B&W 705 S3 Signature Lab Report

This is the first occasion that we've tested a 705, in any iteration, but this version does include the same 25mm carbon dome tweeter, with new grille, and a 165mm bass/mid variant of the 150mm (midrange only) Continuum-coned driver used in the 702 S3 Signature . Here, the axial response shows an uptilted mid/presence/treble [see Graph 1], the ~8dB lift from 1kHz-10kHz reflected in ±4.1dB and ±3.9dB response errors, respectively, but this is clearly intentional because the pair matching is a tight 0.8dB (all 200Hz-20kHz). The grille is very transparent [blue trace, Graph 1] and, once again, the primary resonance of the dome tweeter is deferred to a high 48kHz/+12dB [pink shaded area, Graph 1], also seen on the CSD waterfall [Graph 2] alongside a driver mode at ~2kHz. Toeing the speakers in/outwards by 15° takes some of the 'sting' out of the 10kHz bump, revealing the 60kHz+ extension of that treble dome without exposing the resonance [grey trace, Graph 1].

Sensitivity at 1kHz (84.1dB) is far from B&W's rated 88dB but, averaged over 500Hz-8kHz, comes out at a higher 86.0dB. By contrast its 4.7ohm/175Hz minimum impedance is rather easier than the rated 3.7ohm and this, combined with the maximum +49°/-56° phase angles between 20-100Hz, results, from the amplifier's perspective, in a fairly agreeable EPDR of 2.2ohm/120Hz. Finally, the large port is tuned to a high 44Hz but also provides a 'window' onto cabinet resonances at 400-800Hz [seen on Graphs 1 and 2]. However, combined with the 65Hz roll-off of the 165mm Continuum cone, it assists in a worthy, diffraction-corrected extension of 53Hz (-6dB re. 200Hz). PM

Above: Response inc. nearfield summed driver/port [green], freefield corrected to 1m at 2.83V [yellow], ultrasonic [pink]. L, blk; R, red; ±15°, grey; grille, blue

Above: One mistermination/cone mode is visible at 2Khz with very mild treble resonances at 8-14Khz

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 84.1dB / 86.0dB / 84.7dB
Impedance modulus: minimum
& maximum(20Hz–20kHz)
4.65ohm @ 174Hz
45.7ohm @ 23Hz
Impedance phase: minimum
& maximum(20Hz–20kHz)
–56° @ 91Hz
+58° @ 19Hz
Pair matching/Resp. error (200Hz–20kHz) 0.8dB/ ±4.1dB/±3.9dB
LF/HF extension (–6dB ref 200Hz/10kHz) 53Hz / 67kHz/69kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.7% / 0.25% / 0.35%
Dimensions (HWD) / Weight (each) 413x192x337mm / 10.4kg
Price £3400 (+£799 Fs-700 S3 Stands)
COMPANY INFO
B&W Group Ltd
0800 232 1513
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