Loudspeakers

Just as we saw with the R3 Meta [HFN Sep '23], this latest 'Meta' version of the original R11 [HFN May '19] has also witnessed a top-to-toe refinement. Sensitivity is essentially unchanged at 89.6dB/2.83V/1m while the forward response is slightly downtilted [see Graph 1] with errors of just ±2.7dB and ±2.4dB (200Hz-20kHz), respectively. The dished area of its response is covered by the top-end of the 125mm alloy-coned MF section and lower end of the 25mm dome tweeter, either side of the 2.5kHz crossover, within the 12th-gen Uni-Q driver. This is also where any residual bass driver modes are visible for, once the labyrinthine MAT disc takes over, the R11's output is remarkably 'clean' [see CSD waterfall, Graph 2] just as conventional THD is squeezed down to a fabulously low <0.1% (re. 90dB SPL).

Once again, the metal dome resonance is pushed out to a high 40.8kHz [pink shaded area, Graph 1] but its severity – some +12dB above the mean midband output – is rapidly curtailed by toeing the speakers very slightly away from direct line of sight. For the bass, its combination of four 165mm reflex-loaded alloy/paper-coned units, working over 60-440Hz (woofers 2 and 3) and 60-280Hz (woofers 1 and 4, all re. –6dB) are supplemented by two sharply tuned ports at 34Hz to deliver a 45Hz bass extension (–6dB re. 200Hz). Far deeper extension is possible in-room with boundary reinforcement. Importantly, this extension and sensitivity has not been won at the expense of a tough amplifier load – KEF's 4ohm (3.2ohm min) impedance rating and modest ±41° phase angles are precisely met in practice while the worse-case EPDR remains a 'driveable' 1.6ohm/945Hz. PM