A modest question

I never had an Etherwave Pro in my hands, but reading here and elsewhere, I got the impression that concerning linearity and waveshaping it must be much better than most of the other theremins on the market.

So I have been interested in the question: "How did the Moog people achieve this?"

But contrary to all other Moog theremin designs, it seems that there are no schematics and no construction details on the web.

Does anyone know why? Or am I just too silly to find these informations?

The Moog staff, on being asked about this some time ago, said that it was now their policy not to make this info public for instruments that were still in production. Some thereminists have expressed the hope that now that the E-Pro is off the lines, the schematics will be made available . . .

By the way, I reverted to my Etherwave Standard the other day for ease of carrying to my streetcorner--and I gotta say, it's a really great instrument. The sweetness of its voice is wonderful, and it has a quality that the E-Pro cannot match, although, of course, the Pro has other areas of greater versatility--more pitch stability (less drift), a wider range, more timbres, and the octave switch.

But I LOVE and very highly recommend the Standard as a fine instrument on any level.

Eliot

The Etherwave Standard is a much more expressive instrument, and its timbre is rather less jagged and overtone-ridden that the Etherwave Pro's. The latter is also cursed with numerous technical bugs and a sluggish volume control.

Hopefully the successor of the two (which, if I'm correct, is on the drawing board) will combine both instruments' strengths.

...a super bionic theremin.....

Hurray. What a treat to see Charlie here (so to speak.) I like the E-Pro, though. I never understood what "sluggish volume response" could mean. Surely, there is no discernible gap between moving your hand and hearing the volume change--it's instantaneous as far as the human nervous system is concerned. As to the distance you have to move your hand to get a specific change in volume--that's all adjustable by a hierarchy of knobs and set screws. I like the timbres, too. For me, it's just that you can't get that particular nice warm one that the Standard has all its own. I guess one person's jagged unwanted overtones are the next person's rich and interesting ones.

Today I got a shot of cortisone for my "trigger finger," the middle one on my right hand, the one that has clicked and snapped on bending for five years, ever since a certain love affair, of which let us say no more, but if the injection works, look out, theremin world: new vistas of articulation will open up for Our Hero.

[i]...a super bionic theremin.....[/i]

...leaps octaves at a single bound...

Steve Theremin....

"I never understood what "sluggish volume response" could mean. Surely, there is no discernible gap between moving your hand and hearing the volume change--it's instantaneous as far as the human nervous system is concerned. "

The reason for the "sluggish volume response" is the time constant into the VCA from the volume antenna resonator / rectifier.. R14 is 1M, C27 is 100n, so this gives a (appallingly long) time constant of 100ms (1/10th sec) worst case.

In reality, 'normal' playing one will get a latency of 10 to 20ms.. This IS noticable.

The volume circuit of the Etherwave is quite a sloppy design (to put it mildly!) and the large time constant is required to attenuate the HF volume waveform sufficiently so that it does not cause distortion by modulating the audio fed into the VCA. Inclusion of a single opamp configured as a good active LPF, inserted between the antenna connection (C12/D1) and R14 allows C27 to be reduced to 100pF, and the response speeded up.

It really annoys me when costs are cut in areas like this which "mosty people will never notice".. The additional cost of components for a decent volume circuit would be maximum $3, so say an extra $9 on the selling price.

"The latter is also cursed with numerous technical bugs and a sluggish volume control."

Looks like I got things muddled! - I thought the comment was about the Etherwave Standard, not the Pro..

If the Pro is more "sluggish" than the Standard, then I would expect this 'problem' to be noticable! With no schematic for the Pro, and no access to one for testing, I would be most interested to hear from any Pro player who has noticed this 'problem'.

I am targeting the top-end Theremin market with my designs (will produce some lower end products prior to this, using 'spin off' from the R+D on developing the top instrument) and every bit of information about what people like / dislike about their instruments is extremely useful to me.

Elliot and Charlie wrote about
[i] I never understood what "sluggish volume response" could mean [/i]
It was on the early releases of the Pro It was more you could not slowly increase the volume, you could hear it suddenly start up, like the jagged sound Charlie mentioned. You just couldn't smoothly start a note from silence. Someone, probably PP came up with the plans to change it and James Hendrix came up with the plans to make a small circuit board and a swith idea to make it snappy if needed.
Models after this batch were changed to reflect this repair, so most Pro owners never had to encounter this problem.
Back to my hospital bed,

Andy