SHARP CUTOFF FILTER MODEL 191

In the Buchla paradigm, filters are not usually at the forefront of any patch. The tenets of what would eventually be considered West Coast Synthesis were not about filtering sounds, but adding textural elements with modified waveforms. This was apparent in modules like the 158 Dual Sine Saw Oscillator, where each oscillator could be shaped into different waveforms during the patch.

The Sharp Cutoff Filter is a “clinical” representation of filters as most test equipment had to offer at the time. There is no resonance to be found anywhere on this double wide module, yet has one of the most pronounced and flexible sounds in terms of Buchla filters.

191 REPLICATION

The 191 is a very complicated build, with two stacked boards. Even more confusing is the tuning of each filter. Luckily, as part of our data mining expedition, we were able to find the tuning sheets along with parts placement diagrams. There are many parts on the 191 that do not exist on the schematic, and the whole module is covered on the back with a blank aluminum plate, possibly to suppress noise by shielding against RF interference.