Totem Acoustic Mani-2 loudspeaker Measurements part 2

Laterally (fig.6), the Totem offers almost-textbook dispersion, with the top octaves progressively rolling off with increasing off-axis angle. I have found this kind of horizontal radiation pattern always correlates with good imaging precision and the Mani-2 was no exception.

Fig.6 Totem Mani-2, horizontal response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90 degrees-5 degrees off-axis; reference response; differences in response 5 degrees-90 degrees off-axis.

There were no surprises in the time domain, the speaker's step response (fig.7) indicating that the two drive-units are both connected with positive acoustic polarity, with the tweeter's output leading the woofer's by about 0.3ms. This is not a time-coherent design. On the other hand, the cumulative spectral-decay or waterfall plot (fig.8) is superbly free from resonant decay energy other than that associated with the inaudible tweeter resonance. No wonder I was so impressed by the Mani-2's freedom from grain and clean, clear presentation of recorded detail.

Fig.7 Totem Mani-2, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.8 Totem Mani-2, cumulative spectral-decay plot at 50" (0.15ms risetime).

Finally, using a PVDF accelerometer to examine the cabinet's resonant behavior confirmed that the cabinet construction does an effective job of killing cabinet talk. The side panels had a little bit of low-level activity in the 500Hz region, well above the region where it might damage the music, while the top panel had a mode, again very low in level, at 313Hz. These modes could also be found on the rear panel (fig.9), where they were generally higher in level. As this faces away from the listener, any effect on music should be minimal.—John Atkinson

Fig.9 Totem Mani-2, cumulative spectral-decay plot of accelerometer output fastened to back of enclosure (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

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