The case

I finally made it.

I got a case for my modular synthesizer.

The finished case

Even though I had identified the necessary pieces of wood available at home, I dismissed my initial idea of having a full custom 8U wooden case.
I got inspired by this thread on Muff Wiggler to use a basic tool case to host my first modular synth. 

I reckon my initial idea of 2U 84HP utility panel would have taken me too much time.  So starting from an existing box seems a better idea.

As usual with me, I progressed step by step.

The box is a standard tool case from the local DIY store (Sencys from Brico). External dimensions are 46 x 33 x 15 cm.   This is great for hosting a 6U 84HP Eurorack modular synthesizer.
I'll keep the lid from now.

The Doepfer A100 DIY kit is perfect for the job : four rails, two bus boards, a power supply is all you need to start..

Checking everything is in place ...

I started by checking that everything could easily fit into the box.  And from there I evaluated what would be needed to mount the kit inside.

Apart from the box, I exclusively used pieces of woods already available in the house.  Mainly remnant from a 6mm thick MDF wood panel..



I decided to keep the foam inside.  I only had to tighten the corners and cut out the part where sides were recovering the bottom part.




I bought some 6mm x 6mm square nuts to fit in the rail, as the standard hexagonal ones have a tendency to rotate and block into the rail.  As I miscalculated my needs, I kept 4 hex nuts per rail, two on each end, for a total of 21 nuts per rail.  I reckon this will suffice.




The back of the structure is a bit more than 4 cm deep.  It gets to support the power supply placed vertically and can accommodate 2 8HP modules turned horizontally.  Not as good as the 2U utility panel I initially envisaged, but this will do.




For the bus boards, I decided to fix them from below an horizontal wood piece.  These slats were a bit thick.  The box is not very deep.  This way I keep a full 7 cm clear.  The bus boards are blocked by the foam.  And yes I checked if, by any chance, this would be conductive … which it is not, obviously.

The connection of the power supply to the 240V-15V AC transformer is done via an appropriated connector on the front panel to avoid piercing the box.  No trouble thanks to the parts I collected when I started to make guitar pedal kits.


A green LED connected between the -12V rail and the ground (with the help of a 1k resistor) indicates when the case is powered.

Both fit into a custom panel, drilled with some ventilation holes.





I made sure the power wires would stay nicely on the side and I double checked the connection with a voltmeter.

Before fixing inside the case

Finally, I secured the lot into the box thanks to four 5mm carriage bolts.

Finished.  It's time to add modules.

My first DIY module

Start small they say.

My first DIY Eurorack module is a simple DC mixer.

I made that choice because I reckon it's easy to build and I found tons of examples on the Net.  It can serve the purpose to mix any type of signals, CV and audio.

Schematic was inspired by Yusynth's with some tips from Ken Stone's and Dintree websites.  It's not much, but you have to start somewhere.

Schematic capture on DIYLC

You'll notice that the first stage is at unity gain and I chose to have the second stage with a 2x gain so that I can use the circuit to boost the signal if need be.

I used DIY Layout Creator (DIYLC for short) to capture the schematic and to trace the layout for a perf board.    Layout is OK, but capturing the schema was a pain.

Layout of the simple mixer : power at the bottom, inputs on the left, outputs on the right..

Warning : the schematic and layout are given for illustration purpose only.  Use them wisely and at your own risk.  Don't forget that I don't really know what I'm doing.

I used a lot of space.  It's a luxury I won't have anymore for the next modules.

I did a mistake though in placing the power connector parallel to the bottom side of the module.  It seemed a good idea at first to have the power lines aligned with the IC.  But once placed into the rack, the flat cable will be crooked.  I didn't respect the de-facto standard to have the -12V at the bottom.  My bad.

Before finalising the cabling, I assembled the mechanical parts to check if all fit.

Recto

Verso

I  then started with the cabling that did not concern the board : herebelow the input attenuators. 

Cabling pots

I chose to have PCB connectors on the board to ease with the mounting and un-mounting.  I did it on the next module as well.  It takes a lot of space and does not bring so many advantages I think.  My third module will be different.  I'm still undecided on this.

Fully assembled

Here is my first DIY Eurorack module, alongside the A-110-1 VCO and the next one : the Sample & Hold and Random module from the inspiring project from Yves Usson.   The two DIY modules have a temporary annotated paper facade.

The first three