Loudspeakers

One of the core problems of designing a 'horizontal omni' like the Venus, which attempts to achieve 360o radiation in the horizontal plane using drivers facing upwards and downwards, is that you listen off-axis to the drivers. Compensating for that inevitably results in low sensitivity, and even then the frequency response is typically uneven. Both problems are reflected in the Venus. Duevel claims 88dB sensitivity but our measured pink noise figure was way below that at 81.3dB SPL for 2.83V input at 1m. And even this has taken moderately low impedance to achieve. Our measured minimum modulus of 3.7ohm accords well with Duevel's nominal 4ohm but high impedance phase angles mean that the EPDR (equivalent peak dissipation resistance) dips to lows of 1.7ohm/601Hz and 1.9ohm/87Hz. Coupled with the low sensitivity, this makes the Venus quite a challenging amplifier load.

Measured with the microphone at a typical seated ear height of 95cm, the Venus's frequency response [Graph 1, below] is characterised by a distinct downwards trend up to 3kHz, beyond which the output becomes highly uneven with large peaks and troughs. Response errors from 200Hz-20kHz are high at ±8.5dB and ±6.1dB, respectively, and the pair matching error over the same frequency range is very high too at ±3.7dB, although this falls to a much better ±0.8dB below 9kHz. Its good bass extension of 34Hz (–6dB re. 300Hz) is some compensation for the low sensitivity, but its poor high frequency extension is a consequence of the highly uneven upper-treble. Despite the high-frequency switchback, the cumulative spectral decay waterfall [Graph 2] evinces only low-level treble resonances. KH