Notes on Tilt Sensing for a Wind Synth

The following is a cut-and-paste chronology of my development of a "tilt sensor" for a wind synth. The primary purpose is to add another continuous controller (cc) to the wind synth to permit added user control.

Background and History of the Tilt Sensor:

Back in '95 Ken Barry and I were discussing the use of an electronic level module to add another continuous controller to the WX. The more you swing the WX up, the more a CC get's changed. I've come up with a simpler solution.

Experiment #1:

I took a low friction pot and taped it to the end of my WX11. On the pot shaft I hung a short aluminum arm (1.5" long) with a weight on it. Now, when I tip the WX up and down, the pot turns by virtue of the weight. Works great, though I don't have any midi toys which accept a CC analog input. (I seem to recall a foot controller which accepts external CC - Anatek Pocket Pedal).

This is much simpler than the original digital level approach, though I only have one pot in my collection with low enough friction to work.

Yes, it's an ugly hair ball taped to the bottom of my WX which controlls nothing now other than my ohm meter, but it's a start. I envision a small plastic box which goes between the WX and the cable. Inside the box is the pot and weight arm, with a small, thin wire coming out. Or, for the delux version, the box contains not just the pot, but a CV to midi convertor and a midi-merge. No extra wires.

Experiment #2:

I bought a used Pocket Pedal off the net, and with my weight arm pot taped to the end of my WX, I can get reasonable control of CC via tilt. Damping of the arm is my current challenge. I really get to wiggling around while playing, and I've had the weight arm really swinging.

Once damping is solved, I plan to consolidate the whole thing (pocket pedal, pot, weight arm) into a small bud box with mini-din connectors on each end. Then you just plug it into the tail end of the WX, thus making the WX about 8cm longer. The WX cable would then plug into the end of the tilt module.

Experiment #3:

With the outstanding CC assignment capabilities of the VL1-m, I've been able to get the tilt sensor to apply a 'scream' paramater to a saxophone patch. The VL1 lets you alter not only the CC assignment, but also the shape and slope of the curve for which the controller is applied to the patch. The Anatek pocket pedal I'm using to translate the potentiometer (pot) position into CC messages works well, but it's not as self calibrating as one might believe. It wants to see a pot with greater than 4K ohm range, and it's happiest with >50K ohm. My current pot is 4K ohm range, and the Anatek can only seem to calibrate in one wiring configuration (clockwise rotation, not CCW). Below 4K pot range and the Anatek doesn't know a pot's there. Still, with some hunting for the right resistance pot, and making a crude weighted arm to create the turning force, it works fine.

My original plan of putting the entire anatek box and tilt pot on the tail end of the wind synth is looking to be too bulky. It's rubber-banded into place now. I'm now thinking of just putting the pot and weight arm on the WX, and leave the Anatek in the rack (or on the floor). That will require an extra wire pair coming from the WX, but that should be less of a pain than a 4" long box (plus din connectors) hanging off the end of the WX.

So what's left?

a) I want to find a stock pot that I can easily buy through a local distributor, and put it in a nice, clamp-on package. I also need to make a better weight arm, since I'm currently using a bunch of lead solder wraped around a bolt. I've a machinest friend who I think will make both a nice weight arm and package for the pot, but I haven't talked to him yet.

b) Since the Anatek supports a footswitch too, I'm thinking of adding a mercury switch too.

c) Learn how to program the VL1-m. I've only scratched the surface of the VL1 use of controllers. A well designed patch could greatly benefit from tilt sensing to add growl, scream, or harmonic excitation, but I'm not great at patch design.

Summary: It's cool to lean back and have a sax patch gently scream. I'm having fun with it.