Thiel PCS loudspeaker Measurements part 2

In the vertical plane, the PCS's dispersion pattern (fig.5) indicates that it is very important not to sit with your ears above the tweeter, as a deep suckout appears around 700Hz (presumably where the woofer crosses over to the coaxial unit) even as little as 5 degrees above that axis. High stands will be better than low ones. The spatially averaged in-room response (fig.6) ties in pretty well with my auditioning comment: a basically flat balance with restricted bass extension and perhaps a little too much energy in the region covered by the coaxial unit.

Fig.5 Thiel PCS, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 45 degrees-5 degrees above axis, reference response, differences in response 5 degrees-45 degrees below axis.

Fig.6 Thiel PCS, spatially averaged, 1/3-octave, free-field response in JA's listening room.

As is typical of Jim Thiel's speaker designs, the PCS's impulse response (not shown) is time-coherent, though overlaid by ultrasonic ringing from the tweeter. Accordingly, the speaker's step response (fig.7) is excellent, with a perfect right-triangle shape. The cumulative spectral-decay plot (fig.8) is similarly superb, with a clean decay other than above 20kHz, where the tweeter dome displays the usual misbehavior. However, there is a slight resonant ridge at the cursor position, 4.6kHz, that might be due to the mechanical crossover.---John Atkinson

Fig.7 Thiel PCS, on-axis step response at 50" (5ms time window, 30kHz bandwidth).

Fig.8 Thiel PCS, cumulative spectral-decay plot at 50" (0.15ms risetime).

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