Loudspeakers

While attention is inevitably focused on the efficacy of KEF's Meta disc in dissipating the Uni-Q driver's rear-radiation [see LS50 Meta, HFN Jun '21], the Blade One Meta's driver ensemble delivers a remarkably flat axial response [see Graph 1]. With response errors of just ±1.2dB and ±1.3dB, respectively, coupled with a precise 0.45dB pair matching (all re. 200Hz-20kHz), the Blade One Meta faces competition from a mere handful of active, DSP-corrected speakers [see HFN Apr '20] in the quest for 'flatness'. On the other hand, the extreme ultrasonic treble resonance at 40kHz [+16dB re. mean midband output, pink shaded area] is specific to the Uni-Q driver, this breakup mode successfully deferred by a good 10kHz or so courtesy of the dome's hybrid spherical/elliptical profile. It is clearly visible on both the forward response and CSD waterfall [Graph 2], the latter also illustrating the very 'clean' and quick decay of mid and treble – a likely benefit of its Meta technology.

The flat response also makes for an accurate and subjectively relevant sensitivity of 88.5dB (1kHz) and 88.3dB (500Hz-8kHz), figures in tune with KEF's rated 88dB. Bass extension, too, is impressive at 34Hz (–6dB re. 200Hz), the 46Hz-350Hz (–6dB) output of the quad woofers combining with the slickly judged 26Hz port tuning [green shaded area, Graph 1]. Bass distortion is also very low at ~0.1% (re. 90dB SPL), but all this performance is gained at the expense of a fairly tough load, the impedance modulus dropping to just 2.5ohm/500Hz with max. phase angles of –57°/22Hz and +52°/1kHz. The toughest ±47°/4ohm regions occur in the low bass (24Hz) and midrange (840Hz). PM