KS3P I 21" Passive Subwoofer, 4 Ohm, black

The Thunder-KS3P I is a high-performance 21” passive subwoofer designed to deliver deep, powerful low frequencies for professional audio applications. Featuring a neodymium magnet woofer, it offers a frequency response of 30 Hz – 150/300 Hz, with a DSP-controlled lowpass crossover for precise sound tuning.

With an impressive peak power of 2800W and a maximum ... Read more

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» Thunder-KS_UG_V1.3.pdf

» KS3_DS_0.2.pdf

» CE_2026-01_KApasLoudDECLARATIONOFCONFORMITY.pdf

Highlights

Thunder: Strike the perfect audio balance

Combined with the unique audio solutions of K-array, add exceptional lows to your frequency range for live sound events with a choice of five subwoofer models from the Thunder series present in both active and passive electronic versions.

Integrated Cardioid Technology

The THUNDER-KSCARDIO412P joins the Thunder family as a state-of-the-art cardioid subwoofer, engineered to deliver extremely powerful low-frequency output while drastically minimizing rear sound radiation. Designed for professional live sound and fixed installations, it ensures clean, focused bass that keeps back emissions to a minimum.

ULTIMATE SOUND CONTROL

Low frequencies have always been one of the most challenging aspects of system design. Their natural omnidirectional behavior makes control difficult, often resulting in unwanted energy on stage and a less defined sound.

The combination of integrated cardioid technology and advanced simulation environments allows low-frequency behavior to be predicted and shaped with precision.

This approach enables controlled directivity, reduced rear radiation, and a cleaner, more consistent acoustic experience across any application.

CRAFTED FOR HEAVY TOURING

The Thunder Series subs are built with a choice of Finnish birch plywood so it lightweight and incredibly resistant, making it the perfect speaker for audio rentals.The new polyurea paint and the cataphoresis treatment for the front grill, further treated with powder coating, also give greater resistance to the harsh weather environments often experienced on the road.

OBSESSION FOR DETAILS

The details can really make the difference, the side handles are elegantly integrated into the speaker body beautifully crafted for comfort. The M20 threaded flange on the top which is essential for combining with the speaker stands and pins of the Pinnacle and Axle systems, is made for steadiness with internal strong tubular brackets to give more stability.

Adaptable even off the stage

Thanks to K-array’s signature compact style, without trying to be defined as a design product the Thunder series can easily adapt to architectural installations or even wedding events in the open air where blending in is of great importance, also thanks to the possibility of a custom painting on demand.

EXTENDED LINE ARRAY

Among the Thunder-KS accessories, one of particular importance are the mechanics for hanging in arrays which allow it to be suspended in combination with the line array speakers of the Mugello family, and in clusters composed exclusively of subwoofers. This hardware also allows you to create arrays with corners, in order to follow the set-up of the main array.

INFRA MODELS FOR CINEMA

Sound performance is essential for an unforgettable cinema experience. Equal to the powerful and engaging imagery as seen on the big screen, the Thunder-KS model reveals an untapped potential of cinema sound performance by extending the low-end response even further, making it an easier task to excite the public in vast squares and even arenas.

MORE THAN JUST SUBWOOFERS

In their active version, the Thunders are more than just subwoofers. They include powerful 4-ch class D amplifiers fully managed by sophisticated integrated DSP processors.

This combination allows the electronics of a Thunder to deliver not only the power signal to the subwoofer itself, but offers up to three additional channels of amplification and processing, thus becoming a complete control unit that allows you to drive an entire stereo system using only one active unit. Questo si trasforma anche in un grande vantaggio economico.

POWERED BY INTELIGENCE

Enhanced performance and easy tuning are now managed by the Integrated Electronic Brain (IEB) implemented into K-array amplifiers. More than a traditional DSP, the built-in micro electronics driven by the integrated operating system osKar features expansive sound processing, offering complete user control over the system performance.

Dante Enabled

K-array amplifiers come with Dante already enabled, with the license built directly into the unit for immediate use without any extra activation steps.
According to the IEB or IEB+ version, different digital channel counts are available, offering flexible network integration and expanded audio distribution options.

Custom colors available upon request

The Thunder series is offered in black or elegant white finish and can be customized to match any RAL code to better integrate them in a wide variety of venues.
Thunder subwoofers are manufactured to achieve exacting standards and are subject to rigorous quality control system in Italy.

IP54