During the month of November, 2008, I had some free time, so I decided to try and build my own Ondes Martenot.
It's an early French electronic musical instrument, that has not been produced for decades.

Inventor Maurice Martenot, seated at his namesake instrument.

The hardest part of designing this re-creation, was trying to theorize what was inside the original.
I could tell it was based on a pulley system, to move the ring controller, but I wasn't sure what it was
moving, deep inside the instrument.

I studied lots of YouTube videos, and finally sat down and drew out many, many sketches of my own approach.
After discarding many designs, I finally settled on a system, where a single potentiometer was turned
by an arc'ing, telescoping arm. In my first YouTube video, you can see the arm. (I eventually abandoned this
approach, and used a 10-turn potentiometer, attached to one of the four pulleys.)

Instead of trying a faithful re-creation of the original Martenot, I decided to just build the ring controller section,
based on how it worked on the original instrument. The actual Martenot was much more complicated, and had a self-contained
oscillator and filter bank. One could adjust varous types of envelopes for the notes,
and you could also control what kind of reverberation system the sound was heard through.

One of the Martenot's more interesting design elements, was a speaker with chromatically-tuned strings
placed in front of the speaker. The strings vibrated sympathetically to the sounds created by the instrument.
These were interesting features, but I really just wanted to keep it simple, and come up with the
ring controller on a string to play "theremin-style" on a tactile surface.

The most brilliant element of Maurice Martenot's original design, was a series of depressions
drilled in front of a keyboard, that one's finger could land in. Unlike the theremin, this gave physical musical landmarks
on a tactile surface, that could help in landing on the correct notes, while using the keyboard (mostly) for visual reference.

So, my goal was to build a ring controller, with depressions in wood, that could control
a voltage-controlled oscillator on my modular synthesizer.

Yes, I could have bought an Analogue Systems' "French Connection", but I didn't want to spend $2500.
This project cost me about $150 in parts to construct, not counting the Q125 Signal Processor (synthesizers.com)

My father is a retired carpenter, so he graciously agreed to construct the instrument for me, in his spare time.
I drew up the basic plans, although Dad made important re-design suggestions that we used in a few places.

We began the project in November, 2008, and finished it in February, 2009. It's thanks to my dad
that I was able to pull this off, since I have no woodworking skills, and he's a master craftsman.
Thanks, Dad!

 

Here is my original sketch of my design ideas -- the blueprint that my father and I used.
(click photo for more detail)



I decided to build the Martenot Controller around one of my two DX-7's. It could have been any keyboard, actually.

 

We purchased about $50 of nice 3/4" and 1/2" oak at Lowes Hardware.
Here's Dad, cutting one of the first pieces.

 

Making grooved cuts, in preparation for later assembly.

 

The initial box, that the keyboard was designed to sit on.

You can see one of the four pulleys, laying on top of the left-hand side of the oak box.

 

The addition of the ring controller / pulley housing section.
Note two slots carved in the wood for later addition of two of the pulleys.

 

Measuring and marking where the finger depressions and string will go.

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