Abnormal

This work is made, and the filter which replaced the noninverting amplifier of the bandpass filter of a Sallen-Key circuit to the state variable filter was evaluated. The bandpass filter in the Sallen-Key circuit is referred to as filter 1, while the state variable filter is referred to as filter 2. In the previous iteration, the center frequency of filter 1, which corresponds to the cutoff or center frequency of filter 2, was controlled by an analog photocoupler. In this instance, the sensitivity of filter 2 is controlled using an analog photocoupler. However, to improve the timbre, the center frequency of filter 1 is controlled using a variable resistor. The control signal input into this analog photocoupler is generated through the frequency division of the pulse width modulation signal from the input, accomplished by a binary counter, and then inverted using an inverter. When there is no input signal, the sensitivity of filter 2 is attenuated by the output signal of the inverter. Furthermore, to manage oscillation in this filter configuration, the output signal of filter 2 is fed into filter 1, adjusting the output voltage using a variable resistance. By controlling the sensitivity of filter 2 through an analog photocoupler, the resulting timbre exhibits percussive qualities. This work introduces a novel auditory experience, amalgamating harsh and rhythmic noise elements. A four-channel input mixer was also developed, contributing to and enhancing the sound quality.