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nitro27
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Joined: 10/11/2015 - 18:27
A Kinda Crappy Probability Drummer using Modular Voodoo

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A probability drummer is an instrument that decides whether or not to trigger a sample based on a probability that can be tuned per step. I love using these things as VSTs on my computer, one was included in the venerable Buzz for Windows, they're great, Caustic doesn't have one.

What I have here is really hacky, requires 3 instruments plus two per extra channel of probability, and only modulates the volume of an instrument instead of triggering samples itself. However, you can decide with what probability you will hear an instrument per note, basically using velocity as a numerical percentage chance, and that's just cool.

With all that out of the way, let's get to explaining what's going on here:

Hat Src is playing straight 16ths on a hi hat. Its volume is turned down.

Neg is outputting a purely negative voltage. It has to be a PCMSynth because AFAIK, that's the only instrument that won't immediately cancel out the voltage by pushing it to zero. If anyone has a way of making a negative voltage easily in Modular, that would make this a lot cleaner.

Hat Prob is the actual probability engine we'll be focusing on. Signal flow starts upper left, then goes down and wraps to the the right, roughly.

We take Hat Src and wire it to the output, we'll use the built in volume mod to turn the hat on and off. Fun fact, this would be quite a bit easier if this volume mod interpreted a negative voltage to mean it should turn off the signal. Instead it actually inverts the signal, which is wacky.

So first we take a noise module and find a way to control the probability it lands above or below zero. Here I'm using note velocity to push it up, and our handy dandy PCMSynth to pull it down.

Throw these into a mixer and tune their volumes so that, at full velocity, the noise is just barely all above zero, and at low velocity, it's just below zero.

Since we want the volume to be either completely on or completely off, We'll put the output through a saturator on max. This doesn't do a perfect job. I kind of like it like that, but you can put it through another saturator at this point if you want. This is where the first oscilloscope is in my patch.

Now we put the signal into a sample and hold with a very short decay going to its gate, so that the volume changes on every note instead of all the time.

Since the volume mod needs the signal to be at zero to turn off, we need to push our signal up so that the lowest it goes is zero. Here I'm using a DADSR to do that, (something you can blame paulovski for,) because when you mix the output and inverted output of the the DADSR, you get a constantly positive voltage.

We already have a negative voltage being piped in from the PCMSynth, and we could totally use that to pull the signal down instead of up, and save 3 Modular slots in the process, but then the lowest velocity would give the highest probability of being heard, and that's just silly.

So anyway, we mix the DADSR outputs together, then mix that with our carefully crafted signal, remembering to adjust its volume properly, and we have our probability gate! Finally we put an AR ENV on the final mixer's mod, because we don't want it playing when there's no note being played, and hook it up to the synth's volume mod.

There! We made a rough facsimile of a probability drummer that takes a bunch of CPU and only modulates the volume of one channel! Is there anything we can't make with Caustic? Will I spend three hours explaining every patch I make? Is there a character limit on this forum? I guess we'll never know.

RobFarley
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Joined: 11/02/2013 - 16:43
I have no idea what the

I have no idea what the flipping heck you are doing there... I'm going to download this patch later and take a look, it sounds fascinating! Even if I get absolutely no use out of this I am massively impressed that you have done this and bravo sir!

UncleAfx
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Joined: 03/06/2016 - 20:08
Wow. This will give my brain

Wow. This will give my brain a nice workout. :-)
Would this be the negative voltage you were looking for?

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nitro27
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Joined: 10/11/2015 - 18:27
Woah, that's weird, the band

Woah, that's weird, the band pass filter is an inverting output, check it out!

...

Whyyy? I feel like that's a bug. Hey Rej, don't fix that bug!

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I make Chillout Electronic Music, and sometimes Ambient. http://floatingbeyond.tk
https://soundcloud.com/floatingbeyond

UncleAfx
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Joined: 03/06/2016 - 20:08
A bug? Maybe, but I'm not so

A bug? Maybe, but I'm not so sure. Why? Well I'm not so sure about that either, but if it was truly inverting you should be able to cancel out the two sides, but so far I can't seem to manage that.

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paulovski
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Joined: 09/19/2012 - 06:13
That's another bit of

That's another bit of outstanding kit. Splendid stuff.

Um. I'm a bit puzzled about the last bit (in this very particular setup). The DADSR arrangement. This thing doesn't make any noise, so I'm not sure that that envelope needs to govern the final output. I might have missed something. Let's say I have. So to hear it, you have to trigger it. And at that point, with the DADSR as is, the inverted output is zero. So you could strike my little contribution to this setup and just use an AR.

 

UncleAfx
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Joined: 03/06/2016 - 20:08
To be honest, I feel like I'm

To be honest, I feel like I'm the one missing something and doing all of this stuff on accident haha. But the DADSR wasn't for outputting audio, only voltage. By itself plugged straight into an oscilloscope it shows a positive voltage. Run through a SVF with bp gives negative voltage.
So once the negative voltage was created i combined that with the original positive signal coming from the DADSR hoping that would cancel both signals out.

UncleAfx
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Joined: 03/06/2016 - 20:08
It was more just an example

It was more just an example to show that the bp signal isnt a perfect inversion.

nitro27
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Joined: 10/11/2015 - 18:27
@UncleAfx I mean, it's not

@UncleAfx I mean, it's not going to be perfect, because it's inverting the signal AND actually being a bandpass filter. What in Modular synthesis is ever perfect, emulated or analog?

@paulovski you're totally right, that was redundant. Here's a song that features the probability drummer without the DADSR or the external voltage source, and uses panning to get two whole channels out of the Beatbox.

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I make Chillout Electronic Music, and sometimes Ambient. http://floatingbeyond.tk
https://soundcloud.com/floatingbeyond

paulovski
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Joined: 09/19/2012 - 06:13
And thank you very much

And thank you very much UncleAfx.

Those wacky mod inputs :)

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UncleAfx
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Joined: 03/06/2016 - 20:08
You're welcome. :-)

You're welcome. :-)
But now I'm confused with YOUR file. I don't see the difference between running straight out from the inv out jack into the variable filter vs running both outs into a mixer and combining them first. I'm sure there's a reason, I'm just not getting it.

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paulovski
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Joined: 09/19/2012 - 06:13
Before you trigger that

Before you trigger that envelope, it's output is zero. You trigger it, and it runs through it's attack stage, however long that is, up to 100%. And then the other stages. The inverted output value is 100% until you trigger it. Then it runs through it's attack stage down to zero. When one is at 75%, the other is at 25% and vice versa. When one is at 50%, so is the other. So, no matter what the front panel settings, as long as the two outputs are equally mixed, the sum of the two is always constant. 

So in that first setup you have there, the signal out of the mixer never changes.

UncleAfx
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Joined: 03/06/2016 - 20:08
Ah yes. I see now. Makes

Ah yes. I see now. Makes perfect sense Thanks for making that clear.

paulovski
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Joined: 09/19/2012 - 06:13
If you were to run cable out

If you were to run  cables out from that mixer into everything in a modsynth patch that will accept a control signal, you can change the lot with just that one mixer out level control. It's very useful ;)

twojima
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Joined: 02/26/2016 - 20:48
I was going to suggest

I was going to suggest another way to do this with a pcm synth with a bunch of empty samples + the arpeggiator in the modular section set to random, but that's going to use just as many instrument slots (maybe less processing though?) the biggest advantage to doing it is that you can choose the probability of a sample triggering from 1/1 to 1/88 by the number of keys held in the pattern. Am I making sense? Am I missing the point?

 

for a partially related example, here is my crappy amen break randomizer 1.0

 

EDIT: shit, nevermind. did you see the thread below this one?

 

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