Hats off to Wendy Carlos

First off if you have 2 free hours someday, do watch Stanley Kubrick's Clockwork Orange - you'll never hear Beethoven the same way again. This assignment is to make a simple polyphonic synth that (to my ears at least) hearkens somehow to Wendy Carlos's soundtrack for that movie.

The assignment is to build a polyphonic wavetable synthesizer. The synthesizer's design itself is quite simple - just two slightly detuned oscillators each playing a hand-drawn waveform using tabread4~. The main point of the exercise is to learn how to use Pd's abstraction mechanism to manage four-voice polyphonic synthesis. There are more complicated examples how to do this in the textbook, but this one can be quite simple - it should just play four-note chords (or, in music speak, four-voice chords), set off by simply sending a message with the four desired MIDI pitches. For example, the first chord (C major) should be set off by a message box with these contents:

48 52 55 60

To make the patch (each of the following steps is worth 2 points for a total of 10):

• Make a patch that plays one voice of the synthesizer; you can call it "voice.pd" if you want. The patch should take a pitch as input (either as an inlet (easiest) or via a receive (neater but you'll have to use a "$" variable to disambiguate it between the copies you'll later make)). The patch should then have two wavetable oscillators in the style of the example patch, 01.15c-more-wavetables.pd, whose frequencies are set, respectively, to the frequency corresponding to the desired pitch (via mtof) and to 0.5 Hz. higher. Use a line~ - controlled envelope generator to control the amplitude of the sum of the two oscillator outputs. (I squared the output of my line~ to get a nicer-sounding envelope.)
• Make a network of message boxes and delay objects to send messages to the line~ object to make an "envelope". On attack (which can be triggered every time you receive a new pitch to play) make a fast attack up to 1 (the peak value of 1 needn't be variable since there's no "velocity sensitivity", also known as "dynamic control", needed in the patch). This way, you can square the output of the line~ and the constant "1" will just translate again to "1". Another message box after a delay equal to the attack time (the time you took to ramp up to "1" should decrease the output to a "steady state" around 0.5 (after squaring if you're going to square it, so about 0.7 before squaring in that case). Then after another delay that will set the (constant) length of the note, around 1000 msec, "release" the envelope by ramping it gently down to 0 again.
• Either make a signal outlet for the voice patch, or else (more sophisticatedly) use "throw"" to send all the amplitude-controlled outputs to a shared "catch~. Now make a parent patch that invokes four of the voice patches as abstractions, summing their outputs, but, since each of them will have a peak amplitude on the order of 1, multiplying the output by 0.1 or so before sending it on to a dac! object.
• Now make a few message boxes with chords (like the one above). THe first six chords will suffice to make it clear that the patch is working. Use an unpack object, invoked as "unpack 0 0 0 0" to get four outlets, to unpack the messages' four arguments and rout them via lines or via send/receive, to the four copies of the "voice" abstraction. At this point when you click on any of the message boxes you should hear the corresponding chord.
• Put the two patches in an otherwise empty directory ("folder") which you could name, for instance, "miller-homework-4" so that it's unlikely to clash with anyone else's name; then make a zip archive of the folder and upload, so that when it's unpacked it makes the directory with the two files in it; upload the zip file and not the individual patches.

Your successful patch should sound something like this.

Here's my version of the first six measures of score, not guaranteed to have perfect voice leading:

48 52 55 60
45 52 57 60
41 50 57 62
43 50 55 59
45 50 57 60
47 50 55 62

48 55 60 64
45 57 60 64
41 57 60 65
43 55 60 64
44 53 59 62
45 52 57 60

41 53 57 62
43 52 55 60
43 50 53 59
36 52 55 60

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