This patch shows how to mix detuned oscillators with modulation.
There are certain wave types that are historically used in electronic music, known as "classic" waveforms: sine, sawtooth, square, and triangle. These are the four waveforms generated by the classic Moog synthesizer oscillators, and are still quite useful in computer music.
When you play a note with MIDI, you usually want the note to sustain as long as the key is held down, then you want it to turn off (either immediately or gradually) when the key is released (when the note-off message is received). Because MIDI is designed to function in real time, in live performance, there is no duration information contained in a note-on message. The duration can only be known once the key has been released.
The line~ object calculates and performs that interpolation, sending out a signal that arrives at a specified destination value in a specified amount of time. Once the signal arrives at that value, it stays there until it receives another message telling it to transition linearly to a new signal value.
Two oscillators, one in the left channel and one in the right channel, play notes that have a continuously changing frequency, at a continuously changing note rate. Every few seconds (some randomly-chosen number of seconds from 2 to 8) each of the two oscillators gets a new destination frequency and destination note rate, and heads toward those destination values over the next few (randomly-chosen number of) seconds.
This example repeatedly arpgeggiates the first 16 notes of the harmonic series based on the frequency 65.406395 Hz, which is the fundamental frequency of the open C string on a cello. The note rate can be adjusted anywhere from 1 note per second to 100 notes per second. The default initial rate is 8 notes per second.
If you want to change the coefficients of biquad~ in real time while a sound is playing, it's usually better to use MSP signals rather than individual Max messages, to avoid causing clicks. In that case, you should replace filtergraph~ with filtercoeff~ and send the frequency, gain, and Q parameters into filtercoeff~ as smooth signals (as shown in the left portion of the example).