K-Array Thunder KS3 I – Self-Powered 21" DSP Subwoofer (Black)

Product Overview

The K-Array Thunder KS3 I subwoofer is a self-powered 21" subwoofer with onboard DSP designed for commercial AV installation and sound reinforcement where deep, controlled bass matters. Its single 21" neodymium woofer reaches down to 30 Hz — the deepest extension in the Thunder KS I line — and a four-channel 2500W Class D amplifier produces 139 dB peak SPL. Like all self-powered Thunder models, its amplifier power outputs can drive passive K-array loudspeakers, making the KS3 I a powered system core rather than just a subwoofer. It suits integrators specifying a high-output DSP subwoofer for auditorium installation, house of worship systems, or large multi-purpose rooms.

Product Description

The Thunder KS3 I builds K-array's deepest-reaching KS I subwoofer around a single 21" neodymium magnet woofer in a bass reflex enclosure, paired with a 4x 2500W @ 4 ohm Class D amplifier module. For system designers, the decisive feature is its set of audio power outputs: two SpeakON NL4 connectors let the KS3 I power passive K-array midrange loudspeakers and passive subwoofers directly from its onboard amplifier channels, replacing a separate amplifier rack in many commercial deployments. The DSP engine — running on the embedded osKar operating system with a quad-core 1.5 GHz processor — 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.

Signal connectivity covers both analog and digital paths: two XLR inputs accept balanced analog or AES3 with matching link outputs for daisy-chaining additional units. An RJ45 port enables wired control through K-Framework3 software for multi-unit installations, while the K-array Connect mobile app gives technicians wireless access to DSP parameters during commissioning. The Finnish birch plywood cabinet wears a rugged polyurea coating and carries an IP53 rating for dependable service in commercial environments. This black model is also offered in white as the Thunder KS3W I, and compatible passive satellites are in our K-array collection.

Key Features

• 21" Neodymium Woofer with 30 Hz Extension — The single large-format driver reproduces program material down to 30 Hz, the deepest response in the Thunder KS I family.
• 139 dB Peak SPL Output — High maximum output lets one enclosure cover auditoriums and large rooms that would otherwise need multiple smaller subwoofers.
• 4x 2500W Class D Amplification — The built-in four-channel amplifier supplies 2500W per channel at 4 ohms for the subwoofer and connected passive loudspeakers.
• Power Outputs for Passive K-array Speakers — Two SpeakON NL4 outputs drive passive K-array satellites and subwoofers, making the KS3 I the amplified hub of a complete 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 commercial integration.
• Ethernet and App Control — K-Framework3 software manages multiple units over wired LAN while the K-array Connect app provides wireless DSP access.
• IP53-Rated Polyurea Cabinet — The coated Finnish birch plywood enclosure resists dust and water spray in demanding installation environments.
• Black, White, or Custom RAL Finish — Factory finish options let the cabinet match the architecture of design-conscious venues.

Typical Applications

• Auditorium installations needing deep extension for music and program audio
• House of worship systems where one unit powers passive satellite arrays
• Multi-purpose rooms hosting concerts, presentations, and community events
• All-hands rooms and large commercial meeting spaces with live program content
• Broadcast studio environments requiring accurate full-range monitoring support

Technical Specifications

Frequently Asked Questions

Which passive K-array speakers can the Thunder KS3 I power?

The KS3 I's four 2500W amplifier channels and SpeakON NL4 outputs drive passive K-array midrange loudspeakers and passive subwoofers using dedicated presets loaded onboard. Our team can verify channel loading against K-array's amp-to-speaker matching table for your specific design.

Why choose a single 21" driver over dual 18" drivers?

The 21" woofer in the KS3 I extends to 30 Hz — deeper than the dual-18" KS4 I's 35 Hz — in a narrower footprint, making it the better choice when low-end depth and floor space matter more than absolute maximum SPL.

Can the KS3 I serve as the only amplifier and processor in my system?

Frequently, yes. With 4x 2500W of amplification, a routing matrix, parametric EQ, limiters, and channel delay onboard, one KS3 I can power and process a complete satellite-plus-subwoofer system without an external rack.

How does the KS3 I integrate with installed control systems?

Configuration uses K-Framework3 software over wired Ethernet or the K-array Connect app over Wi-Fi, and K-array publishes control plugins for Q-SYS, Crestron, Control4, and other commercial AV platforms.

Can the KS3 I be flown or pole-mounted in an installation?

Yes. K-array offers the K-EXTFRAME3 suspension hardware kit and K-HCFLY2 I fly bar for rigging the KS3 I, plus the K-POLE2 extendable pole for mounting a satellite speaker on top of the cabinet.

What warranty and support are included?

K-array products carry the manufacturer's five-year warranty, and Creation Networks provides system design assistance before purchase and integration support after delivery.