Solid State Micro Technology SSM2044 4-Pole VCF
A 4-pole (24dB/octave) resonant low-pass filter IC known for its warm, liquid self-oscillation (Korg Polysix, Korg Mono/Poly, PPG Wave 2.0).
# Mathematical Formula & Architecture
Logic SpecificationH(s) = 1 / (1 + s/omega_c)^4 with negative resonance feedback.
# 4-pole Butterworth / Ladder filter slope:
# Attenuation rate: -24 dB per octave (or -80 dB per decade) above cutoff frequency f_c# Deep Technical Analysis & Historical Context
Designed by Dave Rossum and Ron Dow of Solid State Micro Technology (SSM), the SSM2044 is revered as one of the most musical analog filter chips in audio history. Using a patented differential gain-cell topology, the SSM2044 emulates the classic warmth of the transistor ladder filter while providing voltage-controlled Q (resonance) that can be pushed into pure, undistorted sinusoidal self-oscillation. Unlike the Curtis CEM3320 which has a sharper, aggressive bite, the SSM2044 maintains rich low-end fundamental body even when resonance is pushed near oscillation.
Common Studio Pitfall & Hardware Hazard
The SSM2044 is extremely sensitive to electrostatic discharge (ESD). Touching input pins without an antistatic wrist strap during repairs easily destroys the differential input stage.
# Hardware Synthesizers Using This Technology
Click any synthesizer below to explore its specific memory protect routine, factory soundbanks, and Web MIDI SysEx cloud backup engine:
# Frequently Asked Engineering Questions
What synthesizers feature the SSM2044?
Korg Polysix, Korg Mono/Poly, PPG Wave 2.0/2.2, E-MU Emulator I, Octave The Cat (late revs), and early Crumar synths.
Related Engineering Concepts
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