Dayton Audio ND90-8 3-1 - Manual (Page 10)

Kms Symmetry xc(x)
This curve shows the symmetry point in the nonlinear compliance curve where a negative and positive
displacement x=xpeak will produce the same compliance value
kms(xc(x) + x) = kms(xc(x) – x).
A high value of the symmetry point xc(x) at small displacement amplitudes x » 0 indicates that the rest
position does not agree with the minimum of the stiffness characteristic. This may be caused by an
asymmetry in the geometry of the spider (cup form) or surround (half wave). A high value of the
symmetry point xc(x) at maximal displacement x» xmax may be caused by asymmetric limiting of the
surround.