Módulos para síntese subtrativa analógica de áudio com efeitos digitais

Abstract

Synthesizers are musical instruments widely used in various musical genres due to their versatility and ability to provide different sounds. Since popularization and widespread commercialization in the 1960s, synthesizers have experienced significant technological and conceptual advances. Recently, especially since the 1990s, it is possible to state that the community has consolidated an appreciation of the synthesizer not only as a musical instrument but as a tool for exploring new sound possibilities. In this context, modular synthesizers that employ subtractive synthesis gained much space among theorists and professional musicians. This work presents modules’ development, construction, and tests for the subtractive synthesis of audio and digital effects. The subtractive synthesis is obtained through the generation of signals by a voltage-controlled oscillator (VCO), and in the sequence, these signals are submitted to a voltage-controlled filter (VCF). The developed VCO uses the JSC ALFA integrated circuit, model AS3340, and provides triangular, sawtooth, and rectangular/pulse waveforms with adjustable frequencies (through knobs) and modulable (through external signals). For the VCF, the AI Synthesis module, model AI004 OTA, is used, which enables high-pass and low-pass filtering, with an adjustable cutoff frequency (through a knob) and modulable (through external signals), in addition to enabling resonance control (quality factor 𝑄). The digital effect implemented was reverberation, using the development board of the digital signal processor model FXCore, from the manufacturer Experimental Noize. This effect has the following parameters: reverberation time, diffusion, damping, and mixing level. The analysis of the functionality and behavior of the modules was initially carried out individually, using oscilloscopes and function generators, in addition to the acquisition of audio files of the generated sounds. For testing the modules together (integration), audio files of the generated sounds were acquired. The project obtained satisfactory results from the tests in implementing modules for subtractive modular synthesis and audio effects, thus fulfilling all the proposed objectives.