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Iron Ether Pithoprakta - probabilistic gate/trig sequencer
MUFF WIGGLER Forum Index -> Eurorack Modules Goto page 1, 2, 3, 4, 5  Next [all]
Author Iron Ether Pithoprakta - probabilistic gate/trig sequencer
Taylor
Update April 2019 and onward: 25% off discount on the Pithoprakta to all Wigglers! Just email me at info at ironether dot com to receive the discount.

Update Mar. 17 2016: the Pithoprakta is now available. Visit http://ironether.com/modules/pithoprakta/ for more.












Original post follows:
Hey everybody. I've been reading and occasionally posting on this forum for a few years, but today I want to introduce myself properly and show you a module I've been working on for a while now.

My name is Taylor Livingston, and for the last five years I've been making some unusual effects pedals at Iron Ether. I started putting together a Euro case in 2012, got into composing using nothing but Eurorack, and have been working on ideas for modules ever since. It would have been easier to just port the effects I make over to Eurorack, but I was more interested in creating something truly in the spirit of modular, so the first Iron Ether module is a rhythm sequencer called Pithoprakta, a Greek word coined by Iannis Xenakis to mean "actions through probability." The firmware is written by Michael Barton.



Pithoprakta is a probabilistic gate/trigger sequencer, able to create 8 channels of gates or triggers whose probability/density can be defined by the panel controls and/or CVs. The looping function will loop up to 64 steps, the loop length being CV-controllable in powers of 2, and an external gate signal can be used to enter/exit looping seamlessly.

The Probabilities of Channel 1 and 8 are defined directly by the panels controls/respective CV inputs. The other 6 channels' probability levels are interpolated from these two values, so if channel 1 is at 10% and channel 8 is at 80%, channel 2 is 20%, channel 3 is 30%, etc. The thinking behind this is that it allows you to have 8 channels with different probability, or the same if you choose, which can be controlled by just two modulators, rather than requiring a separate modulator for each channel - good for smaller systems or if you just don't want to tie up a ton of modulation sources just to control this one module.

Div mode clocks the 8 outputs, each with a different division of the input clock - divide-by-two down to divide-by-sixteen. The upper 4 channel outputs are "on beats" and the lower 4 channels are "off beats," allowing the user to easily create drummer-like rhythms which evolve over time or improvise infinitely.

Once loop mode is active, the Probability controls become "probability of change," in other words they control the likelihood that a given step of the loop will be overwritten, rather than whether that step is on or off. To keep from deleting the loop as soon as one enters looping mode, the probability controls are ignored when entering loop mode until the user turns them down to 0% and back up.

Ideas for usage
    Create rhythms that sound like an improvising human drummer, without resorting to preset sequences. Beats can evolve over time in a way you control.
    In div mode and with looping off, it functions as a clock divider, with probabilistic skipping.
    8 channels of random triggers or gates with CV-controllable density - clock it fast and try using them to gate WMD Digital VCAs for low-level granular synthesis.
    Record two gate sequences from another module into Pithoprakta by sending them into the probability CV inputs. You'll get six new sequences from outputs 2-7, each resembling the "parent" rhythms to a varying degree.
    Use it as an evolutionary algorithm that's very open and low level - with 8 outputs and 6 inputs, everything is exposed so it can work well in more experimental use cases.
    Mult the gate outputs to a CV mixer, to generate up to 64 step CV sequences with direct control of the probability of change over time.
    Can be clocked up to 1000 Hz, so it works as an 8 channel audio source, with various flavors of digital noise and octave generation, morphable with CV.


Physical details/specs
    16 HP
    Full size attenuators for all three CV inputs
    Potentiometers are metal shaft, bolted to panel, 100,000 cycle life
    Very skiffable due to single-PCB parallel construction
    Reverse polarity power protection, full over/under voltage protection on all CV/gate inputs
    Jumper selection for internal/external 5v
    Header for the 8 outputs allows for future expander connection


I made a demo video to show a bit of what it can do. This video doesn't show any CV inputs being used, so I'm just creating and shaping rhythms in real time using the front panel interface. There's a lot more that it can do, but I think this shows the basic concept enough to give your imaginations something to grab onto until more demos are made.

The sound source is an Alesis DM8 drum module, because I don't have enough modules to create 8 fully modular percussion voices simultaneously. The triggers coming from Pithoprakta are sent to a Ladik Trigger to MIDI converter module and the MIDI signal is connected to the DM8. All rhythms and events come from Pithoprakta, not the drum module.



Please note that the module in this video is a prototype with a handmade panel. The final version of the module will have a Metalphoto panel and some details of the interface and build will change. If some people are interested in engraved and airbrush-painted panels, in the style of the IE pedals, I can certainly do that, including transparent gradients, candies, sparkles, but I know most Euro users seem to prefer the greyscale look, so I was planning to stick with Metalphoto unless I hear a lot of interest in the more artistic looks. I can still do the latter in short runs as that's what my business is set up around already.

Normally, I would prefer to only show something when it's done and ready to start shipping. But, since this is IE's first Eurorack module, I wanted to get your feedback before finalizing the design. Please let me know what you think. I'm sure you'll all have some ideas that I hadn't thought of.
meatbeatz
yeaah! Following...

Also FrantaBit in Euro would be killa! Awesome sounding unit!
oscillateur
That looks quite interesting. screaming goo yo

Just one thing: the loop input is labelled Gate, it would probably be useful to have the option to use triggers to toggle it on and off instead of a gate...
z3r01
I like the idea of the module, and the demo was pretty damn cool. thumbs up
adnauseam
Seems really awesome.

I'd volunteer to be a tester but I'm in Canada. I'm sure the shipping wouldn't be Atrocious hihi

Although you about emulating a drummer I'm sure there's lots to be had in terms of SnH and more. I love triggers for melody generation.

Anyways. Cool to see someone doing something new! Keep going
Taylor
meatbeatz wrote:
yeaah! Following...

Also FrantaBit in Euro would be killa! Awesome sounding unit!


Hmm, OK, I'm certainly open to it. I figured that there were already a fair few bit/sample rate reducer modules in Eurorack, and that a new one would likely be met with a bit of a yawn from the Euro community. Maybe I was wrong though? I do have a few ideas for what it could do that would differentiate it (stereo, with special ways to control both channels simultaneously but differently).

oscillateur wrote:
That looks quite interesting. screaming goo yo

Just one thing: the loop input is labelled Gate, it would probably be useful to have the option to use triggers to toggle it on and off instead of a gate...


Yeah, I can see that being useful. Right now there's no extra hardware available that could be used to select that change, but potentially something like holding down the reset button while powering it up, could change it like a system setting. I don't want to lose the gate ability though, because I see that as being a bit more useful, e.g. sending an envelope or LFO, or output of an envelope follower, would loop while that signal is above a threshold.

You could always turn your two triggers into a single gate with a flip flop or regular gate divider, but it would be harder in most people's systems to go the other direction - you'd need a clock multiplier that doesn't average over time, but just turns both rising and falling edges into rising pulses. Don't know if there's a module that works like that. But this is good feedback and I'll think about how it could be implemented.

z3r01 wrote:
I like the idea of the module, and the demo was pretty damn cool. thumbs up


Thank you, I appreciate it. And this finally gives me an opportunity to tell you how delightfully unsettling your avatar is! I mean that in a good way - my favorite director is David Lynch, so I enjoy being made a bit uncomfortable if it's for, uh, art reasons. lol

adnauseam wrote:
Seems really awesome.

I'd volunteer to be a tester but I'm in Canada. I'm sure the shipping wouldn't be Atrocious hihi

Although you about emulating a drummer I'm sure there's lots to be had in terms of SnH and more. I love triggers for melody generation.

Anyways. Cool to see someone doing something new! Keep going


Oh definitely, in fact the next video I make will use it as a melodic sequencer.

You're right about the shipping to Canada, so you can disregard what I said about US only. Anybody from any country, feel free to message me about being a tester.
shuchoco
very cool!
scottmoon
Hey Taylor, that sounds awesome. More like a real drummer might play than some of the other sequencing options I've heard.
Taylor
Glad you like it, Scott! I've been obsessed with drumming and drum-oriented music for a long time, and I'm really eager to see what people will do with it with, e.g. trigger delays on different outputs to get all kinds of unique feel happening.

I just made this demo to show off a very different side of Pithoprakta: audio, specifically clocked digital noise.

The audio is taken directly from outputs 1 and 8 and mixed together. An audio rate oscillator is sent to Pithoprakta's clock input, and a 4MS PEG is used to modulate the Loop Length CV, which is what's creating the initial "pitch sequences." The other channel of the PEG is occasionally used to modulate Probability 1, very slowly. Some of these sounds remind me of those "symphonies from one line of code" (was a name ever created to describe this technique?). I guess this should not be surprising given that it's all about self-modulation by binary signals.

At one point, one of the outputs of the Pithoprakta is connected to its own reset input, creating some surprisingly tonal notes, in between the glitchy noise. I actually don't understand why, but to my ears, notes of a minor triad start to appear. Given that the loop length is quantized in powers of 2 only, that method of modulation can only make octave changes. Where are the third and fifth coming from? Hmm...

[soundcloud url="https://api.soundcloud.com/tracks/222557725" params="auto_play=false&hide_related=false&show_comments=true&show_use r=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /]

Since all 8 outputs are doing (at least slightly) different things at all times, try using them as audio sources to build a few different percussion sounds. Sequence the audio rate clock to transpose the pitched noise. Modulate Loop Length to get CV-controlled octave jumps.
z3r01
Taylor wrote:

z3r01 wrote:
I like the idea of the module, and the demo was pretty damn cool. thumbs up


Thank you, I appreciate it. And this finally gives me an opportunity to tell you how delightfully unsettling your avatar is! I mean that in a good way - my favorite director is David Lynch, so I enjoy being made a bit uncomfortable if it's for, uh, art reasons. lol


lol

Thanks for the compliment!

Quick question about the CV inputs, and corresponding knobs. Are they bipolar, or unipolar? Thanks! thumbs up
Taylor
They respond "natively" to 0v-5v, but since there's an offset and an attenuator for each parameter, you could plug a bipolar 10Vpp LFO in, set both the corresponding attenuator and offset to center, and your bipolar 10V signal would modulate the full range of the parameter properly.

To be clear, the offset and attenuation are done in analog, so you don't have to worry about only plugging unipolar signals in. Any normal Eurorack modulation signal can be attenuated/offset to be in the right range. The CV inputs can actually handle low audio rate signals (up to around 350 Hz), which probably wouldn't make any sense from a sequencing perspective but for experimental purposes or noise/audio generation, I'm sure somebody could think of something cool to do with that.

The attenuators are regular attenuators, not attenuverters. I'm actually not a fan of attenuverters because of the difficulty of setting them exactly to zero while playing, and because they halve the amount of rotational throw available for a given attenuation level. The best solution IMO would be CV inversion switches in combination with standard attenuators, but I felt they didn't add enough to justify the additional space in this instance.
sprout23
Cool module, I like the cv, switches, and multiple outs. Looks like fun to play with drums!!!
nangu
This is fantastic- I'm totally buying one!

I didn't notice this thread until just now- any news on when they'll be available?
acgenerator
This very much aligns to what I've been building towards rhythm-wise.
Taylor
It's coming along, and there's been a hardware redesign as well as a lot of tweaking on the software as a result of tester feedback. The current design looks like this:



I moved some things around to be more wiggle-friendly for the fingers, changed the loop switch to a pushbutton since I found I was using it a lot and wanted a part that can handle heavy usage, but the most significant addition is the CV output.

The CV out is derived by mixing together all the gate outputs with different "weights," to form a crude DAC. When the module is set to gate mode, this output looks like random stairstep-type voltage sequences, and it loops and changes in conjunction with whatever the gate outputs are doing. Send this into a quantizer for pitch sequences, or unquantized as a looping random modulation source.

When the module is outputting triggers, the CV output will send a sequence of triggers with varying amplitude levels, which can be useful for dynamically "pinging" LPGs/filters or for triggering certain drum modules which will change their sound according to trigger level, like the MFB modules.

The CV output is sort of a "freebie" feature. There was room for another jack and an unused opamp available. This output can't be programmed independently and its state is dependent on the gate lengths selected for the main outputs, so while you can definitely use the Pithoprakta for your melody and trigger generation simultaneously, this module is not meant to be a do-everything sequencer. Something I've found with my modular is that the most interesting modules are the ones with multiple types of input and output happening simultaneously. 4MS PEG was the first really striking example of this for me. So with the Pithoprakta, having trigger, gate, and CV inputs as well as trigger/gate and CV outputs going into/coming out of this central probability "core" makes it so much more open-ended to use in different patches.

The regular production run will probably be ready for sale in about 6 weeks. If you would like to get one sooner and don't mind an engraved, handmade panel as in the above photo, I can build those right now. Custom panel colors are even possible for an additional fee. Feel free to contact me at info [at] ironether [dot] com or PM me here if you have any questions.
moloque
applause Guinness ftw! love

Love my IE pedals. Too bad I had to sell some of them to get into modular. But Will get one for sure!!!!
elcoco
This module looks like so much fun, can't wait for it to be available.
Minimoog56
great job Taylor!
woodster
Brilliant !
It's great to see IE in Euro.
Will definitely be keen to get my hands on one of these.
DonKartofflo
i always knew IE would get into euro eventually applause applause
Paranormal Patroler
PMed ! Coulnd't help it, you had me at Pithoprakta as it happens to be one of my favorite pieces by Xenakis. hihi

PolarIceCaves
Taylor I'm loving the idea of playing with this guy. I own a Barton BMC027
Random rhythm, I wonder how similar they are?
Taylor
Thanks guys. I'm (pleasantly) surprised to find that a lot of Wigglers are familiar with Iron Ether pedals. I don't recognize all of your handles, but let me know if I'd know you by another name. Woodster, I think I know who you are. ;-)

PolarIceCaves wrote:
Taylor I'm loving the idea of playing with this guy. I own a Barton BMC027
Random rhythm, I wonder how similar they are?


Yeah, there is some overlap. I haven't used the BMC27 but looking at the PDF for it, here are some differences: Pithoprakta has 8 outputs vs 4, full CV control over everything, and the way the randomization works, I think it would be fair to say, is happening more real-time, whereas the Barton unit randomizes only when it's hit with triggers. Pithoprakta has this sort of "entropy" or loop overwrite thing, which allows for fine-grained control over how much the loop changes each time it repeats, rather than just having the choice to loop or completely re-randomize the sequence. Pithoprakta also has the whole down-beat/up-beat concept available which allows it to slot more readily into conventional rhythmic concepts instead of being pure randomness.

I don't think the Barton unit lets you set the probability/density of triggers in any way, so while it should work great for rhythmic sequences, it wouldn't work for the more experimental purposes like probabilistic burst generation or other things where the probability is modulated in real-time to create certain effects. I'm obviously a fan of Michael Barton's work and I've recommended his stuff to people on this forum a number of times before, so this shouldn't be taken as a negative comment at all - just trying to explain the differences in what they do and how they work. The BMC27 does have a bunch of trigger inputs for the randomization, which the Pithoprakta does not have, so they each have different approaches and capabilities.

I'm working on some new videos showing some other ways to use the module. Something really fun that popped out as a result of adding the CV output is that, when clocked at audio rates, it becomes a sort of "random 8-bit wavetable oscillator." Using the probability controls lets you generate random wavetables which can then be locked by entering loop mode. From here, the Loop Length CV becomes an octave-shift CV, with 6 octaves, but the waveform gets truncated and thus changes depending on which octave you've selected. I'll include oscilloscope shots to give some idea of what kind of waveforms it's producing.
hyena
whoah! this is great! it will pair perfectly with my zorlon mk2 smile
any vague idea of the pricing yet?
M6live
Redacted.
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