Loudspeakers

Expanding the cabinet volume to accommodate a 180mm woofer brings the following top-line changes over the original Accordo standmount [HFN Jan '18]: bass extension is boosted from 62Hz down to a weighty 45Hz (–6dB re. 200Hz), THD is reduced from ~1.5% through bass and mid to just <0.5% here (re. 90dB SPL) but sensitivity is not improved over the original 86dB (1kHz/2.83V/1m) just as the amplifier loading is now that bit tougher. In practice the bass unit has a –6dB bandpass of 52Hz-270Hz [green shaded area, Graph 1], its output free of obvious spuriae, and is supported by the lower port which offers a useful 13Hz-75Hz (–6dB), albeit with a mode at 750Hz. The latter was also detected from the upper port, though this vent for the 150mm mid unit offers no significant LF reinforcement.

The dip in impedance also occurs at LF in the Essence, the 'easy' 4.1ohm/192Hz minimum of the standmount Accordo traded here for a more testing 2.76ohm/160Hz (<3ohm from 106Hz-250Hz). The biggest swing in impedance phase is also more aggressive at –72°/64Hz/7.7ohm. This result, and change in forward response [Graph 1], reflects the necessary recalculation of crossover points from two- to three-way in the Essence. Measured on-axis between the tweeter/mid units, the speaker shows an essentially flat response trend, albeit with notches at 520Hz/1.2kHz and a peak at 6-7kHz that account for the ±3.5dB response variations. The 1.2kHz dip is also resolved as a resonant mode in the CSD waterfall [Graph 2]. Otherwise, pair-matching is exceptional at <1dB (200Hz-10kHz) and the impact of the 'rubber band' grille minimal [cyan trace, Graph 1]. PM