Racer Sessions

Sundays, 8-10pm at Cafe Racer in Seattle, WA

Aaron Otheim - January 26, 2014


Racer Sessions celebrates its fourth anniversary next weekend!

I’ve had the tremendous privilege of being a part of this inspiring, challenging and deeply supportive community for the last four years, each of which has undeniably made me a better musician and (more importantly) a better human.

I’ll open this Sunday with four pieces for solo synthesizer, each using improvisational techniques I’ve gradually developed in response to various musical scenarios I encounter at Racer Sessions and elsewhere. Detailed descriptions of my process for each piece may be found below.

The jam session will incorporate four zones derived from my opening improvisations. The first four groups will focus on one zone apiece, and subsequent groups will integrate combinations of zones. Each improvised piece must be five minutes or less. As more zones are added, the focus should be on crafting strong, intentional transitions—gradual or sudden—between zones. I will coach the first several groups.

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Four Pieces for Prophet 8 Synthesizer

Cipher Canyon

When I realize that it isn’t constructive to focus on predicting or directing harmony in a free piece, I often turn to playing with texture and timbre. Especially when many others are playing at the same time, it can feel like rafting rapids. In this scenario, I tend to prefer to go along for the ride and try to support significant moments or changes in group sound. For example, this could mean adding some growling bass notes to bolster a low drone that is growing or playing adding a cascade of notes from the top of the keyboard to draw attention to a shift in texture.

For this piece, Cipher Canyon, I have assigned a low-frequency oscillator (LFO) to use a random waveform to alter the pitch of any note I’m holding, meaning when the note changes and how much it changes is somewhat indeterminate. I say “somewhat” because I still have control over the frequency and amount to which a note changes, though these values are being “corrupted” by additional random LFOs. For the scope of the piece, I will begin with a low frequency and large amount (i.e. long durations, large intervals) and gradually invert those values.

As the piece unfolds along this course, I will interact with the qualities of the randomly-generated harmonies using the resources I have to control timbre (waveform, filter, reverb and delay effects) and density (number of voices).

“They Say You Are Taking the Sunshine”

I frequently wind up playing things in an improvised setting that are slightly outside my technical “safety zone.” Unless it just sounds bad or sloppy, I find that persisting in this state of vulnerability opens up possibilities and quickly reveals useful limitations. 

This piece employs a technique in which the low-pass filter is made to self-oscillate by maximizing the filter’s resonance value, producing a whistling sine-wave tone. This is sometimes known as “playing the filter.” LFOs, when set at sufficiently high frequencies, can also create the illusion of pitch or overtones. The effect is very similar to the rumbling tone from a spring or engine that sounds like both noise and tone depending on how you hear it.

Controlling these sounds in a meaningful manner necessitates delicate adjustment of knobs and triggering certain combinations of keys, which in turn demands a certain compositional decisiveness and simplicity that I may not have otherwise acquired.


Harmonic interaction in free improvisation still amounts largely to guesswork. Even if my harmonic sense aligns with someone else’s momentarily, one or both of us may move in an unforeseen direction. When I end up improvising harmonically with a group, I try to play in such way that adapts easily to unexpected changes. Sometimes this is as simple as designating one hand as “mine,” which will insist only on my harmonic palette, while allowing my other hand to match any dissonances brought in by other players.

In synthesis, a technique known as a “sync” directs one oscillator to control the periodicity of the other, creating sounds rich in overtones (useful for making bell or electric guitar sounds). The effect is similar to singing into a fan: your voice “teams up” at certain pitches with overtones from the dominant drone of the fan, causing those overtones to pop out. When applied musically, these overtone-rich notes seem to suggest more than just the present harmony. I also layered in a second group of voices that sound slightly after the initial attack, transposed up a fifth to further diffuse a secure sense of key. The result is a harmonic rabbit hole, where the implications of one harmony are continually overtaken by others. What I originally thought I was playing and where I originally thought I was going may be different at every turn. 

In this piece, I am able to control the degree to which the sound “splinters” and can choose to emphasize one side of the mirror or the other at any given point as a means of sonically defining different parts of the form.

Trash Talk

One of my favorite starting points in free pieces lately has involved playing a continual grid of even notes while improvising harmonically. The rigid simplicity and predictability of the rhythmic dimension opens up harmonic possibilities for me (and for the group) that probably wouldn’t be available otherwise. Despite shifting conscious attention away rhythm, I often find that the shapes I am playing naturally suggest certain patterns that become the launching point for other ideas within the improvisation.

The Prophet's arpeggiator facilitates this approach, providing the rhythmic grid while also imposing a specific organization to pitch: all chords are played monophonically (one note at a time) from bottom top, resulting in accents create distinct rhythmic effects.

Despite this limitation, all other usual parameters of the sound are available for play—waveform, filter, envelope—and become more important in carving out the sound and trajectory of the piece.