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Thunder-KMT21 I

Thunder-KMT21 I

Not just an active 21-inch subwoofer, the Thunder-KMT21 I is also a proper instrument for the management and processing of the audio signal. At the heart of the Thunder-KMT21 I are 2 channels of 2000 W @ 4Ω in Class D – one dedicated to the 21" woofer and the other connected to a Speakon output on the rear panel – allowing different configurations in combination with any of our passive loudspeakers such at single mid-high speaker, entire columns of line arrays or other passive subs as reinforcement of the mid-low frequencies in larger applications.

With a 21" woofer, the Thunder-KMT21 I is ideal for medium to large applications where high quality, powerful sound is required.

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.



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


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.


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.


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.



Integrated DSP

Built-in DSP allows for fine tuning of every single sonic parameter of the loudspeaker, providing the sound engineer the highest control on overall performance and fine granularity in system configuration.


DSP Image
Dante Compatible

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


Self-Powered Capabilities

Our self-powered solutions prevent distortion from cumbersome and fragile passive crossovers and power loss due to long running cables, and offer plenty of advantages ranging from the compactness of the solution to the ease of integration with new and existing sound systems.




  • Power Handling 800W (AES)
  • Impedance 8 Ohm
  • Frequency range 30 Hz - 150 Hz ± 3dB (preset dependent)
  • Maximum SPL 136 dB (peak)


  • Omni


  • Type External Crossover Required
  • Frequency Low pass @ 150 Hz maximum


  • Type 1 x 21” neodymium speakers with 3” voice coil

Audio input

  • Connectors 2 x NL4 Speakon
  • Digital Connectors 1+ 1- (signal IN& LINK); 2+ 2-(through)

Physical Overview

  • Dimensions 55.5 x 55.5 x 76.3 cm (18.30” x 18.30” x 23.46”) (1)
  • Weight 12.6 Kg (27.78 lb)
  • Notes for data:

    1. ( W x H x D).
    2. Measured @ 4mt then scaled @ 1mt
    3. Measured with musical signal
    4. EIAJ Test Standard, 1kHz, 1% THD (single ch driven)

    New materials and design are introduced into existing products without previous notice. Present systems may differ in some respects from those presented in this catalogue.

Customers Applications

Thunder-KMT21 I can be successfully used in a range of different settings and events.

Discover all the projects where Thunder-KMT21 I products have been used