Scansonic MB5 B Loudspeaker Lab Report

Lab Report

Scansonic specifies a 90dB sensitivity for the MB5 B, and that fits well with the 89.8dB we recorded from the MB5 [HFN Aug '17]. But we recorded much lower figures this time, the industry standard pink noise figure of 86.1dB and 'music' figure of 85.9dB indicating that an 86dB specification would be more realistic. The treble responses/sensitivities of the 5 and 5B are similar, but it's as if the output of the bass/midrange unit has been slugged in the 5 B. Unusual as it is to specify impedance as '<4 ohm', it's a neat way of incorporating minimum impedance and nominal impedance in a single figure (nominal being 1.25x minimum). But Scansonic's 4ohm minimum is significantly higher than the 2.8ohm minimum modulus we recorded. Impedance phase angles are well controlled but even so this low modulus results in a minimum EPDR of 1.6ohm at 35Hz, with another dip to 1.8ohm at 107Hz, so the MB5 B rates as a more than typically difficult load to drive.

Forward frequency responses [Graph 1, below], measured at 1m at tweeter height, show a distinctly shelved-up treble and sufficient variability to record response errors of ±4.8dB and ±4.1dB respectively, which are a little on the high side. Pair matching error is poor at ±3.2dB over the same 200Hz-20kHz frequency range, although the largest disparities are quite narrow-band at 3kHz and 8kHz. Diffraction-corrected nearfield bass measurement recorded a bass extension of 54Hz (–6dB re. 200Hz), which is not atypical for smaller floorstanders. As we often find with planar tweeters, high frequency distortion was 10x higher than typical of the best dome tweeters. The CSD waterfall [Graph 2] indicates a few treble resonances. KH


The 2.5kHz peak and depressed presence of the MB5 is replaced in the 'B' by a boosted mid/treble


Strong mid-driver resonance seen in the MB5 is much reduced here. Only minor treble modes remain

Sensitivity (SPL/1m/2.83V – Mean/IEC/Music) 87.7dB / 86.1dB / 85.9dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 2.8ohm @ 29Hz, 12.5ohm @ 2.0kHz
Impedance phase: minimum & maximum (20Hz–20kHz) –33° @ 3.1kHz, 34° @ 20Hz
Pair matching/Resp. error (200Hz–20kHz) ±3.2dB/ ±4.8dB/±4.1dB
LF/HF extension (–6dB ref 200Hz/10kHz) 54Hz / >40kHz/>40kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 2.7% / 0.3% / 0.7%
Dimensions (HWD) / Weight (each) 1185x178x319mm / 24kg
Price £6249

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