Electric guitar distortion effects unit using a Raspberry Pi

  • Renato Santos Pereira Centro Universitário Espírito-Santense
  • Rodrigo Varejão Andreão Instituto Federal do Espírito Santo

Resumo


With the advance of electronics, techniques and algorithms for digital signal processing, digital equipment has been gaining more and more space in the music scene. Micro-processed tools now generate several effects such as modulation, echo, and distortion of sounds generated by musical instruments, previously obtained only by analog units. In this context, this study aimed to develop aprototype of distortion effects unit using a Raspberry Pi (a low-cost small single-board computer) and affordable electronic components. Therefore, five nonlinear functionswere used, four of which are present in the literature andone of them was originally developed by the authors. These functions model the behavior of an active element (suchas transistors, valves, and operational amplifiers), which when they exceed their amplification thresholds produce distortions in the audio signals. Throughout this article, all the steps in the development of the analog circuits for signal acquisition and output will be presented, as well as the simulation and implementation of the functions in the microcontroller. At the end, with the finished prototype, the frequency response analysis is performed and the sound results achieved by the algorithms is compared with each other and with other distortion units.

Palavras-chave: Digital Sound Processing

Referências

Nicolau Leal Werneck. Análise da distorção musical de guitarras elétricas. Dissertação (mestrado), Universidade Estadual de Campinas - Faculdade de Engenharia Eletrica e de Computação, 2007.

Neigmar de Souza. Guitarra elétrica: um ícone na cultura pop do Século XX. Revista Vernáculo, 2002.

Thomaz Chaves A. Oliveira, Gilmar Barreto, and Alexander Mattioli Pasqual. Modelagem computacional de efeitos de distorções não lineares para guitarra elétrica. Revista Brasileira de Computação Aplicada, pages 69–84, 2013.

John G Proakis. Digital Signal Processing: Principles Algorithms and Applications. Pearson Education India, 2007.

André Wagner França. Uso de processamento digital de áudio na implementação de efeitos em instrumentos musicais. Monografia (Bacharelado em Ciência da Computação), Universidade de Brasília, 2015.

Robert A Moog. Distortion sound effects circuit, December 25 1979. US Patent 4,180,707.

Pedro Miguel Cruz and Nuno Borges Carvalho. A comprehensive analysis of the clipping effects on signals with different statistical patterns. In 2014 International Workshop on Integrated Nonlinear Microwave and Millimetre-wave Circuits (INMMiC), pages 1–3. IEEE, 2014.

David Te-Mao Yeh. Digital implementation of musical distortion circuits by analysis and simulation. Ph.D thesis), Stanford University, 2009.

Michel Doidic, Michael Mecca, Marcus Ryle, Curtis Senffner, et al. Tube modeling programmable digital guitar amplification system, August 4 1998. US Patent 5,789,689.

Julius Orion Smith. Physical audio signal processing: For virtual musical instruments and audio effects. W3K publishing, 2006.

Pierre Dutilleux and Udo Zölzer. Nonlinear processing. DAFX: Digital Audio Effects, 2004.

Renato Santos Pereira. Projeto de uma unidade de efeitos de distorção para guitarra elétrica. TCC (graduação em Engenharia Elétrica), Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo, 2020.

Andrew Gregory. Review: ElectroSmash Pedal Pi — HackSpace Magazine, 2018.

MICROCHIP TECHNOLOGY INC. 2.7V Dual Channel 12-Bit A/D Converter with SPI Serial Interface, 2006.

Renato Santos Pereira. Audio samples: Electric guitar distortion effects unit using a Raspberry Pi [Album]. https://soundcloud.com/renatostosp/sets/prototype-audio-samples, 2019.
Publicado
24/10/2021
PEREIRA, Renato Santos; ANDREÃO, Rodrigo Varejão. Electric guitar distortion effects unit using a Raspberry Pi. In: SIMPÓSIO BRASILEIRO DE COMPUTAÇÃO MUSICAL (SBCM), 18. , 2021, Recife. Anais [...]. Porto Alegre: Sociedade Brasileira de Computação, 2021 . p. 121-128. DOI: https://doi.org/10.5753/sbcm.2021.19436.