Octatrack probability hack

Elektron Gear Octatrack
#1

Not sure i this has been shared before, but I just discovered it for myself today. Apologies if it’s already common knowlege.

So I’ve been using the OT to sequence a nord rack 2, using a drum kit in one of the slots for freaky electronic drums and it struck me that it’s possible to achieve a kind of probability trigger on the OT. This is ONLY FOR MIDI TRACKS though, and will only work in certain circumstances. Fun though, nonetheless…

Here’s how it works, assuming you have drums triggerable by different midi notes.

[ul]
[li]Enter a trig and p-lock the midi note you want.[/li]
[li]p-lock note 2 to either a different drum sound, or a midi note that is out of range and thus won’t trigger any sound[/li]
[li]Repeat with note 3[/li]
[li]And note 4 if required[/li]
[li]p-lock the arpeggiator to RAND and arpeggiator note length to something long (longer than the actual note length)[/li]
[li]Sit back and appreciate a bit of random in your music[/li]
[/ul]

So you can only achieve 50%, 33% and 25% probabilities, by utilising 2, 3 or 4 note p-locks, but it’s better than nothing and open’s up some cool possibilities. I’ve only tried it with drums but I can imagine it’s fun with notes in basslines, chord progressions, etc.

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Random trigs : probability hacks on old trinity
Odd ‘random’ LFO behaviour when selecting slices?
OT Special Tricks
#2

Nice, I do this with the arpeggiator on my keyboard and a drum machine, but for some reason never thought to do this with the OT sequencer. Or maybe I did and forgot??
Either way, thanks :slight_smile:

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#3

Good idea. Some different approaches have been discussed before (using LFO’s), but anyways thanks for posting. Just referred to the trick in the OT tricks collection thread.

#4

Cool one! I have not seen this trick applied to the OT, although Dubathonic has used something like this for his Monomachine. Anyway, great post with very clear instructions for the OT. Keep the good ideas flowing :slight_smile:

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#5

LFO to Arp type would add another layer to that :slight_smile:

#6

@musicmagus: good point. The trick is more general. For instance, it can also be used in the Samplr app!

#7

Seems you could also do 66% and 75%, no?

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#8

Seems you could also do 66% and 75%, no?[/quote]
Yes indeed!

#9

Nice trick!

I’ve also recently found that you can get some probabilistic modulation of gating by routing a random LFO to arp note length. So, if arp note length is set to “1” and the random LFO depth is also set to “1”, the step is triggered at roughly 50% probability (because half the time it drops the note length down to 0).

Of course this also affects note length in general, but I find it fine if you use it sparingly (which I prefer to – e.g., with 1 or 2 out of 16 steps having these settings p-locked) or with a synth whose envelopes simply respond to triggers rather than variable-length gates.

Discovering this makes me feel considerably better about the lack of probability trig conditions on the Octa, which I use all the time on my Rytm :happy:

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#10

Hmm cool! This makes me think of another thing… what if we do the following:
take a drum sound and combine it with a silent version of it (let’s say repeat the drum sound 5 times and have 3 “silent” sounds). Make one wav file out of it, import it on the :elot: and then slice it so you get 5 slices with a drum sound and 3 with silence. Then modulate the slice selection with a random LFO, that should also work… need to try later when I have a moment to do so.

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#11

I was trying to get a normal sample trig working with LFO probability the other day but unsuccessful… I remember the basic idea was to create an LFO with the designer that is 100% on, then route that to amp vol, but I couldn’t get it working reliably… Anyone remember the trick? Would be cool to have the right values on hand to dial in probability trigs quickly and reliably.

#12

Just tried the trick I proposed earlier, and it works really great! This seems to be an easy way to make probability work for sample trigs.

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#13

Probabilistic sample trigging (along the lines of both @papernoise 's suggestion and @Anfim 's suggestion) was discussed:

What I really appreciate about the OP’s idea is that it applies in the MIDI track realm, which hadn’t been fruitfully discussed much in terms of ‘probability hacks.’

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#14

That one requires making a dedicated sample chain with silence though so it’s not very spontaneous! I’m sure there’s a way to get probability on a single sample

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#15

@Autopoiesis oh I see, thanks for the heads up!

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#16

Thanks for sharing these ideas. Really interesting. The OT and the nord rack 2 drum kits are a quite powerful combination for glitchy percussion

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#17

To follow up on this trick, I realized later on that some midi destinations will still get triggered when the arp note length is 0.

But one other workaround: you can route the random LFO to velocity so it makes velocity hit 0 on some steps (which will prevent the step from triggering for sure). The downside there is you’ll have to disable velocity sensitivity on the receiving synth to avoid unwanted velocity modulation.

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#18

Instead of the random LFO, you can also create a custom LFO with some steps set to 0, and others set to -128. Velocity for the 0 steps will be untouched and on the -128 steps it will always be 0.

You can use a weird speed to make it feel more random, or modulate its speed by a random LFO to make it actually random.

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OT as a hardware sequencer
#19

Cool, that sounds like a more precise way to add probabilistic gating to the OT, and means you could still use velocity on the synth destination. It would also generalize to audio tracks, where you’d just substitute velocity with amp volume.

If I understand correctly, if you set the random LFO (that’s modulating the speed of the “0 or -127” custom LFO) to max speed and max level, each point of the custom LFO should have roughly equal probability of being “sampled” for each step of the MIDI track. To adjust the probability that a -127 point of the LFO gets sampled, you would then adjust the proportion of the custom LFO’s points that are set to -127. For example, if 4/16 LFO points are set to -127 and 12 are set to 0, you would be able to apply a 75% probability condition to any MIDI steps that have the custom LFO’s level p-locked to max. Does that sound right to you?

If this is the case, the downside is that probabilities are tied to custom LFO shapes and consequently you couldn’t do something like p-lock one step to have a 25% probability and another step to have a 75% probability within the same track.

Edit: I tested this out with 2 LFOs in Five12 Numerology and based on the different average values I was able to produce, it does seem to work as above. Cool ! Maybe I should keep in all my Parts a handful of custom LFOs that realize different probabilities.

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#20

FWIW, regarding the approach

you can route the random LFO to velocity so it makes velocity hit 0 on some steps (which will prevent the step from triggering for sure). The downside there is you’ll have to disable velocity sensitivity on the receiving synth to avoid unwanted velocity modulation.

Based on a simulation and my assumption that the OT’s random LFO ranges from -128 to +127 at its maximum depth, it seems you can p-lock these probabilities with the following settings:

  • Base velocity = 2
    • Depth of random LFO modulating velocity = 0 or 1
      • => 100% probability of Note On
    • Depth of random LFO modulating velocity = 2
      • => ~75% probability of Note On
    • Depth of random LFO modulating velocity = 3
      • => ~67% probability of Note On
    • Depth of random LFO modulating velocity = 5
      • => ~60% probability of Note On
    • Depth of random LFO modulating velocity = 10
      • => ~55% probability of Note On
    • Depth of random LFO modulating velocity = 128
      • => ~50% probability of Note On
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OT as a hardware sequencer