A Quadric Surface Model of Vacuum Tubes for Virtual Analog Applications

Authors
Riccardo Giampiccolo1, Stefano D'Angelo2, Alberto Bernardini1, Augusto Sarti1
Status
Published in Proceedings of the 26th International Conference on Digital Audio Effects (DAFx23), pp. 296–303, Copenhagen, Denmark, September 2023
Awards
Best Poster Award
1
Politecnico di Milano, Milan, Italy
2
Orastron Srl, Sessa Cilento, Italy
BibTeX
@inproceedings{giampiccolo2023quadric,
  title={A Quadric Surface Model of Vacuum Tubes for Virtual Analog Applications},
  author={Giampiccolo, Riccardo and D'Angelo, Stefano and Bernardini, Alberto and Sarti, Augusto},
  booktitle={Proc. 26\textsuperscript{th} Intl. Conf. Digital Audio Effects (DAFx23)},
  pages={296--303},
  month={September},
  year={2023},
  address={Copenhagen, Denmark}
}

Abstract

Despite the prevalence of modern audio technology, vacuum tube amplifiers continue to play a vital role in the music industry. For this reason, over the years, many different digital techniques have been introduced for accomplishing their emulation. In this paper, we propose a novel quadric surface model for tube simulations able to overcome the Cardarilli model in terms of efficiency whilst retaining comparable accuracy when grid current is negligible. After showing the model capability to well outline tubes starting from measurement data, we perform an efficiency comparison by implementing the considered tube models as nonlinear 3-port elements in the Wave Digital domain. We do this by taking into account the typical common-cathode gain stage employed in vacuum tube guitar amplifiers. The proposed model turns out to be characterized by a speedup of 4.6× with respect to the Cardarilli model, proving thus to be promising for real-time Virtual Analog applications.

Implementation

Sound samples