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QSC RMX 850a Power Amplifier

Brand:|Model: RMX 850a|Part # 245-690
The recently facelifted RMXa Series power amplifiers continue QSC's tradition of value, audio performance, and bulletproof reliability.
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List Price$479.99
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Part # 245-690
  • Compact size
  • 1/4" (6.3mm) TRS, XLR and barrier strip balance inputs
  • Binding post and Neutrik Speakon® outputs
  • Front mounted gain controls for easy access
  • Selectable low-frequency filters (30 Hz or 50 Hz) protect speakers and increase headroom
  • Signal and clip LED indicators to monitor performance
  • No changes in performance from the popular RMX series

Product Details

QSC RMX 850a Power Amplifier

The new RMXa Series amplifiers from QSC offer true professional quality performance at a new affordable price. This power amplifier's compact chassis is only 2 rack spaces high and less than 16" deep. XLR and 1/4" balanced inputs and Neutrik Speakon® and binding post outputs allow users a convenient choice of connectors, while user-defeatable clip limiters and selectable low-frequency filters optimize sonic performance.

Muscular Power Plant
The power supply is the heart of an amplifier, converting raw AC power from the wall to clean DC for the audio circuitry. The RMXa uses a powerful high-current toroidal transformer and ample filter capacitance to ensure generous energy reserves. This makes a critical difference in sound quality, allowing the amp to effortlessly punch out high level transients, even when driving abusive 2 ohm speaker loads.

Superior Performance
RMXa amplifiers deliver true studio-quality sound. A full complementary output circuit using the highest-grade linear output devices delivers ultra-low distortion (<0.05% THD) and a ruler-flat frequency response. SMT (Surface Mount Technology) triples small-signal component density, enabling QSC to pack up to 2,400 watts of power in a chassis only 2 rack spaces and less than 16" deep. And unlike other designs, RMXa output devices are direct-mounted to the heat sink for optimum thermal coupling and cooling.

Specifications: • Power output, stereo mode (EIA 1 kHz, both channels driven): 200 watts x 2 (8 ohms); 300 watts x 2 (4 ohms); 430 watts x 2 (2 ohms) • Power output, bridged mono mode (EIA 1 kHz): 600 watts x 1 (8 ohms); 830 watts x 1 (4 ohms) • Distortion (typical): <0.01% • S/N ratio (20 Hz - 20 kHz, 8 ohms): 100 dB • Input sensitivity @ 8 ohms: 1.15V • Voltage gain @ 8 ohms: 31.6x (30 dB) • Output circuitry: Class AB • Dimensions: 3.5" (2RU) H x 19" W x 15.9" D • Weight: 35 lbs.

Product Specifications
  • Power Output (RMS Per Channel @ 8 ohms)200 Watts
  • Output Channels2
  • Weight Range30 to 39 lbs.
QSC RMX 850a Power Amplifier
  • BrandQSC Audio
  • ModelRMX 850a
  • Part Number245-690
  • UPC684284062765
  • Product CategoryPower Amplifiers - Live Sound
  • Unit of MeasureEA
  • Product Rating
    (9 Reviews)
  • Weight41 lbs.
  • California Prop 65

    Warning: California residents only. Please note per Proposition 65 that this product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

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QSC RMX 850a Power Amplifier
QSC RMX 850a Power Amplifier is rated 4.8889 out of 5 by 9.
Rated 5 out of 5 by from EXCELLENT AMPLIFIER CHOICEI thought somone might like a reliability oriented review -I bought mine here over five years ago and its still going strong driving a pair of Cerwin Vega LS12's with demanding 6 ohm woofers -- off the shelf retail receivers would not drive my speakers at higher volumes without tripping, so I paired this amp with an HK signature series pre-amplifier/tuner and the combination sounds superb with no signs of strain or tripping at high volume levels. This amp also has multiple protection devices built in and switches on the back for fine tuning the sound etc - If your looking for a solid performing great sounding amp as well as bang for your buck, this one is a serious contender-!
Date published: 2012-08-09
Rated 5 out of 5 by from Excellent for hi-fiI needed a couple stereo amps for bi-amping, and wasn't happy with the commercial offerings that were anywhere near this price range. I don't listen particularly loud, probably using a couple watts average at most, but extra headroom in the amp is necessary for reproducing musical peaks, which can be up to 20dB higher than the average power. For non-engineers, 20dB is 100x the power.The RMX850s have been working very well. The high-frequency amp is directly driving BMS4550s on 511B horns, which because of their high efficiency take about 25mW to drive them to room-filling volume. I expected I might hear crossover distortion, and have to pad the amp output by 20dB to get the output operating point up to a few watts, but so far I've heard no evidence that there is audible distortion even at such a small output.You should also know the RMX850 has a "big brother", the RMX1450, which is the same circuitry, but for a few bucks more adds extra output capacity and has slightly higher rails. That translates to (even better) response on musical peaks.
Date published: 2011-08-21
Rated 5 out of 5 by from Makes An Absolutely Wicked HiFi AmpA long-trusted tech actually turned me on to this amp. He kept telling me..."this is as good as anything new (not used, necessarily) under $2,000". I could tell he was quite convinced of it and, later on, I figured what the heck and tried it. It's replacing a (dead) vintage, single-ended, $1,750 Luxman receiver (whose preamp I'd bypassed and was then using it as a power amp). It was being driven by a modified Behringer DAC through a shotgun stepped shunt attenuator. In went the 850 using the the pro balanced connections. At first everything seemed to be plane-jane vanilla. Not a lot of tone, only fairly dynamic, not the best soundstage, but decent bass. 3 weeks later and it all has opened up...kicking the old amp to the curb - punchy, deep and wide stage and the solidity of tone and especially the even-order harmonics are now kicking in bigtime! Odd harmonics are known to be destructive, they tend to obsure pitch and complex harmonic chord recognition. Incidently, for the first time, what's most readily apparent to me is yet another reason why the Beatles (whom I enjoy and dearly loved back in the day) were such geniouses - their addictive use of harmonics in their music at almost every turn. This is one of the most truly musical amps I've ever heard. Outrageous at the price.
Date published: 2011-08-05
Rated 4 out of 5 by from Great product for the priceHas all the power I needed and has no problem driving low ohm speakers.
Date published: 2009-07-28
Rated 5 out of 5 by from Solid, Reliable Power AmpOur church now has four of these amps plus an RMX 1450 powering the entire sound system. These amps just work. Perfectly. Easy to set up, with lots of flexibility in setting up the input and output modes. I also have one that powers my bass rig. Excellent.
Date published: 2009-06-02
Rated 5 out of 5 by from Very capableI use one of these in a bi-amped hi-fi to drive a pair of old Altec 605As below 1600hz. They do the job intended with no fuss.Sound is clean and transparent with excellent tonality. Imaging is properly spooky at times; in other words the amp isn't inhibiting the speakers' virtues. The only flaw is the fan noise which doesn't matter in pro use but sometimes intrudes with hi-fi use. But it's no big deal either.
Date published: 2008-07-09
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QSC RMX 850a Power Amplifier

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