- Retained from the original design, sets the frequency band over which the Fixed Volt knob operates in two octave steps.
- -1Hz to 5kHz
- -4Hz to 20kHz
- -16Hz to 60kHz
- CV 1 Amt.
- CV 2 Amt.
- varies the amplitude of the resonant peak at the cutoff frequency of the filter.
- Fixed Volt
- sets the cutoff frequency of the filter.
- adjusts the filter input level
- Exponential converters track linear voltage input at 1 volt per octave. This input is primarily used for keyboard tracking and pitch control of filter in self-oscillation mode.
- CV 1
- Control Voltage input with attenuator to control the depth of frequency modulation. Incorporates the standard Modcan inverting/non-inverting sign changer circuitry.
- CV 2
- Secondary Control Voltage input with attenuator.
The 904A Low Pass Filter is a Modcan re-creation of the 4 pole 24db low-pass filter from the Moog Modular synthesizer. The 44A honors the Moog spec. with precision matched 2N3392 transistor pairs through out.