Enhancing The EtherWave Sound

There are many ways to enhance sound and hopefully I have enough energy in my old age to try something from scratch ($50 DIY Project) that no one has done before.

On this thread Peter Pringle talks about how he gets his sound.

After a year layoff I fired up some theremin stuff this week, maybe a fresh mind. My immediate interest is to avoid vacuum tubes and focus on the EtherWave Standard and try to skew the EWS wave-shape for the classic harmonically rich Clara sound. It is all about wave shape, samples when I get there next week. I use a breakout board very similar or spin off of dewster's original YAEWSBM which gives an extreme low end (too smooth) and then I feed the signal pre-volume control into an external 3" x 5.2" board I designed and think dewster already has two of these PCB's in a drawer somewhere, it is analog so probably buried very deep.

This EWS Performance introduced in this forum by Coalport really captures the beauty of the performer not the machine.

Christopher

You probably have ideas already as to how you will be proceeding, but you might give ILYA's mixer a shot while you're at it (found here).

Thank you for ILYA's info. The only mod I make to the EWS board is pulling either C2 or C6, too bad I cannot find a terminal with tiny pins to refit back into the cap holes without drilling, direct wires work fine. I do have the terminal size but the pins are fat. One day I will draw a schematic of this board. If any builders are left and this works interestingly then I will give the two boards away at no cost along with a one-click Mouser parts list.

My secondary goal was to take the audio signal out from the EWS to modify then send it back in to use the EWS volume control. All this has proven to be very effective. I was amazed to find about 1.5 v p-p as I use my own detector diode. The extra Pots give control of the input/output signal level. I found no need  for the extra balance Pot of the YAEWSBM and I added two 3.5 mm TRS Jacks for easy connection of the add-on. This is all from a year ago so now to find the sound I am after. Using dewsters emitter follower allows maximum low end, the theremin has no Null, just goes low and rolls over to the other side, this is why a mute switch is nice.

Christopher

Christopher, we exchanged thoughts on tube preamps and such.  I'd love to hear some audio when you locate the sound you're looking for.  I think you're on the right track with an add on!

Hello Tom,

I have proven the fundamentals. I am not trying to create a unique sound rather discover what sound is waiting for me on the other side of the forest.

In the image below can be seen the second board, minimal components, analog, but it is how I use the small audio transformer that does a trick. FredM once mentioned audio transformers in wave shape but I a sure I am doing something different. One chip is a LM358 amp and the other is the old classic 555 which the skew trick is based upon. If the sound is pleasant then I will order the small break out PCB which fits inside the EWS, already have several of the bare add-on boards seen in the picture. My two boards will be a gift. If the results are poor, me and this thread will just fade away.

I just took this photo outside so those in the cold can see I have grass, barely green due to drought.

Edit: Things went quicker than expected. In the past I could not hear noise in my sound when others could so I will say my method does suppress the third harmonic nicely, this is important. The sound is not as fat as the tube oscillator but has ideal control over the wave shapes, good ears could dial it in. I recorded what for me is a good EWS sound, tell me what you hear. For me it is ideal classic theremin, long ago she said her voice was a gift to me or was it for everyone?

EWS Exciter board by oldtemecula  sound.wav 2.5 meg

The board is powered by the EWS through either TRS jack, uses about 2 ma.

PS: Don't forget to encourage the Indian Princess MM above who re-awoke my theremin spirit.

Christopher

Yes, Christopher, there is a very nice vocal quality to that clip!  I'm going to try and find some time to play it through my studio monitors to get a better sense of girth of that sound. I'd do like that type of older vocal quality that isn't too buzzy or nasal, if that makes sense.

When you talk about dialing it in, do you mean by way of external processing, or are further internal adjustments possible?

Tom I can make a sample holding notes if that helps your analysis. Theremin sound is one of the marvels of the original design, almost an illusion. My wave form has extremes on both sides of sweet in the adjustment which do not sound good to me, a little more edginess maybe. I do not invent the sound as it is a natural phenomenon that I don't think can be captured in engineer modeling.

Edit: The recorded sound is EWS output jack direct to computer sound card, no processing.

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funny #

Europe is so far ahead of us when it comes to theremins I want to make America great again, I will build a wall and make Europe pay for it. I need that guy from New Jersey to endorse me.

I think friend of Snooki or Dan Schreiber could do something with this project to make it widely available to all those EWS owners. From me it is a gift, for them profit. The butt cheeks of Epro owners who read this are now starting to quiver.

Because the board takes the signal out pre-volume seven features exist in the design:

Pitch Preview (best to use external power)

Have Classic Vacuum Tube theremin sound

No more hot EWS output, adjust the level

Use a switch and go back to the exact original EWS sound

Have superb Low end freq response

Mute Switch

Static discharge protection as FredM mentioned. (needs testing)

It is time...

Christopher

Christopher, I like your novel "wire in the tube" ESD protection approach to the volume side antenna (which usually gets touched a lot).  Is there any secondary protection to the volume side?  How about the pitch side?

You say the recording is direct to soundcard, but it sounds to me like there are room reflections or similar for the midrange notes, and the waveshape isn't constant for a given frequency like one might expect from direct recording.  Not an attack on you or your methods, I'm just not sure what's going on there.

dewster, I enjoy your input. I love people who can hear so well. I lied, in Audacity I added a tiny pinch of reverb. The classic theremin wave form naturally changes through the range, it is analog. As in the past... is noise in my sample?

The sound byte does reveal my mild Parkinson's, maybe that is what you hear. lol  I hope Master Thereminist realize the gift they have in many ways. I can record something by request for a test.

Your mind would be a good one to figure out all of what's really going on. One thing I do is adjust the signal level across my mixer/detector diode to a bare minimum while watching the audio on a scope for a more earthy wave shape. There are several connecting wires on the back of the 5.2 x3 PCB out of sight. My very old PCB software only does one side stuff. As a hobbyist this usually worked out fine. I came out of retirement briefly, while walking in a cornfield I heard "It is Time" then boom.  I sent an email to my old friend djpb_designs to maybe get input, I just can't let what I am doing be lost in time if it has value to someone else.

I have those static tubes Fred recommended but never tried a direct connection from the pitch antenna to ground. It seems they have too much capacitance to work without distorting of the pitch field. My small EWS internal board has a spot to add the tube if you pull C2 instead of C6. The pads are marked with an X by VPO. C21 replace C2 on the EWS board.

Christopher

"...in Audacity I added a tiny pinch of reverb. The classic theremin wave form naturally changes through the range, it is analog. As in the past... is noise in my sample?" - Christopher

That explains it, the waveform change I'm seeing in Audition for static frequencies is almost certainly due to the addition of reverb.  Using the frequency view (FFT) I see a suppressed 3rd and 6th harmonic, otherwise linear roll-off (in dB) of harmonics.  Doing an FFT of the entire sample there are small peaks at 5.6kHz and 13kHz, not sure what the origin is but they are so low (-84dB) they aren't audible.  I don't hear any aliasing.

"I have those static tubes Fred recommended but never tried a direct connection from the pitch antenna to ground. It seems they have too much capacitance to work without distorting of the pitch field. The EWS internal board has a spot to add the tube if you pull C2 instead of C6. The pads are marked with an X by VPO."

I only have a little experience with secondary lightning protection for line connected telco equipment, but I believe these types of devices should be mounted as physically close to the ESD source as possible and given as low impedance and direct path to ground as you can manage.  Due to the circulating high instantaneous energies in the high Q tuned LC, introducing a sudden low impedance (protector firing) can sometimes paradoxically cause more damage than if there were no protection scheme in the first place.  So sticking protection in there after the fact isn't the best plan - tight integration into the full design with testing to failure under common scenarios is necessary for any degree of assurance that the cure isn't worse than the disease.  My own experience with this was fairly disastrous; I should have exercised more control over the layout process than I did (someone else who didn't understand the scenario performed the layout, which is a glaring lack for a telco layout department, and none of the old timers familiar with lighting offered me a hand - glad to be out of the industry - all industry actually, though co-workers and the experience have taught me some critically important things that I'm very grateful for).

[EDIT] Back to the main topic, listening to your file the upper range sounds fairly feminine voice-like, though the lower registers don't so much.  As the pitch falls from the upper range I hear what I think of as additive rather than subtractive synthesis, where the waveform shape isn't changing a lot with pitch, so the effect is rather uncanny like that of the Hammond organ - almost like a filter is tracking the pitch.  Voice is much more in the subtractive camp (filtering) so if you want to do voice sounds over a larger range (not sure if that is your goal or not) a fixed rich harmonic source with downstream fixed multi-pole resonant filtering is likely the best and simplest approach.  You might try running your signal through some filtering in Audacity to see what you might like here, software experimentation is a lot easier than firing up the soldering iron.