Audio Review: QSC K12 Self-Powered Loudspeaker
QSC is a familiar name in pro sound circles, due primarily to their ubiquitous power amps. QSC amps have been delivering great sound for decades, in every venue from huge touring rigs to hotel meeting rooms. QSC amps have a reputation for bulletproof reliability and great sound, so the company's decision to offer low-cost self-powered speakers a few years back piqued the interest of the industry. QSC's HPR speakers were (and still are) a hit, delivering excellent sound and value from a line that included a 12-inch two-way, 15-inch two-way, large 15-inch three-way and two subs.
QSC's newest K-Series line is designed for high output from smaller cabinets, offering two-way models with single 12-inch, 10-inch and 8-inch woofers (models K12, K10 and K8 respectively). Each K-Series speaker offers the same 1,000 watts of power, which puts QSC as the current winner of the "horsepower war" brewing between speakers in this class (more on this later). A 1,000-watt subwoofer with dual 12-inch drivers rounds out the line. List prices for the speakers are $999, $899 and $759 from the K12 on down; the KSub has a list price of $1,199.
Each two-way cabinet is made from ABS plastic with integrated high-frequency wave guide, metal grille, handles, suspension points and pole socket. All three speakers use the same 1.75-inch diaphragm compression driver, though the dispersion of each wave guide is matched to that of the low-frequency driver. Since larger cones "beam" higher frequencies, coverage gets progressively tighter as you move up the K-Series line. The K8 offers 105-degree conical coverage; the K10 and K12 speakers offer 90- degree and 75-degree conical coverage respectively. The K10 and K12 cabinets are angled for floor wedge use on one side; the K8 does not have a similar angled side.
A conical horn pattern is rarely as good for smaller venues as an asymmetrical pattern (wider horizontal dispersion), as the latter will keep more of the acoustic energy on the audience. Thankfully, all K-Series speakers have an innovative rotating pole cup that can tilt the speaker down
7.5 degrees if needed. This puts less acoustic energy on the back wall and ceiling, which is a plus when room acoustics are controlled and a lifesaver when they're not. Nice touch, QSC.
The KSub uses a compact birch plywood enclosure of the bandpass persuasion. It includes back-panel casters, handles and sturdy threaded pole mount (pole included). At just 74 pounds, rolling and setting up the KSub is easy.
In and Out
No longer content to just build amplifiers into speakers, some manufacturers are apparently adding mixers, too. The K-Series speakers have decked-out rear panels with multiple inputs, gain controls, direct outputs and a mix output. Inputs A and B have combo 1/4-inch/XLR inputs, gain controls and direct outputs. Input A has a mic/line switch which allows you to plug a mic directly into the speaker; input B offers an additional stereo input on RCA connectors. These input signals move through their respective gain controls and are then summed to the power amp section and XLR line out connector.
Theoretically, a performer could use a single K-Series speaker to amplify a vocal mic, keyboard (or guitar with pedalboard) and backing track without needing a mixer. The speaker's mix output could be routed to a floor monitor. While unlikely, this scenario illustrates the impressive flexibility of the K-Series speaker's built-in mixer. Overkill? Yes, for most applications. But if you need flexibility, the K-Series has it in spades.
Other back-panel controls include a low-frequency switch with three positions. In the “Ext Sub” position, a 100 Hz high-pass filter is engaged for use with an external subwoofer. “Norm” leaves the bass untouched, and “Deep” adds a sizable bass bump with an additional digital protection/limiting circuit. A HF switch offers “Flat” and “Vocal Boost” positions. The latter applies a gentle, broad EQ boost for frequencies between roughly 1 kHz and 4 kHz. This increases vocal level and intelligibility. The final switch controls the front-panel LED, with settings for power indicator, limiting indicator or completely off.
Beyond the locking power connector, the last notable feature on the K-Series back panel is a handy remote gain jack. Add some light three-conductor wire and a potentiometer, and you can have remote gain control over one or many K-Series speakers. This could be a real plus in certain permanent install situations.
The KSub's back panel is simpler, offering two combo 1/4-inch/XLR inputs, direct outputs and a single gain control. The KSub has a “Deep” mode, polarity invert switch and the same power LED options as its high-frequency brethren.
All four speaker models boast excursion and thermal limiting, as well as a 50-mm variable-speed cooling fan that engages only when needed. All K-Series speakers have QSC's "Intrinsic Correction" signal processing which applies dozens of tuned filters for the smoothest-possible frequency response.
In Use
Since speaker performance is mostly about sound, we'll start there. We tested the K12 (and KSub) for this review. Considering the similarities between the K8, K10 and K12, our observations should hold true across the line.
In short, the K12 sounds extremely good. With LF and HF switches flat, the cabinet exhibits a smooth, "hi-fi" sound with an extended top-end and solid bass. The “Deep” setting increases low-frequency output appreciably at lower volume levels, but its effects become inaudible as you approach the maximum output of the speaker. Considering that bass energy levels could be increasing by a factor of 10 with this switch engaged, it's no wonder the DSP has to reign “Deep” mode in at higher output levels. At low to moderate levels, however, engaging the “Deep” switch sounds much like adding a subwoofer beneath the K12. If you need lots of bass at high volumes, the KSub does a great job freeing the K12 up to concentrate on higher tasks.
The speaker's “Vocal Boost” setting really pops a vocal out from the surrounding music, but it does so without sounding harsh or strident. Clarity increases, with only a subtle loss in the speaker's "hi-fi" character. Considering that most of its competition falls into either the push-the-vocal or flatter-is-better camps, it's nice that the K-Series can give you both from the same speaker.
Coverage is smooth and controlled, with off-axis sound exhibiting minimal audible phase cancellation or other coloration. Walking in front of the K12 underscores the fact that 75 degrees is a pretty tight pattern. Folks with a wide swath of seats to cover may need to consider the wider K10 (or even K8), or a pair of K12s splayed for wider coverage.
Thanks to its comfortable handles and light weight, handling the K12 (onto a stand, for example) is easy. The speaker's ABS plastic enclosure feels reasonably solid, but a tap on its sides exhibits more resonance than you'd hear with a well-braced wood cabinet. This translates to power loss, and it's one place where the quest for light weight has its drawbacks.
The K-Series 1,000-watt power amp section deserves a closer look. Other self-powered speaker lines (QSC's included) allocate more power to the woofer than to the horn, often by a factor of 4:1 or 5:1. There's a simple reason for this: bass frequencies take more power to reproduce. Hence the K-Series horn has more power than it needs, and it leaves several hundred watts of amplifier power unused even at maximum SPL. This makes the K-Series' 1,000-watt label a bit misleading. Having identical power amp sections for horn and woofer makes sense from a manufacturing standpoint, but it doesn't make much sense in practice.
The K-Series' 1,000-watt label will undoubtedly cause some buyers to think it will get louder (two times louder?) than the competition. In reality, output of the K12 was respectable but not mind-blowing. Compared to a 12-inch two-way system with half the rated power, the K12 was only slightly louder. As with similar designs, the K12's maximum output is limited by a single woofer, front-mounted in a compact plastic cabinet. There's no cheating the laws of physics.
The K-series line is made in China, with Chinese drivers and components. Whether country of origin is a factor or not, the line's quality is not quite on-par with what we've come to expect from QSC. The stamped-frame woofer isn't particularly confidence inspiring. The back-panel knobs wiggle, and the switches change position with a gritty "crunch" instead of solid "click". The good news is that QSC is a company known for standing behind their products (in contrast to some of their competitors). They offer a generous six-year warranty on the K-Series speakers.
Special K
With its K-Series speakers, QSC has added another layer of refinement to the self-powered speaker class. They offer excellent sound, unmatched input and output flexibility, compact size, light weight and low power consumption. Though the horn will never use the full 500 watts available to it, the K-Series' output is substantial for such a small cabinet. Reliability of the Chinese-made drivers and electronics remains to be seen, but QSC stands behind the speakers with a six-year warranty.
Churches in the market for an extremely versatile, good-sounding speaker would do well to give QSC's K-Series a listen. Houses of worship looking to maximize their gear investment will also appreciate the K-Series' value.
Special thanks to Leo Gunther Enterprises (Orland, CA) for valuable assistance with this review.
Loren Alldrin is a regular contributor to Church Production Magazine.
