AMSynths AM2140 Resonant Filter (MOTM)

fully assembled analog metropolis am2140 resonant filter, in motm format

from rob keeble:

"This module is a clone of the Resonant Filter in the Eµ Systems Modular.

The Resonant Filter is an audio filter with an output capable of producing virtually any two pole pass characteristic. The FREQUENCY control can be varied from 20Hz – 20 kHz, and a resonant peak may be added in the response by means of the Q control. The height of the peak can be adjusted from zero to +40dB.

The filter has three functions; Low Pass, Band Pass and High Pass. The Low Pass and High Pass have a 12dB slope, the Band Pass has 6dB slope on both sides. The filter does not oscillate at high Q settings.

An output mixer sums the simultaneous three filter functions to produce a single output, and three attenuators (HIGH PASS, BAND PASS and LOW PASS) mix the relevant signals. A wide range of responses can be produced and several 2140’s can be cascaded to produce interesting complex resonant formants. Lower input levels should be used to prevent clipping at high Q levels.

There is a signal input and output on the front panel, as well as an internal CV input on the board.

The original Eµ Systems 2140 is a basic filter with no external CV control of Q or FREQUENCY. There was a firmware CV for FREQUENCY on the board, which was typically connected to the 2145 Filter Controller which enabled multiple 2140’s to be voltage controlled.