On Mon, Oct 28, 2002 at 01:30:49 +0100, Tim Goetze wrote: > it's an interesting pov though, in fact i've been thinking > about algorithms that work like IIR filters (that are often > used for HP/BP/LP) with the addition of nonlinear terms for > recreating the tube distortion. the maths of such a thing are > not easy to grasp though.
In my (limited) experince its really hard to make them stable. But you can make interesting non-linear filters by using different parameters for the different halves of the wave cycle. This is what makes the gong sound gongy (waveguide_nl.h). It could also apply to cone modelling, as the characteristics of the deflection in the positive and negative directions will be a bit different. <rambling> To make a nonlienar cone filter you could either use different IIR parameters for signal sign, or you could us different parameters for different amplitudes (or both). Different amplitudes would be equivalent to how you model nonliear systems with FIR impulses - I can't believe I didn't think of it before. - Steve
