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Explore the digital emulation of analog valve amplifiers using Wave Digital Filtering techniques. Learn about modeling non-linear characteristics and the successful emulation process. Discover future work on real amplifier distortion modeling and WDF implementation on ARM-based embedded systems. Questions? Thank you! 8 Relevant
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Digital Modeling/Implementation of Valve Amplifiers Authors: Cody Frye & Mitchell Gould Advisor: Dr. Yufeng Lu Department of Electrical and Computer Engineering May 4th 2019
Agenda Introduction Motivation System Description Methods Triode Valve Numerical Analysis WDF Results Conclusion
Introduction Significance of valve amplifiers Pros of valve amplifiers Smooth clipping Warm tone characteristics Cons of valve amplifiers Weight Heat Cost
Motivation Affordable and Convenient Variety of Amplifiers to choose from Digital components reduce overall size
Methods Frequency Bin / Lookup Table Method Model Individual Blocks of System Wave Digital Filtering
Method 1 (Frequency Bin Method) Separate input signal into Multiple frequency bins bandPass Filters NonLinear transfer function represented by L.U.T.s Sum all the bins together
WDF Method (Method 2) Wave quantities A = incident wave B = reflected wave A = V + RI [eq. 1] B = V - RI [eq. 2] V = (A+B) / 2 [eq. 3] I = (A-B)/2R [eq. 4]
WDF Method (Method 2) WDF port adapters WDF components
Triode Valve Numerical Analysis Nonlinear Triode Currents as a Function of Vgk and Vpk Model of Triode Triode Amplifier
Triode Valve Numerical Analysis Norman Koren’s Equations Leach’s Equations
Leach’s model Vpk = 350 Vgk = 2 Vpk = 300 Vpk = 250 Vgk = 1 Vpk = 200 Vpk = 150 Vgk = 0 Vpk = 100 Vgk = -1 Vpk = 50 Vpk = 0 Vgk = -2 Vgk = -3
Koren’s model Vgk = 1 Vpk = 300 Vpk = 250 Vpk = 200 Vgk = 0 Vpk = 150 Vpk = 100 Vpk = 50 Vpk = 0 Vgk = -1 Vgk = -2 Vgk = -3
WDF 1st Order LPF RC LPF Circuit WDF Equivalent
WDF 1st Order Filter PSpice simulation results for 1st Order LPF WDF simulation results for 1st Order LPF
WDF Single Triode Stage Amplifier Single Stage Circuit Single Stage WDF equivalent
WDF Single Triode Stage Amplifier Single Stage Circuit Single Stage WDF equivalent
WDF Single Triode Stage Amplifier Single Stage Circuit Single Stage WDF equivalent
WDF Single Triode Stage Amplifier Single Stage Circuit Single Stage WDF equivalent
WDF Single Triode Stage Amplifier Single Stage Circuit Single Stage WDF equivalent
WDF Single Triode Stage Amplifier PSpice Triode Stage WDF Triode Stage
WDF Single Triode Stage Amplifier WDF G Chord results
Conclusion In this project, a digital emulation of an analog valve amplifier has been designed. The non-linear characteristics of valve amplifier has been modeled. The overall response of the valve amplifier has been successfully emulated using Wave Digital Filtering technique.
Future Work Model distortion characteristics of real amplifier using cascaded amplification stages and self-tuning algorithm Implement WDF system including R-Adapter on an ARM-based embedded system
Questions? Thank you!
[1] M. Karjalainen and J. Pakarinen, "Wave Digital Simulation of a Vacuum-Tube Amplifier," 2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings, Toulouse, 2006, pp. V-V. doi: 10.1109/ICASSP.2006.1661235 [2] S. D Angelo, J. Pakarinen, and V. Välimäki. New Family of Wave-Digital Triode Models. IEEE Trans. Audio, Speech, and Lang. Process., vol. 21, no. 2, pp. 313 321, February 2013. [3] Bohumil Psenicka, Francisco Garciá Ugalde, and Andrés Romero, “Design of Wave Digital Filters,” Universidad Nacional Autónoma de México, December 2009 [4] M. Antosová and V. Davídek, “Design and Implementation of Wave Digital Filters,” Department of Circuit Theory, Czech Technical University, Prague, Czech Republic September 2001 [5] Ivan Cohen, Thomas Hélie. Measures and Models of Real Triodes, for the Simulation of Guitar Amplifiers. Société Française d’Acoustique. Acoustics 2012, Apr 2012, Nantes, France. 2012. [6] Jyri Pakarinen, David T. Yeh, “A Review of Digital Techniques for Modeling Vacuum-Tube Guitar Amplifiers,” Helsinki University of Technology, Helsinki, Finland, Report, August 2009. [7] James Siegle, “DSP Implementation of a 1961 Fender Champ Amplifier,” B.S. Thesis, Dept. Elect. Eng., Bradley University, Peoria, Illinois, U.S., 2003 [8] Marshall Leach, “SPICE Models for Vacuum-Tube Amplifiers,” Georgia Institute of Technology, Atlanta, Georgia, U.S., Report, March 1995