All my DIY projects have been put on hold for the past few weeks, I am getting stuck/bog down in how to best fit all the projects into their respective chassis… Since I am building multiple effects and amplifiers, I thought I should make everything modular so they can share the same chassis and power supplies, at least that was the goal. But as it turned out, there were many issues to overcome, both electrical and mechanical, I think I now have a good handle on the electrical ones, but as usual, I kept going round and round on how to build the chassis.
Here are some of the alternatives that I am (still) mulling over:
1) Euro-rack style cabinet with the effects mounted on individual strips (easy to switch, add, and remove effects from the chassis);
2) All-in-one panel with pre-drilled holes to fit the modules into (change-out would require taking off the whole front panel);
3) The one panel per box stompbox approach.
I was all geared up to do the effects in an Eurorack style then I had a hard time locating all the hardware to fit them together (without proper tools like table saw, jig saw, etc. did not help either) The All-in-one approach could work but I need to get a large piece of aluminum to provide shielding, the bakelite board that I originally got, while it’s pretty easy to work with, it did not offer any sort of shielding, with so many effects all jammed together, it just seemed like asking for trouble… Hate to go back to the stompbox, although that will look the coolest, since many creative design elements could be used to make it look cool…
As for the amps, I failed to take into consideration of the amp-to-amp power supply decoupling when they are used in unison. I suppose some chokes could be mounted in each of the amps to decouple it from the other amps, but good chokes are not cheap, and it defeats the whole idea of saving “iron”. The original idea was to share a single adjustable power supply among may be 4-6 small amps, if I had to put decoupling chokes on each of the amps, there would be hardly any saving at all, since good choke and small PT are nearly the same price. If I use small PTs, then the amps could no longer be considered “modular”, can’t they?!
Then I came across Decware’s Zenkit 2, which simply use two PT to power 6 SE amp channels, each channel has its own rectifiers and RC filters, that’s it, there is no decoupling between the channels to speak of, so I may still give it a try to see if it is “good enough for rock and roll” in my case.
So many projects, so little time, back to the drawing board!!!
Been gathering more parts for the build for the past few weeks and did a lot of reading of modular effects, signal routing, embedded processors, Arduino, etc. Man, I may be making this thing more complicated than it needs to be! But quite interesting to see what can be done these days.
Also got a hold of some aluminum panels and railing so chassis construction could commence soon, still need to get the table saw and a few more tools, that’s taking up quite a bit of time too since I am as usual can not make up my mind as to what to get – handheld or saw table…
Clear out the “backlog” finally! I made PCB’s for the following effects:
Color Sound Overdriver
Color Sound Supa Tonebender
Love Pedal Super 6
Meat Sphere McBeat
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.
I ordered a bunch of parts for various pedals that I wanted to build, but kept putting the projects off because of the PCB. I even thought about getting a CNC machine to fab them. Well, after more than a year of procrastination, I finally make some boards with the laserjet heat-transfer paper and etching solution. Surprisingly, they came out ok considering it was my first attempt. Sure, the boards were bare looking, and do not have any solder mask or parts layout printed on them, but they worked just fine. Drilling the holes was pretty easy with the small bench drill press as well, no problem with alignment or drill bits breaking (yet).
Here are some shots of the boards:
Now that I made some boards, instead of putting them into separate chassis as I originally planned, I am looking into the possibility of incorporating many of them into a modular multi-effects board like RG and Mark Hammer have been promoting. Not only does it save me the hassle of drilling, finishing, printing graphics for multiple pedal boxes, which is very time consuming and not something I am very good at anyway… the multi-effects approach can potentially provide much more flexibility in signal routing, and sound shaping.
Since I already have a busted Boss ME-10 multi-effects pedal, I am thinking about using its MIDI function and switches (which seem to be functioning still) and integrating it with the multi-effects. This would make for a very interesting project.
Alternatively, I could just stuff all the boards into one large chassis, and wire them up as JABE (just a bunch of effects), in which case, I think an old mixer would make a decent host chassis, since it contain all the knobs and jacks already. I just need to strip it down and re-populate with the PCBs and wire them up. I can also re-do the graphics for the front panel, so the knobs are clearly distinguishable from one another.
But before any of this could happen, I need to finish making the PCBs, so far I have only done three, so I got about 10 more to go…
A more recent shot of the pedal board, the Phaser 90 got new graphics, and the power supply box also got some cosmetic upgrade too courtesy of some “police tape”.