Loudspeakers

Rating its M20 at a nominal 8ohm while also acknowledging a '4ohm minimum', in practice the nominal impedance is 4ohm with a lower 3.35ohm minimum at 3.07kHz. Maximum swings in phase angle are –43°/124Hz and +47°/5.09kHz with the toughest 4ohm/+36°/3.9kHz suggesting the M20 is a little more demanding of your amp than the average compact floorstander.

So does this hungry 2.5-way reward with a high sensitivity? In practice, Scansonic's rated 86.5dB sensitivity is not especially ambitious or over-realistic, our mean figure of 85.8dB (500Hz-8kHz) only slightly behind – the far lower 83.6dB/1kHz figure dented by the dip in forward response [see Graph 1]. Measured some 6in above the top of the cabinet – the 'average' seated height – the response reveals a deep 14dB notch at 6kHz, so elevating these speakers is recommended. The perforated grilles [blue trace, Graph 1] have little effect from 20Hz-20kHz.

The 'flattest' response, with errors of ±2.9dB/±3.4dB (200Hz-20kHz), is achieved on the planar treble unit's main axis where there's a uniform bass/mid but boosted mid/presence [black/red traces, Graph 1]. The latter is reflected in resonant modes up to ~2kHz above which the tweeter is better controlled [see Graph 2] and extended to ~62kHz [shaded pink region, Graph 1]. The mid/bass unit is responsible for the boosted 750Hz-2kHz region, and modest ±1.9dB pair matching, below which it mirrors the response of the lower driver (85Hz-1.3kHz, re. –6dB). The latter is reflex-loaded via rear slots, tuned to 53Hz – but also showing modes at 275Hz, 510Hz and 780Hz – the M20 realising a diffraction-corrected extension of 50Hz (–6dB re. 200Hz). PM