Scansonic M20 Loudspeaker Lab Report

Lab Report

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


Response inc. nearfield summed driver/port [green], freefield corrected to 1m at 2.83V [yellow], ultrasonic [pink]. Left, black; right, red; w. grille, blue


While the presence/treble is very clean, there are resonances near the top of the mid driver’s range

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 83.6dB / 85.8dB / 84.1dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 3.35ohm @ 3.07kHz, 14.2ohm @ 96Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –43° @ 124Hz, +47° @ 5.09kHz
Pair matching/Resp. error (200Hz–20kHz) 1.9dB/ ±3.4dB/±2.9dB
LF/HF extension (–6dB ref 200Hz/10kHz) 50Hz / 62.2kHz/62.6kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.9% / 0.23% / 1.5%
Dimensions (HWD inc. feet) / Weight (each) 935x220x250mm / 12kg
Price £1499

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Supplied by: Decent Audio, Stockton-on-Tees
05602 054669