May 30, 2023

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KEF Expands Extreme Home Theater Series With First Architectural Speaker with MAT: CEDIA 2022

KEF has been riding the LS50 wave for over a decade but what a lot of consumers don’t know is that the British manufacturer is a very strong player in the CI category offering a number of affordable and rather expensive architectural loudspeakers for residential and commercial customers. Their big CEDIA 2202 announcement centers around two new 10-inch architectural speakers for home theater systems.

The KEF Ci250RRM-THX is a three-way coaxial in-wall/ceiling speaker and the Ci250RRb-THX is a high-output in-wall/ceiling subwoofer. Both are THX Certified Ultra for use in large rooms.

KEF’s engineering team in Maidstone, UK is reported to have pushed the technological boundaries to create the best possible sound for a concealed speaker system. Key innovations include KEF’s 12th generation Uni-Q driver array with Metamaterial Absorption Technology (MAT), patent-pending Cavity Radiation Control and Low Diffraction LF Aperture.

Ci250RRM-THX In-Wall

KEF Ci250RRM-THX In-ceiling Speaker Front Grille Cutaway

The Ci250RRM-THX is the first KEF architectural speaker with Metamaterial Absorption Technology (MAST). MAT is a highly complex maze-like structure that absorbs 99% of the unwanted sound from the rear of the tweeter, delivering a more natural sounding treble range. Additionally, the 100mm (4 inch) Uni-Q driver array in the Ci250RRM-THX is derived from the latest generation drivers, sharing many of the technologies found in the latest KEF Blade loudspeaker and the recently launched LS60 Wireless high-fidelity speaker system.

KEF Ci250RRM-THX In-ceiling Speaker Angle

Using its’Cavity Radiation Control,’ KEF claims the that Ci250RRM-THX is able to deliver the highest level of midrange acoustic realism in the market to date. The company says they’ve solved the midrange issues found in typical three-way coaxial loudspeakers. Its unique open-backed midrange with acoustically absorptive foam design eliminates midrange distortion, and up to 30dB of midrange dip which is equivalent to 99.9% of reduced SPL.

KEF Ci250RRM-THX In-ceiling Speaker Side

Another innovation is the implementation of the ‘Low Diffraction LF Aperture‘ in the Ci250RRM-THX. It is a carefully profiled, smoothed housing design for the Uni-Q driver array with an outer acoustically absorptive foam ring that reduces resonance and diffraction. The result is said to be exceptional MF/HF performance while preserving a tremendous bass output thanks to its 250mm (10 inch) bass driver.

KEF Ci250RRM-THX In-ceiling Speaker Back
KEF Ci250RRM-THX (back)


Model Ci250RRM-THX
Series Ci-R Series
Nominal impedance
Sensitivity (2.83V/1m) 89dB
Frequency response (±6dB) open-backed 28Hz – 20kHz
Frequency range (-10dB) 20Hz – 45kHz
Nominal coverage 120°
Max SPL 111dB
Crossover frequency 540Hz, 2.6kHz
LF Driver 250mm (10 inch)
MF Driver 100mm (4 inch) Uni-Q
HF Driver 19mm (0.75 inch) vented aluminum dome with Metamaterial Absorption Technology
Recommended amplifier power 50 – 250W
Recommended high-pass filter (Hz) 30 – 60Hz
Product external dimensions 346mm (13.62 in.)
Cut-out dimensions 175mm (6.89 in.)
net weight 6kg (13.2lbs)
Mounting depth from surface 168mm (6.62in.)
Optional rough in frame
Ideal rear volume 150L
Minimum rear volume 80L
THX certified THX® Certified Ultra
Safety and Regulatory Compliance IP64
Ceiling thickness (Maximum) 30mm (1.18 inches)
Ceiling thickness (Minimum) 6mm (0.24 inches)

Ci250RRb-THX Subwoofer

KEF Ci250RRb-THX In-ceiling Subwoofer Front with cutaway grille

Engineered to deliver incredibly accurate and powerful bass while remaining visually discreet, the Ci250RRb-THX in-wall/in-ceiling subwoofer utilizes an extra long-throw 250mm (10 inch) bass driver with a massive 150 ounce magnet which will require a bit of power. KEF recommends pairing with their DSP-equipped KASA500 amplifier for thunderous, low-distortion bass down to 20Hz with a maximum SPL of 109dB.

Tip: When the KEF KASA500 amplifier powers two Ci250RRb-THX, the performance meets the THX Select standard. When it powers four Ci250RRb-THX, it passes THX Ultra Certification.

KEF Ci250RRb-THX In-ceiling Corner Subwoofer


Model Ci250RRb-THX
Series Ci-R Series
Frequency response (±6dB) open-backed 20Hz – KASA setting
Frequency range (-10dB) 16Hz – KASA setting
Max SPL (dB) 109dB
LF Driver 250mm (10in.)
Recommended amplifier KEF KASA500
Recommended low-pass filter (Hz) 50Hz – 120Hz
Diameter 346mm (13.62in.)
Depth 153mm (6in.)
Cut-out dimensions 300mm (11.81in.)
net weight 5.6kg (12.3lbs)
Mounting depth from surface 147mm (5.8in.)
Ideal rear volume 140L
Minimum rear volume 70L
THX certified THX® Certified Ultra
Safety and Regulatory Compliance IP64
Ceiling thickness (Maximum) 30mm (1.18in.)
Ceiling thickness (Minimum) 6mm (0.24in.)
KEF Ci250RRb-THX In-ceiling Subwoofer Back
KEF Ci250RRb-THX (back)

Price & Availability

  • KEF Ci250RRM is $2200 each
  • KEF Ci250RRb is $1500 each

For more information:

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