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QSC Audio Model GX5 Power Amplifier

It is a stout little power amp, delivering plenty of power with plenty of speed. It is light in weight but not a lightweight in the general power amp world.

About 15 years ago, I employed QSC Audio’s first-generation PowerLight power amps as the heart of a then-new JBL SR system. I have since moved on to A-Line Acoustics line array boxes, yet those same QSC power amps are doing daily duty — rockin’ and rollin’ the non-self-powered section of the system. Indeed, it’s a nice testament to the quality and endurance of QSC power amps, and needless to say, I had great expectations reviewing this QSC model from the new GX Series.


QSC sent us the Model GX5 for testing. It is the big brother to the Model GX3, a slightly less powerful version of the same power amp. The GX5 has a rated power output of 500 Watts RMS output at 8 ohms, both channels driven, and 700 Watts RMS at 4 ohms, both channels driven. There is an internal crossover that allows you to employ the GX5 as a single power amp for a modest small portable system by providing a frequency division at 100 Hz; this would allow you to run two 8 ohm subs in parallel on side A, and run two passive top boxes at 8 Ohms each, in parallel, on side B. If you choose not to avail yourself of the crossover, you may disengage the switch on the rear panel, and the run the GX5 as a straight two-channel power amp.

The brushed aluminum front panel is concise and attractive. It contains two louvered sections, one on each side, for ventilation. The right side draws fresh air in with a generous fan assembly, and exhausts air on the left side. Between the vents resides an On/Off switch and the respective Left and Right volume controls. Between the rotary volume controls are L/R “signal present” green LEDs as well as L/R “clip” red LEDs and a blue “power on” LED.

Fast FactsApplications
Live, concert sound, installed sound

Key Features
Two-channel; 500W RMS at 8 ohms, both channels driven; Class H power supply; built-in crossover; XLR, TRS quarter-inch, RCA Left and Right inputs; concentric NL4/quarter-inch and standard binding post outputs; 26 lbs, 2U high.

$499 list

QSC Audio | 800-854-4079 | www.qscaudio.comThe rear panel is home to the input connectors, which are XLR, TRS quarter-inch and RCA, with a set of each above for Left input and a set below for Right input. For outputs, the GX5 employs concentric NL4 and quarter-inch combo connectors, arranged as the inputs are — above and below — along with the standard binding posts found on most power amps. The rear panel also provides the IEC power connection, a power reset breaker, and a handy legend containing both input and output connector configurations and output power ratings.

According to QSC, the power supply type is Class H, and the entire amp weighs in at 26 lbs. Dimensions are 19 inches wide, 10 inches deep and 3.5 inches (two rack spaces) tall. Power consumption is 6 amps/15 volts and the cable is terminated with a standard 15 Amp Edison plug.

In Use

I completed a series of different applications for the GX5 in air-conditioned ballroom events. We employed it as a monitor amp for Manhattan Transfer, with side one driving a 12-inch woofer and side two powering the two-inch compression driver on our Yorkville TX2 monitors. The GX5 performed admirably as a monitor amp, providing very clean, responsive power with exceptionally clear qualities in the mid-range department. We further used the GX5 as a subwoofer amp, driving a pair of our unpowered A-Line Acoustics LS218 subs. This amp thumped along quite nicely, handling 40 Hz with ease with a nice attack on kick drum.

When reviewing power amps, I believe that there are a few examinations that really put a product to the test. Being an Arizona-based company, I especially enjoy heat-torture testing a power amp; call me twisted, but I like to run an amp at impossible loads in life-threatening heat (power amp life-threatening, not human life-threatening), and see if it keeps coming back for more.

Recently, the publisher of Pro Audio Review asked me if this review was ready and I told him, “Not until I do the heat torture.” On the 4th of July, we were doing full roof, stage, lighting and audio production for Ricky Skaggs in an Arizona outdoor show. Average daytime temps were around 95 (it was a mild 4th) and the amp was placed in a rack along with the older QSC PowerLights that I described earlier. We used the GX5 to drive the double 10-inch woofers in four of our unpowered A-Line line array boxes. The rack sat directly in the rays of the sun, pumping out frequencies of 80 Hz to about 800 Hz. The GX5 cruised along all day and night long — never being anything but slightly warm and never sounding anything but clean and clear.


As I said, I expected great achievements from this power amp given the reputation of QSC Audio, coupled with my own prior QSC experience. I was not let down. The GX5 performed without issue. It is a stout little power amp, delivering plenty of power with plenty of speed. It is light in weight but not a lightweight in the general power amp world. The QSC Audio GX5 earns my full respect as a good quality amp that will, I believe, deliver many years of power at a most reasonable price.

GX5 — Good For The Gigging, PA-Toting Musician, Too

As Will has described, the QSC Audio GX5 is an affordable amplifier that performs well in “full professional” applications. However, it is not only a good choice for the full-time live sound professional; it is an ideal choice for the budget-restricted gigging musician who often runs his own sound, and/or lugs his own monitoring rig to clubs … and much more. Thus, it’s totally worth its “under $500” list price.

In my own experience, the GX5 excelled from gig to gig with a very mixed bag of small/mid-sized live mains and monitors — the brand-new, high-quality JBL MRX512M wedges, a venue’s older, yet good-sounding Peavey SP2 mains, down to a pair of super-cheap, beat-up Kustom wedges, just to name a trio of serendipitous GX5 pairings.

The SP2 mains were used for an outdoor amphitheater “park” show on a hot afternoon; they were driven quite hard by the GX5 for three hour-long sets in which there was nary a sound system hiccup. Both the SP2 mains and MRX512M monitors are equipped with NL4 Speakon input connectors — great for pairing with the GX5. However, I ultimately used nearly every input and output GX5 configuration while gigging with foreign wedges at small, dark clubs/bars with questionable PA options; so, thankfully, the NL4/quarter-inch combos are offered on the amp.

For the first half of this eval, the GX5 traveled in its original shipping box — I’m glad it did. It may seem to be no big deal, but the elementary “hookup examples” schematic on the back of the box was very helpful to me and especially to those assisting the load-in/load-out process (some of which also ran house sound and, in one case, tended some bar, too). As a musician who regularly travels with his instrument and some level of sound reinforcement, this schematic may be a good thing to cut, laminate, and carry as the amp is loaded into a permanent rack; in the midst of setting up your rig, it’s cool to point to the GX5, its schematic, and say, “Oh, it’ll be simple to set up — just look at this!”

— Strother Bullins