QSC is one of the recognized leaders in power amplifiers. Its PowerLight amp series is used in numerous touring and regional sound companies. The company has come out with a more affordable series, the RMX line. It consists of three models: the RMX-850, RMX-1450 and RMX-2450.
Product PointsApplications: Live sound
Key Features: Two channel, 750 Wper side (at 4 ohms); efficient two-stage power supply; barrier, XLR, 1/4″ inputs
Contact: QSC Audio at 800-854-4079
QSC sent me an RMX-2450 ($899), which is a two rack-space, two-channel power amplifier. The 2450’s black, heavy-gauge steel chassis is still relatively lightweight. It features a Class H, two-stage power supply, which helps reduce AC current draw and waste heat by more than 40 percent.
This translates into powerful amps that don’t weigh a ton, which is important when you rack up six or eight of them. Additionally, QSC offers rear rack ears for all its amps — a must for tour- and transport-heavy gigs.
The front panel is simple — an on/off switch, left and right input level controls and signal-present and clip LEDs. The back panel offers a variety of operating parameter controls, including input configuration (stereo/parallel, clip limiters, 30 or 50 Hz high-pass filter), output configuration (bridged mono) and a legend explaining the settings.
The back panel also has the power cord connector and a resettable breaker, located just above the parameter section. A cooling fan is flanked on one side by the input connections (barrier strip, 3-pin XLR and TRS 1/4″ jacks) and on the other side by output connections (Neutrik Speakon and binding posts).
It was a warm Arizona spring day (warm days of 100 degrees really torture-test amps), and I was providing audio and lighting for the Phoenix Symphony at an outdoor concert. The first test was to run a Yorkville TX2m, biamped 12″/2″ monitor, using Yorkville’s TX2 processor. The QSC amp responded to voice, orchestra and drums with very nice clarity. While the system was idle (with no signal passing through) I noticed the RMX-2450 had a relatively low noise floor with just a very minor amount of system hiss.
The next test was for the power amp to run frequencies of 3 kHz and above in the house mix, through Yorkville TX8 three-way speakers. The speaker responded with a highly accurate reproduction of that particular bandwidth, as it did with subsequent tests in the 350 Hz to 3 kHz range and the 100 Hz to 350 Hz range.
The ultimate torture test is, of course, powering sub-bass cabinets with really big wavelengths, for a long time, loudly, on a hot day. Prior to the audience arriving, I revved up the system with a series of CDs, tone generator and kick drum and the RMX performed quite well.
The QSC RMX-2450 is a quality piece of equipment that will complement any speaker system nicely. It held up well under the toughest of conditions, maintained signal quality, never overheated and didn’t draw gobs of power as to trip breakers. I recommend the QSC RMX-2450 for your consideration if you are in need of quality power amps.