Dual Filter page 2

Mad Science Lab SSM2


This unit has two SSM 2040 voltage controlled low pass filters, the exact same chip as used in early Emu Systems and Sequential Circuits analog synthesizers as well as others .... This is the third board revision.

Lots of knobs to twiddle

Unit has two low pass filters, and the frequency and resonance of the filters are voltage controlled.

Also has two low frequency oscillators to produce sine, square, and triangle waveforms. Total of 6 waveforms.

The frequency and resonance can be manually controlled by the larger knobs at the bottom of the unit.

However things get real interesting when you use the LFOs to modulate the filter cutoff and resonance

Also you can mix waveforms by choosing one of the six waveforms, adjusting the level, and setting to the same destination as another waveform.

The two are mixed and then sent to control the frequency and/or resonance of the filter. This can produce ever evolving waveforms. And it's fun to watch on an oscilloscope.


Below the case is opened revealing the wiring to the front panel

Dual Filter Circuit Board

Pictures of the 3rd version of the SSM2 Dual Filter circuit board are shown below.

Below is the circuit board wired up to the controls (click on image for larger shot)

Below is the circuit board without all the cables. (click on image for larger shot)

The 2 filter chips are on the left with resistors over them. LFO is on the right

Below is a close up of the 2 filter chips. Four clear caps help provide the four poles of the filter
Below is the Mad Science logo on the circuit board
Dual Filter page 2

Mad Science Labs is the outlet of strange and musical ideas of James Gideon

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