Thiel CS6 Loudspeaker Measurements part 2

About that apparent upper-midrange suckout, which I imagine correlates with the reticence I perceived in my auditioning: This graph was taken on the tweeter axis, which is a reasonable 37" from the floor when the spikes are used. Fig.4, which shows the changes in response to be expected as the microphone is moved above or below the tweeter axis, reveals that the suckout fills in below the tweeter but gets very much worse for standing listeners. It's possible that the CS6 will not be so fussy about listening axis in large rooms, but in small rooms such as mine, sitting low or tilting the speaker back a touch definitely improved the sound. In the horizontal plane (not shown), the CS6 demonstrated relatively even dispersion, this associated with the stable stereo imaging I noted during my auditioning.

Fig.4 Thiel CS6, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 20 degrees-5 degrees above-axis; reference response; differences in response 5 degrees-10 degrees below-axis.

Fig.5 shows what happened to this quasi-anechoic behavior in my room. This spatially averaged response, centered on the positions of my ears, is flat overall other than a slight treble rising trend, a lack of energy in the lower crossover region, and an excess of bass energy—together, these result in a slightly swaybacked profile to the curve. No wonder the speaker had great bass. In a larger room than mine, the CS6's bottom end would sound more neutrally balanced.

Fig.5 Thiel CS6, 1/3-octave, spatially averaged response in JA's listening room.

In the time domain, the speaker's impulse response on the tweeter axis (fig.6) appears time-coherent, with only a minimum amount of post-pulse ringing. However, the step response on this axis (fig.7) reveals that the woofer comes in a little late, meaning that the speaker is actually time-coherent slightly below the tweeter axis.