Discrete OTA VCF
The E440 is based on the 5U MOTM-440 filter with additional features such as separate outputs for each filter slope and an input Drive control.
You have probably heard of the SSM2040 filter chip, used in the Prophet-5 Rev 2, Voyetra 8, and others. Although short-lived, the SSM2040 filter had a unique sound different from a Moog, ARP, or other 4-pole lowpass filters. Why? The design used a clever discrete OTA gain cell that responds beautifully as additional gain is added to the input signal.
The E440 provides three simultaneous filter slopes: 2 Pole (12dB), 3 Pole (18dB), and 4 Pole (24dB) for selective timbral shaping. Voltage control of filter resonance (rarely found on other filters) is also available.