The intent of the Fixed Filter Bank was to enhance the primary signal of the synthesizer, adding harmonics at specific frequencies or removing them at others. Some wanted completely new and never before heard sonic landscapes to push themselves and their audiences into new worlds of musical experience. Others wanted to create more traditional and familiar sounds, while still pushing the boundaries and making use of the new voltage controls, features, and character not available in a traditional “un-plugged” instrument. Some wanted both.
Enter the new reimagined P915 MEDUSA Fixed Filter Bank. A filter which adds subtle or not so subtle resonances to the signal or removing frequency bands altogether. This process, when mixed in with the unaltered, “dry” signal, can mimic the actual behavior of a traditional instrument. It can also act on its own as a unique and creative source of sound shaping possibilities not available in other filter structures.
Several hardware clones of the 915 were being introduced primarily based on active filter design structures. The original structure of the 915 used simple inductors, capacitors, and resistors for the filter cells, which delivered a subtle interactions were lost in the sterile world of semiconductors. However, a design based on The original structure was begging to be pursued. A source for inductors was found, the schematics were scrutinized, errors in the schematics from copying were weeded out, circuit boards were designed, and the result was an extremely accurate and faithful copy of the original response as published by Moog in their original owner’s manual.
With a solid hardware version in hand, a software model could begin. Careful characterization and measurement of the hardware, along with a software model keeping the unique structure of the Moog FFB with its two stage design, has resulted in a software model that faithfully matches and follows that of the original. Adding some extra features, such as being able to direct the output of each cell to either the left or right channel, opens up additional possibilities that add to the charm, utility, and character of the filter.
The P915 design, implementation and quality control was in collaboration with David Ingebretsen of Analogue Realities The P915 MEDUSA is simply put, a meticulous, spot-on implementation of the Inductor 915 Fixed Filter Bank but taken to the next level in functionality, usability and performance.
