V1.0
V2.x
Probabilistic Quantizer
I’ve enjoyed using the Turing machine clone for melody generation, but although it generates quasirandom sequences, when run into a standard quantizer the note frequency is essentially random. I came up with the idea for a quantizer that has a different probability for each note. This is the result. You set the desired relative probability of each note with the knobs and pull reset high to load the quantizer. The resulting probabilities are displayed by the graph on the right. You can also feed a gate in and get a random gate out. The gate probability is set by the gate knob.
The narrower and wider gates change the probability of each note by the amount set on the inc knob. Narrower moves all the probabilities toward even and wider moves them back toward the original setting. Due to rounding errors the final probabilities will fluctuate when triggering narrower repeatedly. Reset restores the original probabilities. The included file has a random array that will toggle the gates if the attached knob is greater than 0
I/O
Input 
Signal Range 
Notes 
reset 
01 
a high resets the quantizer to the knob settings 
narrower 
01 
a high moves the probabilities closer to even by the inc amount 
wider 
01 
a high moves the probabilities closer to the knob settings by the inc amount 
gate 
gate signal 
can be used to generate a random gate output 
o 
1 per octave signal 

Output 
Signal Range 
Notes 
gate 
gate signal 
random gate output 
o 
1 per octave signal 

Controls
Control 
Function 
Notes 
note probability knobs 
set the relative probability of each note 

gate probability knob 
sets the probability that a gate will pass from 0 to 1 

inc 
sets the increment for the narrower and wider gates from 0 to 0.1 

Displays
There is a green light in the center of the knob for the active note when the output gate is active
The meter array at the right shows the current probability of each note from 0 to 1
Version History
Demos
3 Likes
I also put together a "lite: version that is simply a quantizer without the wider/narrower and random gate functions.
moved to main entry see above
2 Likes
I decided that the “Lite” version was potentially more useful than the original so it became V2.x. I left my earlier one for those that want to fool with it.
1 Like
I am delving into some of the probability/stochastic patches in the forum. This patch is very cool, but I am still a bit green in my Audulus understanding. Is the probabilistic aspect a result of the input signal as opposed to some randomness generated in the patch. Have I overlooked a Random somewhere in the patch?
It may be a bit misnamed. The original 1.0 version did have some internal probability generation with the gate, but I removed that logic in the final 2.x version to simplify the module. As you suspected the randomness is in the input to the quantizer. It could be a Turing machine module or my more recent QRST module or some other source of a random or quasirandom 1 per octave signal. The quantizer allows you to adjust the portion of each octave band which will resolve to a specific note. The knobs function in a similar fashion to the mask on a more traditional quantizer, but instead of fixed divisions such as semitones, change the crossover points in a continuous fashion. With a random signal into the quantizer, the knobs adjust the probability that a given note will play but the quantizer itself is deterministic. The same input with the same quantizer settings will always produce the same output.
1 Like