The KEF Ci200QSb-THX is an 8″ (200mm) square in-wall / in-ceiling subwoofer, sold in pairs. It can run in passive mode with its internal 100Hz crossover to supplement KEF Ci in-wall or in-ceiling speakers, or in active mode driven by the KEF KASA500 amplifier, where KEF quotes THX Certified Select (2 pairs) or THX Certified Ultra (4 pairs) performance.
THX-certified performance requires KEF KASA500 amplification (sold separately). KEF quotes THX Certified Select with 2 pairs and THX Certified Ultra with 4 pairs of Ci200QSb-THX – check the KEF set-up guide for the KASA500 count.
THX Certified Ultra / Select (in active mode with KASA500)
200mm (8″) high-output woofer with extended bass response
Passive mode with internal crossover, or active mode with the KEF KASA500 system amplifier
Paintable Ultra-Thin Bezel (UTB) and magnetic grille
Installs on virtually any surface via dogleg clamps
Optional RIF200S rough-in frame
Sold in pairs
IP64 certified
| Model | Ci200QSb-THX |
| Type | In-wall / in-ceiling subwoofer |
| Drive unit | LF: 200mm (8″) |
| Passive: nominal impedance | 6Ω |
| Passive: sensitivity (2.83V/1m) | 85dB |
| Passive: frequency response (±6dB, open-backed) | 40Hz – 100Hz |
| Passive: crossover | 100Hz |
| Passive: recommended amplifier power | 10 – 150W |
| Passive: recommended low-pass filter | 80Hz – 120Hz |
| Active (KASA500): frequency response (±6dB, open-backed) | 30Hz – 140Hz |
| Active: recommended low-pass filter | 50Hz – 120Hz |
| Max SPL | 104dB |
| External dimensions (H x W x D) | 273 x 273 x 106mm |
| Cut-out (H x W) | 238 x 238mm |
| Mounting depth from surface | 101.6mm |
| Net weight | 3.3kg |
| Passive: frequency range (-10dB) | 29Hz – 140Hz |
| Active: frequency range (-10dB) | 25Hz – KASA500 setting |
| Rear volume (per speaker) | 32L ideal / 20L minimum |
| Certification | THX Certified Ultra / Select; IP64 |
| Optional rough-in frame | RIF200S |





