This is a great amp for a high-fidelity, power-hungry system, and the 6-yr warranty caps it off! FYI I am an audio/HT enthusiast, and will spend money on good picture/sound, but always looking for the best deal.
It is driving Magnepan 1.7 speakers, which are quite power-hungry. Amp feeds them plenty of juice and stays nice and cool.
The QSC is unique in that it does "True Class B", using fancy digital tracking technology, combined with a traditional big power supply, with no energy-inefficient class A circuitry. An oddball tech, but it works well.
The main competitors are the Behringer A500 and the new crop of $200-300 "digital" high-efficiency amps. The Behringer A500 has issues on the volume knobs, causing nasty distortion. Otherwise, it is a very nice, very robust traditional class a/b amp, passively cooled.
The Behringer (and Crown and QSC and Marathon and Peavey and…) “digital” high-efficiency amps are awesomely small and efficient. However I have heard complaints of lack of low-level resolution and detail, and treble attenuation. On a practical note, some of them have only pro inputs, no RCA. Also most of them start at the $300 range. I was able to snag the GX3 on Cyber Monday for $225. Finally, only QSC offers the 6-yr warranty, and has a tremendously positive reputation among the DJ set.
The GX3 sounds great at low volume, and better and better as it gets louder. I’ve not been able to drive it to clipping. All decent amps should sound identical – if they don’t, there’s a design issue. I cannot detect any coloration, loss of detail, frequency attenuation, etc. It has RCA inputs in addition to balanced, and screw terminals in addition to Speakon and ¼”.
The stock fan is noisy (think old computer case whine) and gets louder as the amp heats up. I inserted a 50ohm resistor in the fan circuit to slow it. It is now essentially silent. The amp is in a nice temp-controlled house, not baking in the sun in a pro rack, so I am sure it’ll be fine.
In summary: This is a huge dollar/watt deal, while maintaining quality and uncoloured, accurate sound, and backed up by a phenomenal warranty. If you have a power-hungry system, do not hesitate to give it a try. I got mine from prostaraudio.com, hassle-free.
QSC GX3 fan noise fix!!! Read below.
First some background. I have been involved with music and audio gear since i was a kid. I am now 45 years old. I have built several speakers systems ranging from open baffle, sealed, ported, and even constructed a concrete subwoofer. I have built vacuum tube amps, solid state amps and modified a few.
My past systems consisted of Belles, Jolida, Rogue Audio, Meadowlark, Janzen electrostatics, NHT, Denon, Fourier, PS Audio, NAD, Sony, etc, etc. I have owned a few pretty decent brands. Enter the QSC GX3. First off you will notice it has a very lively presentation. What I mean is that it has excellent micro dynamics, excellent macro dynamics, excellent pace and rythym. A very involving amplifier. The bass is one of the first things I noticed. Very tight, well controlled, and deep. It has some of the best bass I have heard from an "entry level" SS amp. Much better bass control than most tube amps for sure. Midrange...reminds me very much of the first Odessy power amp I heard many years ago, Very open, very true, accurate and very musical. Highs are clear, accurate, not bright and well controlled. Of course proper system balance is needed here too. A bright source, bright speakers, crappy speaker cables, bad room acoustics, etc will all affect your perception of this unit. Why would anyone buy a PA amp instead of a true entry level audiophile amp?....cost. For various reasons I got away from audio for several years. Just started to get back into it and I decided to keep it to a budget. I was able to get this amp at a local Guitar Center for $200. A real steal of a deal. Picked up a great set of ADS L710speakers off craigslist. A Philips CD60 CD player...a real gem too...for 20 bucks. Using a custom passive preamp (gold in/out jacks, ALPS pots, good copper wire inside, etc) I was amazed by the initial listen. Everything clicked! I was floored by the bass line, midrange was sweet and highs were detailed but not bright. All in all a very sweet system and an extremely sweet amp. I swapped out the amp for a Denon model and it was nice bit the QSC just slammed it in terms of bass line and over all presentation. The Denon sounded distant, recessed, congested. The QSC sounded very lively, open, musical. Now for the bad news. The unit is fan cooled. The fan is audible...even up to a few feet away at lower listening levels. What to do...read nearly every internet thread on this amp and its noisey fan and finally found one thread 17 pages long about low noise 24v fans. I ordered one from Digi-Key (great company!). I installed the lower noise fan and it did help but not enough. The real culprit is the plastic fan shroud. It transmits the fan noise and acts like a sounding board. I covered nearly every square inch of the plastic shroud in DynaMat...twice. This helped very much. But the fan noise was still there. Here is the final fix. It worked great. Available at Radio Shack for less than 2 dollars. Drum roll......a 3 pin 12 volt regulator. Its easy!!!...run a 24 volt fan off 12 volts and its dead quiet. Not a single fan whisper even with your ear against the vents. Nothing but a slight breeze. Not a single bit of noise at all. Thats it. a 12 volt regulator. Sure the new fan helped a bit...the dynamat helped more..but the real fix....a 12v regulator from Radio Shack.
Do this mod at your own risk. I mounted the regulator to one of the fan's unused mounting holes. This way the fan cools the regulator too. Actually, the new fan draws such little current you do not need any heat sink on the regulator at all. Plus, mounting the regulator to the plastic fan body meant that the regulator was electrically isolated from the amp at all times..just good housekeeping not knowing what would happen if the reg case was bolted to what may be a common amp ground (chassis). So there you go. This amp is a real giant killer once you tame the fan using my method above. Sad to say but this QSC GX3 really shames a lot of much much much more expensive SS amps. I slight confession before I close. As my listening room is still under construction I cant really comment on this amps soundstage. But from my less than ideal room placement and other "bad things" going on in a semi dedicated lsitening room I can say that the sounstage shows real promise. It does extend beyond the left/right extremes of the speakers. The sound stage is more forward of the speakers rather that sitting 20 feet behind the speakers....this I really love. I hate a very distant sound stage. Sounds like you are lsitening from the rear most seats in a bad theater. Again, I am amazed at the level of performance from such an inexpensive amp. Hope this helps!