K-Array Thunder KS4 I – Self-Powered Dual 18" DSP Subwoofer (Black)

Product Overview

The K-Array Thunder KS4 I subwoofer is a self-powered dual 18" subwoofer with onboard DSP built for high-output commercial AV installation and live event production. Combining two 18" neodymium woofers with a four-channel 2500W Class D amplifier, it delivers 141 dB peak SPL and bass extension down to 35 Hz from a single compact enclosure. Because its amplifier outputs can also drive passive K-array loudspeakers, the KS4 I works as both a subwoofer and the powered core of a complete installed sound system. Integrators specifying a DSP subwoofer for auditorium installation, house of worship sound reinforcement, or large multi-purpose rooms will find it covers amplification, processing, and low-frequency reproduction in one chassis.

Product Description

The Thunder KS4 I is the flagship self-powered model in K-array's Thunder subwoofer line, pairing dual 18" neodymium magnet woofers with a 4x 2500W @ 4 ohm Class D amplifier module. The defining feature for system designers is its set of audio power output connectors: two SpeakON NL4 speaker outputs let the KS4 I drive passive K-array midrange loudspeakers and passive subwoofers directly, eliminating separate amplifier racks in many commercial deployments. Onboard DSP provides a freely assignable routing matrix, three-band parametric input EQ, eight-band parametric output filters, dynamic limiters, and up to 230 ms of channel delay, all running on the embedded osKar operating system with a quad-core 1.5 GHz processor.

Connectivity supports both analog and digital signal paths, with two XLR inputs accepting balanced analog or AES3 and matching XLR link outputs for daisy-chaining. An RJ45 port enables wired Ethernet control through K-Framework3 software, while the K-array Connect mobile app gives technicians wireless access to DSP parameters during commissioning. The bass reflex enclosure is built from high-density Finnish birch plywood with a rugged polyurea coating and carries an IP53 rating, making it suitable for both fixed installation and covered outdoor commercial deployment. This black version is also available in white as the Thunder KS4W I, and you can browse the full K-array collection for matching satellite speakers and accessories.

Key Features

• Dual 18" Neodymium Woofers — Two high-excursion 18" neodymium magnet drivers reproduce low frequencies down to 35 Hz with 141 dB peak SPL for large venues.
• 4x 2500W Class D Amplification — The built-in four-channel switching amplifier delivers 2500W per channel at 4 ohms, powering the subwoofer and external passive loudspeakers.
• Power Outputs for Passive K-array Speakers — Two SpeakON NL4 outputs drive passive K-array midrange elements and subwoofers, letting one KS4 I serve as the amplified core of a full system.
• Onboard DSP with Routing Matrix — Integrated processing includes parametric EQ, selectable IIR filters, dynamic limiters, signal routing, and up to 230 ms of delay per channel.
• Analog and AES3 Digital I/O — Dual XLR inputs and link outputs accept balanced analog or AES3 digital signals for flexible integration with modern DSP-based AV systems.
• Network Control via K-Framework3 — An RJ45 Ethernet port allows centralized design, monitoring, and control of multiple units over a wired LAN.
• Wireless Commissioning App — The K-array Connect mobile app provides Wi-Fi access to gain, routing, and preset parameters during setup and service.
• Durable IP53-Rated Cabinet — The Finnish birch plywood enclosure with polyurea coating resists wear and weather exposure in demanding installation environments.
• Black, White, or Custom RAL Finish — Factory finish options allow the cabinet to match architectural requirements in design-sensitive spaces.

Typical Applications

• Auditorium sound reinforcement requiring extended low-frequency output
• House of worship systems where one unit powers passive satellite arrays
• Multi-purpose rooms hosting music, presentations, and live events
• All-hands rooms and large commercial meeting spaces with program audio
• Broadcast studio environments needing full-range monitoring support

Technical Specifications

Frequently Asked Questions

Which passive K-array speakers can the Thunder KS4 I power?

The KS4 I's four amplifier channels and SpeakON NL4 outputs are designed to drive passive K-array midrange loudspeakers and passive subwoofers using dedicated presets loaded onboard. K-array publishes an amp-to-speaker matching table, and our team can confirm channel loading for your specific speaker complement before you order.

Can the KS4 I replace a separate amplifier and DSP in my system design?

In many installations, yes. With 4x 2500W of Class D amplification, a routing matrix, parametric EQ, limiters, and delay onboard, a single KS4 I can power and process a complete satellite-plus-subwoofer system without an external amplifier rack or processor.

How is the KS4 I controlled and integrated with room control systems?

The unit is configured over wired Ethernet using K-Framework3 software or wirelessly through the K-array Connect mobile app. K-array also offers control plugins for platforms including Q-SYS, Crestron, and Control4 for integration with installed AV control systems.

Is the KS4 I suitable for outdoor or semi-outdoor installation?

The polyurea-coated birch plywood cabinet carries an IP53 rating, which protects against dust ingress and water spray. It is appropriate for covered outdoor and semi-exposed commercial installations; for permanent direct weather exposure, consult an integrator about additional protection such as the K-AMPCOVER II rain cover.

What is the difference between the KS4 I and the smaller KS2 I and KS3 I models?

The KS4 I uses dual 18" drivers with 4x 2500W amplification for 141 dB peak output, while the KS3 I uses a single 21" driver at 139 dB and the KS2 I a single 18" driver with 4x 1500W amplification at 137 dB. Choose the KS4 I when a venue requires maximum low-frequency headroom from a single enclosure.

What warranty and support come with this subwoofer?

K-array products are covered by the manufacturer's five-year warranty policy. Creation Networks provides pre-sale system design assistance and post-sale support for commercial AV deployments.