Theremin pitch changing over time

Posted: 11/29/2010 2:50:11 AM

From: Kyoto, Japan

Joined: 11/29/2010

Hi there, I'm new to this forum so I'm sorry if someone has asked this already...

Does anyone know if there is a technique/tip to keep the theremin's pitch from descending over time? I've done some searching on Google and realize it's a common occurance (ie. the theremin is left on on 'silent' and at some point a low note starts sounding on its own.)

Does it ever stabilize? Are there certain models that do it more than others? I have an Etherwave Plus. Thank you in advance :)
Posted: 11/29/2010 6:43:02 AM

From: Colmar, France

Joined: 12/31/2007

The frequency deviation which is necessary to produce a low tone is less than 100Hz. Compared to the oscillator's free run frequency of about 285kHz it's just 0.035% which can already be considered as an insignificant value, especially if we are working with oscillators which should at the same time react correctly on smallest capacitance changes.

So it is normal that you have to retune your Etherwave Standard/Plus from time to time, especially during the 15min. warm-up phase. After the temperature of the transistors will have settled, the drift will be as minimal as cited above and that's ok.

If you have ever seen a violin soloist performing, you should have observed that he is also retuning his instrument between the different movements of a violin concerto. So what?

I personally minimize this effect by letting my Etherwave always switched on (its power consumption is also insignificant). I naturally switch the amplifier off when I don't play. Out of that you may hang the power or the audio cable over the volume loop (= Bulgarian version of the mute-switch)
Posted: 3/20/2020 3:20:38 PM
RLN Theremin

Joined: 3/15/2020

Hello Thierry, I know it is a very old post, but I read that you always let your etherwave switched on (day and night?); isn't it dangerous for the circuit? I ask this because living in a very old building the electric current is not up to standart I think and there are often variations (noticeable on electric bulbs for example when you turn on other devices) which makes me ask if it doesn't wear or damage my etherwave circuit in the long term? Thank you

Posted: 3/20/2020 4:47:34 PM

From: Colmar, France

Joined: 12/31/2007

Me lives in a 300+ years old house, too. I never worried about electricity since I know two things:
First, the Etherwave’s internal power supply section which complements and stabilizes what comes from the external transformer is relatively robust and can handle up to 40% over voltage for a few minutes.
Second, if something broke, I’d be able to fix it myself. But that wasn’t required in more than ten years.

If these statements don’t give you a good enough feeling, you might still go out and buy a small surge protector adapter, something which you put between the wall plug and the Etherwave power supply. These are normally sold to protect computers, but they’ll also protect your theremin.

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