Mad Science Lab Archives/SSM1

Mad Science Lab SSM1

The Mad Science Lab SSM 1 is a analog filter unit that is compatible with modular synthesizers.

The unit uses a rare SSM 2040 IC chip to achieve a voltage controlled low pass filter (VC LPF)

This was an OPEN SOURCE project. I do not sell finished SSM1 units

I provided the circuit board at cost ($40), and all files needed to build a SSM1 will be on this page

Note: I do not have SSM2040 chips that are needed. I do not know where to get them

I would advise you have a chip BEFORE buying parts

2014 Update

I have no more boards for sale.

Above is a picture of the front panel of the SSM1. The frequency and resonance knob are at the top of the unit.

The 3 inputs and one output are on the bottom of the unit.

This unit is based on my experiments with the Emu Systems SSM Chip Eval Board.

I have dedicated a page to Ed Rudnick that has all the schematics for the SSM Chip Evaluation Board

This layout follows the standard set by Synthesis Technology.

Legal blah, blah, blah --don't blow yourself up, be competent , do not attempt if incompetent, don't blame me if you screw it up

MAD Science Lab SSM 1

This unit has one SSM 2040 voltage controlled low pass filter. It is housed in a MOTM compatible panel

so it can be used easily in modular synthesizers. Power connection is standard +15/-15 MOTM style.

Both the frequency and the resonance of the filter are manually controllable or voltage controllable.

Added a gain switch so you can easily over drive the input stage for extra crunchiness.

These modular versions of the SSM 2040 will be limited to an initial release of 10 circuit boards

Above: Close up of circuit board.

The SSM 2040 is at the bottom and has a temperature compensating resistor over it. See below for board layout.

Resistor available online from Precision Resistor



Front Panel

Above is a close up of the front panel done with Front Panel

The font panel can be ordered online The file will be here_______front panel designer and software here

I used engraved metal and silkscreen, it costs more, but I kinda like it. Also , I used screws through front panel

instead of threaded do hickeys. At top of above picture, you can see small screw.

Improvements to this design are welcome, and will be posted here.

Below are a few pictures to demonstrate how the circuit board mounts

Above the back panel showing the threaded bolts that the circuit board mounting bracket attached to.

This is a MOTM 440 front panel that can also be used. They are available currently by Synthesis Technology.

Below is circuit board mounting bracket. The two holes at the top attach to the threaded bolts above.

The brackets are available from Synthesis Technology. The circuit board mounts to the 4 holes on the bracket

with spacers to separate the board from the metal. So you need a small screw with a matching lock washer,

and a small 1/4 inch spacer that fits on the screw.

Below is a close up of board before installing chips. .


install chip sockets and test both voltages after unit is complete before installing chips

refer to schematic below for pin connections.

SSM1 Circuit Board

Above: This is the circuit board without the chips.

The 3 Input pots are on the bottom along with the resonance control far right.

Inputs to the filter are on the left. One to three audio inputs can be used.

The minimum connections would be 1 audio in, 1 audio out,

one 100k pot to control frequency cutoff, and one 100k pot to control resonance.

power supply +/-15 volts


Parts List

SSM1 Mono SSM 2040 VCF SSM1 Version 2

Bill Of Materials
Item Quantity Reference Part

1 4 C3,C4,C5,C6 1000pf
2 1 C7 5pf
3 1 C8 22pf
4 2 C83,C82 10uF
5 7 C84,C85,C86,C87,C91,C92,C97 .1uF
6 2 D5,D4 D1N914
7 1 J3 Out
8 1 J10 IN1
9 1 J11 Pot2
10 1 J20 IN2
11 1 J21 Pot3
12 1 J30 IN3
13 1 J31 Pot4
14 1 J41 Freq1
15 1 J42 Freq2
16 1 J43 Freq3
17 1 J44 Pot6
18 1 J45 Pot7
19 1 J55 Power
20 1 J77 Pot1
21 1 J78 Rez2
22 1 J99 Insane
23 2 L1,L2 1uH
24 11 R41,R42,R43,R44,R45,R46,R47,R52,R57,R65,R73 10k
25 4 R48,R49,R50,R51 200
26 8 R53,R58,R59,R60,R62,R70,R71,R72100k
27 1 R54 1k
28 4 R55,R63,R155,R156 56k
29 2 R56,R66 46k
30 1 R64 1.00k
31 1 R67 42
32 1 R68 18k
33 1 U2 TL072
34 1 U4 SSM 2040
35 1 U6 CA3080
36 1 U7 TL074 7B
37 1 U7 TL074 7C
38 1 U7 TL074 7D
39 1 U7 TL074 7A

I used the same pots and jacks that Paul uses on MOTM units


Below are a few part numbers I used from Mouser


Below is a picture of board showing placement of parts.

Below is a picture of the board showing the top and bottom traces



Below is the schematic for the SSM1. I would like to thank Ed Rudnick who drew up the original schematics for the SSM evaluation

board, and Dave Rossum who designed the chips.

I have dedicated a page to Ed Rudnick that has all the schematics for the SSM Chip Evaluation Board



2014 Update

I have no more boards for sale.



thanks to E-mu Systems and Universal Audio who have kept me employed for many years

until I could get my own thing going

Also big thanks to Paul of Synthesis Technology. I have learned a lot using, building, and studying his work

Go buy some of his stuff

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questions or comments e-mail james AT

(replace AT with @)

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