Vandersteen Audio 2Ce loudspeaker Sidebar 3: Measurements 2
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.