Vandersteen Audio 2Ce loudspeaker Sidebar 3: Measurements 2
The anechoic response of the 2Ce averaged across a 30 degree window on the tweeter axis is shown in fig.4. The response below 200Hz is the complex sum of the woofer and acoustic coupler outputs. The response is virtually flat to 40Hz, with a -6dB point of about 30Hz—a little worse than the specified -3dB at 29Hz, but still very good. There is some elevation in the upper bass/lower midrange which is probably responsible for the slight warmth noted in the listening tests, followed by a broad but shallow depression in the upper midrange/low treble—the latter likely contributing to the somewhat laid-back quality of the sound. A boost of 1dB in the midrange contour and a cut of 1 or 2dB in the high-frequency contour controls should help to flatten the response—though I felt no compulsion to make such a correction in my listening tests (I was not aware of the measurement results at the time). The tweeter's resonance is mild and at a high 24.7kHz.
Fig.5 breaks out the nearfield responses of the acoustic coupler, woofer, and midrange-tweeter. The coupler's response (the far-left curve) is centered on 39Hz and shows some low-level roughness—possibly due to cabinet resonances—in its rolloff region between about 90 and 250Hz. The nominal crossover between coupler and woofer is about 60Hz; the rapid, highly damped rolloff of the woofer (the middle curve) below this is evident. The midrange takes over from the woofer at a nominal 700Hz-800Hz. There is, of course, considerable overlap in their responses. The upper end of the woofer's response begins to drop off rapidly just above crossover, but the low end of the midrange begins to roll off gradually—at about 6dB/octave. It increases to a much steeper final rate about an octave below the nominal crossover frequency.