Thiel CS3.6 loudspeaker Measurements part 3
Fig.8 Thiel CS3.6, horizontal response family at 45", normalized to response on tweeter axis, from back to front: differences in response 90 degrees-15 degrees off-axis; reference response; differences in response 15 degrees-90 degrees off-axis.
The vertical family of difference curves is shown in fig.9. The curves are from top to bottom: 7.5" above the cabinet, top of cabinet, midway between tweeter and cabinet top, reference tweeter axis, midrange axis, between midrange and passive bass radiators, and on the passive radiator. The lower crossover suckout seen in figs.5 and 6 appears to be corrected at lower listening axes, but with the crossover notches deepening as one listens on higher axes. Thus the CS3.6 will sound hollow to a standing listener, or to those who prefer higher perches. These curves suggest that the optimum vertical axis is between the midrange and passive radiators.
Fig.9 Thiel CS3.6, vertical response family at 45", normalized to response on tweeter axis.
Driving the CS3.6 with a variable-frequency sinewave oscillator and feeling the enclosure revealed a significant cabinet resonance at about 370Hz. The cabinet vibration was accompanied by a "wolf tone," which significantly changed the sinewave's sound at that frequency. There was a similar, but much lower in amplitude, resonance at 480Hz. These were the only two modes noticed using the oscillator; they were never apparent during the auditioning.
The Listening Room Diagnostic Recording (LEDR) found on the first Chesky Test CD (JD37) produced a stable, continuous image on the "Lateral" test. The "Over" signal was somewhat less continuous, and on the "Up" test, the sound didn't appear to move very far above the loudspeaker.—Robert Harley