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

Posted: 6/3/2021 2:57:14 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

wingerr, just from a supply voltage standpoint, the RS358A seems like a much better fit.  All sorts of crazy things start happening when you undervolt an op-amp.

Posted: 6/3/2021 4:38:47 PM
wingerr

Joined: 5/29/2021

Yes, that being the case, the issues with mine all stemmed from when I accidentally overvolted it to the tune of 48V 🙃. Guess it couldn't take the measly 10x voltage on the outputs..oops

Posted: 6/5/2021 3:36:07 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

EW Pro Schematics

While poking around the web looking for the Etherwave Pro manual, I stumbled across EW Pro schematics:

https://www.synthxl.com/moog-etherwave-pro/
https://www.synthxl.com/wp-content/uploads/2020/04/Etherwave-Pro-Volume-Board-Schematics.pdf
https://www.synthxl.com/wp-content/uploads/2020/04/Etherwave-Pro-Panel-Board-Schematics.pdf
https://www.synthxl.com/wp-content/uploads/2020/04/Etherwave-Pro-Pitch-Board-Schematics.pdf
https://www.synthxl.com/wp-content/uploads/2020/04/Moog-EtherWave-Pro-Notice.pdf

The "Notice" document has a ton of info on operation and calibration.

Posted: 6/5/2021 3:54:51 PM
pitts8rh

From: Minnesota USA

Joined: 11/27/2015

Score!

I don't know how you found this, but I never came across anything in the past when I was searching.  I couldn't download these fast enough for fear they would disappear.  They should answer a lot of questions, better late than never I guess.

Thanks for posting!

[Edit] That site is quite a gold mine.  I found a few service manuals for some of my older equipment too.

Posted: 6/5/2021 4:37:26 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Clara de Lune

I've been trying to dial in a voice something like Clara Rockmore's Theremin recordings.  Looking at some of the Claravox samples in SonicVisualiser it appears the 4th and 8th harmonics are suppressed.  So I went with tracking formants skipping those harmonics, and added some fixed band pass filter to make it more female sounding in the upper end where Clara seems to play a lot:

Here's a little of me playing "The Swan": [MP3].  Clara really uses a lot of vibrato!

Posted: 6/6/2021 5:28:52 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"I don't know how you found this, but I never came across anything in the past when I was searching.  I couldn't download these fast enough for fear they would disappear.  They should answer a lot of questions..."  - pitts8rh

I've never encountered them before either, and boy I scoured the web looking.  I think it's a very recent thing.

"... better late than never I guess."

Yes.  Though in a way I'm glad that I didn't see these earlier in my research, they might have taken me down a very different path.

I never did find a PDF of the EW-Pro manual.

Posted: 6/6/2021 5:39:51 PM
pitts8rh

From: Minnesota USA

Joined: 11/27/2015

With these schematics and the detailed photos that we already have one could almost reconstitute one of these for a personal project with new board layouts.  I think with some forensic analysis it would be possible to determine most of the R and C values, but not all. 

Go find that parts list!

Posted: 6/8/2021 9:16:27 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Mortal Flesh

My same old cello preset with added outboard reverb: [MP3]

It's fun to find old, slow, brooding numbers to play it with.  Sliding up and down through the resonances really does make it seem like there is a complex wooden box with strings on it.

Between this cello and my favorite female preset, I don't really play much of anything else.  The Theremin was made for this sort of thing, and it's no wonder many (of the better sounding ones IMO) have an upper female-ish sound and a lower string-ish sound.

Posted: 6/9/2021 8:47:14 AM
Buggins

From: Theremin Motherland

Joined: 3/16/2017

Between this cello and my favorite female preset, I don't really play much of anything else.  The Theremin was made for this sort of thing, and it's no wonder many (of the better sounding ones IMO) have an upper female-ish sound and a lower string-ish sound.
-- dewster

Cello and voices (especially female) are pretty suitable for theremins. Some analog theremins sound similar (with vibrato).
Did you try to implement saxophone preset? I believe it could sound nice, too.

Posted: 6/10/2021 1:19:45 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

"Did you try to implement saxophone preset? I believe it could sound nice, too."  - Buggins

I gave it a try but couldn't get anywhere.  Part of it might be my sax audio samples, which have tremolo / vibrato baked in.

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