Input: +6 dB peak sine wave
y = x. The input is clipped at ~3.5 dB.
Using the tanh equivalent equation 2/(1+exp(-2x))-1 the input is clipped prior to the waveshaper.
If, instead, a unity gain sine wave is input and the equation is changed to 2/(1+exp(-4x))-1, the correct waveform is produced.
