Changes in Tuning

Posted: 2/16/2008 4:07:51 PM
therem13

Joined: 9/25/2007

Yesterday, I tuned my home-made Etherwave to 3000Hz when I touch the antenna, and then I got zero beat about 2 feet away. This was all with the pitch tuning knob in middle position (it's just a 5 Kohm potentiometer). Today, the air is much, much drier (there was a considerable cold front last night), and I can't even get to zero beat from 10 feet away with the pitch tuning knob turned all the way. I suppose it makes sense, because now the air is less conductive, but should I be experiencing this much change to the internal tuning done (that's done by changing the variable inductors)? Is it common to have the weather dramatically change how my Theremin is tuned?

I didn't expect that I'd have to retune the instrument internally very often...


Thanks,
Dan
Posted: 2/16/2008 5:42:44 PM
Thierry

From: Colmar, France

Joined: 12/31/2007

Tuning is, as I saw this evening, a very delicate task.

As I told, my Etherwave Standard arrived on thursday an I just could try out its basic functions.

Now, this evening I took the time to try it out in a more detailed manner and I found that I wasn't able to make a whole octave jump without moving the arm, because I have small hands. So I decided to re-tune it on 5000 Hz when grasping the pitch antenna and I had to restart often, since all adjustment seemed to be for nothing when I closed the housing. So I saw how delicate it is.

What I found is the same effect as you got: no zero beat under some circumstances when the playing zone was too small or too big in middle position of the pitch knob. So try to adjust L5 a little bit counterclockwise and then re-adjust L6 for 3000 Hz ++ as long until you get zero beat when your hand is above the left edge of the housing at the beginning the volume antenna. This finally worked for me.
Posted: 2/16/2008 6:32:19 PM
therem13

Joined: 9/25/2007

Thanks... I definitely had a similar experience.

I think that the pitch tuning knob will never really be in the middle, but 5Kohm gives enough variation to have zero beat at the right spot with varying weather and conditions.

I used Zelscope as an oscilloscope to to tune my theremin, and it was very easy using that and following the instructions for tuning Etherwaves.

How low does your Etherwave play? I'm interested to see how my home-made one compares to the real thing...

-Dan
Posted: 2/16/2008 6:37:43 PM
Thierry

From: Colmar, France

Joined: 12/31/2007

I didn't connect a frequency counter, because I think I may hear where I am.

My Etherwave lets me go down to E or D, almost 2 octaves below middle C.

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