Field Test: QSC Audio SRA2422 Studio Reference Amplifier

Mar 1, 2004 12:00 PM, By Steve LaCerra

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QSC Audio has established itself as a leading manufacturer of amplifiers for live sound reinforcement. In conjunction with breakthroughs in amplifier technology, such as its patented PowerWave switching power supply, which drastically reduces the weight of high-powered amplifiers, QSC also developed QSControl, a networking technology for remote amplifier management, and RAVE (Routing Audio Via Ethernet) digital audio networking.

Most recently, QSC turned its attention toward developing a line of high-powered amplifiers for critical use in studio and home theater applications. The result is the new Studio Reference Amplifier series that comprises three models: the SRA1222, the SRA2422 (reviewed here) and the SRA3622. Power outputs are rated at 200, 425 and 725 watts per channel, respectively (both channels driven into 8 ohms across the audio band @ 0.03% THD). For those who require more power, all SRA amps may be bridged for mono operation, resulting in a threefold increase over the rated stereo output.

SOLID, VERSATILE DESIGN

SRA amplifiers were designed with a variety of installation scenarios in mind. Rear panel DIP switches are provided (per channel) to configure the amps for stereo, parallel or bridged mono operation, and to turn the low-frequency filter on/off, select 20Hz or 50Hz roll-off and turn the clip limiter on/off. According to the well-written user's manual, the limiter kicks in only when clipping occurs, quickly reducing gain to remove the possibility of damage to the speakers. Rear panel input uses locking XLRs (pin 2 hot) and RCA connectors — unusual for a QSC amp, but this facilitates use in home theater applications. Speaker output is available on Speakon connectors and touch-proof binding posts that accept bare wire, spade lugs and dual-banana plugs. To facilitate bi-amplification, output from channel 2 is available on pin 2+/2- of channel 1's Speakon jack. With amps as powerful as these, it's comforting to see that all of the outputs are safe from prodding fingers.

The only obvious control on the SRA2422's beautiful aluminum front panel is an on/off switch. A small security cover hides the gain controls, enabling the gain pots to be locked out from unwanted tweakers. The gain controls will come in handy for anyone using small monitors or in need of adjusting speaker levels in a multichannel system. QSC includes rack ears, a hex wrench to remove the security cover and a 12-volt cable for use with the remote turn-on function.

IN THE STUDIO

I put the SRA2422 to work in my studio with a Yamaha 02R Version 2, Westlake Lc8.0 monitors and Monster Cable Z3 reference cables. (The SRA2422 took the place of a Bryston 3B amp.) Initially, I was concerned with the fact that the SRA2422 uses a fan for cooling, but in practice, the fan never became audible because it's a variable-speed unit producing only the amount of airflow necessary to keep the amplifier cool.

It takes about eight seconds for the SRA2422 to go through the soft-start sequence — a welcome feature for anyone who has blown a circuit breaker while turning on a high-powered amp. When switched on, the green power indicator illuminates dimly and then brightly while the red clip LEDs light. When the SRA2422 is ready, the red LEDs extinguish. Audio is muted until the amp has stabilized, so you'll hear no pops or thumps during power up. The SRA2422's green signal LEDs indicate the presence of audio.

With no input connected, the SRA2422 was virtually dead quiet. With my ear next to one of the Westlake monitor's tweeter, I could barely hear the slightest hiss and absolutely no hum, so it was easily established that the SRA2422 has a very low noise floor. Even with the 02R connected and its volume cranked up, there was still virtually no noise. In addition to the SRA2422's high S/N ratio, its other obvious strength is the seemingly limitless power reserves. When playing hard rock or dance tracks at volumes that were way too loud to be comfortable for extended listening, the SRA2422 cruised along without an audible gasp or a flicker of the clip LEDs. In fact, I never saw the clip LEDs illuminate. With this kind of reserve, the SRA2422 will have no trouble running mid-field or large main-type monitors cleanly to high listening levels. Both the high- and low-frequency extremes were uncolored and extended, though I preferred running the amp with the low-frequency filter bypassed. In the 50Hz position, kick drums and synth bass were thinned a bit, while in the 20Hz position, the difference was barely noticeable. No doubt the filter will be useful for powering monitors with limited low-frequency capabilities, such as the Yamaha NS10M or the Tannoy Reveal.

The QSC SRA2422 does what a reference power amplifier is supposed to do: make the audio signal louder and get out of the way. Along with its technical strengths, the SRA2422 looks good and stays cool without intrusive fan noise. Combined with its low noise floor and ample power reserves, the SRA2422 should be on the audition list for anyone requiring a top-notch power amplifier.

QSC Audio, 714/754-6175, www.qsc audio.com.


Steve LaCerra, a veteran pro audio journalist, is based out of New York City.






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