Let's Design and Build a (mostly) Digital Theremin!

Posted: 8/24/2019 6:47:28 PM
Buggins

From: Theremin Motherland

Joined: 3/16/2017

Good bell. Not sure if it's possible to get its recorded ringing sound.

BTW, does it make sense to use bell harmonics as theremin voice? Or it's supposed to hit the bell by fast volume hand move/acceleration?

Did you try to simulate wind instruments?

Posted: 8/26/2019 2:42:47 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"Good bell. Not sure if it's possible to get its recorded ringing sound."  - Buggins

I think a better recording of it is possible.  That one is so distorted / weirdly EQed / compressed / artifacted - and there seems to be some sort of wow & flutter going on.  It probably started out life in a sorry state and got further mutilated going through the video compression puke funnel.

"BTW, does it make sense to use bell harmonics as theremin voice? Or it's supposed to hit the bell by fast volume hand move/acceleration?"

Not a lot of sense, more or less honing my analysis / synthesis skills.  Though it did prompt me to significantly expand the high end of the filter Q control (lower end of damping, actually) by making it exponential.  For stimulus I'm using either pulsed noise or the steep falling edge of the oscillator (max harmonics ~= sawtooth) at subsonic frequencies.  I could set it up so that fast movements of the hand would trigger it too.

"Did you try to simulate wind instruments?"

I've done a human whistle, muted and unmuted trumpet, as well as trombone and tuba, and intend to try for more.

[EDIT] I don't think I've read anywhere that the damping control could / should be exponential, but it makes sense to do this as the frequency is exponential as well, and they are both feedback / feedforward terms in the state variable loop.

Posted: 9/12/2019 9:35:24 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

First Post Index of Topics & Links *Updated*

I updated the first post in this loooong thread to bring the hot-linked index of topics up-to-date: [LINK].  We're in year 7, baby!  7 big ones...

Posted: 9/14/2019 2:50:04 AM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

More Mock-uping

Playing with the cardboard mock-up again:

The black Sharpie line at the top is at 17" tall from the bottom, which is the max for 1/2" plywood and 16" smoked Lexan forming the control panel / bezel.  I've got the tuner located right at the very top which seems OK in terms of viewing angle, I don't have to crick my neck too much to watch it while playing.

Side view shows the plate angles which seem perhaps the most comfortable to play.  The body is angled back more than 45 degrees, this angling places the pitch plate at a good distance past the volume plate.  The pitch rod is centered for gravity reasons on the mock-up, and not what I intend for rod users.  External coils here are just 2D.  I want the plates & coils to fit in the removable lid of the enclosure, which seems maybe possible with the sizing shown here.

Anyway, I'm doing this more for rough dimensioning, to see how the ergonomics might work out.  No clue on how to attach anything to anything.  Owners would pick between a rod or a plate on the pitch side, and not have both as shown here.

Posted: 9/14/2019 8:57:39 AM
JPascal

From: Berlin Germany

Joined: 4/27/2016

Did you plan for the elbows to be almost fixed while hand moving? I like this cardboard model.

Posted: 9/14/2019 2:54:28 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"Did you plan for the elbows to be almost fixed while hand moving?"  - JPascal

Yes, exactly, that's the general plan, where the upper arm is more or less immobile and next to the body, particularly for the volume axis. 

[EDIT] Another ergonomic factor I didn't mention that is at work here: I don't feel comfortable having my hands come very close to the plates when I play, maybe 4" or 6" minimum.  Some players routinely interact with the volume loop at much closer distances.

You must be logged in to post a reply. Please log in or register for a new account.