Monitor Audio CS140 Slim In-Ceiling Speaker (Single)

The CS140 is part of Monitor Audio’s Slim series — a range of architectural in-ceiling speakers engineered specifically for installations where ceiling void depth is restricted. Launched in 2017 alongside the larger CS160 and CS180, the CS140 is the most compact model in the series, designed to deliver Monitor Audio’s signature sound quality from a mounting depth of just 99 mm.

Driver Technology

At its heart is a 4-inch MMP II (Metal Matrix Polymer) bass driver — a polypropylene cone loaded with metallic particles to create a structure that is both rigid and responsive. This is paired with a 25 mm C-CAM (Ceramic-Coated Aluminium/Magnesium) Gold Dome tweeter, formed from an aluminium/magnesium alloy that is gold-anodised to a specific thickness to achieve an optimal balance of stiffness and damping. The tweeter pivots on its mounting, allowing it to be aimed towards the primary listening position for improved high-frequency dispersion and imaging.

Installation

The CS140 is built from mineral-filled ABS for a lightweight yet sturdy enclosure. Tri-Grip dog fixings in three positions secure the speaker firmly into the ceiling, while inward-mounted gold-plated push-type terminals simplify cable connections in tight spaces. The magnetic grille attaches cleanly without visible fixings, and is available in both round (180.2 mm diameter) and square (176.7 × 176.7 mm) formats to suit different interior aesthetics. An optional CB4 pre-construction bracket and CCBOX-R back box are available for new-build installations.

Performance

With a frequency response of 75 Hz – 30 kHz and a sensitivity of 85 dB (1W at 1m), the CS140 is well suited to background music, multi-room audio, and Dolby Atmos height channels. It handles up to 50 W RMS and is recommended for use with amplifiers rated between 10 and 50 W. Maximum SPL is rated at 102.8 dBA, ensuring clean output at moderate listening levels without strain.