Creating a radio effect using a convolution filter


Puredata is a Real-time graphical dataflow programming environment for audio, video, and graphical processing. It is possible to define complex effects and processing patches by building graphical signal chains in the puredata environment. Puredata has similarities to the MAX/MSP environment, however more detailed description of puredata is beyond the scope of this document. Interested readers can find out more information at

For the purpose of this exercise, puredata was used to generate the effect of a “Single-Sideband” AM radio tuning into the correct frequency.


Sequoia is a widely used Windows-based DAW distributed and developed by MAGIX in Germany. Sequoia supports VST effects, necessary for the PDVST adapter. More information is available at


Puredata is a standalone application. In order to use it with a VST host, a bridging plugin must be used. PDVST is such a bridging plugin. It allows a VST plugin to be created for a PD patch and for that VST plugin to be loaded into a VST host. Furthermore, it allows definition of automation parameters and for those automation parameters to be read and written by puredata. In order for PD to be used in this way, some modifications are made to the PD codebase, consequently the version of PD supplied with PDVST is different to that distributed with the standalone version. More information is available at

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