WAVE – an introduction to waveshaping and wave-terrain synthesis

Michael TerrenFree Downloads, Max for Live, noisemakerLeave a Comment

WAVE-oscilMax offers seemingly limitless possibilities in terms of digital signal processing (DSP). Experimental and avant-garde composers have been using it for nearly two decades as a way to create interesting new ways to process or synthesise sound. I’ve already talked about how one can go about stuttering incoming audio, and now I’ll talk about two ways to drastically manipulate and distort your sound, and how I’ve made a sort of hybrid as a single Max for Live audio effect.

Download the WAVE effect device as part of Michael Terren’s suite of Max for Live Devices

Waveshaping

Waveshaping is a technique that, quite literally, lets you shape the waveform of a signal. It’s generally used to add harmonics to a signal, and often that means distortion.

Ableton Live actually has a really great waveshaper built in, and it’s very well hidden inside the Saturator device. Press the arrow next to the Device On button, and in the dropdown menu where it says “Analog Clip,” select “Waveshaper.” A slew of new controls becomes available for you to use.

Digital sound can be described as a sequence of varying numbers, between -1 and 1, “played” one at a time very very quickly, usually 44100 times a second.

Think of a waveshaper as a big table or a spreadsheet, with ry possible value from -1 to 1, laid out in order from lowest to highest. Next to that column is another set of numbers, also between -1 and 1, but they aren’t laid out in order—they’re laid out in different ways. A waveshaper looks at the incoming audio signal, gets its value, and then gives it the new number in the next column, and it does this 44100 times a second. That’s essentially what waveshaping is—it takes the numbers that make up an audio signal, and gives them new numbers.

Back to the Ableton Waveshaper now. When its “Lin.” (linearity) value is at 100%, that means the waveshaper doesn’t do anything—that’s basically like having two identical lowest-to-highest columns. When you start messing with “Drive,” “Curve,” and “Period,” the sound starts distorting and mangling, anything from subtle sizzle to outright decimation.

saturator drysaturator funky

Waveshaping is a technique used in a lot of kinds of synthesis, and it’s an easy way to make distortions or add harmonics to your sound. The next technique is similar, but works over three dimensions as opposed to two.

Wave terrain synthesis

A more advanced technique of synthesis is what’s known as wave terrain synthesis. This kind of synthesis is esoteric—I don’t know of any mainstream software synths that use it—but it can be used to create some phenomenal sounds.

The analogy I like to use is that of a record player. As you probably know, records are made up of grooves which have tiny dips and peaks inside each groove, that represent the sound made by that record. As the stylus plays over these dips and peaks, the electronics in the turntable convert it to the movement of your speaker, i.e. sound. Wave terrain synthesis is like that, but your “stylus” isn’t limited to moving around in a circle. It can move wherever you want it to, at whatever speed you want—we call this path the *orbit*. And the “record” can be any assemblage of dips and peaks that you like—we call this the terrain.

Wave terrain synthesis needs two signals: one that tells you where the stylus is horizontally, and another for the vertical position of the stylus. These two signals are scaled—a process where you change the range of possible numbers, e.g. numbers from -1 to 1 scaled to 2 and 5) and then plugged into an equation that creates a terrain. The equation that I’ve chosen is useful because it can create a very complex terrain if you scale the numbers highly, but also the terrain will always stay between -1 and 1, i.e. the lowest and highest values an audio signal can be.

That’s basically all there is to wave terrain synthesis. Of course, people can and do make wave terrain synths that are much more complex, where the orbits and terrains are increasingly complex and require a much greater knowledge of mathematics to achieve and conceptualise.

WAVE

My audio effect device WAVE is a sort of hybrid between these two techniques. The two input waves are the left and right input channels, and they both get laid over an equation that converts them into one signal, which is usually quite distorted and harmonic. The “stylus” is the green oscilloscope, and the black and white pattern is the terrain/”record.” White parts are positive (i.e. closer to the number 1) and black parts are negative (closer to -1), while grey parts are generally near 0.

Sounds get more distorted when the sliders to the top and right of the display are further from the middle. The more “noisy” the display looks, the more noisy it’ll sound, basically. You can also effectively zoom in and out of the terrain by moving the “X width” and “Y width” dials. You can lock the “Y width” dial to the “X width” dial by pressing the Lock toggle switch, allowing for nice, smooth zooming. Of course, because this has the capacity to make the sound a bit louder than it was before, there’s an output gain dial, and a Dry/Wet dial to mix in the original sound.

Some other notes about this device: most of the audio processing is done inside a poly~ device, with the argument “up 4.” I’ll talk about poly~ in another post, but one of its most useful features is known as oversampling, in which all the stuff inside that patch runs at a higher sample rate, in this case 4 times the sample rate. Why? At lower sample rates you run the risk of aliasing, in which high-frequency artifacts are accidentally created. This is talked about in Livemaker 1, so I won’t repeat myself here.

WAVE-oscil

This is just one approach to using waveshaping and wave-terrain techniques to create some pretty devastating and harsh sounds. If you’re into that sort of stuff, then you’ll like this audio device. If not, at the very least you’ll have fun with the oscilloscope—I recommend running sine waves (from the default Operator preset, for example) into WAVE, turn up the De-phase dial, and make some cool shapes. Have fun!

Michael TerrenWAVE – an introduction to waveshaping and wave-terrain synthesis

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