Is the theremin supposed to be linear? Etherwave

Posted: 2/28/2009 4:09:37 PM

Joined: 1/24/2009

So I built a Etherwave theremin 4 days ago and the pitch was very screwy at first. To the point where it was completed inverted (moving closer the antenna makes the pitch go down) and the pitch knob was almost completely useless. So I fiddled around with the insides and tuned it so it was atleast not inverted with a reasonably playable pitch range. But now, after just fooling around with it for these 4 days, I can play many different songs but my theremin pitch is still very exponential.

my main question is:

Is a theremin SUPPOSED to have linear pitch-to-distance ratio? I would imagine that it isn't possible with these type of electronics but I dont have a deep understanding of electrical engineering.

Moog has offered for me to send it in to be tuned. If I just send the theremin and its tuned by them, will a metal mic stand make it so even tuning it using the pitch knob ineffective, thus making the entire tuning effort useless?
Posted: 2/28/2009 4:32:41 PM


Joined: 4/14/2008

Just have them tune it on a metal mic stand, if you're not comfortable tuning it yourself... :)

As for linearity... I've read that older EStandards were much worse than the current versions sold today. Not sure if that's really true, as mine is pretty new-- but it's certainly more linear (i.e., the highest range is more useuable) than my Wavefront Classic is. And of course, I freakin' *LOVE* my EPro.

It sounds like this is your first Theremin, so congrats and have fun learning to play such a challenging instrument! :) Are you planning to update yours to a Plus, when they're available?
Posted: 2/28/2009 6:06:54 PM

From: Colmar, France

Joined: 12/31/2007

The actual version of the Etherwave Standard (if well tuned) is designed to have a almost linear range of 4 1/2 octaves, 2 1/2 above and 2 below middle C.

The problem is that pitch tuning and some other effects also affect the linearity. In order to obtain an optimal result (only valid for the Etherwave standard, other models have to be broken in a different way):
a) Do not try to play melodies in the first four weeks. You will most probably learn bad habits which will be hard to overcome later. Make only interval exercises in order to get familiar with the theremins physics.
b) Switch the theremin on but let the amplifier still off. Let the theremin warm up for about 15min so that the oscillators may stabilize. Have a coffee and a cigarillo.
c) Position yourself in front of the theremin, not in the middle, but facing the wooden part on the left of the control panel and step back as much as possible on this axis until you are able to reach the pitch rod only with an almost fully extended arm.
d) Coarse pitch tuning: adjust the pitch knob so that the theremin produces no sound when you have you right hand near your body.
e) Move your closed right hand near the pitch rod until you hear C4 (middle c). Open your right hand towards the pitch rod without moving the arm until you hear C5. This should correspond to an octave width of about 3" to 3.5".
f) Repeat the previous step with C5 and C6 as a verification.
g) Store this "default octave width" in your muscle memory. Repeat this some times with other tones and their octave in the C4 to C6 range. After some days of practicing this, we may continue and extend the pitch range:
h) Fine pitch tuning: Make an octave jump this time starting on C4 with the open hand and hear where you land. Above C3? Turn the pitch knob slightly clockwise. Below C3? Turn the pitch knob slightly counterclockwise. Repeat the jumps C5 -> C4 and C4 -> C3 and the fine pitch tuning until you get an equal octave space.
i) If you are familiar with this procedure of "octave equalization" between C5/C4 and C4/C3, make the same with C5/C4, C4/C3 and C3/C2. The lower you come, the more even slightest turns on the pitch knob will make effect. Adjust fine-tune it until you have really three equal octaves. The fourth one, C5 to C6 will then fit automatically.

Steps b, c, d and i should be repeated each time you want to play. Besides the warm-up phase, you will learn to tune your instrument then in a few seconds.
Posted: 2/28/2009 9:07:52 PM

Joined: 1/24/2009

Thank You for the advice!

I'll be sending my etherwave to moog for tuning of the internals.
Posted: 3/2/2009 12:39:02 PM

From: Kansas City, Mo.

Joined: 8/23/2005

Generally, I tune a theremin in three steps.

1) I adjust the placement of the zero-beat point. I stand away from the theremin at the approximate place where I want to tune zero-beat and then set zero-beat.

2) I then fine tune to intervals. In my case, since I use Rockmore/Pringle/Kurstin style aerial fingering, I tune up and down the scale in fourths.

3) I then play a my "warm up" melody. (For me, it is "Somewhere over the Rainbow"). Choose a melody that you can play consistantly. I then may tweak a little if I feel uncomfortable with the intervals. (Note, if you are a beginner, it will take you a year or so to develop this kind of consistancy in your playing.)

I generally tune with my pitch-preview to spare listeners from hearing this warm-up.

The Etherwave Standard has decent linearity however is not as linear as the Epro. The intervals are a bit compressed as you move towards the rod.

My solution to this is to move towards an imaginary rod that is about 3-4" to the right of the real rod. As you get close to the rod, your distance decreases tangentially and you can squeeze a few more linear notes out of it.

I often sight the rod out of the corner of my eye to assure that my arm is tracking to and from the rod rather than off "into space" somewhere.

In order to set your intervals, you must choose the note-spacing that suits your chosen technique. If you choose a technique such as Carolina Eyck's, then your note spacing will be closer than say, Peter Pringle's.

For example, when I play the zero-beat point is behind me -- in order to play bass notes I must lean back to increase my distance from the rod.

[i]-- Kevin[/i]

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