Multi-level trigger

[CaptainPoopface]

This block was designed for triggering an envelope in response to audio input.

With a basic gate that opens at some amplitude threshold, you must make the amplitude fall below that threshold in order to close and reopen the gate. For an audio signal, this usually means you have to introduce a moment of silence between notes, which can be an awkward and limiting articulation.

With this building block, it is assumed that the input is slightly louder on an "attack" than the rest of the time. There are three thresholds, where thresh 1 < thresh 2 < thresh 3. The gate opens when thresh 1 is reached. It momentarily closes and reopens when thresh3 is reached, but only if the signal has fallen below thresh 2 since the last time thresh3 was reached. See the picture below.

This means that when you are playing several notes in succession on guitar or flute for example, you just have to make sure the note attacks are slightly louder in order to retrigger an envelope, and adjust the thresholds as needed. Hopefully playing with slight accent or marcato is more natural than playing a moment of silence between notes (this is definitely true on guitar).

Simply patch the output of an envelope follower to the blocks labeled Thresh1, Thresh2 and Thresh3. Adjust the thresholds and your envelope follower until you have the desired behavior. The output gate comes from the XOR gate labeled "Gate out."

Instructions can also be found in the textpad.

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