Effect adder circuit with a coefficient smoothing circuit for an electronic musical instrument

摘要

An electronic musical instrument has an effect adder circuit for adding sound effect which is controlled by coefficients for filtering operations and amplitude control. The instrument also has a smoothing circuit for smoothly changing a coefficient to a target value by interpolating between the coefficient current value and the coefficient target value to be updated. Smoothing is implemented by repeatedly adding or subtracting a given value to or from the coefficient current value until it reaches the coefficient target value. The precision of the smoothing coefficient depends on the word length of the coefficient current value so that the word length of the coefficient target value can be smaller than that of the coefficient current value. The effect adder circuit and smoothing circuit are independently provided to operate in parallel.