Mosaic modular

This all started back in 2010 when I first discovered the wonderful world of stanley lunetta and his simple but complex method of making synthesizers. I had always been interested in electronic music but without a background in electrical engineering I always thought it would be too complex to start. But thanks to the good people over at the electro-music.com lunetta forum I got over my initial fear and soon I had all kinds of strange noises coming from a plethora of different circuits. For me it was the perfect way to experiment with electronics, simple yet infinately expandable and complex.

So back in 2011 I made my first lunchbox sized lunetta synthesizer to collect all my random circuits in one place. It was a lot of fun but I soon discovered that just using header pins without any sort of marking didn’t result in the best of user experiences so I started thinking about a way to make it actually playable and interesting for musicians.

Fast forward 8 or so years and due to the current corona crisis I finally found the time to collect all the ideas I had over the years and make it into something tangible.

The main challenge with the lunetta style of synthesizers has always been the sheer amount of in- and outputs. While a normal synthesizer module in for example eurorack format might have 2-8 IO, a simple lunetta circuit with a fraction of the capabilities can easily have 10 or more. The whole fun of a lunetta synthesizer is to experiment and explore all the different options, more of a quantity then a quality approach to exploring sound. So over the years I have been researching and trying a variety of different options. The main goal was to keep it simple and cheap but keep it user friendly. So finally I settled on my favorite connector, the 4mm banana socket. Infinitely stackable, very tolerant of abuse and most of all cheap and ubiquitous.

Over the years since my first lunchbox synth I have learned a lot about electronics and design so this time around I started with some CAD modelling to explore the different ideas I had. I knew I wanted it to be modular and most of all cheap. Or maybe I should say affordable, cheap sounds like bad quality but I really mean affordable, a system where you can experimentand expand easily without breaking the bank.

I know, that was a lot of talk and little action. So without further ado the basic guidelines for this new modular format I am proposing is:

  • Grid size of 50x50mm.
    -Easy and cheap to produce with online PCB prototype services.
    -Can be expanded in any direction.
    -20mm m3 hex standoffs create a affordable and flexible way of mounting.
  • 4mm banana sockets.
    -Soldered directly to the PCB for a easy and reliable connection with a minimal footprint.
    -Unlike the standard 3.5mm trs connector, banana jacks are stack able and much more reliable.
    -All outputs have leds shining through the FR4 material from the underside of the board.
    -Silkscreen can be used to indicate different functions of in and outputs.
  • The top side of the PCB acts as the front panel.
    -This eliminates the use of a extra interface board and greatly simplifies construction.
    -16mm alpha potentiometers are mounted directly through the board and simple slide or momentary switches can be used.
    -This also leaves a lot of room for interesting graphics on the silkscreen layer :).
  • The bottom side of the PCB acts as the main circuitboard.
    -SMD construction makes the circuits smaller and leave the top side of the PCB completely blank for the actual user interact able components. It might be a little harder to solder but I have found that 0805 passives and most basic SMD components are easily done with a soldering iron and using a hot air station makes it really easy and fast.
  • Mounting corners double as ground connections.
    -This means the entire modular acts as one big ground plane wich greatly reduces interference.
    -VCC is supplied by simple smd mount terminals or by just soldering a wire to the pads. This has the advantage of being easily expandable and flexible. You can use modules to power other modules or mix and match different power supply’s.