Paradigm Reference Active/20 loudspeaker Measurements part 2

The spatially averaged response, taken in my listening room (fig.7), was the flattest I have measured. Once above the room-interaction region, and with the exception of a minor peak at 4kHz, the output between 400Hz and 6.3kHz met astonishing ±0.9dB limits. No wonder the speaker sounded so neutral! And the useful bass response can be seen to extend down to the 32Hz band. I measure both speakers to derive this graph, by the way; the pair matching at the listening position was impressive.

Fig.7 Paradigm Active/20, 1/3-octave, spatially averaged response in JA's listening room.

In the time domain, the step response on the tweeter axis (fig.8) reveals that the speaker is not time-coherent, as expected from the flat baffle, but with units connected in the same positive acoustic polarity. Other than some ridges of ultrasonic resonant energy from the tweeter, the associated cumulative spectral-decay plot (fig.9) is superbly clean. The slight treble graininess I noted in my auditioning must originate somewhere else, perhaps in the amplifier.

Fig.8 Paradigm Active/20, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.9 Paradigm Active/20, cumulative spectral-decay plot at 50" (0.15ms risetime).

Finally, attaching a simple plastic-tape accelerometer to the cabinet sidewall and calculating a waterfall plot from its output (fig.10) revealed a small amount of panel resonant behavior, with one mode present just above 200Hz and another at 400Hz. The levels are low, however, and I noticed no congestion in this region.

Fig.10 Paradigm Active/20, cumulative spectral-decay plot of accelerometer output fastened to cabinet sidewall (line-level MLS driving voltage to speaker 410mV, speaker level control set to "0").

Summing up, this is superb measured performance for an affordable speaker. There is obviously some superb speaker-engineering talent in residence at Paradigm.—John Atkinson

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