Friday, 22 February 2013

Tannerin / Electro-Theremin

About 3 years ago I began thinking about making an electro-theremin (or Tannerin as some might call it) after Gakken released the SX-150 synthesizer kit. I finally got round to it this year.

Basically, I've just replaced the original resistor ribbon and touch pen with a multi-turn potentiometer of the same value (100K) and put it all together in a case. I disabled the pitch envelope as that wasn't needed and added a slider pot to the output in order to give volume control. This is sprung so it will always kill the sound unless held open. I wanted to have some kind of soft control over the volume - a bit like the controls on an Ondes Martenot.

The current set up has a 2 and a half octave range. I've printed out the keys for guidance. It would be nice to have them permanently marked out on the case but I'm finding their position can be prone to wander!

It sounds pretty awful - check the video below 

tannerin1

A cord from an old radio turns the potentiometer.

pot

The cord wraps around pulleys and the tension is maintained by a spring.

spring

The handle and slider - this runs up and down an aluminium runner and pulls the cord to turn the potentiometer.

slider1

Placing the thumb and forefinger on each side allows you to see which note you are 'hitting' in the space between.

handle

The slider on the runner protrudes through a slot in the case.

slider2

This is the volume control -  a lever is connected to a nylon line that wraps around the slider pot and then to a spring. Holding the lever open controls the volume accordingly.

vol_con

The controls.

tannerin2

Here's a video of it in action - I'm trying to play along to some simple backing.  It sounds truly awful but some delay and a little overdrive helps..

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