B&W 702 Signature Loudspeaker Lab Report

Lab Report

While the performance of the 702 Sig is broadly unchanged from the measurements published for the 702 S2 [HFN Dec 17], it is now possible to reveal some extra valuable detail. The forward response, measured on B&W's preferred midrange axis, shows the same distinctively irregular ±4.2dB pattern although the significant dip at 16kHz [red trace, Graph 1] was less obvious on one of the pair [black trace], resulting in a 3.3dB imbalance. Between 200Hz-10kHz, however, pair matching is an excellent 0.6dB and sensitivity close to B&W's 90dB spec. at 89.6dB.

B&W also demonstrates that a speaker grille need not introduce large cancellation notches in response [blue trace, Graph 1] and we can now also see the primary resonance of the 'carbon' dome tweeter is at a high 48kHz/+7dB [pink shaded area]. This is also visible on the CSD plot [Graph 2] along with a mode in the Continuum mid cone at ~4kHz. At the other end of the spectrum [green shaded area] corrected nearfield analysis reveals a steep roll-off beyond the triple woofers' 105Hz peak and what might seem a limited 50Hz bass extension (–6dB/200Hz). However, it's worth noting that the rear-facing port, tuned to 21Hz with –3dB points at 17-30Hz, offers a limited contribution and so the 702 Signature may be safely used near a rear wall and its bass further 'tuned' without fear of boominess.

High sensitivity, meanwhile, is achieved at the expense of a fairly tough load, the impedance minimum of 2.95ohm/118Hz joined by a dip to 3.25ohm/660Hz where there are ±20o phase angles. The biggest swings in phase angle of +47o/1.4kHz and a significant –70o/72Hz at 8.3ohm will test some amplifiers. 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


Major modes decay quite quickly here, exposing a mid-driver resonance at 4kHz [see Graph 1]

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 89.8dB / 89.6dB / 87.5dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 2.90ohm @ 118Hz, 23.7ohm @ 59Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –70° @ 72Hz, 47° @ 1.35kHz
Pair matching/Resp. error (200Hz–20kHz) 3.3dB/ ±3.7dB/±4.2dB
LF/HF extension (–6dB ref 200Hz/10kHz) 50Hz / 63kHz/61kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.5% / 0.15% / 0.5%
Dimensions (HWD) / Weight (each) 994x200x337mm/29.5kg
Price £4499

B&W Group Ltd
West Sussex
Supplied by: B&W Group Ltd
0800 232 1513