MOTM-440 VC Lowpass filter

via this auction

"MOTM-440 Description

"If you are familiar with music electronics, you have certainly heard of the SSM2040 filter chip, used in the Prophet 5 Rev. 2 synthesizer, the Voyetra 8, and other classic designs. Although the production run of this coveted chip was short-lived, the SSM2040 filter has a unique sound different from a Moog, ARP or other 4-pole lowpass filter. Why? The design used a clever discrete OTA gain cell.

The MOTM-440 offers an updated SSM2040 architecture using matched NPN/PNP pairs and features a switch that adds in a second audio feedback path to boost bass response at higher Q levels. This makes the filter "growl and rumble" even more! In addition, voltage-controlled Q allows for more flexible and unique sweeping effects. Three audio inputs and three CV inputs make the MOTM-440 the killer lowpass in your system. The internal gain structure is such that over-driving the filter is now possible (unlike the Prophet 5) to get even more nasty sounds."

- write-up from synthtech.com

MOTM-440 Electrical Specifications

The MOTM system was designed to be compatible with existing synthesizer equipment, featuring:
• 1 volt-per-octave response for control of pitch-related parameters (i.e., VCOs and filters)
• Positive-going voltage Gates (+1.5V threshold)
• Positive-going voltage triggers
• Audio levels of 10V peak-to-peak
• VCAs respond to amplitude control voltages from 0 to +5 volts
• Most modules use +/-15VDC (some modules use internal regulators). Some of the 500/600 Series use an additional +5V supply.
• Power supply connector is standard AMP MTA-156 4 position or 6-position for 500/600 Series

"The MOTM-440 is the best-sounding analog filter I have ever heard."
- Robert Rich"