Random drum sequencer step trigger

JunoX Member Posts: 6 Newcomer
edited March 24 in Building With Reaktor

Hi everyone,

is it possible to randomly trigger the steps of a step sequencer with individual trigger probabilities?

So for example when random is hit, the first step will be triggered with a probability of 50%, the second step at 25%, the third step at 100%,...

How would I have to connect that?

Sry, just started using reaktor πŸ™ˆ

Thank you in advance.



  • Paule
    Paule Member Posts: 1,328 Expert
    edited March 15

    Here you can use left of the row the β€žSβ€œ to set randomly new steps. The zero on the right side delete all steps. It works with IC-Send to each step:

    You can down load the ensemble here:


    In front is a button and a separator.

    Myself use the range of 0, 0.25, 0.5, 0.75 and 1.0 for the velocity iof the sequencer.

  • Brett Lavallee
    Brett Lavallee Member Posts: 25 Member

    Yes, it is possible using logic modules. This sequencer I built does just what you asked; feel free to explore the code.


  • colB
    colB Member Posts: 665 Guru

    Are you asking about a specific sequencer, or just in general?

    If its the latter, then pretty much anything that you can imagine sequencer wise is likely possible in Reaktor. If its the former, then please say which sequencer you are using. That matters - there are a LOT of sequencers in Reaktor (and synths and everything else too). And they all do it a bit different from each other.

  • JunoX
    JunoX Member Posts: 6 Newcomer

    Hi colB, thank you for your answer.

    Here's where I wanna go in the end:

    I wanna do a drum pattern generator that uses a kind of "intelligent random".

    So, if a user wants to create a Deep-House Pattern, the plugin would treat each track with it's separate "intelligent random" genre based specifications.


    Kick: would be triggered at every 1/4 note.

    Hats: would be triggered at every 1/16th note, with random velocity

    Clap: would be triggered at every second kick trigger

    and so on...

    So, the outcome would always be a good sounding beat pattern, and no 1/16th notes triggered kick messing things up for example.

    For each track the user (or the genre preset itself) can define the intelligent random ranges for Velocity and Trigger probability (maybe also pitch and offset).

    I'd also implement a groove/swing option.

    With a tutorial I could build a simple step sequencer with toggle buttons in reaktor.

    But now I am failing to do the rest πŸ™ˆ

    Here's a sketch:

    (the midi and sample load stuff would be nice, but I am more than happy when the intelligent random range definitions work)

    So, if you or anyone else wanna help me, feel free to answer here or message me 😊

  • colB
    colB Member Posts: 665 Guru

    Generally, you would need a lane in your sequencer to have probability settings per step from 0 to 1, then for each step, you generate a random number per step, and if its value is less than or equal to the probability for that step, you send a trigger, otherwise you don't

    so if probability is 1 then a random value between 0 and 1 is always going to be less than or equal to 1, and you always generate a trigger, whereas if probability is 0.25, then a random value between 0 and 1 is only going to be less than or equal to the probability about a quarter of the time... pretty simple really.

    For fun, here's an ensemble using factory blocks that demonstrates the idea:

    This works slightly differently due to the limitations of the available blocks. The velocity lane of the shift sequencer is used for probability setting per step. A sample and hold block generates random values per step, those are added together. The result is sent to a gates & trigs module. Now if the value is above the threshold we get a trigger, so with a low probability, we need a really high random value to get a trigger, whereas a high probability pretty much always gives a trigger. The gate driven VCA guarantees that the trigger/gate is always reset.

  • colB
    colB Member Posts: 665 Guru
    edited March 17

    Here's a different version using multiplication (VCA) instead of addition. This means that 100% isn't possible!... so better to just use a comparator if RND <= PROB if you are rolling you own :)

    (I remembered to do it as a rack this time, so 6k instead of 7Mb :))

    try hitting the 'VEL' button on the shift sequencer, that will randomize the probabilities!

  • JunoX
    JunoX Member Posts: 6 Newcomer

    Hi colB,

    thank you for your answer and examples. I am not sure if I got you right.

    Should the Vel lane define the probability of each step? (Gate, Hold?).

    When I set the Vel lane like in the first picture and hit the "gate" random button for example, it still seems to randomly trigger steps. Shouldn't it look more like in the second picture?

    Sry, I guess I missed something.

  • colB
    colB Member Posts: 665 Guru

    For that patch to work, the gate needs to be on for all steps on the sequencer. The probability part is created by the combination of the velocity output of the sequencer and the other blocks in the patch. The gates & trigs block is where the actual probabilistic triggers are generated.

    Like I said though if you are scratch building a sequencer, better to use the simple comparison approach.

    Do you have a basic sequencer that you are working on? If you post that, then it might be easy to modify it for probability!

    That might be the best way forward - build a simple sequencer, then modify

  • JunoX
    JunoX Member Posts: 6 Newcomer

    That's the ens so far πŸ™ˆ


  • colB
    colB Member Posts: 665 Guru
    edited March 18

    OK, basic idea would be to duplicate the row of velocity knobs (fix the first one so that its 0..1 instead of -1..1 ;))

    Then send the gate (i called it trg) signal and the probability value through a new macro that looks like this:

    This generates a random value between 0 and 1, then compares it with the probability, if its less than or equal it outputs 1 otherwise 0. You then multiply that with the actual gate, and the gate passes dependent on the probability.

    I also noticed that your lamps are 1 off what they should be - not sure why you included that -1 in there?

    There's a buch of other stuff to do, but this should get you some basic probability!

  • JunoX
    JunoX Member Posts: 6 Newcomer

    Got it to work! Thank you so much!

    Is there a way to also randomize the velocity, but only values within the given range

    (V Range - Min Max per step) are used?

  • colB
    colB Member Posts: 665 Guru
    edited March 19

    Is there a way to also randomize the velocity, but only values within the given range

    Manipulating stuff with Maths is much easier and better in core, but what you are asking is still pretty easy in Primary.

    If you look to the pic in my last post, the Randomize module has two inputs, Rng and In.

    What you get at the output is a random number between In-Rng and In+Rng (yes it's weird, but then it's Primary).

    Tip: there are info hints for all the modules, and they are usually pretty good descriptions of what they do!

    So anyway, with a min and max control...

    'In' would need to get the halfway point between min and max, which would be: (max+min)*0.5

    'Rng' would need to get half of the difference between them, which would be: (max-min)*0.5

    IMO it might be easier just to have a single random amount setting for each velocity, then just send the velocity to 'In' and the random setting to Rng, then you get random fluctuations above and below the velocity setting by and amount specified by that single control.

    Or if you do go with min and max, ditch the velocity knobs because they become redundant in that context!

    ...Or, have a velocity setting and a 'humanize' that uses the velocity setting as max, and humanise as a min for the min/max version... then you can still set the maximum precisely, but you still only need one extra control... I would also be playing with applying a curve to the probability so that more of the hits fall nearer to the 'correct' velocity and fewer are further away... this sort of thing is much better done in core where you don't get punished so much (in complexity and cpu) for doing a lot of basic arithmetic processing...

  • Octaviu5
    Octaviu5 Member Posts: 47 Member

    I would honestly avoid reaktor al together for any logic type of processing.

    Visual coding is a nightmare in terms of upscalability.

    I wasted months of my life on a multipattern step sequencer because implementing the most minute change would take endless hours of mousing and clicking which could almost always not be ported from one situation to another.

  • colB
    colB Member Posts: 665 Guru

    For something like a complex sequencer, it helps to use something like iteration system from partials framework. With some discipline it's possible to get quite far... then the limitation tends to become the core compiler being able to deal with the size of the code graph. There are tricks to help with that too.

    There is a more significant limit to what is practical in primary though for sure.

    I don't think Reaktor was ever intended to be used for building application scale projects... although it's still possible ;-)

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