Oh, I see what you were referring to. You meant the dipole peak. It occurs at the same frequency in both cases. In the dual driver case there is only a dipole peak. For the CRAW that would be at about 300 Hz. For the H frame configuration with same front to back length there is a dipole peak at the same frequency but there is the possibility of the peak being augmented by the 1/4 wave resonance of the H, which is also at the same frequency. The peak is at WL = 2D and the 1/4 wave resonance is at WL = 4D/2 = 2D, WL = wave length.
The effect of the resonance (H) is typically to make the roll off locally a little shallower than it is with the dual driver dipole. For instance reducing the slope from 4 th order to 3 1/2 order. It is easily compensated for with a notch filter is necessary. Above the peak you generally start to see steeper roll off due to the effects of VC inductance.
I haven't heard any significant subjective differences between the CRAW and a similar H used with the same crossover filters.
Well, yes and no. What I was getting at, is that it could never be an exact comparison, because as you noted, the H would have a measured resonance different than the enclosed dual driver dipole (like the CRAW), among other differences (not to mention they could not occupy the same position in room at once). But what I was really asking is, how much of what we hear subjectively when listening to an
open baffle subwoofer, like an H, is power radiation and/or how much is the fact that the driver is unenclosed (assuming that the driver is quite mechanically, etc.)? Note that I am not referring to upper bass/midrange frequencies.
cheers,
AJ
