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DIY Audio: UNPLUGGED

by on Apr.11, 2012, under building, Craque

Probably around five years ago now, while much further in the depths of a thrice-laid-off financial hole the technology industry bestowed upon me, I became fixated with actually building my own electronic instruments. Ensuing the expertise to make music that way, I departed into the wide unknown universe of DIY audio.

The first time I encountered a small, personal modular synthesizer was during a long gallery installation and collaborative work by Achim Wollscheid in Chicago (I also happened to have given him a ride to where he was going his first night there, and had rich conversations for the short time we were all together). I had my motley collection of contact-mics and sampling objects and looping pedals and probably what could be called a portable John Cage concert, which I used to improvise alongside Achim as he did the same over enormous loudspeakers placed in the ceiling of the large public space in this gallery (yes, I recorded). Anyway, someone else coming in to collaborate set up next to me on the balcony overlooking the space, revealing a portable Doepfer A-100 suitcase model.

That’s when it was over. That’s the exact moment when a lot of things clicked, but apropos to our topic it was definitely the first time I felt the urging pang of modular desire, and barely realized it.

Fast forward ten years; as of 2012 I am the proud owner of a new disease known casually as idiomatic modularsynthacropy, or the addiction to building complex systems realized by modular synths. I think it’s genetic, because this is an occupation my wife lovingly calls “The Rocket” due to my studio resembling a half-built starship cockpit (or at least the bar in one), and my brother being an actual rocket scientist.

It first manifested itself after Chicago “event” in the form of electronic tinkering and eventually the building of my own simple devices, made specifically to be used alongside other analog/acoustic instruments of improvisation. As it happened certain events also related to my unlucky job streak in the Internet business ended up affording me a barebones entry-level one 3U rack half-full beginner outfit: 8 ‘eurorack’ style modules, the format Doepfer popularized, and in fact some are the very same kind I had first seen in that suitcase ten years ago.

Muffwigglers is the forum for this disease, and there’s even a forthcoming documentary. A lot of the musicians I admire the most are modular users, and I’m happy and fortunate to join their ranks along with a pretty decent wealth of electronic building knowledge under my belt in addition to the musicality. So I shared some of my accumulated knowledge recently on that forum, and wanted to post it here and add a bit of history.

 


Everything listed here except for the first book were published after I started into the DIY world of audio, and after spending literally DAYS of searching and reading electronics tutorials and articles online, they have become my ‘go-to’ stack for reference and inspiration.

1. If you aren’t familiar with Forrest Mims, get familiar with him. I just picked up Vol I. of his “Engineer’s Mini Notebook” series, which is titled: Timer, Op Amp & Optoelectronic Circuits & Projects. It should have been titled: The Building Blocks of Analog Modular Synthesis, and I wish I had discovered it five years ago when I first started into building this stuff, cause it is indispensable. All the “how do i build a 555 timer?” and “how do i correctly power an opamp?” or “what frequencies do i get if i change these resistors?” questions that you search for hours on the Internet? It’s all in here – there’s even a chapter on photocouplers – aka ‘varactors’ – which are used a lot for CV audio systems.

2. Another specific project-oriented book but much more glossy and full of awesome examples and a DVD (which I haven’t gotten around to watching yet, shame on me) is Handmade Electronic Music by Nicolas Collins. This one is specific to DIY audio hacking and electronic building, covering everything from building oscillators (different chips than the Mims books!) to circuit bending and experimental electronics.

3. Make has started releasing awesome print publications (I have two of the Maker’s Notebooks and love them). The one I’ve found the most applicable and helpful to audio DIY is by Charles Platt and is one of the first: Make: Electronics. Simple, easy to understand tutorials on the foundations of… well, making stuff. With Electronics.

4. Finally the most general of all of them but something that is a great learning resource for a wide range of electronic applications, by Michael Jay Geier, How to Diagnose and Fix Everything Electronic. The title doesn’t lie. Every chapter is basically a Cliff’s Notes on that particular subject or piece of equipment, summarizing how it works, what might go wrong with it or often does, and how to troubleshoot and fix it. It also includes quick introductions to fundamentals of physics and other things related to electronic parts and machines… and most importantly to us, a wonderful introduction to oscilloscopes and how to both choose and use them.

All these books together will probably cost you as much as a good VCO module! lol But they are worth it, I highly recommend any of these to the DIY audio muffer.


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Line6 ignoring Mac users?

by on Dec.06, 2011, under building, External

Someone showed me this incredibly awesome looking ‘DIY’ pedal being done by Line6 called the ToneCore DSP Developer’s Kit. At first I think, aaah what a cool platform for custom DSP pedal effects, what a nice little generic pedal with cool ways of creating my own DSP configurations… you can imagine the excitement, so unfortunately diffused by this paragraph:

Will this platform be available on the Mac?

Probably not, sorry. Freescale, the company that makes the processor, writes the development tools and as far as we know, they have no Mac development tools planned. However, it may be possible that these tools may work on an Intel-based Mac using one of the Windows emulating solutions.

WHAT? Are you kidding me? Come on, Line6, couldn’t you have picked an actual OPEN platform like Arduino or something?

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“Booglitchoo” Synth Prototype

by on Jun.22, 2011, under building, Craque, Uncategorized

Here we go… I’ve optimized the way I’m using power, love the way the dual jfet opamps (TL082) sound, and have the mixing elements mostly decided.

To be done on this prototype:

  1. use either capacitor switching or a simple 4017 sequencer to change up the textural possibilities of the oscillator
  2. add switches to the voice modulator to allow for “skipping around” pitches instead of only up or down changes
  3. CV input

I went through quite a few opamps before finally deciding on the dual jfets, and now I really dig how they’re working with the complex waveform of the four NAND gates (NTE4093)… I use it first as a multipole low-pass filter to shape the sound of the chained oscillators.

Because of the nature of the sounds I don’t find much use for the vibrato section of the voice modulator (HT8950), but don’t mind at all because it reduces the component count and I’m finding an incredible amount of possibilities already. You’ll also notice I’m using my fingers on a couple of resistors to change the pitch… I discovered this by accident, but really like the gestural aspect of it so much that I’m planning on building a touch interface into the final design. :)

The whole thing is finally mixed into another dual opamp, with a follower/buffer and a high-gain resonant Q notch filter to add some harmonics and really cool sweep possibilities.

Excited to have this core design done, LOVE playing with it! Now it’s just a matter tweaking and expansion.

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Matrix Mixering

by on Apr.03, 2011, under building, External

I’m building a 3×3 matrix mixer and have been scouring the Internet for examples and technical ideas. Even though a Google search can give you days of examples of opinions on which OpAmp to use at what stage, I’m more interested in the actual pedagogy of building the thing in the first place. So here are some of the better links I’ve uncovered that are useful for getting your head around the entire idea of designing a matrix mixer.

A lot of good guidance here, using OmAmps for buffering, though I think the best thing about this page is the nice wiring schematic at the very bottom on how to wire buses.

This JFET style mixer is basically a step up from a passive mixer with no buffers, sometimes used in place of an OpAmp:

These are a selection of great starting points for learning how to build simple input/output buffers, focused mostly on JFET, but with some discussion of JFET OpAmps:

Ken Stone’s well known mixer designs. PCB’s are no longer available, but the theory and technique is there:

The Doepfer A-100 DIY Matrix Mixer example schematic (about halfway down the page):

The Bucha Matrix Mixer Clone thread at Electro-Music contains vtl5c3’s posts about his 8×8 project, which follows the Buchla design. The only place I’ve been able to find the Buchla schematic online, and has great photos of the mixer’s guts:

 


UPDATE:

I’ve breadboarded the input/output stages with NTE451 JFET’s using a 50k pot and 56k ‘mixing’ resistors, I think I’ve found the perfect combination out of parts I already own… I need to swing by Orvac later today and possibly pick up more transistors and resistors so I can build the protoboard. -mrd 20110411

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New on sounding: galleries!

by on Feb.20, 2011, under building

I’ve decided to pull all my sculpture and art photography here to a central gallery, and have a new page for my sculpture that for now features most of the photos I have up on Deviant Art.

There’s a couple of new large works going, one that’s nearly complete and another just begun, photos to come soon!

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Doepfer DIY audio circuits

by on Sep.18, 2010, under building, External

Check out these great DIY schematics and tutorials for audio electronics published by Doepfer… found this while working on a passive mixer for Long Beach SoundWalk.

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My synth project: complete!

by on Mar.11, 2009, under building, Craque, Music Tech

Here’s something I thought I’d never see myself do in my own lifetime: build a synthesizer from scratch.

Actually it’s a simple design: 2 555 timers in astable configuration producing square-waves. This means it’s a burst of sound every interval, pretty annoying and not very useful except for maybe starting earthquakes. So to give it a little flavor, I put a low-pass, 2-pole filter on the output of each oscillator, using a traditional operational amplifier.

K2 Schematic

A bit over a year ago it started out as a learning experience for me, I had never gotten into building things with analog circuitry – although I dated a chick in college who was an EE, so I was vaguely familiar with a breadboard. As a result, my design is über simple, and in reality was the design I could “get to work” from the opamp (a weird beast in itself, I will be tackling it again soon enough).

After a lot of experimentation and research on the web (these days a DIY’ers first reference), I came up with a 2-rail power design that provided 9V for the oscillators and 4.5V for the bipolar opamp (just left of the battery in the schematic). Moving left, the 741 opamp (NTE941) provides a low-pass, 2-pole filter to the signal from the 555 timer (NTE955).

completed synthguts

The cutoff frequency of the filter is controlled with a potentiometer, as is the pitch of the oscillator. You can also see my modification in the lower left for a “range” switch, which wasn’t on the breadboard prototype, but made it onto my final PCB because I think it adds a lot more interest and possibilities.

This was an intense project, no doubt. I got some training on soldering little kits that got made into sculpture, and I am a proud builder and owner of a bleep labs thingamakit, and have recently built the wave sheild for my new arduino board (which I haven’t quite gotten to work yet, so I hope it’s my programming skills and not my soldering skills).

As much as I tried to plan out wire distribution inside the chassis where the pots and switches would not interfere too much with the PCB, sure enough I drilled the holes sort of on the wrong end of the enclosure, so the edges don’t match unless I flipped it, and of course I only discover this after everything is screwed into the front. So, fixing it meant pulling all the knobs and switches back out, and removing the PCB from its mount on the inside and flipping it 180 degrees, then re-attaching everything.

In the end it really didn’t make that much of a difference and the whole thing came together fairly perfectly anyway. What I haven’t really done is add any decoration or labels, which I do want to do… inspiration will strike when I least expect it, perhaps it will not only get illustration but also a name, and it will evolve!

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