Equalizadores para pré-amplificador valvulado

Abstract

This work presents the study, design, simulation, and implementation of passive equalizers applied to the preamplification stage in vacuum tube amplifiers for electric guitar and bass. The research begins with a bibliographic review on audio preamplification and its relevance in vacuum tube amplifiers. Next, the principles of analog filters, their topologies, and frequency responses are discussed, with emphasis on passive filters. The operation of equalizers within the preamplification chain of vacuum tube guitar and bass amplifiers is also analyzed, addressing circuit types, parameters, and their effects on the signal. Using MATLAB and LTspice, different equalization arrangements are simulated to evaluate their characteristics. Finally, two equalizer circuits—one for guitar and one for bass—are designed and implemented on a test bench, and their experimental results are compared with theoretical and simulated responses, allowing the validation of the presented models.