A Series: Basics of DIY Wind Controllers

Over the past few years I've spent some time thinking about and designing wind instrument controllers. I thought a good way to give something back would be to produce a series of blog posts describing what I've learned while tinkering with my projects.

As it turns out, I'm not a very skilled craftsman, so most of my projects end up looking like something Homer Simpson would have created. But I think I've learned a few things about building the electronics and writing code. So, in this series of posts, I'm going to concentrate on sharing some basic building blocks and core concepts, like the following:

• Why electronic wind instruments are hard
• Breath Sensing 101
• Mapping analog readings to MIDI continuous controller values
• MIDI note selection methods
• Using sensors to alter performance data in real time
• And more, as I think of them

Since I've been using Arduino and Teensy microcontrollers to do my experiments, I'm going to focus on those, so the code examples will target those platforms.

If you are a performer who uses an EWI, EVI, or WX-series controller, there won't be a lot of practical advice for you here, but the circuits and code may help you understand what's going on inside your instrument. Also, the posts on building synth patches that work well with wind controllers will certainly be applicable to your live rigs. So, please - read on!

So, onto post number one:

Why Electronic Wind Instruments are Hard

First of all, if you're not familiar with what an electronic wind instrument is, I'll define the term.

An electronic wind instrument is a musical instrument that employs electronics to produce the instrument's sound, and is articulated by blowing into the instrument.

There are a number of commercially available electronic wind instruments. The most common instruments are the EWI series from Akai, and the WX-5 from Yamaha. Both are woodwind-style controllers - that is, they are fingered in a way that is easily learned by someone who knows how to play the saxophone, clarinet, or flute. The Akai instruments also support a mode that is more natural for trumpet players to use.

The Akai instruments are the latest in a long line of wind controllers that started with Nyle Steiner's work in the 1970s. For more information on this history of the Steinerphone/EWI, see the Nyle Steiner home page. For more links to learn about wind controllers, check out the Wind Controller links page from Patchman Music. These two paragraphs don't come close to describing the history of wind controllers, but the links page on the Patchman site is an excellent resource to learn more.

(Aside: Nyle Steiner also invents lots of other crazy stuff. And he's a ham like me.)

ADSR

The majority of electronic instruments you can buy are really good at emulating instruments that can be modeled with the ADSR model (Attack, Decay, Sustain, Release):

 
This model describes how a sound evolves over time. For example, when you hit a key on a piano, there is an initial attack A, when the piano's hammer hits the string. After the initial strike of the hammer (the attack phase of ADSR), the string starts vibrating, and the vibration starts to lose energy. In most cases, the majority of the string's vibrational energy dissipates quickly (the D - decay phase), but then the string continues to vibrate at a lower volume, fading out gradually (the S - sustain phase). When the key is released, the piano's felt damper touches the string, stopping the vibrations (the R - release phase). Most synthesizer patches have a fixed ADSR envelope, a "recipe" for the sound as it progresses through time. For a plucked or struck instrument, the performer has some control over the duration of these phases, and can also exert some control over the initial input, e.g. how hard the string is plucked or how hard the drum head is struck.

ADSR works really well for modeling instruments that are plucked or struck, which includes most of the staple instruments of popular music like:

• Guitar
• Bass
• Drums
• Piano and other keyboards

Wind instruments, on the other hand, don't follow this model at all. The sound is produced by a column of air emanating from the performer's lungs, which in turn causes something to vibrate - a single reed (clarinet/saxophone), two reeds (oboe/bassoon), lips (trumpet/horn/trombone/tuba), or the air column itself (flute/recorder). Articulation (the starting and stopping of sound) is generally accomplished by interrupting the stream of air using the tongue. The ADSR model simply doesn't reflect the way wind instruments work. It also doesn't model the way that bowed instruments like the violin make sound either.

Due to the popularity of the instruments that ADSR models well, manufacturers of electronic musical instruments have generally not found other types of instruments to be commercially viable. Yamaha and Akai have a series of wind controllers that emulate woodwind instruments, and some smaller companies produce small quantities of instruments that emulate other types of instruments, including trumpets and violins, but for the most part, wind players have not been invited to the electronic music party until they learn to play a different instrument.

For this reason, even if you have a wind instrument controller like one from Yamaha or Akai, you're faced with the difficult task of finding synthesizer patches that work well with your controller. If you *want* to sound like a Fender Rhodes electric piano, no problem, but if you want to make that Rhodes fade in from nothing, swell up, and fade out, sorry, you're out of luck. The ADSR envelope of the Rhodes patch you have models the characteristics of the real Fender instrument.

I'll cover this topic in more detail in a later post, but the important thing to remember is that if you want to play your wind instrument controller in an idiomatic way, you're going to have to either go find some patches specifically designed for wind controllers, or build your own.

I should also mention that my work has focused on building instruments that send MIDI data, but an equally valid approach is to build instruments that send raw sensor data to a device that makes the sound itself, rather than relying on a MIDI synthesizer to make the sound. The original Steiner EWI and Akai variants had a dedicated synthesizer that directly read the instrument's sensors. Another option is to feed all the sensor outputs to a computer. The computer, in turn, uses a sound system like pd or Max to realize the sound. There are a number of artists using that approach, but one of the most exciting, in my opinion, is Onyx Ashanti, who is really pushing the envelope on the form factor for wind controllers. He started with a Yamaha wind controller, deconstructed the functionality it provided, scratched some personal itches he had with performing live, and arrived at the Beatjazz Controller. I encourage you to follow his work.

What's Next

In the next post, I'll select an inexpensive sensor that you can use to sense breath pressure in a wind controller. We'll cover how to connect it to an Arduino or Teensy controller, and how to connect tubes to the sensor so you can blow into it and measure the breath intensity.