Loudspeakers

Bass extension, on/off-axis response flatness, distortion, load impedance and sensitivity – these are the competing parameters that face every loudspeaker designer, but in a box as compact as the Clarity 4.2 the first and last of these become all the more acute. Nordic/Radiant has eschewed porting – avoiding bringing pipe modes into play – for two 100mm Purifi Ushindi ABRs that draw out the 59Hz (–6dB) roll-off of the ‘driven’ 100mm Purifi unit to a diffraction-corrected 37Hz. This is very low for the box size, but bass does dive quickly below the ABR’s sharp 41Hz tuning. The response is very flat [see Graph 1] with the largest irregularities appearing after the 2.3kHz crossover, albeit adding up to just ±2.0dB and ±1.8dB, respectively, just as pair matching is a tight 0.8dB (all re. 200Hz-20kHz). There are also modes on the CSD waterfall [see Graph 2, below] from 2-6kHz, and dissimilar on L and R samples, but the AMT tweeter looks ‘clean’.

The latter has a resonant peak at 26kHz, with a full 39kHz extension [pink shaded area, Graph 1], but Radiant acknowledges the speaker is ‘hot’ on axis and recommends a 20° toe-in. Testing 15° off-axis [blue trace, Graph 1] illustrates this quite clearly. Sensitivity is the big casualty – the Clarity 4.2 musters a mere 78.7dB (re. 2.83V/1m), or 78.3dB over 500Hz-8kHz, even if THD remains very low at <0.1% through the midrange, and just 0.7% at 100Hz (all re. 90dB SPL/1m). As a result, the Clarity 4.2 may require a lot of amplifier volts but it does not hog current – the impedance minimum is 3.5ohm at a high 5.3kHz while the maximum +54/–63o swings in low frequency phase angle contribute to a manageable 2.08ohm/110Hz EPDR. PM