HetrickCV Announcements Thread

trickyflemming · August 1, 2023, 4:23pm

To get everyone started, I just posted 4 tutorials for phase-based sequencing:

mhetrick/hetrickcv/blob/master/docs/Topics/Phasors.md

# Phasors
A "phasor" in DSP terms is a rising, linear ramp wave that moves from a value of 0.0 to 1.0. They are enormously useful, and are used for almost all time-based, cyclical behaviors. For example, phasors are used for most oscillator algorithms, and they are also used a sample accurate timers.

What does that mean for VCV, though, and why are they useful? Two clear functions are **Phase-based sequencing** and **Phase Distortion Synthesis**.

### First, some credits:

Thank you immensely to Graham Wakefield and Gregory Taylor. Their remarkable book [Generating Sound and Organizing Time](https://cycling74.com/books/go) made up the bulk of the research and design ideas that went into this set of modules. Graham was a graduate student at UCSB's Medaia Arts and Technology department as the same time as me, and has long been a source of inspiration. Additionally, I would like to thank Claes and the Bitwig team for the Grid, and David Alexander for the [Toybox Nano series](https://www.toyboxaudio.com/pages/nano-pack), a powerful collection of Reaktor modules that really put phase-based sequencing onto my radar.

## Phase Based Sequencing

**Phase-based sequencing** is a fairly old concept in modular synthesis, with one of the earliest examples being the "Analog Stage Select" input on the Buchla 245. Phase-based sequencing has been increasingly more popular lately, with modern software examples including the Bitwig Grid, Toybox Audio's Nano Pack for Reaktor 6, K-Devices' ESQ sequencer, and the Max 8.3 update (which included a large number of sample-accurate phase generators and modifiers). In hardware, phasor-based sequencing concepts are used in exciting ways in Mutable Instruments' classic Marbles, or ioLabs' FLUX.

That's great, but what is it?!

If you are reading this document, then you are likely familiar with how most sequencers work in modular synthesis: the sequencer receives a gate or trigger, and that gate or trigger advances the sequencer by one step.

Phase-based sequencing takes a different approach: a control voltage is used to select the active stage of the sequencer. For advancing forward through a sequence, an ascending ramp is used. For a backwards sequence, a descending ramp is used.

This simple difference provides significantly more information to a sequencer. With only two samples of an incoming phasor, a sequencer is able to calculate the frequency/BPM of a sequence, along with the direction that the sequencer should be heading. With only one sample, the sequencer is able to look up the exact step that it should be on along with the exact phase of the step (i.e. how "far" through the step we are). What this means in practice is that you can have a number of sequencers all responding to a leader phasor in lockstep: all BPM changes, directional changes, and any other shifts occur instantly without artifacts since the sequencers do not need to calculate timing between pulses.

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I hope that this is a helpful guide for this exciting technique!

auretvh · August 1, 2023, 6:03pm

Thank you so much all for the work you have put into these tutorials, I finally understand phase based sequencing . And of course, your modules are incredible!!!

Funky40 · August 2, 2023, 12:26am

VERY much appreciated ! Thank you !

FiroLFO · August 2, 2023, 6:55am

Excellent modules! And the manual is a great help to experiment with any sequencers based on the same principles!

m9dfukc · August 2, 2023, 2:58pm

This is so cool! On a side note, Philip Meyer just introduced a phasor based sequencing toolkit for Max/Msp called Rhythm and Time Toolkit.

Nice to see that this concept now also gets traction in VCV Rack thanks to your tireless effort

trickyflemming · August 2, 2023, 3:00pm

Yeah, it’s so good! I forgot to cite him and Polarity in the tutorial, so I’ve put that in now. I’m going to push two more tutorials in a moment. I’m wrapping up Tutorial 6: Navigating Rhythmic Space.

trickyflemming · August 2, 2023, 3:37pm

Tutorials 5 and 6 are now up! I’m very proud of these and can hopefully find time to write more. I started work on a Phasor Burst Generator last night, so I’m going to get back to finishing that one up.

github.com

mhetrick/hetrickcv/blob/master/docs/Topics/PhasorTutorials/6-NavigatingRhythmicSpace.md

# Phase-Based Sequencing Tutorial 6 - Navigating Rhythmic Space

I can't help it: I'm a drummer. We're back to rhythm sequencing, but from a different viewpoint. We're going to look at [Phasor to Euclidean](../../Modules/PhasorEuclidean.md) and [Phasor Rhythm Group](../../Modules/PhasorRhythmGroup.md), two modules for quickly turning phasors into rhythmic sequences.

## Euclidean! Euclidean! Euclidean!
Electronic musicians love Euclidean Rhythms. They're everywhere these days. I won't dive into the theory here, but if you aren't familiar with them I recommend looking at the [Wikipedia Page](https://en.wikipedia.org/wiki/Euclidean_rhythm). The quick summary is that it's a way to generate many of the world's most used rhythms by using three numbers: Steps (N), Fill (K), and Rotation (R). 

(Side note for the fellow nerds: Rotation can be done by phase shifting the input phasor, but the Rotation control inside of this module is quantized to Steps and can additionally by time-quantized to change only on the generation of a new step).

To save space on this tutorial, I'm going to use the [VCV Drums](https://vcvrack.com/Drums) modules. If you would like a free alternative, check out [Tutorial 4](./4-PolymeterPolyrhythm.md) for recommendations. 

To get started, add a VCV LFO, a Phasor to Euclidean module, and a kick and hi-hat of your choice:

![EuclidBasic](./EuclidBasic.png)

Wire the Euclidean Gate output to the Kick drum, and the Clock output to the Hi-hat. Set the Euclidean Steps to 16, and the Fill to 4. You should hear a common four-on-the-floor pattern with sixteenth-note hi-hats and quarter-note kicks. If you set Fill to 8, the kicks will happen twice as frequently, Fill 2 gives kicks half as frequently, Fill 0 gives you no kicks, and Fill 16 gives you a kick for every hat. In between all of those Fill values are a bunch of great rhythms. Try Fill 7 for a great rhythm where you get four kicks grouped together, a pause, and then three kicks grouped together.

Now that we have a nice kick + hat pattern, we need to add a snare as a backbone. Add another Phasor to Euclidean module along with a snare drum of your choice.

![EuclidSnare](./EuclidSnare.png)

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EDIT: Whoops! Forgot to add the envelope topic to Tutorial 5. It has just been re-uploaded.

branadooks · August 4, 2023, 6:11pm

These are great! I think these are becoming my favorite sequencers in Rack.

I’m going through the tutorials (thanks for these) and the Phasor->Waveforms is crashing Rack. See: Phasor->Waveforms crash · Issue #29 · mhetrick/hetrickcv · GitHub

I see now that he’s responded already to my report on github. So, a heads up to anyone else, who may be experiencing this.

trickyflemming · August 4, 2023, 8:09pm

Thanks for the report. I think this is fixed with the latest commit, but I wasn’t previously having crashes on my end. Can you test the latest automated build in a few minutes when it’s ready?

trickyflemming · August 4, 2023, 8:20pm

Just pushed another commit. While investigating this I noticed that the sine and triangle were out-of-phase from each other. Trigonometry strikes again!

branadooks · August 4, 2023, 8:58pm

Perfect! Works great! Thanks.

Rodney · August 5, 2023, 2:15am

In tutorial 4 " Poly What" are the definitions of polymeter and polyrythm switched?

trickyflemming · August 5, 2023, 2:47pm

The definitions are correct, but they are confusing for a number of reasons.

I should use more exact language, as I wrote the tutorials pretty quickly. Putting “clock speed” in the definition for Polymeter is bad, since a) that depends on modular sequencer familiarity instead of music terms, and b) clock speed is different from phasor speed, especially within these two definitions. I’ll clean that up when I get a chance.
Almost every sequencer manufacturer gets it wrong. The Squarp Pyramid is the only hardware sequencer I’ve ever used that explicitly defines a polymeter vs. polyrhythm setting. Other than that, there’s just a lot of bad repetition in telling users that what they’re doing is “polyrhythm” when they’re changing sequence lengths.
Honestly… if you’re a big time music pedant a lot of it can be arbitrary You could take the Steve Reich example in polychronics and just say “No, no, that’s not two tempi, that’s just a really, really big polyrhythm”. You could take a polymeter where you have overlapping 3/4 and 4/4 and say “No, no, that’s not polymeter, that’s just 12/4 with different notation” etc. A lot of it is just how you look at it or listen to it.

trickyflemming · August 5, 2023, 2:50pm

As a heads up, once 2.3.0 is released on the Library, I would recommend against using my Phasor Generator until 2.3.1 is released. I set up the frequency knob in a way that doesn’t save/load correctly if you’re using the Fast frequency mode. I will try to push a fix soon, although I have a ton of family visiting this weekend. 2.3.1 also has a Phasor Burst Generator which you can use for 1-shot phasors, repeating phasors, toggled cycling, etc. Overall, it’s a better-designed module than the regular Phasor Generator.

Squinky · August 5, 2023, 5:28pm

I don’t see any of these phasor module in my VCV. Is this one of those infuriating cases where I need to delete my HetrickCV folder and re-download everything again? Where is if that you “subscribe” to a plugin? I can never find that…

Curious to see if the new “waveforms” has Alias suppression

pachde · August 5, 2023, 5:32pm

VCV Library - Plugins (vcvrack.com)

Squinky · August 5, 2023, 5:36pm

Tx! I am subscribed. The phasor modules should in the library, right?

cthonophonic · August 5, 2023, 5:45pm

I think the 2.3.0 changes have been submitted but not yet published in the library, so you still need to grab the nightly build. I’ve never needed to delete the existing folder in the plugins directory to use a beta. Just putting the binary in the plugins directory and restarting Rack seems to be enough.

trickyflemming · August 5, 2023, 6:01pm

github.com

mhetrick/hetrickcv/blob/master/docs/Modules/PhasorToWaveforms.md

![Module](../Images/Modules/PhasorToWaveforms.png)

# Phasor to Waveforms

This module takes in a phasor signal and outputs traditional LFO waveforms. This can be used primarily to generate modulation signals. Additionally, it can be used at audio-rates for Phase Distortion Synthesis, but be aware that the waveforms are not anti-aliased in any way.

The left set of outputs are unipolar, while the right set is bipolar. 

One thing worth noting is that the Unipolar Saw output is almost always going to be identical to the input as long as the input is within the proper unipolar range. However, there is a protective phase wrapper at the input, so you could try unusual things here like placing a mixer before the phasor input and mixing together multiple signals to get unpredictable phase wraps.

“This module takes in a phasor signal and outputs traditional LFO waveforms. This can be used primarily to generate modulation signals. Additionally, it can be used at audio-rates for Phase Distortion Synthesis, but be aware that the waveforms are not anti-aliased in any way.”

I’m planning on writing one eventually using the mip-map antialias technique described by Wakefield & Taylor, but it’s very low priority. Everything in this set was made because I’m building a sequencer for the Unfiltered Audio drum synth and needed a large library of sample-accurate sequencing code.

pachde · August 5, 2023, 6:03pm

FYI you can check the release status of plugins that have been submitted on the projects page of the library: VCV Rack Open-source Plugins (github.com)

Just now (2023-08-05 11:00am Pacific)) I see that this plugin is in the build update category, which means that it’s passed all validations and just waiting for the next library publishing cycle.