In previous columns, I have talked about the joys of using granular-based iPad apps, such as iDensity and Borderlands. But what does it mean to do granular processing? And what are the options for guitarists who have not yet been bitten by the iPad bug.
Granular audio refers to the process of dividing audio into very short snippets (grains) of about 1 to 50 milliseconds. At such short lengths, the snippets no longer sound like the original source, but become atmospheric or glitchy, depending on how the grains are played back. Granular effects let you manipulate those minute sections of digital audio by varying their speed, volume, direction, density, and pitch.
You can get a sense of what it is like to hear a grain by recording an audio clip of your guitar, putting it in a sampler, and then adjusting the start and end points of the sample to a tiny section of audio: It no longer sounds anything like a normal guitar.
IN THE BOX
My first experience with granular processing was with Ableton Live’s Grain Delay plug-in, an effect that can individually delay and re-pitch the grains (see Figure 1). By using the Spray parameter, you can introduce a level of randomization in the delay time, adding noise and rhythmic chaos to the sound. The size and duration of each grain is set by the Frequency parameter. These parameters are highly interactive, allowing you to create spacey pitch-delay tones, as well as unique flanging effects. I find Grain Delay especially useful for adding texture to loops.
More recently, I discovered Robert Henke’s Max4Live Granulator II, a software sampler that, as the name implies, is based on granular synthesis. It takes short crossfading sections of the source sample and allows you to modulate the pitch, position, and volume of each grain.
How is a software sampler relevant to guitarists? As discussed in my September 2017 column, the “Divided Fretboard” (available at emusician.com), you could put any audio sample into Granulator II and control it using any hardware or software product that allows your guitar to output MIDI. What I found more exciting, though, was its ability to grab live guitar audio on-the-fly through a Henke audio plug-in called GranulatorInput. Once installed on the guitar input track, hitting the plug-in’s Grab button would send guitar audio to the Granulator synth over on its MIDI track (see Figure 2).
The real fun began when I set up a MIDI clip to control Granulator II. Whenever I triggered Grab on the audio track, whatever I was currently playing on guitar was entered into Granulator II as a sample and played by the MIDI clip. One simple effect is to run a number of MIDI notes that total the length of the clip, and then slap Live’s Arpeggiator MIDI effect in front of Granulator. Any guitar sound I grabbed was instantly turned into a granulated rhythmic pattern (see Figure 3).
ON THE FLOOR
For those who are hardwired for hardware, Red Panda’s Particle is a granular delay/pitch-shifting pedal that lets you adjust the grain size, delay it, and shift the pitch up or down an octave depending on the mode. It also features an auto-freeze/stutter option with an adjustable threshold.
Aside from the effects I mentioned in the July 2017 column about Glitch, the Particle is capable of a wide variety sounds that are only possible through granular processing. Delays can not only be reversed, but also can be made to go forward or backward by an adjustable percentage of the time. An effect like Particle’s random pitch-shifting mode is not for all occasions but it can be inspiring for sound design and experimental music projects.
In a world where so much DSP is harnessed for emulating vintage analog effects, granular processing revels in its digital nature. Red Panda Particle is already showing up on a significant number of pedalboards. As electronic guitar embraces its future, you will likely be hearing hardware and software granular effects like these more often.