MartinLogan Motion B10 Loudspeaker Lab Report

Lab Report

Does the shared 'Obsidian Folded Motion Tweeter' mean the B10's top-end performance closely mirrors that of the huge, floorstanding XT F200 [HFN Jul '23]. In practice the more compact 26x36mm thin-film tweeter used in the B10 offers a slightly more uniform response [see Graph 1] – yes, still uptilted following the 2.4kHz (McCracken-Vojtko) crossover, but a reduced +3dB in trend that assists in holding the B10's overall response to tighter ±2.8dB errors. The CSD waterfall [Graph 2] shows a marked reduction in HF resonances but also reveals two port modes, at 900Hz and 1.8kHz, that punch through into the response. Pair matching is slightly poor at 1.3dB through the mid/presence region but the snug-fitting circular grille has no adverse impact on response [blue trace, Graph 1].

Amplifier loading is not arduous. The largest –59°/+46° phase angles occur through the bass with an identical peak of +46°/950Hz as the inductance of the 140mm woven fibreglass bass/mid unit starts to build towards crossover. The FMT falls to a fairly flat (unreactive) 5.3ohm at the highest frequencies, leaving the minimum 3.49ohm impedance at 225Hz and the worse-case 1.5ohm EPDR at a lower 160Hz – perfectly 'driveable' for a good budget integrated. With high current not being sucked from the amplifier, MartinLogan's rated 92dB sensitivity looks wildly optimistic – 87.9dB/1kHz is more realistic with 87.6dB reflecting its 1m sensitivity across 500Hz-8kHz. Bass is respectable for a small 'bookshelf' unit, the 92Hz-720Hz/–6dB bandwidth of the 140mm 'woofer' supplemented by the 65Hz tuning of the port to yield a diffraction-corrected 68Hz (–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

MartinLogan Motion B10_Waterfall_L_35dB

While the FMT 'ribbon' is well controlled, there are port resonances at 900Hz and 1.8kHz

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 87.9dB / 87.6dB / 86.3dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 3.49ohm @ 225Hz, 25.4ohm @ 107Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –58.7° @ 122Hz, +46.1° @ 37Hz
Pair matching/Resp. error (200Hz–20kHz) 1.3dB/ ±2.8dB/±2.8dB
LF/HF extension (–6dB ref 200Hz/10kHz) 68Hz / 33.2kHz/34.3kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.55% / 0.45% / 0.55%
Dimensions (HWD) / Weight (each) 318x178x248mm / 6.6kg
Price £1395 (£699 for optional stands)

Lawrence, KS, US
Supplied by: The Professional Monitor Company Ltd, UK
01767 686300