A Bandpass Twin-T Active Filter Used in the Buchla 200 Electric Music Box Synthesizer

This paper analyzes an unusual active bandpass filter employed in the Buchla Model 295 10 Channel Comb Filter, a synthesizer module developed as part of the Buchla 200 Electric Music Box by Donald Buchla. The filter consists of a peculiar rearrangement of elements in a classic Twin-T configuration; to our knowledge, it has not been previously addressed in the literature. As an example, we explore its specific application in the Model 295.