Loudspeakers

Given its compact dimensions and 15ohm nominal impedance, you'd expect Falcon Acoustics' LS3/5a to be insensitive and it is. The specification is 83dB, which accords well with our simple FFT average of 82.8dB but not with the more representative pink noise and 'music' figures of 81.2dB and 80.8dB which indicate that 81dB is a more realistic figure. This would nonetheless be impressive for a 15ohm speaker of this size – but the LS3/5A is not a genuine 15ohm design. Its minimum modulus of 7.3ohm indicates an 8ohm nominal figure and large impedance phase angles drop the minimum EPDR (equivalent peak dissipation resistance) down to 3.6ohm at 120Hz. This adds up to a speaker that is still easy to drive compared to most modern designs, just not quite as easy as the 15ohm specification might suggest.

Forward frequency responses [Graph 1, above] were measured at 1m on the tweeter axis, with the grilles in place because the front baffle has a lip around the edge that's exposed with the grille removed. The overall trend is flat to around 10kHz, above which output is raised by about 4dB. This increases the response errors to ±4.4dB and ±3.9dB, respectively, and pair matching over the same 200Hz-20kHz frequency range is disappointing at ±1.7dB, although up to 7kHz it's much tighter at ±0.8dB. The apparent rise in output at low frequency is not an anomaly: diffraction-corrected nearfield measurement showed the output to climb below 400Hz to a peak of about 5dB at 140Hz. Below this it falls away at 12dB per octave, as expected of a closed-box design, to reveal a high 70Hz bass extension (–6dB re. 200Hz). The CSD waterfall [Graph 2] shows a number of treble resonances, but most of them at low level. KH