you must ensure that the source can deliver
the extra volume without overload distortion. If this does not
reduce hum, it is coming from the source.
If the speakers or speaker cables are shorted or defective,
the amplifier may distort at lower-than-normal levels, with
increased flashing of the red CLIP LED. This should be
checked by trying an alternate speaker and cable.
If too many speakers are connected to each channel
(impedance below 4 ohms), the amp will overload more
easily and will probably run hot.
AMPLIFIER NEEDS SERVICING
The following conditions indicate possible unsafe conditions
that require service before using. If observed, unplug the AC
cord from the wall and when safe, remove the amp for
servicing.
If the sound is distorted or garbled without flashing the red
CLIP LED, the distortion is not occurring inside the amplifier.
Either the speaker is bad or the input signal is distorted.
• Confirm that the speaker is OK by trying a different unit.
• Input overload can occur if the amplifier Gain controls are set too
low, and the input source is overdriven to compensate Reduce the
source volume until the distortion clears up, and increase amp Gain
to reach the desired level. It is generally desireable to keep the
amp gains at or near their full, clockwise, position.
• If the amplifier emits smoke or burning smells
• If the case is severely dented or deformed
• If the amplifier is soaked with any fluid
• If internal parts sound loose
• If the AC breaker trips when power is applied
• If the amplifier is dropped, carefully inspect for damage or
loose parts before attempting to use.
• Check all input connections. Do not plug two different sources into
the same channel. Use a mixer to blend sources.
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11
SPECIFICATIONS
GX3
GX5
SPECIFICATION SUBJECT TO CHANGE WITHOUT NOTICE.
OUTPUT POWER, 1 kHz, 0.1 % clipping
8Ω, both channels driven
8Ω, single channel driven
4Ω, both channels driven
4Ω, single channel driven
2Ω, both channels driven, 1% clipping
SIGNAL TO NOISE (20 Hz – 20 kHz)
INPUT SENSITIVITy
300 W
350 W
425 W
500 W
200 W
100 dB
1.2 Vrms
32.2 dB
Class B
6.3 A
500 W
600 W
700 W
850 W
350 W
EN
VOLTAGE GAIN AT 8Ω
34.4 dB
2-tier Class H
6 A
OUTPUT CIRCUITRy
POWER REQUIREMENTS (1/8 power, pink noise
at 4Ω 120 V AC)
DISTORTION (1 dB below rated power, 20 – 20 kHz)
8Ω, less than 0.05%
4Ω, less than 0.1%
FREQUENCy RESPONSE
DyNAMIC HEADROOM, 4Ω
DAMPING FACTOR
20 – 20kHz, +0, -1dB
2dB
100
INPUT IMPEDANCE
Greater than 20K ohms (balanced or unbalanced)
+24 dB (16 Vrms)
MAXIMUM INPUT LEVEL
INPUT CONNECTORS, each channel
3-pin XLR and 1/4” TRS, balanced, parallel
Phono, unbalanced
OUTPUT CONNECTORS, each channel
AMPLIFIER AND LOAD PROTECTION
Speakon®, 1/4”, Binding Posts
Short circuit, open circuit, thermal, RF protection
Load protected against DC faults
CONTROLS AND INDICATORS, FRONT PANEL
Gain controls, 21 detents
Red Clip LEDs, proportional, 0.1% THD threshold.
Green Signal LEDs, threshold -35 dB
Blue Power LED, AC-on.
CONTROLS, REAR PANEL
Full Range / Crossover switch
100 Hz, 3rd order LP (sub), 2nd order HP (top).
DIMENSIONS (HWD)
WEIGHT – Shipping / Net
AGENCy APPROVALS
3.5” (2RU) x 19” x 10.1” (89 mm x 483 mm x 257 mm)
30 / 25 lbs (13.5 / 11.5 kg)
31 / 26 lbs (14 / 12 kg)
UL, CE, RoHS / WEEE compliant
AC POWER CONSUMPTION 1/8 power, ohms (AC Current and Heating, 120Vac)
GX3
GX5
Operating Condition
Idle
AC amps
0.2
BTU / hr
44
904
1160
1109
1515
2105
2297
AC amps
0.3
BTU / hr
60
734
1456
1891
1160
2162
3754
8 + 8 ohms, 1/8 power (1)
8 + 8 ohms, 1/3 power (2)
8 + 8 ohms, full power (3)
4 + 4 ohms, 1/8 power (1)
4 + 4 ohms, 1/3 power (2)
4 + 4 ohms, full power (3)
4.1
6.1
9.75
6.3
9.4
3.3
8.5
16.2
5.8
11.2
24.5
15.0
(1) 1/8 power represents typical operating conditions. (2) 1/3 power represents peak program levels.
(3) Full power is breaker limited to short periods. (4) For 230V, multiply AC current by 0.5. For 100V, multiply AC current by 1.25.
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WARRANTY
(USA only; other countries, see your dealer or distributor)
Disclaimer
QSC Audio Products, Inc. is not liable for any damage to amplifiers or any other equipment that is caused by negligence or
improper installation and/or use of this loudspeaker product.
QSC Audio Products 3 Year Limited Warranty
QSC Audio Products, Inc. ( QSC ) guarantees its products to be free from defective material and / or workmanship for a period
of three (3) years from date of sale, and will replace defective parts and repair malfunctioning products under this warranty when
the defect occurs under normal installation and use - provided the unit is returned to our factory or one of our authorized service
stations via prepaid transportation with a copy of proof of purchase (i.e., sales receipt). This warranty provides that the examination
of the return product must indicate, in our judgment, a manufacturing defect. This warranty does not extend to any product which
has been subjected to misuse, neglect, accident, improper installation, or where the date code has been removed or defaced.
QSC shall not be liable for incidental and/or consequential damages. This warranty gives you specific legal rights. This limited
warranty is freely transferable during the term of the warranty period. Customer may have additional rights, which vary from state
to state.
EN
In the event that this product was manufactured for export and sale outside of the United States or its territories, then this
limited warranty shall not apply. Removal of the serial number on this product, or purchase of this product from an unauthorized
dealer, will void this limited warranty. Periodically, this warranty is updated. To obtain the most recent version of QSC’s warranty
How to Contact QSC Audio Products
Mailing address:
QSC Audio Products, Inc.
1675 MacArthur Boulevard
Costa Mesa, CA 92626-1468 USA
Telephone Numbers:
Main Number (714) 754-6175
Sales & Marketing (714) 957-7100 or toll free (USA only) (800) 854-4079
Customer Service (714) 957-7150 or toll free (USA only) (800) 772-2834
Facsimile Numbers:
Sales & Marketing FAX (714) 754-6174
Customer Service FAX (714) 754-6173
World Wide Web:
E-mail: [email protected]
TM
QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, California 92626 USA
©2007 “QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office.
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