Loudspeakers

The 360° (horizontal) radiation pattern of the BL Diamante necessarily reduces its measured sensitivity when compared to a speaker employing the same two drivers with a more focused, directional output. However, while Duevel's 91dB rating is a tad optimistic – our figure of 85.1dB (averaged 500Hz-8kHz) being a full 6dB lower – the speaker's energetic reverberation field may well create a subjectively 'louder' sound. Amp loading is fairly tough, especially through the bass and between 90-300Hz where the lowest impedance (3.4ohm/270Hz) meets high negative phase angles (–65°/97Hz). The load is sub-8ohm from 105Hz-5.5kHz, and the nominal is 4ohm rather than 6ohm.

Measured on the tweeter 'axis' between upper and lower reflectors, the speaker proved not only to be phase inverting, but possessed of an inherently flat forward response trend [Graph 1], albeit pitted with narrowband peaks and cancellation notches at 235Hz, 1kHz, 3.6kHz and 6-7.8kHz. These are also reflected in resonant modes captured on the very busy CSD waterfall [Graph 2]. The sharpest notch at 19.3kHz was more acute in one of our pair [red trace, Graph 1], accounting for the ±7.7dB response error and high 6.3dB matching error (but tightening to a respectable 1.3dB from 200Hz-10kHz). The dip at 235Hz was also detected on the nearfield analysis and on both impedance/phase spectra, suggesting a cabinet mode. Duevel's 220mm woofer works out of four shaped vents in the foot of the cabinet which, despite their complex profile, are clearly tuned to 48Hz – within a few Hz of the diffraction-corrected –6dB bass extension of the entire system at 51Hz (re. 200Hz). PM