Bring Order Out Of Chaos

The developed synthesizer system can control a filter's cutoff frequency, center frequency, sensitivity, phase/frequency of the Wien bridge oscillator, etc. with the universal serial bus (USB) device. A filter can be manually operated as well. A USB device connects with a computer via a USB interface and outputs pulse width modulation (PWM) and control signals. A PWM signal is a filter's input signal that is input via a line selector. With a filter's binary counter, the frequency division of the PWM signal can be carried out and also be used as a control signal. The control signal output from a USB device is input into a filter directly. This work tried to produce the timbre of a filter using a new control signal. A USB device outputs five PWM signals that include random signals, modulated signals by low-frequency oscillator, and rhythm signals. Each PWM signal is a different type of signal. Four PWM signals are input into a line selector, and one is input into a filter. A line selector changes the connection of a PWM signal and filter. The output signal of a line selector is set to P0, P1, P2, and P3. For example, when the input signal of a filter is P0, in addition to the conventional control signal, P1 is used as a control signal. In order that a line selector may change the connection between a PWM signal and filter, the type of PWM signal for P0 and P1 is changed. In this way, the timbre changes in various ways, and the five PWM signals can be performed asynchronously using a computer. Therefore, the timbre of the filter changes to irregular. Furthermore, because these signals are more complicated than the control signal output from a USB device, the filter can create a novel timbre. To evaluate the timbre by a control signal, the manual operation of the filter was not carried out.