Build Project: Prototype III - D-Lev Digital Theremin

"But I'm actually getting a little tired of the vertical cabinet style of my "Pro" D-Lev (and the Claravox too, and it hasn't even shipped yet)."  - pitts8rh

Ha!  I couldn't warm up to the slanted vertical orientation much as I thought I would either.  One problem for my P2 is the volume coil is right at gut level, which makes body proximity rather touchy for volume axis auto-calibration and play.  I'm experiencing this with P3 too but it isn't quite as bad, and there are more options to explore in terms of plate placement.

I haven't gone through it with a fine-toothed comb, but it probably wouldn't be too difficult to make a lefty option for the tuner purely in SW, using the existing tuner PWB.

Roger, now that you've got some Melodia playing under your belt, what's your feeling re. a left plate rather than loop?  What about maybe making that plate horizontal?  I think the loop is mainly so the hand can get very near the loop without actually touching it, a feature that isn't required for digital Theremin volume side operation.

"I've also wondered if it would be possible to have PCAL and VCAL swap positions when the system PV reverse is enabled. Seems like a logical thing, if possible."  - pitts8rh

There are quite a few vmod & pmod knobs that should probably swap as well to fully accommodate lefties.  Might be best to fork the SW load in order to do this.

"But I'm always thinking that the best approach for either of these antennas is a socket that can take any antenna that the player prefers."

I agree, though with (my usual, monotonous) reservations.  External antennas are so fragile and fiddly, and invite ESD.  I was constantly brushing against the P2 plates, almost knocking it over like every time. 

And, beyond some basics, I tend to view optional physical adjustments as a net negative, as any little change can easily throw off muscle memory.  Sorta like having the neck of one's guitar or violin, or the keys of one's clarinet, subtly change between playings.  Breakdown and setup of one's Theremin shouldn't change basic ergonomic dimensions even slightly (unless that is the desired goal, which it won't be after one plays it enough).  Maybe I'm a princess with a pea, but just changing the D-Lev stand height 1" throws me off for a while.  I think I'd rather adapt to fixed, slightly sub-optimal ergonomics, than have everything shift like desert sands between gigs.

"...I've recently developed a left hand problem and I'm not sure if it has been aggravated by the Melodia. For now I'm changing hand positions quite a bit to try to minimize stress on it, and I may have to go back to a loop theremin for a break."

Oh, sorry to hear that.  The repetitive small movements of the volume hand could easily lead to injury.

Roger, I'm wondering if one of your issues with the RP2 / EWPro ergonomics is the narrowness of the body?  You have a "wide stance" Subscope which I presume is comfortable for you, and maybe that's somewhat driving the width of your RP3?  I mean (I guess) maybe it's more than just antenna distancing?

What's your feeling on increasing the front to back horizontal dimension (over the ~6" or so of the EW) to make things more like the T-Vox?  Use that dimension to move the pitch antenna up and away, volume antenna lower and nearer?  Kinda like a wide RP2 angled back a lot more?

With my P3 (as with P1) I'm not seeing a ton of height difference needed between the plates, and a similar difference in terms of front to back distance, which could conceivably be accommodated by some moderate tipping up of a rectangular case like the T-Vox.

Beautiful (as usual) Roger! 

Pop quiz:
1. You're "riding bareback" with no ESD ICs on the AFEs?
2. I see Dith=2 on your pitch axis, do you find that necessary?
3. What's the electrical connection inside the printed volume loop support?
4. Where are the audio outputs (they seem to be hidden in the pix)?
5. What are the bottom facing LEDs on the audio board for?
6. Why does the audio board have a missing cable on the right?
7. Can your audio board drive headphones?
8. So it seems everything except the AFEs and coils are mounted to the clear panel?
9. How is the tuner being held in place?
10. How is it powered?

TIA!

2. I see Dith=2 on your pitch axis, do you find that necessary?

That's grandfathered in from the imported settings taken from my Pro.  I suspect it's not needed, possibly not on the Pro either.

A setting that low probably isn't hurting anything (they are actually applied as powers of 2) but as a general rule I would keep the Dith knob settings as low as possible (mine are zeroed-out).

3. What's the electrical connection inside the printed volume loop support?

That is one of the five antenna mounts that I printed for PII that has the brass cup and uses a split brass sleeve.  It's still the fastest and most positive mount yet, but I do think that I'm going to end up using a standard chrome/brass compression fitting (like the volume end of the EW) except with the nut pressed into a large printed knob like this one.  The metal fitting is more compact on the inside.  The fine thread takes more turns to tighten it, but ultimately it will still look the same and be wrench-free.

With the metal compression fitting nut pressed into the printed knob (great idea BTW!) what sort of fitting would it mate to?

9. How is the tuner being held in place?

At the moment it's friction, but when I make the opaque cover there will be printed rails that the boards screw onto that are attached to the back of the panel using structural foam tape.  Same for the MUTE/LED board.  The boards will be removable but the rails will stay.

I would be sorely tempted to take this opportunity - the clear plastic - to forgo machining any holes (which you have doubtlessly contemplated).  Not trying to tell you what to do (I do the same with my printed tuner plates)!  And there is something more immediate to having the LEDs completely exposed.

During the great lemming stampede of 2020...

Ha ha!  Sooo glad those stupid days are mostly behind us.

"I've had it both ways at various times and the tuner with fully exposed LEDs behind clear isn't really a good look, particularly for this off-center design."   - pitts8rh

Oh, gosh, I completely agree and wasn't expressing myself well at all.  LEDs in the raw, not behind clear, seems to be the best way to go with the tuner.  The clear (and present danger) temptation is to not to do that, but it's a siren song IMO.  I wouldn't have guessed it, but the raw colored LED domes poking out make for the highest contrast presentation.

"If faced with manually machining those holes again however I would consider making a single large cutout and printing a thin black panel/overlay, with holes, to surround the whole tuner."

I agree.  Sometimes, when playing in total darkness, I think there should be an option of barely illuminating all the LEDs, just so the pattern itself is clear.

Lookin' really sharp Roger!  It's nice to make things modular - so many physical design problems then seem to take care of themselves.  Printed panels to hold and mount all the encoders, LCD, main board, tuner, and axis plates can vastly expand and simplify the otherwise extremely limited enclosure possibilities.

Having the encoders separately plug in like this would help with field replacements, though I'm hoping we can find a supply of more reliable ones.

I'm looking forward to getting my grubby little mitts on these, and I appreciate all the work you've put into them!

Yowsa!  Roger, that is an amazingly pro looking build!  Mega kudos!

"The paper covering that protects the surface is hard enough to remove on fresh sheets and nearly impossible to remove past a couple years. I can't imagine how any production user of this material deals with this miserable stuff."  - pitts8rh

I got this stuff called "Formula 747 Plus Adhesive Remover" from Home Despot to remove that tar-like floor tile adhesive from the plywood underflooring.  It sort of worked but it leaves an oily residue with a lot of odor (but not a get you high / knock you out / blow you up solvent type odor) - I ended up removing the subfloor and replacing it.  But it's come in quite handy for removing sticky labels and such, I use it all the time for that and it really works well.

"The fluorescent green acrylic is a pretty strange material.  Aside from the fluorescence there almost seems to be a dichroic effect going on where the reflected and transmitted colors are complements with all of the edges glowing in a brilliant orange.  I don't know what's causing this.  But even in mild light the orange borders look like the panel is powered with a light source."

It's quite snazzy looking!  The whole fluorescence / light pipe / dichroic thing going on is mezmerising.

"Under black light the effect is a little underwhelming.  It's mostly a ghostly green that sort of dominates over the orange highlighting.  I do like that you can still see the coils and boards through the glow.  This material is as you might guess extremely scratch sensitive (note the orange scratch to the left of the LCD display).  Since I destroyed the clear acrylic panel that was intended to be my bench unit I'll probably use this instead."

Under black light I was expecting a psychedelic acid flashback experience!  Maybe it used up all it's gaudiness in the visible spectrum?  Is it being illuminated with deep or near UV (asking for a scorpion)?

"The mineral-spirits materials like the adhesive/tar remover don't do much, and anything else in my solvent arsenal runs the risk of crazing the  acrylic at some later date."  - pitts8rh

You're right, Formula 747 does smell like mineral spirits.  No list of ingredients on the container though, which one would think would be mandatory from a poison control standpoint.

Roger, for some reason all of your pictures are blank in my browser?