Regarding the Last 3 Posts

The last 3 posts were chapters from my PhD qualifying exam at UCSD, which I wrote over the course of 12 days (to the hour!) from Dec 12th to Dec 24th, 2013. It's a document I had to write so that I could start working on my dissertation. The stuff I wrote may make it into a publication or two, but in the meantime I thought it'd be nice to share it on the internet. In case my server doesn't display the equations right, you can grab the print version here. I recommend reading it in bed, as a cure for insomnia. 😉 Enjoy!

Remote and Coupled Vibration Measurement Methods

"Imaging small vibrations have been of interest since Chladni first placed sand on a vibrating plate to make modal patterns visible. Discuss methods that have since been developed to remote sense and optically image sub-micrometer vibrations (e.g. laser Doppler vibrometry, holographic interferometry, electronic speckle pattern interferometry, etc.) including your own method currently being developed. Discuss the pros and cons of each method, and how your own method capitalizes on the strengths---or attempts to overcome any limitations---of its predecessors in the context of your particular application requirement(s)."

-Tamara Smyth

Continue reading

Laser Triangulation Microphones

I've completed two laser microphone components that use the triangulation technique in conjunction with a high-bandwidth photodiode. These can be used to pick up vibrations remotely on any reasonably reflective surface. A production run of 12 is almost complete. Click through for pictures!
Continue reading

Photodiode Amplifier Design for Optical Vibrometry

The central goal of this project is to design a geometric optical vibrometer array. This device will be capable of measuring transverse waves across a wide band of frequencies, without mass-loading the object. The design parameters to be minimized include cost, power consumption, and noise floor. The parameters to be maximized include signal gain, bandwidth, and versatility. The device is intended to be suitable for both researchers and artists interested in mechanical vibrations.

Continue reading

ADC Pre-Amp Stages

in a previous post, i mentioned that the adc's on the cortex m4f microprocessor were unipolar, and i included a link to a simple op-amp circuit that could provide the appropriate voltage shift and scale operation. yesterday, i went from designing a layout to fabricating 9 boards in 24 hours. actually, i made 11 boards, but lost two in the process, because of issues relating to old pcb stock. in the future, i might design two layouts for each board, with the alternate layout applying wider tolerances, to account for older pcb stock. i used a positive photofabrication method for applying resist to the boards, which in my experience provides the sharpest lines. i used eagle cad to design the layouts, and gimp to beautify them. as per usual, the values for the components are etched right into the copper, so no silkscreen layer was necessary.

Continue reading

A Linux-Based Open Source Toolchain for the STM32F4

ST Microelectronics has released the STM32F4 "Discovery" evaluation board for the M4f Cortex ARM processor chip. In addition to the M4f ARM microprocessor, itself a pretty awesome tool boasting 32bit floating point precision and a vast array of assignable I/O capabilities, the STM32F4 is loaded with tons of sensors, USB hosting capabilities, and even a fully accessible ST-Link V2 programmer, which allows the user to program other M4f microprocessors. Check out this great demo / explanation here.

Continue reading

Hrokk On

i have been working on a new instrument design, conceived of during a few conversations with berglind tomasdottir. it's called a "hrokkur," which is a play on words in icelandic, a blend between the words "rokkur," meaning spinning-wheel, and "hrokk," meaning rock ('n roll). the instrument is very similar to a hurdy-gurdy, which is a medieval stringed instrument that makes sound with a circular bow. i designed the instrument using readily-available, frequently recycled materials-- mainly a guitar and a bike.

Continue reading

This Is Not Art: Australia, 2011

this fall, i was privileged with the opportunity to participate in two arts festivals in newcastle, australia. these festivals were "electrofringe," whose focus was on the practice of electronic arts, and "critical animals," whose focus was the critical theory underlying creative endeavors. both of these festivals are components to a larger meta-festival called "this is not art." i was invited to engage in a variety of artistic and pedagogical events, some of which were newly realized just for the festivals (viz. songbirds).

Continue reading

Bugs!

alright, so nobody's perfect. when i drew up my board layouts in the last post, i made a few mistakes which prevented the initially stuffed boards from working. most of these mistakes are super embarrassing because they're pretty obvious. i will attempt to write these out linguistically, and eventually i will get around to actually drawing up a new board layout that implements these changes. refer to the schematic for the part numbers and their place in the topology.

Continue reading

DIY Etching: Songbird b

i've been working on a networked sound installation inhabited by simple automatons called "songbirds." i have previously done another incarnation of this idea, so i'm working on version "b" now. the idea for this particular version actually came from cicaidas, not birds, but the name has stuck for better or worse. maybe the "b" stands for "bug?"

Continue reading

DIY Mbira

The Universal Language Orchestra is continuing into this fall with a new grant from UCIRA! As part of our proposal, we have been coming up with musical ideas and instruments to stimulate our young (8 - 12 year old) students' imaginations. This summer, my role has evolved into research and development of these instruments, with the intention of breaking down the expectations and implicit hierarchy concomitant with traditional instruments.

To this end, Adam Tinkle and I have come out with designs for a very inexpensive mbira, or "thumb piano", which can be easily amplified and otherwise extended to include all sorts of other sound-making possibilities. While the prototype demonstrates something very similar to a traditional (albeit non-Western) instrument, we see this as a platform on which to extend into further sonic zaniness and fun.

Continue reading

Bovina Clovis

Shortly after their tour, the EYEBALL FRIENDS became infected with a strange and seductive sickness. They labored day and night, sleeping next to their tools, only to wake up in the same cold sweat, and with the same inexplicable drive to press onward. All told, the episode lasted a little under two weeks, but by the time it had run its course, a terrible and gorgeous new member of their band was born.

Continue reading

Songbird a

I am building a series of squelchy, tree-dwelling analog synths called 'songbirds.' Here's a picture of the prototype, whom I've nicknamed Tyagaraja, after the 18th century Karnatak composer. Songbirds are designed to react to ambient conditions. Tyagaraja responds to changes in light, because photocells are simple and cheap (at least, for now). He consists of a synth element, which can be calibrated using four knobs, an array of resonators (made from coffee cans), and a speaker. He runs on batteries. Future iterations will consider alternative sources of power- they don't need much current at all. The synth element has two audio-rate oscillators, two low-frequency oscillators, and several filters.

Continue reading

OZ

I recently had the privilege and good fortune to travel to Australia again! This time, I got to play some music and even do some teaching, thanks to Estee and the other kind folks at Electrofringe and UNSW. In the process, I really enjoyed making field recordings of trains & birds (thanks, Sam!), taking pictures of some beautiful street art, and hanging out with friends both old and new. I was again reminded of how incredible the coffee is down there. That alone would be reason to go back! I also got to visit Melbourne this time, which is a truly lovely city, with some lovely people in it.

Continue reading

who is anybody?

On Wednesday, December 1st, I had the pleasure of sharing the stage with MC Justin Zullo (AKA Conundrum), Kimbridge Balancier (AKA sPeakLove), and Diana Cervera. I DJ'ed (from the command line!) for Conundrum for the first half, and played a solo set for the second. Due to a few technical problems, I was unable to record the set with Conundrum, but I was able to reconstruct the solo set. I've decided to release this set online as an EP, in a manner similar to "gosling_glider_gun."

Continue reading

give me everything.

on thursday, october 28th, this piece made its debut at brooklyn college for their biannual "international electroacoustic music festival." despite the fact that i couldn't be there in person, i couldn't pass up the opportunity to have it premier in brooklyn, due to the subject matter. i'd been planning this piece for two years, and it was awesome to finally see it through to completion.

Continue reading

crudspades ginormous thing at bent 2010!

Left_SideCenterRight_Side

the crudspades ginormous thing went up at bent last week! i had to restrain myself from putting documentation online too early, because i didn't want to spoil any surprises. steve litt and i had a great time working on this project, and i look forward to working with him in the future... we have been talking about recording an album of crudbox music. i'll post updates here, of course.

here is a link to the concept art and proposal. the installation consisted of a small ensemble of self-amplified trash sculptures, with steve's crudbox as the conductor. we ended up making 6 pieces and finding 2 prefab appliances. they were:

  • a large metal slinky with several metal beaters hanging inside it, shaken with a solenoid
  • a metal grate, previously used as a gong with mike clemow for our performance at the silent barn a few weeks ago (as the todd walker tabernacle choir), hit with a solenoid
  • two amplified cans hit with solenoids
  • a piezo-speaker feedback synth, activated with a relay
  • an electro acoustic sculpture we came to call "richard." richard was made from a flat ribbon speaker i pulled out of the trash over a year and half ago. on either side hangs a small electret microphone. the mics are ring-moded together, using the jar, and the amplified signal is fed back into the speaker. crudbox sequenced richard by turning a small, hidden led on and off, which was paired with a photoresistor to pulse the feedback on and off. when used in this way, richard mainly provided a low end "wump!" sound. however, running in stand-alone mode, independently from crudbox, richard could generate a huge array of tones, and was immediately playable. furthermore, the no-frills interface provided an opportunity for meaningful collaboration with others. i am curious to build out the other flat speaker i found and make a second richard. i feel like i could play an entire set on this instrument alone. if i made a second one, it could be interesting to have three people interacting with the system onstage. i will post video of richard running solo in a later post.
  • an old vhf analog tv, activated by a relay. steve and i were amazed at the beautiful shapes and patterns one could get simply by turning the television on and off. we even got it to change stations sometimes! steve is now obsessed with tvs.
  • an old turntable, activated by a relay. steve had tried this approach before during the mmix festival last fall. we used an lp of 500 lock grooves.

Some video, taken in my kitchen just before we installed in dumbo, may be seen here.

hacksaw fuzz

i have been working on this fuzz / tremolo circuit on and off for a few weeks. i am very excited to put it all together, although at the time of the recordings below, it was not housed. i ran into some logistical problems with putting the circuit into the chassis of an old countryman di box, but i think i've figured it out at this point. its unhoused state was messy but totally functional:

open_fuzz_trem

the fuzz comes from a variation on craig anderton's circuit with two gainstages. the difference between mine and anderton's is that i used a 2n3904 npn transistor in the feedback path of the first gainstage, in parallel with a silicon diode. the result is a smooth, creamy fuzz with tons of overtones and plenty of sustain. it's nearly identical to the fuzz used in this previous post. the difference is that now the tremolo is optical, resulting from a blinking led and photocell pair. the trem has a variable speed and can also be completely bypassed. since i can't play the guitar to save my life, i invited my friend kunal prakash over to try it out.

here's an audio sample of a fast trem setting.

here's an example of a slower trem setting.

here's an example with less fuzz.

i was very pleased with this pedal's sound on a guitar. also kunal can really shred. we played for a few hours after these samples were made, using my ring mod to create a hybrid texture between his guitar and my laptop. i was livecoding on my eeepc in supercollider, starting with a simple sine tone to test the effect, and eventually experimenting with lowpassed sawtooth tones. sadly, i had stopped recording at this point so description is the only documentation i can provide. suffice it to say, it was lots of fun.

this morning, after naming the pedal the "jack chop fuzz," i tried to fit the circuit into the di chassis. in order to fit everything in, i ended up taking a hacksaw to it. thus, i arrived at the perfect name for this pedal: the hacksaw. unfortunately, the archive pages still say "jack chop," so i will accept either name, although "hacksaw" is more appropriate, in my opinion. housed, it looks like this:

hacksaw_side0

i've already got one taker. who else wants one? ^_^

concept art for crudspds ginormous thing!!

crudspds ginormous thing will be installed at bent 2010!!! stay tuned for updates!!!

the crudspds ginormous thing is an interactive installation by steve litt and me. it will consist of eight self-amplified, electro-acoustic trash sculptures that are activated by steve's crudbox sequencer. since the crudspades ginormous thing derives its sound from amplified physical objects, the user can appreciate the source of the sounds and control them intuitively, creating a wide range of noises. the sound sculptures are constructed from recycled junk, both as a statement of resistance to the throw-away culture that created them, and to subvert their iconic visual language into objects of creative empowerment.

the ‘brain’ of the crudspades ginormous thing is the crudbox, an open-source diy step sequencer designed to turn other devices on or off. instead of playing sampled sounds or controlling a synthesizer, the crudbox works by simply sending power to one of eight outputs. plug any device into an output channel, and that device can be sequenced in a manner instantly recognizable to electronic music fans everywhere. two or more crudboxes can be synced over midi, for virtually endless possibilities.

the sculptures are each unique in look and behavior. they are all brightly colored, dumpster-dived, electro-acoustic instruments that either generate enough sound acoustically, or contain embedded amplifiers and speakers. while most of these objects come already set up, a few of them will be made available for the user to experiment with. this way, the installation will not only serve as a source of passive entertainment, but of active collaboration.

confinement

prototype

click here to listen to the wav file (or play above).

this is a prototype i've been passively tweaking on for a while. i think it's near the point where i'd like it to be. all that remains is a true bypass switch. it's a fairly simple circuit that uses an fsr as an expression surface. there is a switch that engages this function, and it happens after the fuzz. the fuzz is generated with a variant of craig anderton's circuit, with an npn transistor's collector and base bridging the input and output of the feedback bus, respectively. in parallel to this, there is a silicon diode with its ground side facing the output of the feedback bus. schematics will follow once the design is completely set.

the transistor gives a warm, rich fuzz tone and the silicon diode adds plenty of harmonics. the expression pad is engaged such that pressing on it brings the amplitude up. this made the most sense for performance.

the recording was made from two tracks of a fender strat playing through the pedal, one note per track. the rhythms are the result of tapping the expression pad. i expect this to be really cool with my electric piano...

cold war fuzz

click here to listen to the wave file.

the above pedal is basically a squelchy octave-drop fuzz effect, with a fair amount of self-modulation and hard-clipping due to the silicon diodes used. the fuzz tone component and the octave-drop component both make use of cmos logic ic's, which is part of the reason why the octave drop is so easily fooled and modulates around.

the pedal has no bypass: the switch literally turns it on or off. at some point during testing, the unit was passing signal through without needing to be connected to power, however this is no longer the case. the three knobs are, from top (big red) to bottom: input gain, ???, output gain. a very nonlinear effect, the pedal's knob settings interact with each other and the source material in unpredictable ways.

i have tested this beast on guitars, electric pianos, and synths. a previous version also sounded great on bass and vocals. i love the inhuman, 8-bit sound of the dropped octaves. the fuzz is surprisingly smooth and complex. the build is also pretty solid. who wants one??

aggressive slinky improvisation, part II

last week, i discovered that the quality of the lm386 amp could be vastly improved by increasing the operating voltage. in so doing, i increased the headroom considerably. i am currently supplying 20v to the amp.
i implemented the amp in a simple feedback instrument, pictured below.
spring_fb1
by coupling the slinky to the contact mic, and draping it over the speaker cone, feedback is produced. there is also a small stone phaser - which i've fixed for someone- involved.

rings

ringmod_in_jar

click here to listen to sinewaves pumping through this jar.
click here to listen to 3 minutes of carl sagan's cosmos pumping through this jar.

a few people who caught the concert at theaterlab on sunday made remarks about the above piece of handmade equipment, so i thought i'd explain it in this post.

ring modulation, theoretically speaking, refers to the multiplication of two signals. in a software system, depending on your context, the same term can sometimes apply to somewhat more complex operations such as the product plus the sum of two signals. some software synthesis environments, such as supercollider, have a bevy of ring modulation operators, since the mathematical implementation may change depending on the intended application.

the preserves jar contains the original ring modulation circuit. the term 'ring modulation' in fact comes from the diode ring through which the signals pass, after going through center-tapped transformers. this particular ring mod uses two fairly high-quality, vintage transformers, and the diode ring is made from four vintage germanium diodes, desoldered from some ancient piece of gear. my source for parts is richard matthews, bob seer's tech, who works out of a massive unmarked garage in greenpoint. love that guy.

while i can't tell you exactly what it does from a mathematical standpoint, i can tell you that it's not any of those definitions i mentioned above. germanium diodes have a particularly crunchy sound to them, which is why they are so sought after for distortion circuits. i don't think i could satisfactorily model this effect in software.

n.b. the carl sagan recording introduced some weird buffer artifacts, so while it still sounds cool, the sinewaves do a better job of demonstrating the effect.

balu, II

many people who have run into me at festivals are familiar with 'balu,' that lovable little handheld noise synth that reacts to light. for ages now, people have been asking me to make them their own similar synths. since i have a lot of trouble turning people down, the waitlist for these things is rather long. however, a few proud friends of mine already have received theirs for occasions such as boxing day and shark week. the above synth is for a friend of mine who lives in atlanta. behind me, as i do the demo, you'll notice the original balu, sitting on my workbench. he needed a new switch, and now he's good as new!

yay noise synth friends!!! ^.^

barren neptune

i made another distortion circuit. this one is very stable, and very loud. based on my limited understanding of the subject, this one works by overdriving the components inside the opamp, rather than using a diode to clip the peaks of the waveform. despite how primitive and brutal this circuit is, it doesn't do much self-oscillating, and actually gates a lot of low-level signal, which is a good thing when dealing with amps and guitars.

actually, the gain is so high on the output that i believe it will need a third opamp to attenuate the signal, because otherwise any guitar player who uses it will most likely just destroy their amp.

to test this and future pedals i'll be using an actual electric guitar, since the impedance isn't quite the same coming from a contact-mic'ed kalimba. it's an american strat-- not mine-- and i have almost no competence with the instrument anymore. regardless, i refuse to tune it, because i really like the sound of a well-detuned guitar.

this pedal currently has no knobs or switches; it can only be on or off. eventually, a volume control and wet / dry knob might make an appearance.

improvisation on hacked reverb unit.

ah the yamaha r1000. possibly the worst digital reverb ever invented. it has four discrete settings which are labeled, cryptically, 1 through 4. it sounds nothing like reverb. it was a gift from my flatmate. i've been looking forward to hacking this thing for some time, and it has not disappointed me.

last night i almost killed it completely. i was messing with it manually and decided i wanted to use bare metal to bend the circuit instead of my hands. big mistake. everything got really cool for about fifteen seconds, and then all went dark and the sound got somewhat less cool. then it wouldn't fully turn back on. i rued the day.

today i woke up and tested the four fuses in the non-power-oriented part of the circuit, and found that all of them had been blown out. on replacing them, the unit sprang back to life. sort of. more accurately, its zombified body sprang into soulless action. it no longer works as a reverb unit- which it sucked at anyway, let's face it - and now only works as a hacked instrument. it's probably my favorite instrument in my rig now, if only because it's so massive and novel. i spent today isolating interesting regions on the circuit and getting some chops on the board. i practiced until my hands started bleeding and i had to stop. i still have a ways to go.

hubris, for tape

i have been playing with this reel-to-reel, which i fixed for one of my clients, for the past few days. it has been an amazing experience working with tape. for the recording, i used only analogue equipment, most predominantly, an ancient and tortured fostex mixer that i used for "no input" mixing. additionally, i used a hacked small stone analogue phaser, some commercial distortion pedal, and two of my own pedals: a distorted bandpass kind of thing, and an arpeggiating octave divider. there is also some amplified spring in there. when i finished the improvisation, i digitized several versions of the tape, with slight variations in mix, tape speed, and additional slinky reverb. i arranged these different versions so they would line up at some points, creating a manual flange / delay effect. truly beautiful things happen to tape when you overdrive it. the tone is so dark and warm. i'm considering recording some computer music to tape and re-digitizing it, just for the saturation. i don't want to give it back!

fostex_with_2025_and_small_stone

yeah -  that one pedal's housing is from an old-school motion detector.  that's the octave arpeggiator, otherwise known as the lunar lounge 2025.

a slow, hopeless fire

today i made a battery-powered amplifier out of an LM386 chip and some other, mostly recycled components.  the schematic i used can be found in the datasheet (it's a pdf).  i went for the 200x gain circuit.  it's housed in what appears to be a jewelery box, but really it was a container for one of those space pens.  funny how during the space race the americans thought space pens were such an important design problem, while the soviets used pencil.  maybe that's just an urban legend.  i don't know.

fuzzy_amp

the easy access this case provides is certainly a bonus.  i will definitely be improving on the circuit as time progresses.  i decided to house the amp so neatly because it's something that comes in handy often.

after i had some wine, i got into playing with amplified slinkies and the filter / distortion effect circuit from a few nights ago.  the whole setup looked like this:

i'm calling the track that resulted from improvising with all this "a slow, hopeless fire."  it's a bit aggressive.  i'm still pretty angry about the most recent hand i've been dealt.  this is the most constructive thing i can think to do about it.  enough said.

aside from a little dynamics processing, everything was improvised and totally analogue.  the sound comes from feedback from the little speaker -driven by the new amp- through the spring, and that crazy filter.  i think i'll house that thing the next night i spend here in my studio, which unfortunately won't be for a few days.  it's just as well; there's plenty of computer music to make, too!

distortion

for today's hackpact, i made a new distortion effect, starting with the circuit from last night as a base.  this circuit is a bit less stable, and it's harder to tell exactly what's going on sonically.  it sounds a bit like a ring mod with a filter that occasionally self-oscillates.  it's still very simple in terms of design, but its tone is more complex.  here's the schematic:

to make the previous circuit, simply replace the photoresistor that connects the input to ground (the one at the top of the schematic) with a 220 MΩ resistor, and remove the 220 μF capacitor.

i tested this circuit with the same amplified kalimba from the previous post.  what a fun instrument!  i added a few delays in supercollider:

{Limiter.ar(Mix.ar([CombC.ar(SoundIn.ar(0), 2, [8/7, 6/5], 32), Mix.ar([CombC.ar(SoundIn.ar(0), 1, 1, 16), SoundIn.ar(0!2)])]), 0.9)}.play;

click here to listen to part one.

click here to listen to part two.

electric kalimba

for my fourth hackpact, i decided to go with something electronic.  i spent a while getting back into the workflow; it's especially difficult because I'm at my parents' house and not at my typical space.  i ended up prototyping a simple active filter / distortion effect from an op-amp and a few other components.  using a piezodisc as a pickup, i tested the circuit with a kalimba i found.  i believe it's from a resort gift shop in jamaica.  i'll draw up a schematic tomorrow.

kalimba

click here to listen.