## Courses on sound synthesis with maxmsp patches (idea, feedback, question)

Jul 31 2006 | 3:33 pm
Hi :)
First post here, i've recognize some quite famous persons here !
Anyway, i will present a short course on sound synthesis (my hobbie) in paris. I ve decided to present different sound synthesis according to J.O SMith classification
I ve implemented simple maxmsp patches with temporal and spectral representation for each synthesis (patches are made for pedagogical issue, the goal is not to create incredible soundscape :) ). You can download patches here:
Does anyone have some critism about the patches ? Some idea to make patches more adapted for educational issue ?
Then, I ve a problem with my additive patch. In fact i would like to show how to obtain square, swatooth and traingle wavform by summing 6 sines (In fact this waveform need to have an infinite harmonics, but with matlab i ve verified that 6 sines can give good apporximation).
My problem is: " when i look to the oscilloscope, i don't obtain the correct waveform".
I believe that there are some phase problems ? How to synchronise the phase of each sine ?
Some idea ?
thank's !

• Jul 31 2006 | 4:28 pm
Quote: Choc wrote on Mon, 31 July 2006 09:33 ---------------------------------------------------- > My problem is: " when i look to the oscilloscope, i don't obtain the correct waveform". > > I believe that there are some phase problems ? How to synchronise the phase of each sine ? > > Some idea ? > > thank's ! ----------------------------------------------------
i've not had time to look at your patches, but the answer to your question is to use a phasor to drive your cycle oscillators via the second inlet (phase inlet).
j
• Jul 31 2006 | 5:21 pm
> My problem is: " when i look to the oscilloscope, i don't obtain > the correct waveform".
keep in mind, that summing sine waves (not cosines) will give you the typical rectangular waveform. use the right inlet of cycle~ to set the initial phases of your partials to something like 0.75 or -0.25.
• Jul 31 2006 | 6:19 pm
Also, get info on scope~ and change it from line~ (or free-run) mode to "up" mode. This will make the oscilloscope phase synchronous.
Peter McCulloch
On Jul 31, 2006, at 1:21 PM, vb wrote:
>> My problem is: " when i look to the oscilloscope, i don't obtain the >> correct waveform". > > keep in mind, that summing sine waves (not cosines) will give you the > typical rectangular waveform. > use the right inlet of cycle~ to set the initial phases of your > partials to something like 0.75 or -0.25. > >
• Jul 31 2006 | 8:42 pm
On 31-Jul-2006, at 17:33, Choqueuse wrote:
> My problem is: " when i look to the oscilloscope, i don't obtain > the correct waveform".
I did exactly this in a workshop last week. And, yes, the waveform is not what you expect. And, yes, it's the phase. The standard Fourier models for square wave & Cie. use sine waves; cycle~ produces a cosine wave.
The thing is, the ear tends to be less sensitive to phase offsets in static wave forms, so the difference is more striking visually than acoustically.
Nevertheless, if you want things to look right, you'll need to send a phase offset into the right inlet of your cycle~s before starting audio. I think 0.25 will do the trick.
Good luck, Peter
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• Jul 31 2006 | 9:18 pm