Road Test: QSC KS212C Subwoofer In Review

Evaluating a new cardioid, dual 12-inch-loaded subwoofer.

The new KS212C from QSC is a cardioid subwoofer that utilizes dual 12-inch cone transducers powered by a pair of class D amplifiers (each rated at 1,800 watts peak).

It’s a 6th-order bandpass design, with ported chambers on either side of the woofers, which can enhance efficiency and output capabilities.

The arrangement of the long-excursion woofers, combined with onboard DSP, delivers cardioid output stated to provide 15 dB more at the front than at the rear of the unit. In addition, QSC’s proprietary TFR (Turbulent Flow Reduction) port is designed to deliver enhanced resonant tuning and higher velocity air flow.

The KS212C is rated to produce maximum sound pressure level of 132 dB (at 1 meter) with a frequency response of 39 to 118 Hz, -10 dB. The rugged painted birch enclosure measures just 24.5 x 15.5 x 33.5 inches (HxWxD) and weighs 88.5 pounds. Two M20 sockets built into the cabinet accept a 35 mm loudspeaker pole (included with the sub) in either horizontal or vertical orientations. Aluminum handles and four rear-mounted casters make transport easy. An optional cover is available to provide added protection.

For this evaluation, QSC also supplied a pair of K10.2 powered full-range loudspeakers to accompany the KS212C. (I evaluated the K.2 Series in September 2017 LSI and found them to be quite good for a range of live reinforcement applications.)

Getting Acquainted

The first thing that caught my eye with the new subwoofer right out of the packing box was the 3-inch casters. Many subs either don’t come with casters at all, or they’re optional. The casters on the KS212C are heavy duty, and as I found out later, don’t rattle or make noise when the unit is playing.

I also noted the pleasing aesthetic look of the cabinet with its dual ports as well as the inclusion of thick rubber feet that keep it elevated slightly off the ground while also providing added stability when stacking multiple units – there are small routed-out “sockets” in the wood to accept the feet.

Further, I quickly discovered that the front ports (positioned near the cabinet edge) make perfect handles to flip the unit down into playing position or back up on its casters. One person can easily move the sub around and position it.

There matching dual ports on the rear reside with a control panel that’s very well laid out. On the left side is an IEC power input, fan and power switch, while the right side contains a pair of combo TRS/XLR inputs and XLR outputs for the dual channels as well as a single volume knob that controls both channels. Above that is a nicely sized display with two menu push-buttons and a large knob to scroll through the menu.

Note that users can’t adjust the cardioid setting – the sub will always operate with that directionality. However, the DSP offers an adjustable crossover, delay and scene storage for saving and quick recall.

There are two primary system configurations for the KS212C. One or more units can be used on each side in a typical PA system setup or a single unit can be deployed with stereo top cabinets. By sending a stereo signal from the mixer to the A and B inputs on the single sub, users can output the stereo signals to full-range loudspeakers via the channel A and B “thru” (output) jacks. This is great for smaller gigs where two subs might be overkill.

Control functions and I/O on the rear panel.

After unpacking everything, I was able to easily set up a system and began playing a series demo tracks. The cardioid design did not disappoint – it really does provide a high degree of attenuation to the rear of the enclosure. One of the techs in our shop noted how nice it was to attain cardioid performance from a single box rather than having to stack two or more subs and then fiddle with processing to get the same result.

The KS212C sounds great with all types of music program, and at all levels. The bass is solid and tight, delivering plenty of thump from a relatively compact package.

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