A Digital Model for the Prologue Voltage Control Filter

Lazzarini V, Timoney J. A Digital Model for the Prologue Voltage Control Filter. J Audio Eng Soc. 2024;72(1/2):79-88. doi:10.17743/jaes.2022.0120

@article{Lazzarini2024_22380,
  author = {Lazzarini, Victor and Timoney, Joseph},
  title = {{A Digital Model for the Prologue Voltage Control Filter}},
  journal = {Journal of the Audio Engineering Society},
  volume = {72},
  number = {1/2},
  pages = {79--88},
  year = {2024},
  month = jan,
  publisher = {Audio Engineering Society},
  doi = {10.17743/jaes.2022.0120},
  url = {https://doi.org/10.17743/jaes.2022.0120}
}

TY  - JOUR
TI  - A Digital Model for the Prologue Voltage Control Filter
AU  - Lazzarini, Victor
AU  - Timoney, Joseph
T2  - Journal of the Audio Engineering Society
J2  - J. Audio Eng. Soc.
VL  - 72
IS  - 1/2
SP  - 79
EP  - 88
PY  - 2024
DA  - 2024/01/06
DO  - 10.17743/jaes.2022.0120
UR  - https://doi.org/10.17743/jaes.2022.0120
PB  - Audio Engineering Society
LA  - en
AB  - The Prologue polyphonic synthesizer features a voltage control filter (VCF) employing an original topology. This paper examines its circuit and extracts a flowchart, which yields a set of analog filter equations. From these, the authors were able to develop a transfer function to describe its ideal linear time-invariant form. Then a linear digital version of the filter to validate the analysis was put forward. Noting that the filter operation within the synthesizer is fairly nonlinear, a number of modifications yielding a nonlinear model of the VCF is proposed. These were compared with the outputs of the original analog filter, and it was found that they approximate them consistently.
ER  -