Wayne Parham Messages: 18787 Registered: January 2001
Illuminati (33rd Degree)
There are a couple of things that cause midrange response to rise in a midwoofer. One is collapsing directivity and the other is cone flex resonance, modes where the cone is twisting and a resonance sets up on the membrane. Collapsing DI causes a flat line of rising response but resonance modes cause peaks. You can equalize collapsing DI in the crossover, and it is a useful feature when paired with a HF horn, because you can crossover in the frequency range where directivity is similar between the two subsystems. Breakup modes are a little trickier to work with, because they make the driver surface act a sort of like a chaotic array of sound sources that change with respect to frequency.