Moog Theremini!

Fred, the instrument you describe above sounds vaguely like the Haken continuum. While the continuum fingerboard is not a "touch screen", it is an exquisitely sensitive slippery-slidey surface that responds to motion in three directions: up and down for volume, left and right for pitch, and backward and forward for timbre. Not only that, it is multi-timbral so both hands can play. If you use only one hand, the other is free to play another instrument (which is what I do in the following video). Unfortunately, video does not give the viewer any visual idea of pressure sensitivity (up & down volume control) because you're dealing with millimeters, but you can HEAR it.

http://www.youtube.com/watch?v=PnBhR8RLJN8

Gordon wrote: "<snicker> I wonder how some of our more prima-donna-ish precision thereminists would feel about being relegated to the chorus. ;-)"

Refusing to be relegated to the back of the hall (at a desk behind the last bassoon players), I have already refused positions as principal theremini player from no fewer than five of the world's major symphony orchestras! Yes, the great orchestras are now scrambling to hire theremini players.

Relegated to the back of the hall???

Why, the very thought!!!!! 

Quel culot!!!!!!

Or, as the Americans would say, WTF!

OT - Not about the Theremini

Hi Peter,

Yeah, its a bit like the continuum I guess, but much simpler - Monophonic, and only sensitive to one parameter - capacitance - which is determined mainly from position (x axis) and a little by proximity / area.. Its a theremin antenna which mainly detects along its length and not by distance.

And MUCH cheaper ;-) entirely passive, it consists of a fancy network of ovelapping capacitive plates which are individually trimmed to get linearity, so one can get as many octaves as you want - (not user trimmable - one would make the required length in the factory and tune it there)

Antenna tuning would be for a specific theremin - any theremin could be fitted, but practically it will be best to have one design so that the antenna strip can be standardised for this and trimming minimised (or possibly eliminated) - I am looking at about 1.25cm per semitone, giving 5 octaves for a 75cm strip, and up to 8 octaves with a 1.2 metre strip.. The theremin will need to be capable of the range required... I want 16Hz to 4096Hz.. ;-)

But from the theremins perspective, its just an antenna.. And the astounding thing about it is its simplicity - this could have been produced in the 30's !

Fred.

I have just watched your continuum "demo" - Ive seen demos of this instrument before, but this is the first where a monophonic "lead" was being played..

Its superb -

As I understand it though, its got "key" positions which can be "detuned" or "bent" - yet your opening scene you were sliding it as though it had no key "assignments".. Then you played it "as if" it was a keyboard ... bending individual notes etc..

It looks to me like there were two different modes in operation.. Or were you actually 'landing' on precicely the right points on the board to get the perfect pitches you did ? .. You see, for me, even with visual cues, I would still need audio preview to do what you were managing... (well no.. I could probably never do what you were managing, but you know what I mean ;-)

My horizontal antenna behaves a bit like your opening 'gliding' scene - pressure only affects pitch not volume (actually, I am exploring having a seperate sensor "track" so that the thumb controls the volume - I find this really instinctive - moving the thumb above this strip with about 7cm from max to min volume, and having a raised pitch sensing antenna about 3cm above the volume sensor strip - the other fingers are bent over the pitch sensor which is curved and facing away from the player..

But I will still need preview - because one can raise the pitch by an octave if one has 4 fingers on the strip rather than one, or one varies finger distance or pressure - One only gets linear note spacing if one slides a fixed finger configuration on the sensor with a consistant distance or pressure.. And if one moves all fingers from the sensor more than about 5mm, one rapidly gets into extremely non-linear area - pitch dropping by octaves - and this gets more extreme the further from the bass end of the antenna one gets...

Still a lot of work to be done ( I have only messed with proof of concept really - cutting tiny pieces of aluminium tape, shaping these with a craft knife,overlaying cellotape, placing the layers, trimming - days of work just to get the tiny capacitances "right enough" that I have reason to believe it will work..)  - but its ok if one keeps ones fingers lightly touching the sensor. (ground coupler is just a full copper fill to capacitively improve performance - does not need to make contact)

*Many of the "details" (if not all) that I give in this and the last post may be inaccurate - LOTS of simulation has been done, but little other than proof-of-concept has been built, and so lots of what I say is speculative. I have no possible way to fund full development, my hope is that I can afford a prototype and get crowd funding through this.

The continuum interface is a neoprene pad that has a satiny-smooth woven upper surface applied to a thin rubber sheet (same stuff as a mouse pad). It is sensitive to the slightest motion of the hand. The "keyboard" that you see printed on the fabric is strictly a visual aid for placement of the finger (or fingers) and if you want to hit a note precisely, you must be in the exact center of the printed "key". If you are off by the slightest bit, you will be flat or sharp (similar to the theremin). Yes, you can quantize your sound if you want to, but I do not.

When I want to play the pad like a keyboard, I hit the notes precisely and then apply pressure for volume. If I want to "gliss" like a theremin, I apply pressure and then slide to where I want to go. There is no "toggling" as there is on an ondes - I was landing on precisely the right points to get the correct pitches.

Underneath the neoprene pad there is a mind-boggling row of thin metal bars that "float" on hundreds of delicate springs made of steel as fine as hair. Woe betide those who attempt to look underneath the neoprene without knowing exactly what they're doing. I had my own baptism of fire, thank you very much!

On the other hand, I now know how the damn thing works.

Many thanks for that detailed description, Peter.

It sounds truly astounding, and I cannot even begin to contemplate the complexities, both mechanical and electronic, in crafting such an instrument - particularly with it being polyphonic and multi axis sensitive.

As I have said before, us engineers here in the theremin world, even the best of us, are only "big" fish because we are in a tiny pond - Throw us into the ocean where engineers are producing instruments like the Continuum, and our real "status" would be quickly exposed - LOL ;-)

Fred.

What do you mean WE kemosabe? ;-) 

Never seen one in the flesh, but one thing I really like about the Continuum is that it has built-in voices.

(That thing's crying out for capacitive sensing via FPGA.)

OFF TOPIC

"That thing's crying out for capacitive sensing via FPGA." - Dewster

Having now seen pictures and explanations etc of how the Continuum fingerboard is constructed and operates, I agree with you Dewster -

This instrument is just crying out for simplification, and this simplification could probably be achieved with capacitive sensing and FPGA better than by any other means.

The the magnetic fields from the fine magnetic rods in the fingerboard are sensed by hall devices at each end of each rod, so that finger pressure and placement can be determined and processed - if these rods were non-magnetic, grounded, and capacitive sensing pads placed beneath them, exactly the same data could be derived with even higher resolution than the hall sensors are capable of.

The mechanics could be hugely simplified, the grounded rods would be between the player and the sensors, so there woulf be no capacitive interference problems, and my guess is that the whole fingerboard could be produced at a fraction of its current price. 

All the existing algorythms and firmware (which is the clever bit of the Continuum IMO) should work with a capacitive fingerboard, and the 2 hall sensors required for each rod replaced with simple copper sensors (probably just PCB tracks).

But you were right, its certainly a better way to engineer this instrument... And im wrong when I say "Throw us into the ocean where engineers are producing instruments like the Continuum, and our real "status" would be quickly exposed" - The real difference is that in this tiny pond anything we do gets noticed, whereas out "there" even truly great ideas rarely get noticed.

Fred.

OT as well

"The mechanics could be hugely simplified, the grounded rods would be between the player and the sensors, so there woulf be no capacitive interference problems, and my guess is that the whole fingerboard could be produced at a fraction of its current price."  - FredM

I'd try to leverage the huge I/O count in even a low-end FPGA to simplify the hardware even further.  From top to bottom:

1. The top neoprene mouse pad stuff.

2. A flexible ground layer.

3. A flexible insulating layer.

4. A flexible layer of short narrow conductive parallel strips, maybe 5mm wide spaced 5mm apart, running front to back.

5. A springy insulating layer of some sort (more neoprene?).

6. A layer of long, narrow conductive parallel strips with the same dimensions as layer 4, but running from left to right.

This forms a huge XY capacitive grid.  Sequentially drive the layer 6 strips, and watch the response on the layer 4 strips using RC time constants.

With this setup you could track loads of fingers on the thing.  You could probably DIY it for almost nothing (<= big talk).

OT - Re Fingerboard..

So, we are getting into major Hijack teritorry here ;-)

I have created a thread where we can continue if we wish..

http://www.thereminworld.com/Forums/T/29468/fingerboard-design-construction-ideas?page=0

Fred.

Hi,

I'm new to the forum. As a composer and budding thereminist there's a lot to take in on all this information posted on the Theremini. I have an Etherwave Plus (I've been playing this for less than a month now and I am totally hooked) and recently bought a Theremini thinking it would help me with my technique. Well after playing with the Theremini here is my simpleminded view.

1. The Thermini is kind of cool - but not for being something that is going to help me learn the theremin. I view it as a totally different animal. It's a tool to use to get effects using some Animoog sounds and as a controller. When you look at the video of Dorit Chrysler on the Theremini - that's about all she does - noodle around with Animoog effects (because likely its hard to do anything else with it compared to the real thing).  In my opinion, it's not a Theremin. It's a wave table-based synthsizer with a Theremin-like front end controller. That doesn't mean it's bad. As a composer I might be able to make good use of this function. Even with quantization all on, with enough delay some of the Animoog sounds could be useful for certain programatic settings. I'm sure some bands will use it. It's not useless. But it needs to be used for what it is. And it needs more sounds (I think this is an upgrade in the works?)

2. What it isn't (contrary to the marketing) is a good tool to help you learn the theremin. First, it's just a heck of a lot easier to play the Etherwave even when the pitch quantization is dialed all the way up on the Theremini. For me, way to hard to pick out notes compared to the Etherwave. The pitch field is too tight and the calibration on the Theremini is also unforgiving. Auto calibration is a distaster. I have no idea what the pitch range I just set was from just performing their calibration routine. You need that pitch knob to easily dial in your personal configuration. Perhaps some of this can be tweaked in a firmware release. Moog needs to study hand positions used on the Etherwave and try and emulate similar spacing on the Theremini. That's the single best thing they can do in a firmware upgrade in my option (doesn't Moog want people to buy Etherwaves after first playing this?)

3. Digital delay function - nice to have. Speakers - nice to have. Portability - nice. CV out and MIDI - nice to have. Pitch display - who really needs this (I'd rather have pitch preview - can't seem to find it). If you have to be constantly looking at a tuner to see if you are in tune, you will never be able to play the theremin. You play it 99% with your ear as far as I'm concerned. Other than to give you a starting pitch, I don't see much use for the tuner.

4. But the absolute worst thing about the Theremini is that if I had bought it first I might have given up on the instrument and never known the joy of playing a real theremin - as it's darned near impossible to play the Theremini as a "classical instrument" in theremin mode. I'm so glad I bought the Etherwave first. Anyone who wants to learn the Theremin should just go get themselves the real thing and be prepared to struggle like everyone else. The reward comes in the practice.

Bottom Line: When I want to play Theremin and improve my technique, I'll go to my Etherwave. When I want to create Animoog effects or want a more portable Theremin-like controller, I'll use the Theremini. But never the twain shall meet.