Source of Uncertainty

A study in synthesizing the sound of a room full of people clapping -- from "scratch" using: - A white noise generator - A resonant low-pass filter - Two envelope-driven, voltage-controlled amplifiers - A voltage-controlled panner - A random voltage generator

https://soundcloud.com/paperwwwork/white-noise-handclaps-study

I recently picked up the RxMx, a unique and inspiring mixer module by Make Noise. It's a six-channel mixer with a crossfader that sweeps across all six channels, but you can also change the "radius" of the crossfader to blend neighboring channels -- all the way from one to six at a time. Crucially, both the position and radius of the crossfader can be voltage-controlled, so channels can be scanned and mixed automatically using interesting voltage sources in the rest of the system.

This is a little study made using the Turing Machine Random Looping Sequencer to control the RxMx. I think the Turing Machine's mostly-repeating, gradually-shifting random patterns provide a particularly compelling modulation source for the RxMx.

First, here are the 6 channels being fed into the RxMx. The seventh sample here, some echoes and a kick drum, are an extra layer on top of the RxMx's mix.

https://soundcloud.com/paperwwwork/rxmx-turing-study-parts

Here's the study itself. You can hear how much dynamism & movement the automatic mixing of the RxMx adds:

https://soundcloud.com/paperwwwork/rxmx-turing-study-mix

First patch with the Wogglebug, a "random voltage generator" (and then some.)

A short sketch in rhythmic randomness.

https://soundcloud.com/paperwwwork/sketch-noisy-rhythms

Randomness in this patch is generated by "Noisecore," a program written by Karl Gruenewald for the Ardcore re-programmable module. Noisecore emulates another module designed by Grant Richter called the "Noisering," which itself is inspired by a classic module by Don Buchla called the "Source of Uncertainty." All these devices share a certain approach to creating more "musical" randomness than just a raw noise source or other random number generator.

This Sunday, I'm starting a new weekly broadcast series on NUMBERS.FM, the internet radio station my friend jonCates & I operate. The series, called "Patchwork," is meant to be a sort of live, public sketchbook. I'll be experimenting with my modular synthesizer setup without attachment to any specific results -- just exploring process & possibilities.

Here are two recordings from a couple weeks ago that I’ve been meaning to upload. I’ve been really enjoying the 4ms “Quad Clock Distributor” module. It’s four clock streams (a series of regular trigger signals to generate notes or otherwise trigger events elsewhere in the system), which can all be based on a single clock so they’re all basically in time. But what makes it interesting is that these four independent rates can be dialed in as a division or multiple of the root clock rate, so one is at 1/3rd speed, one at 4x speed, etc. Additionally, each clock’s rate division can be controlled externally, but they’re always locked to some interesting division of the root speed.

https://soundcloud.com/paperwwwork/sketch-clock-feedback

In this sketch I have one of the clocks triggering a sequencer, causing it to advance to the next note. Then, in addition to setting the note for a tone generator, the output of the sequencer affects its own clock’s division. So there’s a feedback loop, where the clock advances the sequencer and then the sequencer causes the clock to change the speed at which it triggers the next advance. I added an attenuator between the sequencer and the clock, so I can dial in how much feedback is happening, and riding that control makes up the shape of this sketch.

https://soundcloud.com/paperwwwork/sketch-two-sequencers

My modular synth experiments lately have been focused on sound design: trying to create interesting sonic timbres and shapes, instead of full songs, etc. In response to the really strange and synthetic character of the most recent oscillator I've added to the machine -- the Malekko/Richter Anti-Oscillator -- I've also been focusing on sounds that don't have any straightforward analog in acoustic instruments. So, more clicks and cuts than hand claps and hi-hats :)

This sketch was made by aggressively filtering and modulating two simple bass lines. There was also a white noise generator being cut very sharply to create a click sound (I used a short gate signal instead of a proper audio envelope to modulate the noise's volume). One of the filters I used here is vactrol-based, which gives it a sort of slow, natural character when closing. That's the one responsible for what sounds like a kick/bass sound. Really enjoying that kind of natural decay among all these super synthetic sounds.

I've been experimenting with a couple new modules: the Toppobrillo Quantimator and the Malekko Anti-Oscillator. Quantimator is a quantizer: it takes in a CV signal and snaps it to the nearest real note value, optionally limiting those notes to a particular scale. It has some other cool features to drive multiple oscillators playing different pitches generated from a single note. The Anti-Oscillator is an oscillator with some pretty gnarly built-in distortion that can be modulated. In this sketch, I was taking the output of a sequencer and passing it through a slew limiter before it went into the quantizer. The slew limiter makes changes gradual instead of snapping to new note values, so you can hear this kind of melodic "staircase" effect as the quantizer snaps the incoming signal to each of the notes in between the old note and the new one.

Not much to say about this sketch. I'm still exploring sequencing intuitively with interactions between the  Rotating Clock Divider module and my "Rotating Pattern Emitter" Ardcore program. Also playing with some ideas for percussion synthesis. I have a pretty limited palette for tone generation right now (one oscillator and a multi-colored noise generator, and two filters). This sketch started out with me trying (and failing) to synthesize a handclap sound!

Too hot to do any work of substance this afternoon, so I've been sweating over the modular, experimenting with a few small patches to explore the Echophon pitch-shifting delay module. This is a three-track sketch I came up with, made up of three different Echophon-centric patches.

I made a cheesy synth melody in the Figure app on the iPhone & then pitched it down into a murky loop using the Echophon's "freeze" function. The second track is a crackly "no-input" patch: the module's input is its own "feedback out" signal. The third track is the first two tracks being run back through the Echophon, but also with a squelchy resonant filter inserted in the feedback loop to get that distortion that comes in near the end of the recording.

I built a new version of the "rotating pattern emitter" Ardcore sketch described in my last post. The previous version output two separate channels of 4-step trigger patterns. This version can be dialed to output patterns in 3,4,5,6 or 8 steps. This is quite a few more patterns to select with the Ardcore's analog knob, so I split it between the two channels. Channel one does patterns in 4 or 8 steps and channel 2 does 3, 5 or 6. I split it up like this because as a matter of personal taste I'm nearly always trying to have different elements of a patch running in different time signatures.

This is a two-track recording, made in two passes on my tape recorder. You can hear the Make Noise "Echophon" module (a super cool pitch-shifting echo module) being used in two different ways here. On one track it's synced to the beat and behaving as a pretty standard echo effect. Being able to easily sync to divisions/multiplications of an external clock is one of my favorite features of the Echophon! On the other track, I didn't sync to the clock but instead set a very short delay with quite a lot of feedback, shifted the pitch a bit and then ran a tone through it. So it came out as this sort of pleasant harmonic drone sound you can hear in the track.

https://soundcloud.com/paperwwwork/sketch-echophon-drone-ft

Here's the code for the Ardcore sketch:

I built my first sketch for the Ardcore module, which I'm calling a "rotating pattern emitter." The Ardcore module is an Arduino built into Eurorack format with a USB port for easy re-programming, two analog inputs, one digital input, four knobs, one analog output, and two digital outputs. Two of the knobs are forced to operate as attenuators for the analog inputs if a cable is plugged in, but can operate as parametric dials if you're not processing any input.

The Ardcore, as a re-programmable module, is extremely flexible, but its potential is restricted by its inputs/outputs/knobs, particularly in the Eurorack version (Ardcore is also available in another format with an optional expander that adds more inputs/outputs). It seems to me best suited for generative applications rather than signal processing, since when you pass in a signal via the analog inputs two of the knobs automatically become attenuators and you can't access their values from code, leaving you with only 2 knobs to work with. But the Ardcore is most powerful when it comes to generating clocks & control voltage. Computer programming languages are extremely good at playing with math & numbers -- in fact, they're specialized to precisely this task!

This sketch takes in a clock and then spits out a pre-programmed sequence of triggers based on a pattern like "off, on, off, off." It's inspired by an unreleased module I saw a video demo for but can't find now (dammit!). The basic idea is: there are actually very few patterns that can be expressed in a sequence of off/on steps (ie classical "step sequencer" patterns), if you take "rotation" into account. So something like "on, off, off, off" is the same pattern as "off, on, off, off," just rotated one degree to the right. This sketch stores all possible unrotated 4-beat patterns, takes in a clock, and emits two channels of pattern sequences with independent pattern selection and rotation via the four knobs (two per channel).

In this recording, I'm also using the 4ms "Rotating Clock Divider" to play around with odd rhythmic divisions.

https://soundcloud.com/paperwwwork/sketch-rotating-pattern

Still trying to find a good process for experimentally & playfully sequencing rhythms on the modular system, this evening I tried combining a clock multiplier sketch running on the Ardcore with the Rotating Clock Divider. The clock multiplier takes in a clock and then sends out two independent clock streams at some multiple of the input (twice as fast, three times as fast, etc). Most of what's identifiable as rhythmic in this recording is actually in a pretty tame ratio: the "hi-hat" sound is at 2x the speed of the kick drum, some filter sweeps are running at 1/3 and 1/6, and then a pitch-shifting echo is set to some other division I don't remember. So, many more interesting rhythmic combinations left to play with there!

I also tried out something I've had in mind for a while: recording the kick drum on its own track (I'm recording on a dusty old 4-track tape recorder) and then using that signal out the recorder's effects send, back into the modular in subsequent passes to clock the whole system (via a Doepfer external input module that sends out a trigger whenever the input passes a certain threshold). It seemed to work pretty well, if a bit sloppy when first starting up.

This is the 4ms Quad Pingable LFO. This module has four LFOs that don't have knobs or CV control over their frequency, but instead take in clock signals to set their rate. It sounds very powerful, especially for the kind of rhythm-centric music I want to work on, but so far I hadn't found it especially compelling or useful. So, this evening I set out to focus on this module specifically and try to probe it a bit deeper. It definitely demands extra consideration -- I'm already finding more to do with it!

I also wanted to explore using some of the low-frequency / control modules in the system closer to audio rate, and see what shook out. In this sketch, I was clocking everything with this simple Doepfer A-145 LFO, which happens to have a switch that shifts it between low/medium/high frequency ranges -- it goes from "one cycle every several minutes" in the "low" setting up to 5khz in the "high" setting. The Doepfer LFO is driving the 4ms Rotating Clock Divider, which is then sending out clock signals on a four different divisions to the QPLFO. Those LFO outputs are summed in a 4 channel mixer and then that mix is fed into the oscillator's frequency modulation input.

There are some filters and other nonsense in there, too :)

This afternoon, I dug into the Ardcore module for the first time. Ardcore is an Arduino built into a Eurorack module, with a USB port on the front to easily upload new sketches or do serial communication. It comes with a few dozen Arduino programs designed mostly for control voltage processing/generating.

In this case, I used a note-quantizing program to quantize the output of the Pittsburgh Modular Sequencer into a sequence of tuned notes. These notes are driving the Malekko/Richter Oscillator II to  make a short, looping bassline, which is then being fed into a really squelchy filter (the Blue Lantern LM4250). That filter is also being frequency-modulated with an envelope generator at twice the rate of the note sequence.

I'm planning to modify this quantizer into a program that lets me dial into a specific musical scale, and then quantizes to that set of notes. I think that'd make experimentally dialing up interesting melodies with the PM sequencer a lot faster.

I used a 4ms Rotating Clock Divider to get a set of rhythmic divisions from a simple LFO acting as a clock source. Totally loving the RCD, and I've just scratched its surface so far. I hope to pick up its counterpart, the Shuffling Clock Multiplier, at some point. Playing with rhythmic ratios is a lot more fun and exploratory than programming in arbitrary sequences & patterns.