Theremin out of large steel tube.. possible?

hello! I'm a sculpture and spatial practice student from Melbourne and I am making a piece for an exhibition revolving around sound art - which we have actually been given a small budget for as it's going to be exhibited in a large gallery space here - hence I'm being a bit ambitious - but it's a really great opportunity. My idea at present is as follows:

Buy stainless steel sheeting to create a large round tube that freestands on the floor - about 1-1.5m in diameter and 3 meters tall. This will have a door on the side so you can enter and enclose yourself in the space (either a door that goes all the way up so that the whole tube cracks open when you open it, or a cut in door). The stainless steel will have a no. 8 (mirror) finish on the inside. The outside treatment is up for grabs.

Ideally I would love for you to be able to stand inside the tube and generate sounds by interacting with the tube - either by moving your body through your proximity to the metal - in the style of a theremin, or perhaps there is another solution I haven't thought of yet, like just touching the metal. It would be nice if there was a sliding scale in the sounds emitted as the work is based upon a composer called Percy Grainger who created these incredible "free music machines" where he wanted to escape from the limitations of notes and scales in classical musical instruments. he's a very interesting guy (1882-1961).

Anyway - The design of the tube is also up for grabs - early days - perhaps it needs to be insulated from the floor in which case it could potentially hang from the ceiling so it sits just above the floor, or sit on something insulating. I think it is ok for the sculpture to react to both inside and outside persons, or just one or the other. I was also wondering around relaying the sound created to a different part of the gallery so there is a listening section where you gain insight into the occurrences happening somewhere else - live. But that is just another little other idea floating around...

I am not electronically savvy and don't know the ins and outs of how these things can work very well. If anyone reads this and has any thoughts / ideas for solutioning / some home truths about "your dreaming!" that'd be really valuable for me.

Thanks for reading this far anyway - much appreciate your time!!!

All the very best,

nicki

Hi nicki,

Not saying it's impossible, but unfortunately I don't think you'll find an off-the-shelf solution to "Thereminize" a large metal tube. 

It is entirely possible to perform theoretical capacitive studies to see what effect a person inside and outside might have on the intrinsic and mutual capacitances.  There would be a lot of intrinsic capacitance to deal with, which would probably lower the voltage swing, which might make it more susceptible to 50/60Hz mains interference.

I imagine capacitive interaction with a person inside the tube might not work too well as moving near one portion of the tube means moving away from much of the rest of the tube, though C varies as 1/d and people have arms and such so it might work.  You might have to retune things when a person with a different BMI entered.  Probably more luck with people capacitively interacting with it from the outside of the tube. 

Try to find someone who really understands Theremins to help you perform some proof of concept experiments before you go too far.  The static and delta C the coil sees will determine the value of the inductor.

Hello Nicki,

You want someone else to invent your idea and you have no skill to advance it?

dewster is correct there is no practical RF theremin approach to your idea, but...

nich said: Buy stainless steel sheeting to create a large round tube that freestands on the floor - about 1-1.5m in diameter and 3 meters tall. This will have a door on the side so you can enter and enclose yourself in the space (either a door that goes all the way up so that the whole tube cracks open when you open it, or a cut in door). The stainless steel will have a no. 8 (mirror) finish on the inside.

Use a method of optical theremin, if you lived in my neighborhood I could help you with this project.

As an example here is my better method of optical theremin.

Here is my very simple optical theremin circuit.

Good Luck

Christopher

"dewster is correct there is no practical RF theremin approach to your idea, but..."

I actually do think there is a practical RF approach, Theremin himself made the Terpsitone which employed a big antenna plate on the floor, which by accounts did work after some fashion.

hi nicki, you must be dreaming! no, just joking. sounds like a real cool project..but building something like a theremin driven freemusicmachine will cost $$$  and takes time to develop. as far as i know did grangier wrote music for theremins and lydia kavina played some of it? maybe you saw that pyramid in melbourne?

to control somehow interactiv 8 oscillators or more and varies them too must be a real challenge theremin wisely. all in a steel tube? hihi i doubt that this can be done in reasonable time. on a satisfing level.

i recently stumbled over this board from www.axoloti.com . sounds also cool. maybe could be used for a newer version of a FMM. it's pretty easy to hook up quite a lot of sensors of many kinds and asign them to whatever parameter of a synth you like. i imagine that producing a interesting sound sculpture could be done more swiftly and on a budget. 

yeh not very theremin-likely. apologies.

Thanks so much dewster, christopher and xtheremin8! Whoa, all so interesting. Yup you're right Christopher I'm starting from a pretty ridiculous place of complete noob-ism to electronics, and the technical side of electronic music... but I can only hope that throwing myself in like this leads to some serious learning. You guys have already really helped and I feel super grateful.

I think I'm just going to get this steel tube fabricated anyway - as worst case scenario and there is no sound interaction with the pipe/tube I still think it will be a satisfying experience - to enclose oneself in a dark place - with your own eerie reflection around you - coming out of the darkness - (which I link to the idea of legacy, and the inescapable ego - but either way - interesting space to experience for people). If the sound aspect doesn't work I'll still have that. BUT when I have this tube I would REALLY LOVE to give it a good shot of experimenting with these sound components - so that you also make it a space of "creation" too (with: that inescapable ego/you surrounding you as you do so) - well I think that could be a really interesting thing.

I wonder if I could also experiment with pick-ups on the top of the tube or something so that you can hit/knock the sides and create sound that way... might be more simple... I need to take some online tutorials in this stuff I think and work out what kind of equipment I'll need to buy to experiment with it all. I'll definitely look into the optical theremin too - thanks Christopher. (too bad we aren't in the same neighbourhood so could collaborate) 

Dewster I have two friends here that may be able to help me - one is an Electrical engineer and one is a computer programmer / composer so they might be able to point me in the right direction. I'll get them to read this thread too to make the most of all your advices.

xtheremin8- Yes I have heard some of percy's stuff done with theremins. It's so great - I'm glad you know it. And yes I saw that pyramid in melbourne! It used motion sensors didn't it? I have a vague memory of it working like that - I also saw one in Hobart at the mona foma festival back in 2013 and now I'm wondering if they were the same one. I'm pretty sure the mona foma one used motion sensors.. But great interactions anyway. And thanks for that link to the board!

If you guys / people have any more thoughts / advices please brain-dump away. But yes - I really appreciate your responses and taking the time here - sending big thanks through the earths magnetic field right to yas. (well - that's how I like to imagine it working anyway - it's fitting).

Nicki

If you go the Theremin route you will definitely need to distance it some from the floor with air (suspension) or an insulator like plastic (as you seem to be planning to do).  I haven't simulated this at all, but maybe a foot or so?

[EDIT] With a structure this large you might be up against more in the way of RF transmission, so your oscillator could likely have a harder time driving it.  It might look" more inductive and less capacitive.  Just throwing that out there.

TW needs these conversations.

Nicki said: "If you guys / people have any more thoughts / advices please brain-dump away."

We are at the round table of collecting ideas, I believe in the Edison approach of try everything!

You could stick a sound transducer on the side of the metal enclosure so the whole thing becomes a non-directional speaker. I have tried some of those that use adhesive to stick on but something with screws would be better. This one is mostly in the Bass range so that got me to thinking about thumping the chamber with someones own heart beat. 

Link to the above image

My Nordic Trac monitors my heart beat with two handles which is more convenient, not sure what circuit they use?

Link to below

I ran a 1.5m diameter, 3m tall cylinder, positioned 0.25m above a 4m diameter floor, through fastcap:

It's telling me 212pF total, 138pF mutual (between the cylinder and the floor), and 212pF - 138pF = 74pF intrinsic (between the cylinder and the universe).  Not sure how much influence a nearby body would have in terms of mutual C, but the above can give you some kind of idea for a starting point regarding the coil inductance (it would nominally resonate with 212pF).

dew is there software that can edit a gerber file to change a footprint or add a track, just curious?

dewster, wouldn't your approach be swamped with 50/60 hertz hum from the environment? The amplitude of the AC field would be fairly constant so touching the wall of the cylinder could shift the level to trigger a midi single note sequence per touch?

Who is going to make all this stuff, is it practical?

Christopher

Amazon has this