Intermodulation Distortion Analysis of a Guitar Distortion Pedal With a Starving Circuit

Inui M, Hamasaki T, van der Veen M. Intermodulation Distortion Analysis of a Guitar Distortion Pedal With a Starving Circuit. J Audio Eng Soc. 2021;69(1/2):80-103. doi:10.17743/jaes.2020.0068

@article{Inui2021_21018,
  author = {Inui, Masaki and Hamasaki, Toshihiko and van der Veen, Menno},
  title = {{Intermodulation Distortion Analysis of a Guitar Distortion Pedal With a Starving Circuit}},
  journal = {Journal of the Audio Engineering Society},
  volume = {69},
  number = {1/2},
  pages = {80--103},
  year = {2021},
  month = jan,
  publisher = {Audio Engineering Society},
  doi = {10.17743/jaes.2020.0068},
  url = {https://doi.org/10.17743/jaes.2020.0068}
}

TY  - JOUR
TI  - Intermodulation Distortion Analysis of a Guitar Distortion Pedal With a Starving Circuit
AU  - Inui, Masaki
AU  - Hamasaki, Toshihiko
AU  - van der Veen, Menno
T2  - Journal of the Audio Engineering Society
J2  - J. Audio Eng. Soc.
VL  - 69
IS  - 1/2
SP  - 80
EP  - 103
PY  - 2021
DA  - 2021/01/06
DO  - 10.17743/jaes.2020.0068
UR  - https://doi.org/10.17743/jaes.2020.0068
PB  - Audio Engineering Society
LA  - en
AB  - Despite the recent trend of digital transformation in the music industry, the popularity of guitar effects pedals (GEPs) designed with analog components has not declined. This paper describes the complexity of the nonlinear characteristics of the analog circuitry in a distortion pedal, which originates not only from clipping diodes but also from the integrated operational amplifier itself. It is well known that variation in the supply voltage of a distortion pedal influences its sound. Based on this phenomenon, we have designed a voltage-starving circuit to control various distorted transfer functions depending on the frequency. Particular attention is given to the difference between odd and even nonlinearity in the mechanism of generating intermodulation distortion (IMD) for two-tone dissonance and consonance. These transfer functions are analyzed in detail using a 9th-order polynomial approximation. As a result, all peaks of the intermodulation frequencies are successfully identified in a complex spectrum. Furthermore the spectral shape of the measured IMD peaks is reproduced with an error of less than 50 dB by the simulation of their approximate formula.
ER  -