Review: QSC PLX2 Series
Six new models from QSC are given a hammering… but not too much of a hammering.
12 September 2006
Review: Lucas Kungl
It’s been about 10 years since we saw the first generation of QSC’s Powerlight series amps in Australia, and while they took us all pleasantly by surprise then, they have continued to be pretty good since.
Following closely in the wake of the successful Powerlight 2 and PLX amps, is this range of PLX2 switch-mode amplifiers. There are six models in the range: four fully-optioned touring models (ranging from 320 to 720W a side into 8Ω), and two cutdown versions (310W and 550W into 8Ω). I had access to the larger of these two compact models, the PLX1804, which can still push a healthy 900W per side into its recommended minimum 4Ω load. These are QSC’s figures, and are produced utilising the arbitrary 1kHz tone under controlled conditions, of course.
QSC has continued the PLX move away from the spartan flat-black no-nonsense aesthetics of the Powerlight series to a rather sharp-looking aluminium, stylised front, with the all-important blue LED that is a must-have these days – when it comes to LEDs, blue is surely the new green. At least red is still red… and it still means ‘bad’ – or at least an indication that QSC’s circuitry is earning its keep, and – to ‘turn it down stupid!’.
The PLX range also has proper little handles on the front so your fingers don’t get squashed racking them up like the old Powerlights! (They weren’t that light!)
To many, there is not much to say about the top end of the touring power amp spectrum; if they’re reliable, affordable, powerful and suited to their application then they’ve got the job. If the new QSC’s lacked these basic principles then they wouldn’t even get a mention here – so what sets them apart?
WEIGH IN
Firstly, the two compact models, the PLX1104 and PLX 1804, weigh in at a under 6kg, and all four of the full-size models are under 10kg. This is why switch-mode amps were developed in the first place: no toroidal transformer to lug about!
These two lightweights are basic, stripped-down models to suit the budget conscious. They have the same impressive current management to ensure plenty of power is always available, but next to no user controls. Many of the features common throughout the series are still present, functioning behind the scenes – input clip limiting, output protecting current limiting, DC fault, thermal, short circuit, on/off muting and so on. They would be well suited to installations and as an all-round ‘little rig’ amp, as they are pretty much plug in and go. They cannot be bridged, have Speakon outputs only, and to parallel the inputs one must physically link one channel into the other. They are also only recommended for loads as tough as 4Ω, which will suit many ‘anti low-impedance’ audio purists just fine. So why do away with 2Ω capability, user configurable switches, etc? Simply put, they are even cheaper, even lighter and about 10cm shallower in depth. Good reasons (although I do think a $1 input link ‘parallel’ switch should still be there).
LIGHT HEAVYWEIGHTS
On the other hand, the four larger units – the PLX 1802, 2502, 3102 and 3602 – are far more user-configurable, including some very useful filters. They are touted to happily rock down to 2Ω, can all be bridged, input paralleled and feature binding posts as well as NL4. If you’re too lazy to patch a crossover, use the 100Hz low- or high-pass filter to give yourself an instant two-way. The limiter can also be switched out (if you could think of a reason to). The output wiring even saves some adapter time, with both outputs wired to CHA’s Speakon for two-way four-wire applications – quite useful features without spending the extra dosh for extra equipment, extra patching or amplifier cards. Even the most powerful in the range is still under $3000, which makes them very tempting indeed. This top-of-the-range model will deliver 725W per side into 8Ω, 1800W per side into 2Ω, or a whopping 3600W bridged into 4Ω – all for less than 10kg and three grand.
NEED TO KNOW
SO DO THEY WORK?
My most frown-worthy memory of the first Powerlight amplifiers was their ability, or lack thereof, to keep up with fast transient bottom-end information. I’m pleased to note that there has been great improvement in this area. Not wanting to give the 1804 too hard a time, I left it swinging away with various low frequency and broad bandwidth tasks all day, without any complaints. The cooling is good, without being a whirring annoyance, and with transients as smooth and detailed as our inventory’s far more expensive, far heavier workhorses.
I do not believe in running any amplifier into its danger zones, even for the purposes of testing. There is a lot of current and lots of expensive equipment on the line. If one chooses to run an amplifier to within an inch of its life night after night, there is something wrong with the system designer, not the amplifier. If you need more power, spec a larger amp, like the PLX3602 for instance! I do like to tempt the manufacturer’s figures however, and, in this case, they’re pretty accurate. There is considerable power in this little amplifier and while I didn’t push it into internal limiting, a sine wave was perfectly clean even at very high outputs – as it should be. They are very quiet, and one must break all the gain structure rules to hear any considerable noise.
It has been commented, and should be considered for highly accurate system builds, that the different models have different input sensitivities and different voltage gains from each other. This is not so much a criticism as something to be aware of, if different models are to be employed within the same PA build, or fed from the same system controller for instance.
I’ve also noticed that certain QSC die-hards have also complained about the smaller gain controls, but I fail to see how big knobs maketh the amplifier. What ‘makes’ these amps is they’re fast, clean, of very high quality and reasonably cheap. Which all adds up to a pretty decent piece of audio electronics as far as I’m concerned. If you have plenty of QSC in stock already, you should be very impressed with the PLX2. If, on the other hand, you’ve been wary of switch mode amps (or at least you can’t afford the 10 grand switch mode amps) then make sure you audition the PLX2.
RESPONSES