Envelope Identification Method for Guitar Amplifier Modelling with Wiener-Hammerstein Models

T. Fernandes (NOVA School of Science and Technology, Portugal), N. Paulino (UNINOVA-CTS ,NOVA School of Science and Technology, Portugal)

Vacuum tube guitar amplifiers are regarded as the best in terms of sound, and the clear choice for many professional musicians. Their warm sound is featured in countless records since the 1950s and has shaped music as we know it today. Amplifiers with other technologies have tried to reproduce or emulate this characteristic sound, with varying degrees of success. Nowadays, digital signal processing is becoming increasingly more powerful, and methods are being studied to digitally emulate this desired sound. This paper describes a modelling method using envelope identification to measure the frequency response, with the goal of adapting a Wiener-Hammerstein model to closely replicate the amplifiers' behavior. This model consists of two filters, with a non-linear block between them, the latter was optimized through a genetic algorithm. The resulting models for different presets of a BOSS Katana, were evaluated in the time and frequency domains, as well as through listening tests, demonstrating that the system was able to accurately model different types of amplifiers, with the whole modelling process taking approximately 5 minutes.