"Any other theremin with a smooth timbre like this will also be welcome!"
Thierry - Having seen Lydia play, I bet she could make the Gakken an object of desire!..
You have an etherwave with 6 playable octaves.. You are unhappy witrh the tone - but (I presume) not unhappy with its playability.. You are thinking of possibly designing / building your own Theremin to get improved tone..
This MAY be a simpler solution - "Understanding, customising...your EW Theremin" gives details of a pitch to voltage converter - It is not the most elegant design, but it works.. One can also tap the volume voltage (buffer it with simple opamp voltage follower).. and one can take the raw audio (pre VCA) and 'mis-shape' this quite easily to get higher harmonic content...
Take the audio into a good VCF, have potentiometers to mix desired portions of the Pitch and Volume CV, and feed this to the CV of the VCF..
With the above you can get the tone as mellow or rough as you want, and get tone (Harmonic) variation as a function of pitch and/or volume as desired..
If one has a multi-mode VCF one can also select bandpass instead of lowpass filtering, and even get the filter to oscillate producing pure sine.
I am almost absolutely sure that the Tvox uses a technique like this - I think there is a 24db/octave Lowpass VCF into which the audio is fed, and that both pitch and volume voltages are mixed to give a filter cut-off which tracks changes to signals from these antenna. It is also possible that Q is voltage controlled in a similar manner.
It is just a shame we dont live closer - I would love to strap some modules into your EW and see if we could get the sound you want..
Or perhaps I should buy an EW and build a module to do this.. AAaarghhh! - So many options, so little time and money!!!
