The Ci250RRb-THX is KEF's flagship in-ceiling subwoofer and part of the Extreme Home Theatre collection within the Architectural Speakers range. Engineered for discerning music and cinema enthusiasts who demand full-range, reference-quality bass from a completely concealed installation, it combines the performance of a dedicated studio monitor subwoofer with the practicality of an in-ceiling fitting.
Extra-Long-Throw Bass Driver
At the heart of the Ci250RRb-THX is an extra-long-throw 250mm (10 in.) bass driver with a massive 150oz magnet in the motor system. This combination allows the driver to move far greater volumes of air than a conventional in-ceiling unit, producing thunderous, low-distortion bass reaching down to 20Hz and achieving a maximum SPL of 109dB. The result is a genuine full-range low-frequency extension that matches the output of large freestanding subwoofers, entirely hidden within your ceiling.
THX Certified Performance
The Ci250RRb-THX carries THX certification, reflecting its ability to meet the tonal accuracy and output standards demanded by the filmmaking community. Used in a system of four units powered by one KEF KASA500 amplifier, it achieves THX Ultra certification for large-room home cinema environments. A pair of Ci250RRb-THX speakers driven by a single KASA500 meets the THX Select standard, making the system scalable to the size of your listening room.
Designed for the KEF KASA500
The Ci250RRb-THX is designed to work exclusively with the KEF KASA500 DSP-equipped amplifier, which applies optimised equalisation and protection specifically calibrated for this driver. The KASA500 provides not only the power headroom needed to unlock the driver's full dynamic potential, but also the signal processing that shapes its frequency response and ensures long-term reliability in a fixed-installation environment.
Robust Build and Easy Installation
The Ci250RRb-THX is constructed to withstand demanding installation environments. It carries IP64 certification, meaning it is protected against dust ingress and splashing water, making it suitable for use in bathrooms, covered outdoor areas, and humidity-prone spaces. The bespoke Ultra-Thin Bezel (UTB) keeps the visible rim to an absolute minimum, casting virtually no shadow and preserving the clean lines of any interior. Both the bezel and magnetic grille are paintable, allowing the speaker to blend seamlessly with any ceiling finish. A thoughtful mechanical design using a dog-leg clamp system allows straightforward fitting with the minimum of fuss, accommodating ceiling thicknesses from 6mm up to 30mm.