Deep, Cinematic Bass Engineered for THX Ultra Performance

The KEF Ci200QSb‑THX is a powerhouse in‑wall architectural subwoofer engineered to deliver cinematic low‑frequency impact with the precision and tonal accuracy demanded by THX®. Certified to both THX Ultra and THX Select performance levels, it brings the emotional intensity, scale, and drama of a professional theatre directly into your home.

At its core is a high‑output 200 mm (8‑inch) sub‑bass driver, purpose‑built to deliver deep, controlled, room‑filling bass. In passive mode, the Ci200QSb‑THX enhances the low‑frequency extension of KEF’s in‑wall and in‑ceiling speakers, adding weight and authority to music and home cinema systems.

In active mode, the Ci200QSb‑THX becomes a true THX‑grade subwoofer system.

• 2 pairs powered by 2 × KEF KASA500 amplifiers achieve THX Certified Select performance.

• 4 pairs powered by 2 × KEF KASA500 amplifiers achieve THX Certified Ultra performance.

This scalable architecture allows installers to tailor output to room size and performance requirements while maintaining THX‑level accuracy and consistency.

Designed with the same acoustic principles as professional studio monitors, the Ci200QSb‑THX reproduces the filmmaker’s final mix with remarkable fidelity. Explosions hit with visceral force, musical bass lines remain tight and articulate, and dialogue‑driven scenes retain natural warmth and clarity.

Blending seamlessly into any interior with KEF’s Ultra‑Thin Bezel (UTB) design, the Ci200QSb‑THX delivers true THX surround sound performance from an architectural form factor that disappears into the wall.