Thiel CS7.2 loudspeaker Measurements part 2
Fig.3 Thiel CS7.2, vertical response family at 50", from back to front: differences in response 15 degrees-5 degrees above tweeter axis, reference response, differences in response 5 degrees-15 degrees below tweeter axis.
Fig.4 shows how the CS7.2's response changes (in 5-degree steps) as the microphone moves 90 degrees to either side of the tweeter axis. The dispersion is superb even up to about 2.5kHz, with then some very slight beaming before the speaker's radiation pattern widens again as the upper-midrange unit takes over. An off-axis notch develops in the exact region of the on-axis peak, which might work against its audibility. Probably most important, the tweeter becomes quite directional between 11kHz and 16kHz, presumably because of the modifying effect of the very slight flare of the upper-midrange cone. Brian did comment on the CS7.2's lack of high-frequency air; as the speaker actually has a slightly rising treble response on the tweeter axis, I imagine he is responding to the lack of top-octave energy in his room's reverberant field, this due to the tweeter's directivity in this region.
Fig.4 Thiel CS7.2, lateral 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.
This can be seen in fig.5, a spatially averaged response centered on the listening position, the measurement taken in Brian's room. If you compare this with the quasi-anechoic response (fig.2), you can see that the measured lack of on-axis energy in the upper midrange has disappeared, and that the in-room balance from the middle of the midrange to the mid-treble is impressively flat. The on-axis peaks at 5.6kHz and 21kHz continue to make their presences known. However, note how well this graph correlates with Brian's subjective comments about the CS7.2's overall balance: somewhat elevated low bass, recessed lower mids, neutral midrange and low treble, and a lack of top-octave energy.
Fig.5 Thiel CS7.2, spatially averaged, 0.1-octave smoothed response in BD's listening room.