A closer look at the QSC GX5 Power Amp.

Written By Darius Van Rhuehl, Musician’s Friend Staff Writer

What if I were to tell you that you can have real QSC-quality power for your system at a price you’d never expect? To begin with, the GX5 has been designed specifically to provide high-end performance for professional entertainers on a limited budget. Tailored to accommodate the power ratings of the most popular PA loudspeakers out there, the GX series assures you a perfect fit without endless compatibility searches on the web. Along with greater portability, GX power amps offer connectors for all possibilities, easy, yet precise adjustment, and good old QSC sound quality and reliability.

What’s in your rack, Jack?

After being asked to review QSC’s HPR122i powered monitors, the first thing that came to mind was comedian Steven Wright’s quote, “It’s a small world, but I wouldn’t want to paint it.” I was performing in a duo in Southern California in ’93. Our concept was to offer studio-quality sound in live performance. Researching the gear we’d need to pull it off, I discovered QSC power amplifiers. Meanwhile, we had landed a steady gig at a very posh establishment right on the water in Newport Beach. One evening, I was introduced to two gentlemen who had come to see us play. One of them asked what power amp I was using. I just assumed they were fellow musicians, and being a helpful sort I lectured them about the virtues of QSC. As it turned out, the two gentlemen in question happened to be Pat Quilter and Barry Andrews, the founders of QSC. Lucky for me I liked the product, or the experience might have pinned my embarrassment needle in the red.

So what does this have to do with the GX5? Meeting Pat and Barry makes for an interesting story, but the real point is that I’m not just some guy sitting in a cubicle writing about a power amp I’ve had only a month to test. I’m a guy who spent 10 years depending on a QSC power amp to make a living—and in all that time, it never let me down.

With great power . . . comes great response-ability

The thinking behind the GX5 is as follows: QSC looked at the speakers that are most used by entertainers and the way entertainers use them. This enabled them to eliminate things you’ll never need while putting in everything you will. The end result is a more compact, lighter, and best of all, more affordable high-quality power amp.

On the front panel, you have cooling vents on either side of a center section, which is where the gain controls and LED Power, Signal, and Clipping indicators live. The gain knobs are detented for setting repeatability and level-matching. On the back panel, you have XLR, TRS, and even RCA inputs for compatibility with virtually any source, and for output, Speakon combo jacks (accepts NL4 or 1/4" connectors) and binding posts handle any speaker wiring needs.

At the heart of the GX is a premium toroidal power transformer. Keeping it cool is a variable-speed fan that draws cool air in over the power transformer and heat sink. During excessive clipping or extreme overheating, QSC’s exclusive GuardRail technology reduces gain just enough to preserve the integrity of the music and protect the speakers without pumping, distortion, or shutdown. The GX5 also features technology from QSC’s upscale PLX Series, which accounts for its higher power output. Another muy-cool professional touch is the built-in subwoofer/satellite crossover. The crossover switch sends 20Hz-100Hz to the sub (Ch. 1), and 100Hz-20kHz 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 dynamic range, which in turn provides greater musical impact.

QSC GX5 Power Amp Rear Panel 

Battle with the Band

My test was a simple one. I took the GX5 to some friends whose band was playing at a local club. We swapped their budget power amp for the GX5. The improvement to their PA was immediately obvious—much greater clarity at higher volumes. Expecting it to be a high-ticket item, they figured I was teasing them—until I told them the price. Despite the fact that they could easily afford one, they still don’t want to give it back.


Would I buy a GX Series power amp? In a New York nano-second. If you’re in the market for an affordable power amplifier but want pro features and national-tour reliability, the GX is the clear choice. If it takes you more than the aforementioned New York nano-second to decide on QSC, then I haven’t explained it properly—or you’ve skipped over the important bits. But I’m going to trust that I’ve done my job, just like you can trust the GX to do its job, year after year, without so much as a whimper or a hiccup. Now that’s gig security.

Features & Specs

  • Power levels matched to the most popular speakers used by entertainers
  • Optimized for maximum real-world headroom into 4-ohm and 8-ohm speaker systems
  • Inputs: XLR, 1/4" TRS, and phono (RCA) input connectors
  • 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 fits in compact, inexpensive effects racks
  • Lightweight—less than 26 lbs.
  • Detented gain controls for precise setting and matching of sensitivity
  • GuardRail automatically protects amplifier and loudspeakers from damage due to temperature rise or overdrive
  • Front panel LEDs monitor power, signal, and clipping
  • Subwoofer/satellite crossover built-in
  • Distortion: 20Hz-20kHz, 1dB below rated power
  • 8 ohms: less than 0.05%
  • 4 ohms: less than 0.1%
  • Signal to noise (20Hz-20kHz): 100dB