Loudspeakers

It's a notable feature of modern B&Ws that they don't have particularly flat frequency responses – even the 800 D3 series. So it is no surprise to find that the 603's forward frequency response [Graph 1, measured at 1m on the tweeter axis] is on the uneven side, although it is unexpected to see the deep if narrow notch just below 6kHz. This has the effect of increasing the response errors to a high ±6.1dB and ±6.0dB respectively, well outside B&W's claimed ±3dB. Despite this, pair matching is excellent at ±0.6dB over the same 300Hz-20kHz frequency range. Diffraction-corrected near-field measurement showed the bass response to reach 52Hz (–6dB re. 200Hz) – typical for a floorstander of this size although shy of B&W's 29Hz spec.

B&W's claim of 88.5dB sensitivity we couldn't quite match either, our measured 88.1dB on pink noise and 87.6dB with a 'music-shaped' noise spectrum suggesting that 88dB is perhaps more realistic. Low impedance is used to help achieve this, the measured 2.7ohm minimum modulus belying both the 8ohm nominal rating and B&W's quoted 3ohm minimum. Large impedance phase angles at low frequency drop the EPDR (equivalent peak dissipation resistance) to a very low minimum of 1.1ohm at 92Hz, with further dips to 1.6ohm at 736Hz and 2.0ohm at 10.5kHz completing the picture of a loudspeaker that is notably challenging to drive, particularly at this price point.

As usual with B&W, total harmonic distortion is low at 100Hz, 1kHz and 10kHz – certainly lower than many competitors. The cumulative spectral decay waterfall [Graph 2] is pretty clean, the Continuum driver displaying only a few well-damped treble resonances. KH

Sensitivity (SPL/1m/2.83V – Mean/IEC/Music): 88.8dB / 88.1dB / 87.6dB
Impedance modulus: minimum & maximum (20Hz–20kHz): 2.7ohm @ 129Hz / 29.3ohm @ 53Hz
Impedance phase: minimum & maximum (20Hz–20kHz): –75° @ 64Hz / 51° @ 1.3kHz
Pair matching/Resp. error (300Hz–20kHz): ±0.6dB / ±6.1dB / ±6.0dB
LF/HF extension (–6dB ref 200Hz/10kHz): 52Hz / >40kHz / >40kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m): 0.4% / 0.1% / <0.1%
Dimensions (HWD) / Weight (each): 985x190x340mm / 24kg
Price:: £1249