Description

I was discussing waveshapers with a friend, and flipping through various Desmos graphs that I'd made. He stopped me when he saw this one and told me he thought it should be its own effect. Well, here it is!

While experimenting with an implementation of a crossover distortion (_Trans_N) in Reaper's ReaScript, I was hunting down an exponential form of tanh(), as that isn't a native function in JSFX. I came across this modified tanh expression that adds an "a" and "b" term to skew the expression. Unfortunately, I couldn't find this source again to cite.

This expression proves useful for creating asymmetric distortions (more even order harmonics), especially when combined with the bias. The second photo shows a configuration that approximates the response of a tube amp overdrive.

One consequence of this expression is that the output no longer clamps in the -1 to 1 range, so it is much easier to clip. Watch your levels! The output level and input level are displayed with side-by-side meters making gain staging a little easier with the output knob. The mix knob will also play a role in this of course.

I was originally going to add this algorithm into B-314, but it felt clunky to try and fit in two extra parameters just for one algorithm. The graph also plots the range (y values) from -1 to 1, with horizontal lines to show the -1, 1 points, which makes more sense to do in a standalone effect.

If you want to see the expressions, I made a desmos plot with only this expression. You can walk through the steps to develop the equations by showing/hidings the fuctions and moving the sliders (check the folders).

www.desmos.com/calculator/cv8va8erae