Vintage

Tested in its ‘horizontal’ guise [see pic, p120], the Red Line 60.2’s performance exceeds what might be anticipated from this unusual driver/cabinet solution. For example, the poor 2.4dB pair matching is only >14kHz so a figure of ~1.3dB is more reflective of the bass/mid matching. Far greater shifts in mid/ presence balance occur if the speakers are twisted even 10o off the horizontal axis [blue trace, Graph 1], presumably as a result of diffraction in the output of the rebated soft treble dome. The axial response [Graph 1] is essentially ‘flat’ except for a ~6dB notch at 7kHz that is largely responsible for the overall +3.0dB and ±3.8dB response errors, respectively, and is also revealed as a mode in the CSD waterfall [Graph 2]. Another mode correlates with the small peak in output at 1.7kHz just prior to the notional 2.5kHz crossover but all this suggests that small adjustments in the speakers’ angular position will reap rewards in tonal tuning.

Sensitivity is high at 90.4dB/1kHz and 90.1dB/500Hz-8kHz, if not quite the 93dB B&O had specified, but high bass levels are necessarily limited, hence the ~5% THD at 100Hz (re. 90dB SPL/ 1m) with odd-order harmonics dominating the far lower ~0.3% midrange THD. Nearfield bass calculations are complicated by the grille ‘socks’ but the 130mm drivers show a 66Hz-2kHz/–6dB response lifted by the 36Hz port tuning to deliver a diffractioncorrected 53Hz (–6dB re. 200Hz) – floor or wall boundary gain will boost this, of course. Finally, B&O rated the 60.2 as an 8ohm load which, with its 4.8ohm/172Hz min. should read ‘6ohm’. Nevertheless, with mere +33o/–42o swings in phase through the bass it poses a very ‘driveable’ 2.3ohm/124Hz EPDR. PM

Above: Response inc. nearfield summed drivers/port [green], freefield corrected to 1m at 2.83V [yellow], ultrasonic [pink]. Left, black; right, red; ±10o, blue

Above: A Mode At 1.7Khz [Also Seen In The Response, Graph 1] Is Joined By Another Linked To The Dip At 7Khz