Thunder-KS4 I

The Thunder-KS4 I is a compact active subwoofer featuring a 2x18” cone drivers and a powerful 4x 2500W @ 4Ω audio amplifier module with built-in DSP. The audio power output connectors allow the Thunder subwoofers to drive a wide range of K-array passive loudspeakers. Compatible with midrange loudspeaker and other passive subwoofers, the self powered Thunder subwoofers with DSP are designed to be the core devices in K-array sound reinforcement systems.



Ultra-light, high power subwoofers



  • Type:  

    Active subwoofer

  • Transducers:  

    2 x 18" neodymium magnet woofer

  • Frequency Response:  

    30 Hz – 150/450 Hz (-6 dB) crossover dependant

  • Crossover:  

    DSP-controlled, Low Pass @ 150 Hz, preset dependant

  • Max SPL:  

    141 dB

  • Coverage:  


  • Connectors:  

    Line Input
    2x XLR-F analog / AES3
    Line Output
    2x XLR-M Link analog / AES3
    Speaker Output
    2x SpeakON NL4
    powerCON TRUE1 TOP
    Networking and Data
    1x RJ45
    4x USB-A

  • Nominal Impedance:  

    4ohm subwoofer

  • Controllers:  

    Wi-Fi dedicated Mobile APP
    K-framework3 via wired Ethernet connection

  • Built-in DSP:  

    Input gain, routing matrix, delay, full parametric IIR filters (Peaking, Shelving, Hi/ Lo pass, Hi/Lo Butterworth), Onboard preset, Remote monitoring

Handling and Finishes

  • Dimensions (W x H x D):  

    1106 x 500 x 580 mm
    (43.5 x 19.7 x 22.8 in)

  • Weight:  

    60 kg (132.3 lb)

  • Material:  

    Polyurea coated birch plywood

  • Colors:  

    Black/White/Custom RAL


  • IP Rating:  




  • Amp Module:  

    4-ch Class D

  • Output Power:  

    4 x 2500W @ 4ohm

  • Power Consumption:  

    600 VA @ 8 Ω load, Pink noise, 1/8 rated power

  • (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
  • (4) In case of permament, long lasting installation in critical environments (swimming pools, beaches, yachts..), we recommend to further protect the subwoofer. Contact K-array directly to discuss best protection practices.
  • (5) CTA-2006 Standard single channel driven
  • New materials and design are introduced into existing products without previous notice.


Thunder-KS4 I Datasheet

WEB APP Quick Start Guide


Amp-to-speaker matching table

KS4 Layout

Thunder-KS4 I BIM


CRESTRON plug-in

Q-SYS Plug-in

Rev 1.0.0

Dante Ready Activation Guide

Ver 0.1

CE Declaration of Conformity

osKar System Update 1.6.8

KFramework3 v1.8.6 Windows

Ver. 1.8.6

KFramework3 v1.8.6 Osx

Ver. 1.8.6

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