[sdiy] tanh distortion in a filter

[Olivier Gillet]

>> Can I just ask if there's anything particularly special about tanh in this
>> situation?
>>
>> It seems to me that you could use pretty much any sigmoid function.

tanh is what's actually happening in an analog system. If you are not
concerned about exact modeling of the analog system, you can use
another clipping function, for example a lowly (x - x ^ 3 / 6) (as
used in csound) or x / sqrt(1 + x ^ 2) (as used in bristol), or some
crazy rational fractions
(http://www.kvraudio.com/forum/viewtopic.php?t=262823)