Theremin Mod? Volume CV Invert

The Moog Forum Theremin Forum
1

Hi Gang,

I frequently find myself using my Etherwave Plus as two independent Control
Voltage sources with little relation to their original roles.

To be clear, I still also use it as a self-standing instrument, but when I do
use the CV Outs I don’t use them as Pitch and Volume controllers.

As such I’d rather have both of them send positive voltages as I get closer
to each antenna.

Is this a tricky mod to do?

And at the risk of being branded a heretic (a Theretic?) I sometimes wonder
if it would be more natural for me to play regular theremin with the volume
response being reversed in that case as well?

Is there a historical or technical reason why Volume needs to behave the
opposite of the Pitch antenna?

I ask because if it was easier to switch both the Volume and the Volume
CV I could live with that.

Can anyone educate me?

2

Is this something that requires a Modification?

I mean, in theory, couldn’t you change the settings of the volume to make the theremin sound when you bring your hand closer to the antenna and wouldn’t the volume voltage output be proportional to this?

And couldn’t you reverse whatever volume voltage you are putting out by running that into a cp251 attenuator or the mixer’s negative output?


Respectfully,
Eric

3

Hi EricK,

I did use my CP-251 for that very purpose this past weekend (see the Pink Droyd post
in the Moogerfoogers forum) but it took both of the Attenuators in series to get the
voltage high enough for what I needed. One was set at -5 and the other was a smaller
negative number.

I just hate to give up either of those valuable Attenuators.

4

Sounds like you need another CP251 then. :wink:

5

I belive there are instructions for how to invert the volume antenna on the etherwave page. With my paia theremin, which I use as a cv controller all i had to do was tune the volume antenna differently, I assume it should be the same for the etherwave, but have not tried, as i don’t have cv on mine.

6

I have a similar issue.

As soon as I got my Etherwave I flipped the response of the amplitude antenna so it is loudest when my hand is close.

Then, some years later, I purchased and installed the Etherwave Plus upgrade kit with the intention of running the Amplitude CV out to my old skool Moog Rogue. However, while the line out responds the way I want it to, the CV out is running the way Moog intended, so my Rogue triggers inversely to my Etherwave; that is, I take my hand away and it gets loud. This is not so good for me.

Is there an existing fix, or does anyone know how to fix this?

Thanks.

7

If the “reversing” of the volume response has been done as described in the Hot-rodding manual (removing of D5, exchanging the connections of pin 13 and 14 of U3) the VCA out signal on which the Plus Kit acts should also be reversed. So the Volume CV output of the Plus should also be reversed… But as I have no schematics of the plus kit, I can’t tell what they do exactly on the supplementary circuit board.