Preserving the structure of the Moog VCF in the digital domain

A discrete-time version of the Moog VCF structure is proposed based on the explicit computation of the delay-free loop contained in that filter. Compared to previous solutions, the model presented here shows accurate frequency responses when working in linear regimes meanwhile preserving good numerical stability and direct access to the parameters of cutoff frequency and feedback gain. These features make the proposed model a candidate for efficient implementation on fixed-point architectures as well as in normal PC's, in the form of software plug-in. The structural correspondence with the Moog VCF will allow future direct transpositions of the analog system in the discrete-time model.