…life under hylaster

Here’s one project I’ve managed to complete this semester. For a while I have wanted a tactile controller for my analog setup. As much as I enjoy letting the machine play itself, there are certain situations where it is preferable to have the instrument “shut up” when I’m not touching it (as David Wessel would put it.) This kind of control has been notably absent in situations where I am playing with acoustic musicians.

I was initially inspired by the touch capacitance controllers designed by Don Buchla for his modular synths. Here is one of two Buchla touch controllers we have at Mills:

I like how Buchla’s design doesn’t really have anything to do with a traditional keyboard - this seems logical given how new the electronic instrument paradigm was when Buchla built his first synth in 1964. Buchla’s synthesizers were designed to make experimental electronic music, or live “tape music” as it was called back then. But the Moog approach caught on commercially, and soon people associated synthesizers with piano style keyboards and electronic emulations of acoustic instruments.

Each touch plate is pressure (actually capacitance) sensitive and has adjustable control voltage (cv) range. There is also a sample and hold circuit to “remember” the most recent voltage. I wanted to make something similar, but quickly realized that with today’s sensor technology I could make something with the same functionality and a lot less trouble using force sensing resistors, or FSR’s. James Fei has a small box with FSR’s and I tested James’ controller to make sure this was what I wanted.

I wanted my controller to be compact and easy to play with one hand, with an ergonomic layout of the touch pads. I also wanted a linear potentiometer used in ribbon controllers to supplement the pressure sensors with a different kind of gestural control. I decided that each sensor should have an adjustable cv range like the Buchla, separate cv out, that the two larger touch pads and the ribbon would have individual trigger outputs for opening VCA’s and triggering envelopes, and that there would be a master trigger output. The circuitry is quite simple - 12v comes in, each sensor has a voltage divider to send the variable voltage out, and a LM339 comparator chip is used to process 5v trigger voltage outputs.

Here are some photos of the build process.

Filed by chuck j at 5:57 pm under handmade electronics, synthesizer, works-in-progress
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Filed by chuck j at 12:20 pm under handmade electronics, travel
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(appropriated image)

It’s time to catch up on some recent recordings. There hasn’t been much time since school started, but I’ve made it a personal goal to record a synth jam every couple of days.

I posted something similar a few months ago, but I think this one is a bit more refined: Here is a synthesizer pretending to be “Nature.” Noise -> Sample and Hold.

Here is feedback-generated rhythm. Notice how voltage fluctuations throw you off just as you are getting your dance move down.

This one’s namesake is some bad news I received about my car yesterday.

And here are some pieces that resulted from recent course work:

A soundwalk piece (for a seminar with Zeena Parkins.)

And a piece programmed and performed in Supercollider (for a Computer Music seminar with Chris Brown.) This one makes gratuitous use of an object based on Xenakis’ GENDY program that does “dynamic stochastic synthesis.”

“The lab” circa last week:

Filed by chuck j at 1:55 pm under handmade electronics, sounds, synthesizer, works-in-progress
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I’ve been flu-stricken and confined to my house for four days now. In that time I’ve watched two Yimou Zhang epics (Hero and House of Flying Daggers), some global warming docs (Inconvenient Truth and Who Killed the Electric Car), Mike Judge’s Idiocracy, A Scanner Darkly, caught up on recent episodes of House and Rome, and read a lot. I’ve consumed several gallons of hot and cold liquids and soup, blown my nose hundreds of times and coughed up some green stuff. Being too sick to leave my house is now officially getting old and I’m starting feel a bit like Howard Hughes. The early spring onset of carpenter ant activity in my kitchen isn’t helping. So before I slide into full-fledged boredom-fueled dementia and insect-OCD, I thought I’d document some of what has come out of this involuntary alone time.

Remember the Comparsa? I discovered a nifty new use for it: providing control voltage for my little modular synth. Turns out the Comparsa’s output is hot enough to be used as a controller, which isn’t surprising given that the 4093 chip peaks at 9 volts. So those rhythmic thumps and chirps heard in its direct audio output can act like a sequencer or FM source for an oscillator. The results are much more interesting than the direct output.

I was delirious with fever when I recorded these and don’t remember all the details for each track. But the basic setup was the Comparsa into various CV inputs on the modular, then a straight VCA output or ring mod output into a mixer. There was a noise swash (dark box with knobs to the left of the Comparsa in the photo above) in the aux loop of the mixer for adding a little fizz, so you might hear some of that as well:

cascading patterns and more chaotic, industrial-sounding patterns (both feature the Comparsa driving two cross-modded oscillators, I think)

fat bassline (Comparsa controlling a self-oscillating filter)

Filed by chuck j at 1:55 pm under handmade electronics, sounds, synthesizer, works-in-progress
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With five(!) grad school application deadlines behind me and the Rocaterrania film project on hold, the past few weeks have afforded me a little time for some projects that I have been putting off. So I thought I would try to document what I’ve been up to.

Hopefully the cute dog pic from March 4 softened you up for this, because unless you are interested in DIY electronic music, just intonation or audio programming software, this probably won’t be your thing. You have been warned…

So the projects I’ve been bumbling through are mostly open source in nature and fall roughly into three categories: 1- DIY hardware for electronic music (i.e. - standalone hardware instruments) 2 - experiments in the the media programming environment Max/MSP, and 3 - new hardware interfaces for controlling audio software (sort of combining categories 1 and 2, if you will.)

So, first up (from Category 1) we have a device that actually only took a few hours to put together after several days of experimentation and tweaking. I like to call it “Comparsa,” both in recognition of Carnival season as well as it’s endearing ability to make polyrhythmic thumps and chirps. This is what it looks like now:

And here are the incarnations it has gone through to get there:

…earliest breadboard version

… and the “temperamental” perfboard period.

Once I found the right configuration of parts in terms of component values and whether it sounded better to have certain components in series or parallel, it was just a matter of retrofitting some old stereo knobs, drilling holes in the box (recycled drill bit case) and slapping it all together.

Comparsa is a variation on a very simple circuit found in Nicolas Collins’ book Handmade Electronic Music. Two chips, four variable resistor pots, three capacitors, three switches, and a couple of diodes. Basically it’s a CMOS Quad NAND Gate Schmmitt Trigger (CD4093) chip oscillating and modulating itself followed a CMOS Binary Counter/Divider (CD4040) adding some more fun. When the main oscillator is tuned low enough to create a beat the following switchable stages chop it up and add new layers to create hypnotic little patterns.

Here is a sample that starts with an audio-range drone with some frequency modulation from a second stage in the inverter chip and amplitude modulation (tremolo) caused by the binary divider chip (like a VERY low octave effect - in this case so low it that acts as an LFO modulator on the drone). Then the main oscillator is turned way down and we go through a series of rhythmic patterns. Cute, isn’t it?

I highly recommend Collins’ book. I’ve been reading it for months and have played around with some of the projects, but this is the first one I liked enough to actually put in a case. His circuit designs are easy and can be pretty quick if you have some basic soldering skills and don’t try to re-invent the wheel. It’s also a good introduction to circuit bending and hardware hacking if that’s more your style.

These guys have some similar circuit designs (note that they are “copyleft”) although they seem to favor 555 chips. They are also big proponents of the open source Arduino platform for using sensor interfaces to control noises from a computer (and other physical computing uses). I’ve been experimenting with an Arduino lately as well, and I’ll show you the results soon….

Filed by chuck j at 2:10 pm under handmade electronics, sounds, synthesizer, works-in-progress
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