Actually, the true formula for Sd is:
Sd = (3.1416 * D^2)/4
Where D is diameter of the cone (the actual cone itself...not the sub's diameter) plus one-third of the surround at both ends of the measurement.
Sd = (3.1416 * D^2)/4
Where D is diameter of the cone (the actual cone itself...not the sub's diameter) plus one-third of the surround at both ends of the measurement.
