Wednesday, July 22, 2009

Max/MSP synth building

It has been quite some time since I have posted anything related to Max/MSP, Puredata or PWGL. In many respects for synthesis building I find PWGL much easier to work with, this might be a result of errors I encountered in some of the tutorials for Max/MSP. Some of the tutorials[1] for Max/MSP have errors partly due to the version they were developed for. The main issue I was experiencing surrounds the use of the umenu with the filtergraph~ and biquad~ objects. The problem with the tutorial example is the point at which the umenu item is connected to the filtergraph~ element. This connection should not happen at the right most outlet but rather should connect to the center outlet. This outlet is labeled as "Menu Item Text Evaluated as a Message" which should be connected to the leftmost inlet "a0 coefficient."

This organization of objects changes the filtergraph~ objects filter curve depending on the option selected in the umenu object. Perhaps due to changes and additions in Max/MSP there are a few missing filter types in the example on the Cycling '74 site. However, here is a complete list of filters: display, lowpass, highpass, bandpass, bandstop, peaknotch, lowshelf, highshelf, resonant, allpass. It is beyond the scope of this post to explain what each one of these filter types do. If you are interested in learning more about these filters I would recommend the book "The Computer Music Tutorial." The new filter types include resonant which is similar to bandpass but to use a definition from physics, "resonance is the tendency of a system to oscillate at larger amplitude at some frequencies than at others." And although not technically a filter allpass, functions as a bypass for the filter.

[1] Max/MSP Synth Building with Max/MSP #3