Loudspeakers

The Signature 5’s axial response [Graph 1, below] is dominated by its bass alignment, both directly in the peak output of the 140mm woofer at 115Hz, supplemented by the very low 38Hz tuning of the port, and indirectly with the port’s pipe mode (and possibly a cabinet quarterwave resonance) clearly revealed in the +5dB boost from 800Hz-1.1kHz [see boxout]. These features are responsible for the perfectly acceptable, ±2.9dB and ±3.1dB response errors (200Hz-20kHz), respectively, in what would otherwise be a fairly flat response. Pair matching is a very tight 0.65dB while the diffraction-corrected bass extension is a creditable 56Hz (–6dB re. 200Hz). Also, the soft-dome tweeter has a useful extension to ~40kHz [pink shaded area, Graph 1] without the bold ultrasonic resonance shown by metal/hard dome types.

However, despite its ‘DXT’ waveguide, the Signature 5’s off-axis response [grey trace, Graph 1] shows a drop in treble beyond ~14kHz which may yet be subjectively preferable – toe the speakers away from the listening axis by ±15°, listen and decide but take off the grilles first [blue trace, Graph 1]!

SA also claims an ambitious 88dB sensitivity, but this is at ‘1W/1m’ so, bearing in mind the ‘4ohm nominal’ rating and minimum impedance of 4ohm (at 166Hz), it’s far from the 85.8dB measured here at 2.83V/1kHz/1m (or 2W/4ohm). This value also benefits from the speaker’s midband boost so a figure of 84.5dB is more realistic (500Hz-8kHz). That said, THD is held to a low 0.5% at 90dB SPL (100Hz-10kHz) and loading is fairly ‘budget amp friendly’ with swings in phase angle of +42/–53° through the bass and a minimum EPDR of 1.95ohm/124Hz. PM