music, guitars & other obsessions

Pedal Board Planning

Clear out the “backlog” finally! I made PCB’s for the following effects:

6-Band Eq
Big Muff
Color Sound Overdriver
Color Sound Supa Tonebender
Crank Tone
Cranked AC
Echo Base
Engineer’s Thumb
Fat Booster
Highway 89
Keeley Booster
Keeley Centaur
Love Pedal Super 6
Meat Sphere McBeat
Phase 90
Ross Dynacomp
Supa Fuzz
Tremulus Lune

As you can see, that is quite a lot of effects to build one by one, so I am going to build them up a la modular synth style. Since this is a pretty complex project, I plan to follow the steps below:

Modular Effect Rack:
1. make and stuff the PCB’s (DONE);
2. make the power supply back-plane (DONE);
3. make the control PCBs to hold the pots and switches;
4. prepare the chassis with mounting rails and hardware to hold the modules;
5. mate the modules with their respective control PCBs and test;
6. debug and re-work the modules as required;
7. place the modules onto temporary front panels (made out of G4 board);
8. mount the modules into the rack;
9. re-position and optimize module placement and mounting hardware;
10. design front panel layout based on optimized placement.
11. wire the modules as simple effect banks until the Matrix Switch is done.

16×16 Matrix Switch
1. using Commonsound’s “beat matrix” design as the starting point, modify the design to accommodate one more Zarlink 8816 crosspoint switch;
2. re-write the code for the additional switch (see Greg Surges’ snake corral);
3. breadboard and test the switch;
4. integrate into the Modular Effect Rack when it’s ready.

As usual, the mechanical aspect requires the most effort, as there is no Eurorack available in China, so I had to come up with workarounds for everything – the chassis, mounting rail and assorted hardware, what a hassle!

After that, the front panel becomes the next big challenge, there are many good examples of modular synth modules that can serve as inspiration for the design. I think I will keep it pretty plain Jane as a start, since more elaborate designs could always be installed at a later date. The current plan is to use 3mm aluminum plates in two different widths – 40mm and 80mm to keep the complexity down. The modules will either have 3 or 4 controls per 40mm column. The control PCB is designed to handle either version.

The module will mate to the control PCB via 24-pin header. Each module is then connected to the power supply back-plane via a 10-pin flat ribbon cable. So it should be relatively easy to switch modules in and out of the chassis when needed. Ground planes on all the PCBs should also provide some shielding against noise.

The Modular Effect Rack will be powered via external 9V supply to keep the AC hum to a minimum.


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