Subscope Theremin

Posted: 2/7/2018 8:51:56 PM
DOMINIK

From: germany, kiel

Joined: 5/10/2007

JPascal: maybe. Theoretically. But i cannot tell about a 'AHA' difference of behaviour to the normal rod.

Dewster: i am feeling honored, thanks. Unfortunately, whenever i have been asked about solutions and indeed answered or have given away schematics i felt not so good afterwards. I think because it takes that much time for me (who is more into arts than into understanding electronics ~ which i do not understand but: the route is the goal) developing|adapting circuit details (being them a little fancy or nothing but common) and hopp: away..

You were not asking for something to just copy but for a tip. If only i could.. give me some time..

Sensitivity, linearity.. i cannot provide you with data. It behaves like in the videos :) and yes for the EQ coil.

That book would contain more pictures than words. 

Posted: 2/9/2018 6:19:45 PM
JPascal

From: Berlin Germany

Joined: 4/27/2016

Dominik: This theremin seems to be in design, handling, sound and dynamic one of the bests. I think, tips are welcome, secrets shall not disclosed. For me is your instrument a high level benchmark. May be you are creative and others are business minded. 

Posted: 4/5/2018 3:17:41 PM
DOMINIK

From: germany, kiel

Joined: 5/10/2007

Dominik, I've been trying to implement the pizzicato volume thing you demonstrate above with some success, but I haven't been able to get it to a point that I'm happy with.  You're almost certainly doing it on the exponential side of things, and I'm trying to do it on the linear side.  I differentiate the signal to get velocity, only take positive differences (rectify), scale it (strength knob), and then present this to a leaky accumulator, the leak of which gives the decay (rate knob).  It works and everything, but I find that I can "pump up" the accumulator with repeated quick movements of my hand, which I don't like because it temporarily moves the audible threshold around.  Does yours display this kind of behavior?  Are you rectifying velocity?  Any tips you might give me?

Dewster,
it's been a while. And since then you have changed the behaviour of your theremins velocity feature. See here (also interesting videos below that posting).

At least our approaches are different. You seem to be using a specific hands location and a given speed to then trigger attack and decay events with a corresponding max amplitude. Behind that trigger point the normal playing zone starts. So your machine doubles in a theredrum and a theremin :-)

From your posting 1400:

You don't want to have to flick your hand quickly (velocity threshold) to have the envelope generator kick in, you instead want to merely move your hand past fixed positional threshold in space to trigger it, and use the velocity at the crossing to set the attack amplitude.  The position will necessarily be outside the normal playing field (or inside it if you have it set for farther = louder), and you don't want velocity kicking in when you're playing normally, so I believe this is the best approach all around.  Yarg...

Well, if velocity quite generally was a feature.. i think you might want to flick your hand quickly and you might want velocity when playing normal. Because exactly this is what theremin players already do even without a velocity feature. The movements simply follow the players intention. While playing any faster attacks might be comfortable with velocity.

I am not using a trigger to start events, it reacts sort of dynamically. I think it is much simpler than your solution. One possible model (i could be very wrong here.. and i am shure this is not smart):
- let A be the control voltage corresponding to the volume hands position.
- let B follow that voltage, but delayed. Like B'new=B'old+(A-B'old)/2
- A/B'new gives a multiplier to somehow generate the velocity voltage
- *ding*

Don't get me wrong. Your solution is interesting and those supersharp attacks are nice, but one would have to adapt. But there are some unused bits and bytes i guess.

A short video.

Posted: 4/5/2018 3:21:50 PM
DOMINIK

From: germany, kiel

Joined: 5/10/2007

Dominik: This theremin seems to be in design, handling, sound and dynamic one of the bests. I think, tips are welcome, secrets shall not disclosed. For me is your instrument a high level benchmark. May be you are creative and others are business minded.

JPascal, thanks!

Posted: 4/8/2018 11:41:25 PM
Touchless

From: Tucson, AZ USA

Joined: 2/26/2011

Hello Dominik,

Velocity is the word, never knew what to call it but in some of my theremin experiments I used that classic 555 to do a similar simple volume control technique. If the velocity pot was adjusted one way the slower hand movement or voltage rise on the pin 2 that triggered the 555 would bleed off before triggering the output. You then have the normal volume control in a slower volume control window. Higher hand speed would trigger the 555 so the sound would snap off or on, whichever was preferred. Also in my design the outer edge of the volume control window was more aggressive than near the loop for excellent soft sound control. Never had a qualified Thereminst test out my stuff so retired most of it.

D you also have a nice sound, must be analog? Not a che.. ......  .......

T

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