Tutorials and Topics - Peabody Computer Music

Tutorial 7Synthesis:Additive synthesisPreset 7. In this case the partials are spaced a major second apart, and the amplitude ofeach partial rises and falls in such a way as to create a composite effect of an arpeggiatedwhole-tone cluster. Although this is clearly a whole-tone chord rather than a single tone,the gradual and overlapping attacks and decays cause the tones to fuse together fairlysuccessfully.Preset 8. In this tone the partials suggest a harmonic spectrum strongly enough that westill get a sense of a fundamental pitch, but they are sufficiently mistuned that theyresemble the inharmonic spectrum of a bell. The percussive attack, rapid decay, andindependently varying partials during the sustain portion of the note are also allcharacteristic of a struck metal bell.Notice that when you are adding several signals together like this, their sum will oftenexceed the amplitude limits of the dac~ object, so the over-all amplitude must be scaledappropriately with a *~ object.Experiment with complex tones• Using these tones as starting points, you may want to try designing your own toneswith this additive synthesis patch. Vary the tones by changing the fundamentalfrequency, partials, and duration of the preset tones. You can also change theenvelopes by dragging on the breakpoints.To draw a function in the function object:• Click in the function object to create a new breakpoint. If you click and drag, the x andy coordinates of the point are shown in the upper portion of the object, and you canimmediately move the breakpoint to the position you want.• Similarly, you can click and drag on any existing breakpoint to move it.• Shift-click on an existing point to delete it.Although not demonstrated in this tutorial, it is also possible to create, move, and deletebreakpoints in a function just by using Max messages. See the description of function in theObjects section of the manual for details.The message setdomain, followed by a number, changes the scale of the x axis in the functionwithout changing the shape of the envelope. When you change the number in the“Duration” number box, it sends a setdomain message to the function.102