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DEEP (Digital Extension and Excursion Processing) is an exclusive QSC process that allows a K Series loudspeaker to deliver far more undistorted low-frequency output than could be produced by conventional means. DEEP begins by applying an equalization boost at low frequency. Certainly many loudspeaker systems do the same thing (there's nothing new about this). Some even take the next step and apply limiting to reduce the amount of EQ boost as the amplifier approaches overload. The effect may be better than nothing at all, but this process does create audible "pumping" and unnatural high frequency reductions at higher performance volume. DEEP employs sophisticated digital signal processing to identify and reduce only those brief, transient low-frequency peaks that can cause woofer over-excursion or amplifier clipping. Reduction of the transient peaks is nearly inaudible and allows the average low-frequency output to remain high. The result is an astonishing amount of low-frequency output, previously impossible to achieve from compact, smaller-format speaker systems.


There is an important relationship between woofer size and waveguide coverage pattern but it is frequently overlooked. It's known that all woofers have very wide coverage at lower frequencies and narrowing coverage as frequency increases. The smaller the woofer, the wider its coverage will be at a given frequency. However, many speaker designs simply ignore this acoustic principal and pretend that only the high-frequency horn coverage matters. But in reality, a smooth, directional transition from woofer to high- frequency is important in terms of consistent audience coverage and loudspeaker power response. K Series is designed using the Directivity Matched Transition (DMT) approach. DMT matches the high-frequency coverage angle to the natural coverage angle of the woofer at the crossover frequency. As a result, frequency response remains far more uniform across the entire audience area. The chart below shows the three K series full-range models (violet, blue and red lines) along with a theoretical 15" 2-way speaker (the black and gray lines) using a 50 x 100 horn and a crossover frequency of 2.2 kHz. As you can see, the horizontal coverage of this speaker dives all the way down to 50 before the high-frequency horn takes over and brings it back to 100 . What this means is that listeners who are more than 25-30 off axis won't be hearing much of the mid-range content (like vocals or instrumental solos) at all.This brings us to the next point. Many manufacturers offer speaker models with smaller diameter woofers. But typically those components are lower cost and inferior in performance compared to their larger-woofer siblings. QSC took a radically different approach by maintaining the same high performance level across the entire K Series line, regardless of woofer size. Each is powered by the same 1,000 watt amplifier module. The K8 delivers wide 105 coverage making it a great choice for performers who work in more intimate venues where the audience is closer to the stage and spread more widely. The more directional K12 with its 75 coverage is a better choice when more "throw" is needed. The K10, of course strikes a fine balance between both width and throw. No matter which model you select, you'll get flat frequency response across the entire coverage area.

Conical Wave Guide

There are a few basic concepts that guided the design of the K Series waveguides and helped achieve its overall impressive sound quality. First is the understanding that the best, most natural performance in a horn is achieved by avoiding parallel surfaces and abrupt changes in contour. Either will cause phase and acoustical impedance problems that lead to erratic frequency response. Second, while a waveguide with a large difference between horizontal and vertical coverage angles may be needed for specific applications, it will necessarily exhibit compromised audio performance. For K Series, the horizontal and vertical coverage angles are identical. Finally, the mouth (opening) of the waveguide should be approximately the same diameter as the woofer. In speakers where that isn't the case, it's likely that either the crossover frequency is too high or the waveguide isn't really controlling the pattern all the way down to the crossover frequency. Either of the above will lead to lack of pattern control in the critical mid-range. By keeping these concepts in mind, QSC created the large, well-behaved, conical waveguide found on K Series. The sonic benefits, both on and off axis will be clear when you listen for yourself.

1000 Watts

Loudspeaker manufacturers typically have two separate amplifiers in their powered speakers. Although they share a common power supply, the amplifiers operate very differently and output different power levels. While this approach can make for a streamlined, efficient design, it usually results in a less capable high frequency amp. As a result, the amplifier is easily over-driven if the operator pushes the system hard. The resulting high-frequency distortion is audible and may destroy the compression driver. K Series is different. First, K Series gets its name from the industry-best kilowatt amplifier module that drives its performance. Rated for 1,000 watts of continuous available power, this state of the art, light-weight Class-D module is comprised of both a 500 watt low-frequency (LF) amplifier and a 500 watt high-frequency (HF) amplifier (two 500 watt LF amplifiers in the K Sub). The 500 watts of HF amplification makes it nearly impossible to drive the system into distortion by pushing the amp beyond its design limits. The result is a cleaner sound and a far more robust design. The QSC kilowatt amplifier defines another key difference between K Series and traditional powered speaker systems. All K Series models, regardless of woofer diameter use the same kilowatt power module. Only the input circuitry and DSP programming differ from model to model. No longer does a smaller-format powered loudspeaker have to be equated with lower power and less total performance.

Energy Management

When the K Series DSP doesn't sense input to the amplifier module for 5 minutes, it automatically enters standby mode - effectively shutting down the amplifier, conserving energy and extending the life of the product. Once signal is restored, the processor instantly turns the amplifier back on without any noticeable audio delay. In this manner, the energy-conscious operator is able to conserve resources without taking any additional measures, regardless of the number of K Series loudspeakers in the system.

LED Operation

Located on the front of each K Series loudspealer is a blue LED that's more than just a simple power indicator. A switch on the rear panel allows the user their choice of three ways to utilize the light. In the default (PWR) position, the LED will illuminate and stay on as long as the speaker is powered on. For instances when a bright blue light may not be aesthetically consistent with the venue or the event, moving the switch to the (OFF) position defeats the front LED operation entirely but doesn't affect the status of the amplifier module. In (LIMIT) mode, the front LED indicates the onset of system limiting, allowing the operator to monitor the well being of the system from in front of the box.

Remote Control

A unique, yet highly beneficial function for many users of a product in this class is the K Series remote gain control. By way of a three pin block connector, a potentiometer (pot) can be wired to the K Series from a remote location. This pot will then act as an attenuator allowing volume adjustment from a remote location. Multiple speakers can also be wired to a single control knob a particularly handy benefit when K Series speakers are suspended in out-of-reach locations within a venue. Combined with the Energy Management function, this capability presents a compelling solution for many venues.

Professional Appearance

Unlike typical molded enclosures, the professional appearance of K Series makes it at home in any environment. Extensive consideration was given to the K Series industrial design to ensure that an artful balance between form and function was achieved at the highest level. Tasteful lines and curves define a product that enhances a performance rather than detracts from it. From its sleek shape, to its full form-fitted grille, to the elegant non-reflective matte black finish and user-defeatable status light, everything about the K Series appearance is in perfect harmony with the professional quality inherent throughout the product.

Locking IEC Power Cable

Every K Series loudspeaker is equipped with a locking IEC power connector and cable. With a simple "click" the AC cord creates a positive lock with the amp module all but eliminating accidental disconnect during a performance. This feature is especially useful when using either the K10 or K12 as a floor monitor. If damaged or lost, the locking cable can be easily replaced with a standard widely available IEC cable.


The K Series is capable of connecting to just about any audio source a microphone, iPod or other MP3/CD player, a musical instrument or mixing console. Inputs can also be combined and mixed at the K Series rear-panel. For instance, a microphone and CD player can be combined for background music with announcements. Or, a musical instrument, MP3 player and microphone can all be combined for solo entertainer applications. Neutrik Combo XLR/1/4" and RCA inputs are featured, as well as XLR outputs for either daisy- chaining multiple K Series speakers or providing a mixed output to an amplifier, mixer or other audio device.

Threaded Pole

The K Sub features a threaded pole socket which accommodates a 31" positive-fit speaker pole (included). Unlike typical open-cup designs that can cause a speaker to wobble or tilt in the subwoofer receptacle, the K Series threaded mounting system assures a snug, safe fit. At the top of the pole, a 35mm circular end cap inserts into any K Series or other fullrange enclosure outfitted with a standard pole receptacle.

Rugged Construction

Unlike typical molded loudspeakers, K Series fullrange models are made with ABS (Acrylonitrile Butadiene Styrene) which is harder and more rigid than most traditional plastics. Used for high-pressure or high-impact applications, ABS can withstand greater temperature extremes, resist impact and stay rigid against high pressure fluctuations far better than polypropylene, polystyrene, or polyurethane. ABS is used in golf club heads, very high pressure plumbing, car body parts, helmets and other products requiring robust physical performance. Not only is ABS tough, it also delivers acoustic benefits. An ABS enclosure will vibrate less with low frequency audio energy resulting in more and tighter bass. The stability of ABS also makes it ideal for a molded enclosure that is going to be suspended for installation applications. Additionally, all K Series speakers are designed to withstand a rigorous series of drop tests and other abuses that make the wear and tear typically encountered by years of real-world use seem tame. Solid cast aluminum handles and an 18 gauge steel grille round out the K Series road-ready design.

Intrinsic Correction

K Series features Intrinsic Correction, a process found on many of our high-end concert sound products. Far more than just simple signal processing, Intrinsic Correction begins with between 60 and 75 extensive measurements of the loudspeaker's characteristics taken across a spatial field. The results of those measurements are then averaged. Utilizing an average derived from this many sampling points produces results that are far more representative of the loudspeaker's performance than taking a typical, single on-axis measurement. Next, a combination of IIR and FIR filters is applied in the DSP engine to adjust time, frequency and amplitude response to a maximally flat band-pass target. The end result is a loudspeaker with flat "power response", meaning that the overall energy radiated by the loudspeaker is even across its operating range.

Class D

K Series features a state of the art, QSC-designed Class-D amplifier module. The benefits of Class D technology in a powered loudspeaker are many. First, because the power supply is much smaller than other amplifier designs, there is a significant weight savings (The K Series module weighs a mere 6 pounds). Also, because Class D amplifiers generate far less heat, they don't need bulky heatsinks, further reducing the amp's weight. And while amplifier performance in typical designs relies greatly on access to a sturdy, steady AC power source, Class D amplifiers operate with far greater efficiency, drawing less current from the power source. Basic linear amplifiers see significant power losses due to heat generated as they cycle between the positive and negative voltage rails. But an ideal semi conductor wants to be either "fully on" or "fully off" in order to maximize efficiency and minimize loss due to heat. The basic principle of Class D is to utilize fully-on and fully-off "switches" that operate at a frequency much higher than the audio range so the resulting pulses can be filtered and smoothed out, leaving only the desired audio signal. The result is nearly loss-free operation and far less heat build up when the amplifier is driven continuously at high operating levels.


K Series is one of the most robust and trouble free systems available anywhere. First, it benefits from the closed design of an active loudspeaker system, offering more protection of both the amplifier and the transducers than would typically be possible with a component system. Next, K Series features QSC Guardrail technology, originally introduced on our GX Series amplifiers, which prevents destructive clipping distortion and woofer over excursion. Heat dispersion is managed by a number of thermal protections including a virtually silent internal fan that engages on-demand during periods when the amp senses high temperatures and turns off when no additional cooling is necessary. There is also discreet signal limiting technology to prevent overheating of the amplifier and transducers as well as DC and short-circuit protection such as is found on all rugged, reliable QSC amplifiers.

Additional Info

Additional Info

Manufacturer QSC
UPC 684284055323
Package Contents
  • (1) QSC KSub Subwoofer
  • (1) USA Power Plug
  • [100-240V 50/60Hz]
  • (1) M20 Threaded Loudspeaker Pole
  • (1) Threaded Pole
  • (1) Warranty

The KSub is a dual-12" bandpass design, constructed of premium birch and includes high-quality, low-noise casters. The subwoofer features a threaded pole receptacle for a positive, wobble free connection to a threaded speaker pole (included).

Remote gain control capability is offered via a potentiometer (not included) connected to the on-board Euroblock connector. In an installed application, multiple K Series speakers can be "daisy-chained" for total gain control from a single remote pot. Auto-standby mode is engaged after 5 minutes of inactivity.

QSC KSub Subwoofer Features:
  • Lightweight portable powered speakers with legendary QSC amplifier power and reliability
  • 1000 watt continuous Class D power module
  • Extensive DSP enhances system performance
  • Attractive and professional appearance
  • Rugged birch plywood enclosure
  • Tour-grade 18 gauge steel grilles
  • Comfortable ergonomic handles
  • Threaded pole socket with speaker pole included
QSC KSub Subwoofer Overview- PRESS PLAY
Warranty Warranty Information
Product: Period:
QSC KSub Subwoofer 3 Year


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