Kii Audio THREE BXT Loudspeaker Lab Report

Lab Report

Although it's only one of the benefits of using DSP in an active loudspeaker, well controlled frequency response is something you expect and the Three BXT delivers. While it's possible using DSP to achieve a ruler-flat frequency response at a particular point in space, Kii Audio has a more realistic approach to equalisation, which is not individually customised for each speaker and seeks only to correct larger anomalies which are present in both the on- and off-axis responses. So at 1m on the axis of the midrange driver the forward frequency responses [Graph 1, below] proved to be largely flat in trend but without minor wiggles being ironed-out. The resulting response errors, 300Hz to 20kHz, are modest at ±2.1dB and ±1.7dB respectively, and reduce further to ±1.3dB and ±1.4dB over the range 400Hz to 10kHz. This is probably flat enough for any departure from absolute tonal neutrality to pass unnoticed.

Pair matching error over the same 300Hz-20kHz is an acceptable ±1.0dB and reduces to an outstanding ±0.5dB if the upper frequency limit is reduced by a little over an octave to 9.2kHz. These figures don't quite match those we recorded from the Kii Audio THREE [HFN Aug '18], but they remain impressive. Performing a nearfield bass response measurement with the THREE BXT is complicated by the large number of drive units involved, but that measurement issue aside it's clear that the THREE BXT has a bass output that's effectively flat to below the audible frequency range.

When the rear panel rotary control was moved from F (flat) to W (adjusting bass output for positioning near a wall), output was measurably reduced by about 8dB at 20Hz (re. 100Hz), and further reduced to about 17dB when the control was rotated right around to C (corner location). As there are six intermediate settings between the 'F' and 'W' positions and between the 'W' and 'C' positions, it should be possible to adjust the THREE BXT's bass output to suit most installations. The CSD waterfall [Graph 2] reveals some low-level treble resonances. KH


The Kii Audio THREE BXT's forward response is remarkably flat and even, with a sub-20Hz bass


Cabinet is well damped with only low-level driver resonances visible between 3kHz-10kHz

Frequency response error (300Hz–20kHz) ±2.1dB / ±1.7dB
Pair matching (300Hz–20kHz) ±1.0dB
LF/HF extension (–6dB ref 200Hz/10kHz) <20Hz / >40kHz/>40kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.5% / 0.1% / 0.3%
Dimensions (HWD) / Weight (each) 1200x200x400mm / 51kg
Price £29,990-£32,290 (with Kii Control)

Kii Audio
Bergisch Gladbach Germany
Supplied by: Sound Design Distribution Ltd, Cardiff, UK
(0)800 009 6213