AM991 Fixed Filters

Recreation of the Moog Fixed Filters Module

This is recreation of the Moog 991 Fixed Filter module from 1968, an accurate reproduction of the original schematics. A passive design that requires no power. It is a nice alternative to the 923 module, as the 991 fixed positions require no dialing in of values.

DESCRIPTION There are five different value metalized polyester capacitors in each filter with a 6-way rotary switch selecting each capacitor in turn, with a final bypass position at step 6. The cutoff frequency of both filters are the same; 

16Hz, 41Hz,159Hz, 482Hz, 1591Hz 

There is also a fixed attenuator with a high quality Alpha control potentiometer. The module is designed to complement the Behringer System 55 Modular System, with a black anodised aluminium 8HP panel with 2 rotary switches and one potentiometer.

https://www.amsynthstore.co.uk/product/am991-fixed-filters