Proceedings of the International Conference on New Interfaces for Musical Expression, Baton Rouge, LA, USA, May 31-June 3, 2015 Exposing the Scaffolding of Digital Instruments with Hardware-Software Feedback Loops Andrew P. McPherson Victor Zappi Centre for Digital Music Media and Graphics Interdisciplinary Centre Queen Mary University of London University of British Columbia London, United Kingdom Vancouver, BC, Canada
[email protected] [email protected] ABSTRACT transistors produce roughly equivalent results in linear am- The implementation of digital musical instruments is of- plification, but their sound when pushed into distortion is ten opaque to the performer. Even when the relationship noticeably di↵erent, such that tube amplifiers remain dom- between action and sound is readily understandable, the inant despite cost and practical shortcomings. internal hardware or software operations that create that Similarly, in the 19th century, the high-tension steel strings relationship may be inaccessible to scrutiny or modifica- in the piano were the means to an end of creating loud tion. This paper presents a new approach to digital in- and sustained tones, but the design also makes possible strument design which lets the performer alter and subvert John Cage’s prepared piano, the bowed ensemble pieces of the instrument’s internal operation through circuit-bending Stephen Scott, and electromagnetic actuation techniques [3, techniques. The approach uses low-latency feedback loops 14]. A hypothetical digital piano which perfectly emulated between software and analog hardware to expose the in- the sound and feel of an acoustic grand would nonetheless ternal working of the instrument. Compared to the stan- be more restrictive than the original, since these and other dard control voltage approach used on analog synths, al- interventions would be impossible.