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The Thunder-KMT21P is a high-performance passive subwoofer designed with a powerful peak output of 136 dB to provide high-quality audio in the low frequency range for use in mid to large applications. The KMT21P features a 1800 W 21" drive unit with magnet structure and suspension engineered for maximum linear excursion.

The Thunder-KMT21P is ideal for medium throw applications, like theaters, concert halls, and AV installations.

More information about the Thunder line

Unique Performance-to-Size Ratio

Produces an impressive high-power performance by producing a high SPL from a small frame.


Color Customizable

We have the ability to customize your project by color matching your system to any RAL code to help you to better integrate the speakers into a wide variety of venues.



We created a portfolio complete with lightweight products that are easy to transportation and quick to setup optimizing logistics, space, labor costs and time.


Weather Resistant

We utilize the most durable and resistant materials when developing our products to protect and conserve the system regardless of the elements, rendering a K-array installation reliable and long-lasting.



Four-Corner Port Configuration

The unique four-corner port configuration provides symmetrical back loading to the speakers, for extended bass response with very low distortion.


Dante Compatible

With the dedicated K-dante accessory, this solution can be integrated into a Dante network making it interoperable with other devices.




  • Type Passive subwoofer
  • Transducers 21" neodymium magnet woofer
  • Frequency Response (1) 35 Hz – 150 Hz (-6 dB)
  • Maximum SPL (2) 136 dB (peak)
  • Rated Power 2800 W
  • Coverage Omni
  • Connectors speakOn NL4 1+ 1- (signal); 2+ 2- (through)
  • Nominal Impedance 4 Ω

Handling and Finishes

  • Dimensions (W x H x D) (3) 555 x 572 x 763 mm (21.8 x 22.5 x 30 in)
  • Weight 40 kg (82.2 lb)
  • Material Wood
  • Color Black, White, Custom RAL


  • IP Rating IP43
  • Notes for data:
    (1) With dedicated preset
    (2) Maximum SPL is calculated using a signal with crest factor 4 (12dB) measured at 1 m.
    (3) Included 17 mm (0.7 in) removable rubber feet

    Passive loudspeakers require dedicated presets loaded on K-array amplifiers.
    New materials and designs are introduced into existing products without previous notice.

Customers Applications

Thunder-KMT21P can be successfully used in a range of different settings and events.

Discover all the projects where Thunder-KMT21P products have been used