Loudspeakers

Measured on its Uni-Q axis, the Q11’s three 165mm ‘hybrid alloy’ bass units make their presence felt in what is a generally down-tilted, bass-rich response [see Graph 1], albeit with a peak at 14kHz and strong main dome resonance at 45.7kHz (+7dB re. 1kHz). The latter is also seen on the CSD waterfall [Graph 2], as is the impact of the MAT disc in removing any treble modes. Otherwise, response errors are a moderate ±4.1dB and ±4.5dB (200Hz-20kHz), respectively, but with pair matching a superbly tight 0.35dB (200Hz-15kHz), relaxing to 0.9dB up to 20kHz.

KEF recommends toeing the speakers in by 10-15° and this certainly delivers an even smoother response [grey trace] with reduced ±3.4dB errors, but the overall trend is still ‘warm’ with a steady (5.5dB) decline from 200Hz-10kHz. KEF’s integration of its speaker grilles into the overall design is usually spot-on, and while this tall Q model shows a 2dB null near the 2.8kHz crossover [blue trace], the grille’s impact is otherwise benign.

Its sensitivity specs are also usually on the money, but in this case, a dip in response at 1kHz takes its rated 89dB down to 86.3dB, although the mean 500Hz-8kHz figure is a slightly healthier 87.3dB. Meanwhile, that trio of drivers shares the same 55-400Hz (–6dB) bandwidth, augmented by a clean 29Hz port tuning to deliver a diffraction-corrected 45Hz (–6dB re. 200Hz). Deeper extension is possible in-room with boundary reinforcement. The amplifier load is also a little tougher than the 3.16ohm/147Hz minimum suggests, as the impedance modulus tucks below 4ohm from 96-900Hz, while a negative swing in phase angle (–64°/77Hz) contributes to a low EPDR of 1.2ohm/99Hz. PM

Hi-Fi News Measured Specifications:

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC)	86.3dB / 87.3dB / 85.4dB
Impedance modulus: minimum & maximum (20Hz–20kHz)	3.16ohm @ 147Hz 18.0ohm @ 62Hz
Impedance phase: minimum & maximum (20Hz–20kHz)	–64° @ 77Hz +42° @ 1.23kHz
Pair matching/Resp. error (200Hz–20kHz)	0.9dB / ±4.1dB / ±4.5dB
LF/HF extension (–6dB ref 200Hz/10kHz)	45Hz / 24.4kHz / 24.1kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m)	0.1% / 0.25% / 0.4%
Dimensions (HWD) / Weight (each)	1112x317x380mm / 22kg