Spring Waves is an effect card for the Z-DSP from Tiptop Audio and equipped with eight different physical modeling algorithms, which simulate the sound behavior of real objects (strings, tubes, metal rods, wood etc.). The map contains two physical modeling variants called waveguide and spring model. The Z-DSP is an open source DSP for the modular system and can exchange various programs with the help of the plug-in cards.
The "digital waveguide synthesis" describes a number of applications of the Karplus-Strong algorithm. This algorithm is based on a short delay as input pulse, which passes through a low-pass filter and is fed back into the input from the output. The circulation of the pulse in the delay line is comparable to the wave-like movement of a vibrating string.
The pitch is controlled over the length of the delay. There are a total of six waveguide programs on the effect card, which differ in the order of the algorithms they are composed of.
There are also two spring model programs on the effect card. The spring model calculates all Newtonian forces acting on a mass-spring system at sampling speed. Many factors are considered: the spring itself, its restoring force, the potential (non-linear) behavior of the tensioned spring, the point at which the spring is attached and the mass at the other end of the spring, speed, deflection, static, sliding and air/fluid friction.
The audio input is used either to adjust the suspension point of the spring or as a force acting directly on the moving mass. The audio output is directly related to the movement of the mass and is provided by it.