Korg Volca analog synthesizer series is absolutely awesome. Volcas are small, affordable, easy to start with, produce very nice oldschool sound and bring a lot of fun straight from the beginning. Although they may look too simple and very limited at the first glance, there are plenty of ways to step beyond their official list of features.
In order to make something cool, that would involve Volcas, could be controlled by a single MIDI keyboard or a sequencer and play well with my Pocket Operator Briefcase, I've decided to go with the following setup:
- 3 analog Volcas
- effects processor
- single multi-channel MIDI input with internal MIDI splitter
- single power input and USB power output sockets
- several audio inputs and single audio output
- sync clock input and output
As it appeared to be, Korg and Teenage Engineering use the exact same protocol for clock sync, so their synths can synchronize the tempo between each other out of the box.
Step 1: The Plan
I've started by making a 3d model with Tinkercad and a wiring diagram with Google Drawings in order to get an overview of how the components can fit together. But since this project has been a set of trying and failing from the beginning to the end, these schemas have been changed significantly. I've decided to only publish the final drawings here in order to focus on the implementation, but not on the process.
For sampling and effects processing I've chosen Korg mini kaoss pad 2S. Initially I was thinking about using it to post process the final output of the mixer, but when I tried it in action, I noticed a significant drop in the sound quality, especially in the low frequency range, so I've decided to only use it with drums. That way it can still play/loop samples and diversify simple and somewhat boring Volca Beats output with its cool audio effects. It also has a built in microphone, which I've never used.
I've experimented with Patchblocks for clock sync devision, audio effects and MIDI sequencing, but was disappointed with pretty much every feature I've tried, so I had to remove them from the setup.
Step 2: What's Needed
- a toolbox, some stripwood and screws from the nearest hardware store
- micro.tech 6 channel passive mixer: ebay.co.uk
- 3.5mm 3-pole stereo jack socket mount x 8: ebay.co.uk
- short angled USB Type B cable: ebay.co.uk
- 3.5mm headphone splitter x 2
- USB power adapter with 4 outputs
- USB A Male-Chassis A Female 0.3M: ebay.co.uk
- 2m of self adhesive Velcro tapes: ebay.co.uk
- a bunch of audio and MIDI cables
- utility knife, ruler, pencil, screwdriver, small hacksaw, soldering kit, a pair of sushi sticks
Step 3: The Case
I've spent quite a bit of time considering different options for the case, but then suddenly found a fairly cheap toolbox, which had perfect size to contain everything I needed and was deep enough to hide all the guts under the mounting panel. Initially I was going to make the panel out of a solid piece of plywood, but then I've decided, that it would be better to go with a strip wood grid and leave sufficient amount of space between the strips. That way I could easily move the cables around without drilling too many holes. It appeared to be a great idea, because I've changed my mind regarding the placement of the components a lot of times during this project.
Step 4: Audio and Clock Sync
It was challenging to find a 4 channel active mixer, that would be small enough and not ruin the sound quality, so I went with a combination of 6 channel passive and 3 channel active mixers. The passive mixer works great and does not require any power by definition, but it has significant output signal loss. The active mixer has integrated amplifier, so it restores the volume and can be used as external USB sound card with a computer, which is really convenient for audio/video recording and online streaming.
Clock sync setup was really trivial. A cheap 3.5mm headphone splitter worked perfectly.
Step 5: MIDI
Sonic State has a very useful video about their experience with using a headphone splitter for MIDI. I've made some MIDI to minijack adapter cables according to the wiring schema I've found in the Internet and everything worked like a charm. I could control all three Volcas with just one MIDI keyboard by splitting the piano keys into two zones with different MIDI channels and using drum pads with the third channel for Volca Beats.
Step 6: I/O Panel
In order to reduce the amount of cable mess I've decided to make an input/output panel. Luckily I had a small piece of MDF left from my previous portable synth case project.
Step 7: Prettifying
I've used some clear matt wood spray paint I've found in the nearest supermarket to cover the panel.
I've also cut off the soft spring parts of the MIDI and RCA plugs, so that the case lid could close without pushing the plugs, which could risk in breaking the sockets. Another option here would be to use angle plug cables, but I already had plenty of cables laying around and I did not want to buy more of them.
Step 8: Adding Mini Kaosspad and Velcro Tapes
Velcro tapes are very useful when you want to mount something, but still be able to remove it if needed. They appeared to be stronger, than I expected, and did their job just fine.
Kaosspad is a pretty cool thing to play with. However, after I installed it, I had to use a dedicated power adapter for the active mixer because of ground loop noise.
Step 9: Panel Holders
Final steps - fixing the panel to the case
Step 10: Testing
Here is a quick demo of the final setup
Step 11: Conclusion
This project took way longer, than I've planned, but I'm really happy how it turned out. I could probably buy some all-in-one synthesizer for the total amount of money I've spent on it and save a lot of time, but I really enjoyed the build process and learned a ton of interesting things while I was making it. In addition I would like to mention, that this setup could be powered off a single USB power bank, but I could not find a 5v to 9v step up converter, that would not cause Volcas to produce a lot of background noise. As about future plans, I would like to make a simple clock sync divider with Arduino, so that I could make longer sequences with Volcas.
Thanks for reading this through :)