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QSC KS118 Powered Subwoofer

Steve Savanyu • December 2019Road Tests • December 14, 2019

The QSC K Series powered speakers are a popular choice for portable live sound applications including bands, clubs, DJ’s and rental houses. As part of the next-generation K Series, the KS118 high output subwoofer replaces the legacy KW181.

Built around an 18” long-excursion, direct radiating driver, the KS118 incorporates an integral 3,600W (peak) Class-D amplifier module providing 136 dB max SPL. Onboard menu-driven DSP handles the heavy lifting, offering advanced functions, including the ability to array two or more KS118’s in a cardioid configuration.

Additionally, the KS118 offers a “DEEP” mode that boosts low frequency extension below 60 Hz while decreasing sensitivity by 3 dB to maintain headroom. Ideal for EDM and other bass-heavy material, DEEP mode offers a chest-pounding experience without distortion.

The rear panel layout is simple and easy to use. An optional cap can attach to cover the data entry wheel and LCD screen.

‡‡         Menu Please…

The crossover menu selects a lowpass filter crossover point of 80 Hz or 100 Hz. The 80 Hz setting is optimized for the K.2 and CP series, while 100 Hz is optimized for legacy K, KLA and KW model speakers.

The menu provides 0 to 100 milliseconds of delay to “time align” the sub to the top boxes if they are spaced apart, with the display simultaneously showing delay increments in milliseconds, feet and meters — a nice touch.

Two or more KS118’s can be configured for cardioid operation using the built-in DSP settings. In the cardioid menu, select FORWARD on each subwoofer facing toward the audience and select REAR for each sub facing away from the audience. Feed the same audio signal into both subwoofers and set the same gain level on each sub. It is that simple.

Left and right XLR-1/4” combo connectors are used for inputs. The L-R signal loops through to XLR-M output connectors but is summed together in the sub. I use this configuration on smaller gigs. A single input gain control sets the level from both inputs. I like having a physical level control knob rather than digging through a menu to set the gain. LED’s on the rear panel indicate signal present and limiter active conditions.

A settings menu lets users adjust LCD contrast, check firmware version and configure which power LEDs (front-only, rear-only or both) illuminate. Operating parameters can be saved into one of five user “scenes” for later recall, and a “factory reset” function returns every setting back to default. QSC also offers a “lock-out” cover accessory that screws down over the LCD, menu controls and gain knob to keep inquisitive fingers away.

Rounding out the rear panel is a locking IEC power connector. An AC feed-thru connector (IEC or Edison) would be nice, so I could feed an associated top box without having to use a tri-tap extension cord.

The minivan-friendly KS118 in action for outdoor holiday decorating.

‡‡         When the Tough Get Going…

The KS118 is constructed of 18mm birch plywood for durability. A rugged steel grille with foam backing protects the driver. Each KS118 has four pre-installed, low-noise heavy-duty casters and two recessed handles. At first, I thought the wheels were a little stiff to move, but then realized the stiffness was intentional, as they did not rattle during use. A set of runners on the backside helps protect the I/O connectors and controls from damage. Although the KS118 can be used horizontally or vertically, its M20-threaded pole mount receptacle is only located on the top. Unlike some QSC subs, this one does not include a pole. Not a major issue, as I prefer an adjustable pole or separate speaker stand. Large square rubber feet grace the bottom and side of the box. Along with helping keep the sub from sliding around, two subs can be stacked, their feet mating with alignment cups in the second box.

Tipping the scales at 104 pounds, a KS118 is a two-person lift, but its compact size enabled me to load one into my van without much effort.

Until I started using QSC speakers, I never gave much thought to speaker covers. One issue with rear-mounted casters is the grille faces up when the box is rolling, making it easy to get dented or collect dirt/debris. QSC sent a set of the optional KS118-CVR transport covers with the speakers. Made of nylon/cordura material, these heavy-duty padded covers have a convenient pouch for storing the power cord, cut-outs to access the handles and a “grille guard” to protect the grille from being dented by items stacked atop of the rolling sub.

‡‡         Let’s Make Some Noise…

I set the subs up in my shop for the initial “disturb the neighbors” test. Playing an assortment of holiday classics (it’s that most wonderful time of the year), I compared the KS118 to my KW181. With the dance version of “Deck the Halls,” the KS118 seemed to have a tighter, more solid bass. One issue I have with 18” subs is that they sometimes sound a little “flappy.” The KS118 did not.

I take a sound system out and play holiday music to get the local Jaycees in the mood to decorate downtown. Normally, I take out a pair of QSC K12s, but this year I added a KS118 for a little extra kick. We rocked the town with clear sound and punchy bass.

On another gig, I substituted the KS118s for a band’s existing subs. This high-energy dance band plays a wide range of tunes, including some with synthesized bass keyboard. Typically, the band sets up a sub and a top box on each side of the stage. For this gig, I set up the two KS118s in cardioid mode centered in front of the stage. The low-end was punchy, tight and loud, yet the backwash onto the stage was minimal. The band members wondered how I got so much low-end without the feedback problems they typically experienced.

Like other QSC K Series products, the KS118 is well built, looks good in action and delivers a good solid low-end. Priced at $1,499/street, the KS118 does one job, and it does it very well.

At a Glance

Solid, Versatile Low-End Solution

QSC’s KS118 is a high-output active subwoofer producing impressive low frequencies and versatile onboard DSP for mobile entertainment, AV production, clubs, performance venues and portable sound systems.



  • Tight low-end
  • High SPL performance
  • High quality casters
  • Easy cardioid mode (two or more subs required)
  • QSC CVR transport covers


  • Heavier than other QSC subs
  • Would like to see AC outlet
  • Would like to see bandpass output


  • Configuration: Direct radiating enclosure
  • Power: 3,600 watt Class-D amplifier module
  • Frequency Response: 35 Hz to 111 Hz (-10 dB)
  • Max SPL: 136 dB peak (@ 1m)
  • Powering: Universal 100-240 VAC, 50/60 Hz
  • Cooling: Low-noise, variable-speed fan
  • Color: Black (RAL 9011)
  • Enclosure: 18mm birch plywood
  • Dimensions: 25.2 x 20.5 x 31”
  • Weight: 104 pounds
  • Street Price: $1,499

Manufacturer: QSC

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Steve Savanyu operates Buford T. Hedgehog Productions, an independent sound company in Northeast Ohio.

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