uKarplus-Strong

robertsyrett · July 11, 2018, 4:04am

uKarplus-Strong

This module uses Karplus-Strong synthesis, which is a type of string physical modeling that uses a delay line with a lot of feedback to create periodic waveforms out of a short burst of noise.

In this ground-up remake of the library Karplus-Strong VCO module, I was looking to expand the sweet spots of each parameter and balance the knobs so that every nudge makes a difference. To further enhance the string-like quality of this voice, there are 4 delay lines set up in a round-robin meaning each note plucked will ring out without being cut off. This is similar in behavior to the popular Mutable Instrument’s Rings module.

Overall, a great choice for making plucked sounds both subtle and bold.

I/O

Input	Signal Range	Notes
	`0 to 1`	trigger input
	`-5 to 5`	1/Oct Input

Output	Signal Range	Notes
	`-1 to 1`	If saturation is turned up and all voices are active, there is a chance that the signal can go past 1. If this is the case, attenuating the signal will remove any resulting distortion.

Controls

Knob, Button	Function	Notes
	`Feedback`	This is the primary way to control the decay of the algorithm.
	`Saturation`	This is a soft clipping algorithm that had the effect of compressing the signal and emphasizing the volume of the decay.
	`Exciter Decay`	By shortening the decay of the noise exciter you can create accented plucks.
	`Frequency Cutoff`	The cutoff frequency of the low pass filter of the noise exciter is running through can change the type of material the string is made from. The higher the cutoff the more metallic the string sounds.
	`Exciter Mode`	Toggles between unipolar and bipolar noise exciters.