DIGITAL FILTER DEVICE FOR ELECTRONIC MUSICAL INSTRUMENT

摘要

PURPOSE:To prevent occurrence of overflow in digital filter operation. CONSTITUTION:A filter coefficient epsilon to be given to a digital filter operation circuit 12 from a filter coefficient generating circuit 10 is changed and controlled in accordance with a resonance value Q of a filter detected by a resonance value output device 9. When the resonance value Q is set to a large value, overflow is prevented in a filtering operation of the digital filter operation circuit 12 by setting a filter coefficient value epsilon small which decides amplitude of waveform data outputted from the digital filter operation circuit 12 and setting amplitude of waveform data outputted from the digital filter operation circuit 12 so that it does not exceed amplitude of waveform data inputted from a waveform generating circuit 11.