Scansonic MB6 B Loudspeaker Lab Report

Lab Report

Scansonic continues to specify a high sensitivity for its reworked 'B' series but the depressed midband and shelved-up presence/treble of the MB6 B suggests a standard 1kHz figure of just 84.1dB (re. 2.83V/1m) improving to 84.9dB (500Hz-8kHz) and 86.3dB (200Hz-20kHz). As we saw with the MB5 B, narrowband variations in the output of the planar treble driver above the 2.6kHz crossover contribute to response errors of ±4.9dB with a hefty pair-matching error of 3.6dB. On the other hand, HF distortion is lower in this model at 0.6%/10kHz/90dB SPL and break-up behaviour better controlled [see Graph 2, below].

Working with a 'line array' of small woofers brings both benefits and challenges – the low frequency alignment here is decidedly 'peaky' with all four reflex-loaded 115mm bass units tuned to 79Hz and a steep roll-off thereafter [green shaded area, Graph 1]. While the diffraction-corrected bass extension of 54Hz (–6dB re. 200Hz) may seem slightly parsimonious, in practice we found the MB6 B certainly benefited from some near rear-wall reinforcement, these slim floorstanders delivering their smoothest, deepest subjective bass in this location. So the MB6 Bs are certainly room-friendly, but the amplifier loading – particularly below 150Hz – is a little tougher than Scansonic's '>4ohm' specification might suggest. Even though swings in phase angle are limited to +47o/–29o through this region, the impedance minima of 3.1ohm/89Hz and 2.98ohm/25Hz are best handled by heavyweight solid-state amps, particularly when the reduced sensitivity is also taken into account. Then again, a £9000 flagship is unlikely to be partnered with anything less! PM

221scansonic.lab1

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

221scansonic.lab2

Low-level modes visible from the four bass units at 500-1.5kHz but planar treble is well damped

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 84.1dB / 84.9dB / 86.3dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 3.0ohm @ 25Hz, 13ohm @ 69Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –29° @ 78Hz and 2.9kHz, +47° @ 56Hz
Pair matching/Resp. error (200Hz–20kHz) 3.6dB/ ±4.9dB/±4.9dB
LF/HF extension (–6dB ref 200Hz/10kHz) 55Hz / 47.7kHz/44.7kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.35% / 0.28% / 0.56%
Dimensions (HWD) / Weight (each) 1410x178x410mm / 37kg
Price £8999

COMPANY INFO
Dantax Radio A/S
Denmark
Supplied by: Decent Audio, Stockton-on-Tees
05602 054669
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