Karlheinz Essl

Inventing and Performing Live-Electronics

MAPPER Symposium
Final of the FWF-PEEK Project Études for Live-Electronics

University of Music and Performing Arts Vienna (mdw)
2 Jul 2025

Abstract | Introduction | RTC-lib | Sequitur | Coastlines | Collaborations | Outlook

Abstract

Since 1985 I have been working with computers in the fields of instrumental and electroacoustic composition, generative sound installations and multimedia performances. The computer has become an integral part of my creative process as a tool for reflection and experimentation. Instead of just using off-the-shelf software designed for mainstream use, I felt the need to program the computer myself in order to express my own ideas without being distracted by alien concepts. For me, programming is a critical method of gaining knowledge, and so the computer became a kind of mirror reflecting the consequences of my abstract thinking. This led to the development of software for musical composition and performance, mostly written in Max and distributed through my website.

In 2008 I began a series of "live electronic etudes" called Sequitur, written for various solo instruments such as violin, trombone, voice, electric guitar, or toy piano. Each piece in this 14-part cycle consists of a precisely notated score and a computer program that can be controlled by the performers. Although each score is completely individual and tailored to the specific instrument and its playing techniques, the core of the software is based on a similar algorithm with some specific variations.

A new era began in 2022, when I went through a severe creative crisis. I felt the need to start from scratch (as I had done several times in my life) to explore new and unknown horizons. This eventually led me to non-digital methods of creating music without software and computers and resulted in a shift from digital to analog.

After some frustrating experiences with commercial synthesizers that didn't allow me to realise my artistic visions, I discovered a more experimental approach with modular synthesizers and feedback systems. To explore this further, I have begun the work-in-progress Coastlines - an ongoing series of live electronic etudes documented on YouTube.

Karlheinz Essl during his lecture/recital
Photo: Stefan Polzer

Introduction

In 1991, I received a commission from IRCAM in Paris to write a piece for an ensemble with live electronics. For this piece – Entsagung for flute, bass clarinet, prepared piano, percussion and live-electronics – I used the recently completed IRCAM Signal Processing Workstation (ISPW) for real-time audio processing. It was controlled by the Patcher programming environment which would later become known as Max.

During my time in Paris, I ported my computer-aided composition library to the Patcher real-time programming environment. This has changed everything. Before, it used to take all night to calculate the score structure for a composition, which I then had to transcribe into musical notation. Now, however, I can listen to the results immediately in real time. This marked the beginning of my work with live electronics.

Real Time Composition Library (RTC-lib)

This software library is a collection of abstractions and externals for Max. It lets you experiment with various compositional techniques, including serial procedures, permutations and controlled randomness. It provides many functions that are useful for algorithmic composition, enabling composers to focus on the creative aspects rather than the technical ones.

Content of the RTC-lib 8.3
copyleft 1993-2022

The RTC-lib is available through the Package Manager of Max and runs under macOS and Windows. It comes with a Hypertext-like on-line help which provides a perfect overview of the library objects and their multiple relationships.

This library was developed during my extensive work on Lexikon-Sonate (1992 ff.), an interactive realtime composition for computer-controlled piano; a virtual endless piece that never repeats itself, and which does not require a score or a pianist.

User interface of Lexikon-Sonate 5.0
© 1993-2022 by Karlheinz Essl

Despite being conceived for a specific project, it became increasingly clear that the RTC-lib's functionalities are open and generic enough to be used by other composers in different contexts. Based on paradigms extracted from serial thinking, it does not force a particular aesthetic, but provides an environment for testing and developing compositional strategies.

Since then, I have used it for almost all of my electronic compositions, including a significant cycle of pieces called Sequitur, which features interactive live electronics with solo instruments.

Sequitur

Although each score is completely individual and tailored to the specific instrument and its playing techniques, the core of the software is based on a similar algorithm with some specific variations. This software – called Sequitur Generator – creates an electronic accompaniment from the instrument’s live input. It confronts the player with their own performance, creating a situation akin to moving in a house of mirrors where identities become blurred. Most pieces can be performed by the soloist alone. They can control the live electronics using a MIDI pedal and some keystrokes on the computer keyboard. Alternatively, the electronic part can be performed by a second musician using a MIDI controller.

User interface of Sequitur XIV
© 2008-2025 by Karlheinz Essl

The software is distributed as a standalone application, so it does not require Max to run. It generates a complex eight-part canon in real time, the temporal structure and density of which is controlled by random operations. This produces different results each time the piece is performed. Although it follows a precisely notated score, there is always an element of surprise for the musician, which emphasises their awareness and attentiveness.

Score of Sequitur XIV, page 1 © 2009 by Karlheinz Essl

Coastlines

During a general "digital detox", I was searching for new possibilities. In the archives of my studio, I stumbled upon some old analogue synthesizers that I had experimented with a long time ago, like the legendary KORG MS20.

By connecting the different modules – voltage-controlled oscillators, filters, function generators or modulators – with patch chords, one can create individual setups that define an instrument and it’s behaviour. However, apart from this welcome architectural openness, I found it difficult to realise my artistic ideas. These synthesizers have been designed for a genre of music that I'm not particularly interested in. In addition, many of them are equipped with keyboards, which is an absolute "no-go" for me, as it represents a concept of musical thinking based on notes, which does not play a major role for me in the field of experimental electronic music.

Thanks to a recommendation from my friend Gerhard Eckel, I came across the MakeNoise 0-COAST modular analogue synthesizer, which has an unusual system architecture. Neither based on the classic Moog synthesizer of the "East Coast" nor on the Buchla system of the "West Coast", it attempts to combine the best of both worlds. Although it is possible to connect a keyboard or a MIDI sequencer, that was out of the question for me anyway.

MakeNoise 0-COAST modular synth, patched for the MAPPER symposium
© 2025 by Karlheinz Essl

I have to admit that it was quite a challenge to submit to a system that I had not built from scratch. And it took me a lot of sometimes frustrating experimentation to get reasonable sounds out of this little box, because the wiring possibilities are enormous. Also, the individual control signals and parameters cannot be considered in isolation, as they are interdependent. And finally, it‘s nearly impossible to recall the state of the system which cannot be stored. Everything appears quite fragile and volatile.

During my research I discovered how feedback routings can create non-linear systems with chaotic states that sound fascinating. However, this requires constant balancing of the control signals with the countless knobs. Performing live on this newly constructed 'instrument' becomes an adventure that leaves a sonic trail: It's like riding a wild horse across the Lake Constance.

This work-in-progress called Coastlines is documented on my YouTube channel. To date, there are about 80 videos, mostly recorded in my studio. Each one demonstrates a different patching and playing method on my 0-COAST modular synthesizer. One performances took place during the MAPPER symposium at the mdw Klangtheater; it was filmed on the fly by Marko Ciciliani.

Collaborations

The performative use of live electronics emphasises the instrumental aspect of this field. Naturally, this has resulted in further collaborations with other musicians, leading to the formation of the experimental improvisation ensemble m!ndf*kc, featuring Herbert Lacina on 12-string bass, Edward Reardon on grand piano and myself on modular electronics. A live recording of a concert at the Viennese jazz club Porgy & Bess was released by Nachtstück Records in 2025 and as a documentary video on YouTube:

In addition to the 0-COAST, I also use self-developed modular Eurorack systems in the improvisation duo Los Modulinos with the Czech composer Otto Wanke. For this project, I perform also with tactile controllers such as joysticks and touch surfaces, as well as gestural devices similar to Theremin antennas.

Outlook

But this is not the end of my story. There's more to come!

References

Stockhausen, K.: "...wie die Zeit vergeht…". In: H. Eimert (ed.) die reihe (3), pp. 13 ff. Universal Edition, Vienna (1957)

Essl, K.: Real Time Composition Library for Max. Eine Softwarebibliothek zum Design von Strukturgeneratoren. In: Essl, K.: Strukturgeneratoren. Algorithmische Komposition in Echtzeit. Beiträge zur Elektronischen Musik (5,) ed. by R. Höldrich and A. Weixler, IEM Graz (1996)

Essl, K.: Lexikon-Sonate. An Interactive Realtime Composition for Computer-Controlled Piano. In: Musik im virtuellen Raum. KlangArt-Kongress 1997, Osnabrück (2000)

Essl, K.: Sequitur for various solo instruments and live-electronics (2008-2010)

Essl, K.: Coastlines (2022 ff.) sound performances for 0-COAST modular synthesizer

Essl, K.: From Digital to Analog. In: SoundingFuture (2024)

Essl, K. and Uhrmann, E.: The Coastline Sessions (2022 ff.)

Essl, K., Lacina, H. and Reardon, E.: m!ndf*kc (2023 ff.)

Essl, K. and Wanke, O.: Los Modulinos (2025 ff.)

Essl, K.: reJOYce (2025)

Updated: 24 Aug 2025