Freaks are Important Too.....

Posted: 12/15/2015 7:37:18 PM

From: Richmond Hill, Georgia

Joined: 9/18/2005

I've found that the selection of the freeks is important, to say the least. Most important is to make sure that the tonal and volume oscillators are not whole multiples of each other.

These frequencies are very critical as I recently discovered, at least with my Kepp design. Shifting the tone oscillator frequencies more than a certain amount affects the tone. In my case. the two tone oscillators hovered around 205 KHz, while the volume was around 415 to 420 KHz. This arrangement caused issues. So, I dropped the two tonal oscillators down to around 194 KHz. This change eliminated the nasty birdies and fixed the volume loop response. The tone, however, was cleaner but had an entirely different, but not unpleasant sound. I think 194 KHz was too low as the pitch rod response suffered in the higher registers.

I can see how all the art and science of the theremin art has drove many a sane person mad. I've not devoted a whole lot of effort to this issue as I have more science than art in my character.


Posted: 12/18/2015 8:24:49 PM

From: Theremin Motherland

Joined: 11/13/2005


if frequencies are in the "golden ratio" (1 : 1.618...) then their harmonic contents are least affect one another.

Posted: 12/18/2015 8:51:05 PM

From: Northern NJ, USA

Joined: 2/17/2012

In the Theremini they double the inductance of the volume side LC, which makes it ~0.707 the pitch operating point.  But they're not mixing to get audio.

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