SSM 2040 Voltage Controlled Filter with LFO Inside the monster

SSM 2040 VCF



This is serial number 2003-03 of the SSM 2040 with LFO. Here it is in finished form.

This is the 3rd one I built with rev 1.1 circuit boards.

In this early version the LFO and filter are on separate boards.



The board on the left is the SSM 2040 board. The longer chip in the center of the 3 chips is the SSM 2040 VCF chip and it has a temperature compensating resistor sitting on top of it.

The board on the left is the LFO board

Here is model # 03 in it's primitive state.



A picture of my building station where I built and tested the unit.

Below is the board, a little grainy ----Rev 1.1

All resistors are precision metal film and 4 filter caps are high quality polystyrene. A temperature compensating resistor sits on the SSM chip and a high quality Bourns mini pot can be used to fine tune the filter. It is adjusted and does not need to be changed once set up.




I would like to thank several people for helping me make this a very cool and great sounding unit. First of all Dave Rossum who designed the chip way back then. The schematics I based my design on where dated April 15 1978 by Rossum and drawn up by Ed Rudnick. Ed has always been a great source for me to draw on for experience and knowledge.

Gary Hull from Universal Audio helped me to see ways to modernize and improve on the designs with more modern components. Technical analog wizardry at it's best check out Gary's company Trance Audio for superior acoustic guitar pickups at

Riley at Emu has helped me find all the original schematics and documentation that I needed. Most important of all Cathy for putting up with me and my piles of gear and test equipment all over the place


I graciously thank these companies for all past and future employment, and for the experience I have learned along the way. Check them out - Universal Audio - Emu Systems - Music Man








SSM 2040 Manual page

Back to Main SSM 2040 VCF page


More info: SSM 2040 VCF History and past versions

Sequential Circuits Synthesizers Page

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