This design uses some pre-defined mathematical functions to shape the input waveform. The Formulae for the shaping are all held in a Fixed Values (Text) module from where they can be selected.
These values are sent to a Switch > Text module. From there they are fed to the Waveshaper2B module where the mathematical function is applied to the input waveform. The 1 Pole HP filter is to block any DC component that the Waveshaper might introduce. From there the X-Mix module sets the balance between the unaltered input, and the shaped signal.
Notes:
All the Slider controls are left at their default values.
Formula 12 (Folding) is purely a foldback distortion, the Sin and Cos formulae add some 2nd/3rd/4th harmonics giving a formant like sound to a sine or triangle input.
Using Sqrt (Square Root) formulae can give some quite spiky waveforms.
Formulas used:
1) Sin: 6sin((x+2/PI)+(x+2/PI))
2) Cos: 5cos((x+5/PI)+(x+5/PI)) 3) ASin 2asin((x/PI)+(x/PI))
4) Acos: 2acos((x/PI)+(x/PI)) 5) Sqrt 5 sqrt((x/PI)+(x/PI))
5) Sqrt: 5*sqrt((x/PI)+(x/PI))
6) -Sqrt: -5*sqrt((x/PI)+(x/PI))
7) Sin Cos: 6*sin((x+2/PI)+cos(x+2/PI))
8) Cos Sin: 6*cos((x+2/PI)+sin(x+2/PI))
9) Default: 5*sin(x/PI)
10) 3*Sin: 6*sin((x+2/PI)+(x+2/PI)+(x+2/PI))
11) 4*Sin 6*sin((x+2/PI)+(x+2/PI)+(x+2/PI)+(x+2/PI))
12) Folding: 3 *(abs(-abs(-abs(x+1.25)+2.5)+2.5)-1.25)
Other functions can be used, although some may result in outputs with a very high amplitude, or nothing at all, feel free to experiment.
Adding a Butterworth High Pass filter will also greatly reduce any unwanted low frequency “rumbles” which can be introduced.
As you can see in the Frequency Spectrums below the layout with the Butterworth High Pass filter in circuit, a lot of the “noise” below 200Hz is drastically reduced. The filter was set to a cut-off frequency of 200Hz, and the number of filter Poles to 12.
Unfiltered output:
Filtered output (about 200Hz High-Pass):
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