[Column] Modular Drone / Experimental Drones

Column en Buchla Drone Experimental Modular

16 Dec 2025

[Column] Modular Drone / Experimental Drones

Introduction: Experimental acoustic space constructed by sustained sounds

Text: mmr｜Theme: Positioning modular drones as an intersection of the history of acoustic technology, history of musical instruments, and compositional thought, and systematically organizing their formation and development.

Modular Drone/Experimental Drones (hereinafter referred to as “modular drones”) is a trend of acoustic experiments centered on sustained sounds, and has developed in close connection with the structural characteristics of modular synthesizers. A continuum of sound that does not assume a melody or beat creates time by minutely changing elements such as pitch, timbre, intensity, phase, and spatial arrangement. This music emphasizes “existence” rather than “progression,” and changes appear as state transitions rather than events.

What is important in modular drones is that the object of listening is not the persistence of a single sound, but the process by which multiple signal paths interact with each other. Modular synthesizers allow you to freely connect elements such as oscillators, filters, amplifiers, envelopes, LFOs, and random voltages, making the boundaries between stability and instability, control and chance audible. By combining this characteristic with the form of a drone, an acoustic expression that expands the sense of time was created.

Historical premises of the drone concept

The concept of a drone existed before electronic music. Its prototypes include sustained bass in traditional music, sustained harmony in religious music, and stationary sounds in mechanical and environmental sounds. In the history of Western music, the sustained sounds of medieval organums and bagpipes have played a role in spatially supporting music.

In the 20th century, industrialization and electrification progressed, and persistent mechanical noise permeated our daily environment. This environmental change provided an opportunity for musicians to change the way they perceived sound. From a melody-centered view of music to a focus on the texture and temporal duration of the sound itself, drones were redefined as an important element of experimental music.

Combination of electroacoustic and sustained sounds

In the early days of electronic music, sustained tones were the element that most directly indicated the characteristics of electronic sounds. Unlike physical instruments, the continuous waveform produced by an oscillator can theoretically be sustained indefinitely. This characteristic made it possible to break away from the traditional musical structure that divides time into beats.

In tape music and electroacoustic music, attempts were made to sustain sounds over long periods of time or make gradual changes, but there were limitations to real-time control. This is where the concept of voltage control comes into play. The mechanism for controlling pitch and timbre using voltage became the basis for later modular synthesizers, and provided a means to dynamically change sustained sounds.

Establishment of modular synthesizer

Moog system structure and philosophy

The Moog synthesizer was designed around a voltage-controlled oscillator and filter, with a relatively clear signal flow. The structure, which was designed to be connected to a keyboard and focused on pitch stability and reproducibility, played a role in establishing electronic sound as a playable instrument.

This structure is also important in drone production. A stable oscillator forms the basis of a sustained sound over a long period of time, and the internal structure of the sound changes over time through gradual modulation of the filter and amplifier. Moog-style modular equipment provided a suitable environment for producing controlled sustained sounds.

Non-keyboard thinking of Buchla system

The Buchla synthesizer had a design concept that did not assume a keyboard, and strongly set out a direction in which voltage itself could be used as a material for composition. Complex modulations, random voltages, compound oscillators, etc. create unpredictable sonic behavior.

This property is particularly important in modular drones. Fluctuations in timbre and amplitude become more foregrounded than the stability of pitch, and the drone is heard not as a fixed sound but as a constantly changing field. Buchla’s approach allowed for a balance of control and chance to be built into the musical structure.

“Moog”s stable persistence and Buchla”s variable persistence indicate two basic directions for modular drones.”

Acoustic characteristics of modular drones

Persistence and differential change

The core of modular drones is the subtle changes that occur over a long period of time. The extremely slow settings of the LFO and envelope, and the slow modulation of random voltages make the sound feel almost stationary, yet constantly changing.

This change appears not as a melodic development but as a continuous modification of acoustic parameters. The listener experiences the process of change rather than the moment of change.

Feedback and self-generation

In a modular environment, it is easy to build feedback that returns outputs to inputs. Feedback leads sound to a self-generating state, producing behavior beyond the creator’s intentions. Through this self-generation, drones do not simply hold sound, but present the behavior of a sound system itself.

Production techniques and patch ideas

In the production of modular drones, the patch itself is equivalent to the composition. The number of oscillators, the combination of waveforms, and the complexity of the modulation path determine the density and sense of time of the music.

The linear signal path of the Moog system often uses a structure in which multiple modulations are layered on a stable fundamental tone. On the other hand, in the Buchla system, compound oscillators and function generators are interconnected, creating a state in which the distinction between pitch and timbre is ambiguous.

“A patch functions not as a musical score, but as a device containing time.”

Listening experience and time perception

Modular drones directly affect the listener’s sense of time. Because there are no beats or nodes, time is perceived internally rather than measured externally. By paying attention to changes in sound, the listener becomes immersed in the acoustic space and experiences duration itself.

Relationship with other genres

Modular drones share many elements with ambient, minimal music, and experimental electronic music, but are unique in that they foreground the device nature of modular synths. The system is more important than the music, and the process is more important than the result.

Chronology: Main stages of modular drone formation

1950s: Exploration of sustained sound in electronic acoustics
1960s: Establishment of modular systems by Moog and Buchla
1970s: Increase in long-duration drone works in experimental music
1990s: Modular regression and reappraisal of drones
2010s: Expansion of experimental drone production due to the spread of Eurorack

Structure diagram: basic modular drone signal path

flowchart TD OSC["Oscillator"] --> FIL["Filter"] FIL --> AMP["Amplifier"] LFO["LFO"] --> FIL LFO --> AMP

Example of nonlinear structure

flowchart TD OSC1["Oscillator A"] --> MIX["Mix"] OSC2["Oscillator B"] --> MIX MIX --> AMP["Amplifier"] AMP -->|Feedback| FIL["Filter"] FIL --> MIX

Advanced acoustic analysis: internal structure of sustained sounds

Harmonic structure and spectral variation

The sustained sound in modular drones is not created by maintaining a single frequency, but by slow fluctuations in the overall overtone structure. The choice of oscillator waveform (sine, triangular, sawtooth, rectangular) determines the initial spectrum, but over time the harmonic distribution is constantly reorganized as the filter cutoff, resonance, and drive amount change.

Particularly in a modular environment, the filter itself is often used in a state close to oscillation, and the boundary between fundamental and harmonics becomes blurred. As a result, the drone is perceived as a transition in spectral density rather than a collection of pitches.

“In modular drones, the pitch is not a fixed point, but acts as the center of gravity of the spectrum.”

Phase interference and beat phenomenon

By subtly detuning and layering multiple oscillators, a low-frequency beat is generated due to phase interference. This beat is not so clear that it is recognized as a rhythm, but it creates a periodic expansion and contraction within the sound.

In a stable Moog-style VCO, this beat has a relatively predictable period. On the other hand, in oscillations derived from the Buchla system or function generators, the period itself fluctuates, and the beat appears as irregular pulsations. This difference has a direct impact on the drone’s sense of time.

Spatiality and extended listening

Stereo placement and pseudo spatial movement

Modular drones often use extremely slow panning modulation. By shifting the left and right localization every few minutes, the sound is perceived not as a fixed entity in space, but as a floating sound field.

Furthermore, by applying different spectral changes to the left and right sides, the sound image does not have a clear position and is diffused throughout the space. This dismantles the traditional listening position of receiving music from the front, creating an experience closer to that of environmental sounds.

Fusion of reverberation and sustained sound

Long reverberation times are not just an effect in drones, but function as part of the acoustic structure. When the original sound and the reverberant sound cannot be separated, the start and end of the sound become ambiguous, and the sustained sound takes on an infinity.

“Reverberation does not decorate sound, but works as a device that stretches time itself.”

Redefining control voltage and composition act

From score to system

In modular drones, composing is not the act of writing musical notes, but the act of designing the relationship between control voltages. Decisions about which parameters to fix and which elements to allow to fluctuate determine the character of the music.

In this sense, a modular synth is both a musical instrument and a self-contained sound system. Rather than directly manipulating the sound, the creator sets the conditions under which the sound continues to be generated.

Balance between autonomy and intervention

Fully autonomous patches exhibit unpredictable changes over time. On the other hand, by adding human intervention, the directionality of the sound can be adjusted. The balance between these two is an important decision point in the production of modular drones.

“Intervention is done as a dialogue with the system, not as a control”

Performance and installation

Sustained sounds in a live environment

In the live performance of modular drones, the temporal length itself becomes a component. There is no requirement for the development to take place in a short period of time, and the process by which the acoustic space gradually changes in quality is shared.

The presence of visually exposed patches and cables emphasizes the instrumental aspects of how sound is produced.

Compatibility with exhibition space

Sustained sound has a high affinity with galleries and installation spaces. Visitors do not need to enter and leave the acoustic space at any time to hear the entire thing. Modular drones have a structure that can withstand fragmented listening.

Monumental Movement Records perspective

In the context of Monumental Movement Records, modular drones are positioned not just as experimental music, but as a sonic practice that critically presents time, structure, and instrumentality. Here, long durations and differential changes are more valuable than flashy changes or immediate effects.

Vocabulary is descriptive rather than decorative, and structural analysis is prioritized over emotional expression. Sound is both a sensory object and a medium for thought.

“Sustained sounds exist not as a background, but as a foreground that occupies your thoughts.”

Expanded chronology: Deepening of technology and thought

Late 1960s: Generalization of voltage control concept
Early 1970s: Increase in long-duration works and improvisational practices
1980s: Intersection of digital control and analog sustained sound
2000s: Proliferation of DIY modular and experimental drones
2020s: Establishment of sustained sound culture based on instrumentality

Conclusion: Music as a device, sound as time

Modular drone is a practice that presents music not as a series of events, but as time itself. Moog-like stability and Buchla-like variability, and the countless possibilities that exist between them, are made audible through the form of sustained sounds.

What is important in this music is not what happens, but what state is maintained and how it changes. Modular drones are a form of contemporary musical practice that demonstrates the inseparability of device, time, and sound.