Time Modulation

Rhythm, relativity and voltage control

by David Ross

Held in Manchester from 24–26 October 2014, the first Sines & Squares Festival of Analogue Electronics and Modular Synthesis was an initiative of Richard Scott, Guest Editor for this issue of eContact! Some of the authors in this issue presented their work in the many concerts, conferences and master classes that comprised the festival, and articles based on those presentations are featured here. After an extremely enjoyable and successful first edition, the second edition is in planning for 18–20 November 2016. Sines & Squares 2014 was realised in collaboration with Ricardo Climent, Sam Weaver, students at NOVARS Research Centre at Manchester University and Islington Mill Studios.

Modulation brings animation, expression and life to sound. In the world of analogue synthesis, control-voltage modulation is a primary tool in the creation of its classic and yet-to-be-discovered sounds, timbres and textures.

Another form of modulation inherent in music is the modulation of time. The way that time is modulated (or isn’t) is primary to the nature of any musical form and its development.

When a “rate” is set for a piece of music, we fix one its most fluid and organic properties. This electronic music technique now extends to all music composed, performed and recorded using a click track or clock equivalent, accounting for much of today’s musical output across multiple genres.

This highly effective technique demands the attention of our ears. There is an irresistible perfection in the resulting order, and pleasure in the easy observability of all musical processes within predictable linear structures, including those that arc, bend, have precise and multiple subdivision or analogue shuffle.

Before music became governed by precise rates determined by clocks of one sort or another, tempo and rhythmic behaviour were more a product of a continually re-negotiated set of conditions. My experiences of playing composed and improvised music in many groups over the years (including on-going work with adults with profound and multiple learning disabilities) confirms this. Within a group there is usually a collective agreement on the general nature or feeling of the tempo.

If, for example, someone plays an unexpectedly louder or deeper sound, everyone naturally seems to adjust around it. This is usually an act of re-balancing as if the sound has exerted an increased gravitational pull on the actions and sounds other people are making. Someone may choose to play their next sound quicker and sharper. Another person’s response may be to wait and find a space for a quiet sound whilst somebody else decides to drop out entirely for the next passage etc. Musicality seems to enter at the point where there is a collective expression of balance, whatever its character happens to be.

Tempo is therefore more of a shared context for being expressive with time than a diktat. Its nature is informed by a conscious and vibrational connection between the participants in an “Einsteinian” cosmos where the ticking rate of a clock or the tempo of the music is dependent on the motion and interpretation of each observer or participant.

My interest in time modulation techniques in an analogue system is not an attempt to emulate the way that live musicians play and react, but rather to discover new relationships and rhythmic behaviours only possible through the medium of voltage-control processing and distribution.

A synthesizer cannot “hear” itself, or another synthesizer, but does “behave” or produce responses derived from its evolving voltage state in relation to itself and to any others it shares control voltages with. Voltage becomes the analogue of physical vibration as the underlying connective tissue determining the music’s character. Voltages responsible for controlling time can be made to be modifiable and subject to other values expressed in voltage terms, in order to create time modulations.

The alarms heard in Hush/Test (Audio 1–2), are controlled by two 8-step analogue sequencers. The sequencers have a voltage input and are connected for cross-modulation purposes. This causes the behaviour of one sequencer to affect the other. Each are set at different rates with random values. The sequencers are each powered by a 9-volt battery, with their voltage output connecting directly to the battery terminals within each smoke alarm.

In each example we can hear a tussle in the resulting music as each sequencer tries to exert its influence over the other in a struggle for supremacy. Every sound, silence or anything in between that each alarm makes expresses the nature of this struggle. Simultaneous relationships have been made between the responses of each alarm in amplitude, pitch, duration of events and the spaces between them. Timing, tempo and phrasing of the audio material become dimensions of these relationships.

The sound of a smoke alarm is not designed to be listened to; rather its aim is to get you as far away from it as soon as possible. By processing and redistributing the voltage going to the alarms we can create a hyper-detailed ambient landscape of shifting rhythmic patterns and timbres that invite close listening, the antithesis of the device's original function.

In Shelf Life 13 (Fig. 1, Audio 3), two 9-volt Quad-Nand Oscillator devices (Ted Dexter, Crowphonics, UK) were used, each with four heterodyning oscillators, being controlled by the same sequencer arrangement as described in the previous examples. The audio output of each device is hard panned left and right to the mixing console.

The tussle between the sequencers here has produced a relatively stable state that appears to repeat, albeit with some drift. The musical phrasing is full of aggressive push-pull tension, reflecting the voltage state. The tempo and movement within the music is elastic and unquantized.

In Davestation Studies (Audio 4–7), a single Jump Step sequencer provides a voltage signal (no gates) to three oscillators and a voltage-triggered, 4-voice drum synthesizer (Nord Drum). This setup produces non-linear sequences by modulating the distance between three sets of points within an 8-step range, giving six points between which the signal jumps. What jumps where and the nature of the resulting sequence are derived from the combination of these three distances. The amplitude of any of the eight points can be set individually, as with any other sequencer. The Jump-Step is powered by a single 9-volt battery. There is an onboard potentiometer that simulates degenerating battery life, resulting in highly unpredictable sequencer behaviour.

The sequencer output to the drum synthesizer is modified by an audio delay module capable of processing DC control voltages. The delayed voltages are expressed at four individual analogue outputs, each of which is used as a trigger for an individual drum voice. The delay module is able to modify the input voltage with delay-type functions, i.e. time, feedback, etc. Delay-type behaviour is applied to the sequencer output and then converted to four individual drum triggers. This produces many and varied extrapolations of the primary voltage source, all of which have crucial but modified relationships to the other oscillators in the system sharing the unmodified sequencer output.

Fluid evolving contrapuntal arrangements result, with the tempo free to expand and contract as the rhythmic centre of gravity swings back and forth. The feeling is that the elements are in a continual process of self-balancing, analogous to the nature of human musical interaction, but essentially producing results that are idiomatic to, and perhaps only practically achievable through the medium of voltage-controlled electronics.

Setting a rate or BPM for a piece of music accepts an absolute notion of time, a notion that Einstein’s Theory of Relativity has long disabused us of. It is ironic that the quantization of time has emerged to dominate music æsthetics in the 21st Century, 60 years after the death of Einstein. For me, the clock is as irrelevant to the metaphysics of music as it is to the fundamental laws of the universe.

I have presented just a few examples here using fairly crude but effective methods. No doubt there are an infinite number of techniques to discover in the control voltage domain, with which to further explore the subject of time modulation.