Question: Musically useful Theremin ranges. ?

[b]**EDIT** Please ignore this posting and read my posting of 7/23/2010 3:43:14 PM on this page --> [/b]

I am doing the final definitions before my application specific Theremin IC goes into production - I would really like feedback from Thereminists before I cast this in silicon.. Particularly feedback on the bass note stuff - and whether it is worth implementing.

Sorry - but I need to briefly explain what this IC will do.. You can probably skip this bit::[i] It will take signals from the oscillators, and multiply / divide the frequencies to produce resultant frequencies, difference frequencies, etc.. It has an interface (I2C) which can be connected to a controlling microprocessor, and this would allow total control over everything.. However, I have designed it for use without a microcontroller (for simpler / lower cost builds) and in this mode am limited to a few preset parameters.. It is these parameters I must now define. [/i]

There will be a (probably rotary) range control .. This will have 7 positions - position 1 being a range of about 2 octaves.. position 7 being about 9 octaves (each change will add or subtract an octave from the playing area (as in, multiply or divide both pitch and reference oscillator frequencies by 2), whose size remains constant and linear).

Not confirmed:
There will also be a (probably rotary) bass pitch selector - this is the pitch which will play immediately when the muting point is crossed [i](with my Theremin, one cannot play on the wrong side of the null point - the Theremin is muted in this area - there is visual indication [red-amber-green LED] to show when you are in the play,muting, and null zones).. If I implement the bass stuff I am talking about here, the muting will also activate if the difference frequency is lower than the selected bass frequency[/i]

What I want to know is.. is this worth doing, and what frequencies should I preset the bass selector for..? There are 7 values that can be selected.. One needs to select a lower frequency than one intends to play, so that one is not too close to the null point and the risk of silence if one goes off-key..I am thinking:

1 = 0Hz .. No offset, as normal Theremin
2 = 8Hz .. to play above 12Hz.. eg C0 (16.325Hz)
3 = 16Hz .. to play anything above F0 (21 Hz)
4 = 32Hz .. to play anything above F1
5 = 64Hz .. to play anything above F2
6 = 128Hz .. to play anything above F3
7 = 256Hz .. to play anything above F4

The above frequencies could be anything.. but there is a problem.. These frequencies merely set the Theremins muting point.. So, if one selects a range in which the 'bass' pitch is a significant percentage of the range, that 'chunk' of the playing area will be lost.. If one selects range 7 (which has a top frequency of about 5kHz) then setting a bass of 256Hz will reduce the playing area by about 50%
(as in, the lower octaves will be muted) and setting 64Hz will lose you about 1/7th the playing area.. Setting a range of 4 (top frequency ~550Hz) will lose about 50% of the playing area.

The above only applies to the bottom-end build.. the IC's are accessible through I2C and on the higher builds communicate with other ICs and bass frequencies are actually added, allowing a constant sized playing area to have lowest and highest frequencies absolutely defined.. I am just "mopping up" and seeing what I can squeeze into the IC's when they are used in 'low end' mode.

Any ideas / opinions are most welcome!



Any ideas about combining range and bass limits? I could have a 16 position selector, and combine these functions with simple logic..

Fred.

[b]Null[/b] = when VFO and Ref oscillators are at same frequency.. as in, the limit of the playable area.
[b]Muting[/b] = When at null, or wrong side of null.. and when difference frequency is below the selected bass frequency

Hi Fred,

Please can you clarify - one can choose how many octaves are available within the playing field - seven options between 1 and 9 octaves - so presumably in increments of about one octave and two semitones. But if I choose say a field of three and a half octaves, can I select [i]which[/i] three and a half octaves I get - i.e bass, alto, baritone or soprano?

Gordon

[b]**EDIT** Please ignore this posting and read my posting of 7/23/2010 3:43:14 PM on this page --> [/b]


[i]"Please can you clarify - one can choose how many octaves are available within the playing field - seven options between 1 and 9 octaves - so presumably in increments of about one octave and two semitones. But if I choose say a field of three and a half octaves, can I select which three and a half octaves I get - i.e bass, alto, baritone or soprano?" - Gordon C[/i]

In the full version, you will be able to set minimum and maximum frequencies covered in the full playing field (aprox 60cm) and be able to assign these to 'range' presets.

with the simplified version (to which my questions relate) the actual null point is 0Hz (as with all Theremins) and one can limit (if I choose to implement it) the lowest frequency only by muting frequencies below this frequency - the consequence being proportional reduction in the playable area.

One could increase the playable area by adjusting the null point to be further from the antenna - but doing this will not be an automatic function of the range or register controls.

On this simple build, I originally planned to only have a range selector (as in, number of octaves) but "number of octaves" is extremely difficult to achieve.. as the core variable frequency span will change depending on capacitances, and getting this span to equate consistently to a fixed constant number of 'notes' is probably impossible..

The core is designed for a minimum (under worst case capacitance conditions) span of 1 octave, but this span could be 1.2 octaves.. If 'core' span was 1 octave, the selector would give 2,3,4,5,6,7 and 8 octave ranges.. If 'core' span was 1.2 octaves, the selector would give 2.4,3.6,4.8,6,6.2,7.4 and 8.6 octave ranges..

(all the above assumes one is calculating octaves from a starting frequency of 16Hz .. if one starts with a frequency of 0Hz, the number of octaves is always infinite! ;-)

It is possible to have a knob by which one can tune the core span to 1 octave (or whatever you wanted).. and the full instrument will take care of the span automatically.

But the basic answer to your question is no.. one cannot easily select "bass, alto, baritone or soprano" ranges on the simple version.. or at least not if one wants to use the full playing area - and the more I think about it, the more it seems that limiting the bass point in this way is pointless.

Need to see if I can squeeze another PLL into the IC so that I could actually add the frequencies - but I dont think I can - this function is taken care of on the full high-end unit by adding more PLLs.

[b] The Questions --> [/b]



I think I have been making the sort of mistake that Peter (coalport) often chides engineers about.. I am thinking in terms of frequencies and multipliers etc, and trying to ‘shoe-horn’ these into a musical instrument..

The questions I should really be asking are these:

What ranges do you want from your Theremin?
How would you like range selection to be organized?
Is there anything else related to ranges that I need to think about?

Forget everything I said in prior posts on this matter – just tell me what you want, without any regard for its feasibility or otherwise..

Thanks.
Fred.

...and now you're making the other sort of mistake. :-)

The good Mr Pringle has said on several occasions what he wants of a theremin. He wants it all!

I agree with him!

If I don't have to consider practicalities, I will wish for the moon and the rest of the solar system too.

But I realise that does not help you much. What is needed here is a [i]dialogue[/i].

So I am not going to ignore what has gone before. Sorry. :-)

So the first option you have invited to consider is a range variable from one octave (which is probably a bit silly - a minimum of three would be fine as far as I am concerned (*)) to eight and a half octaves approximately. Which would include notes both lower and higher than a piano offers. Yup, that sounds like plenty.

Secondly you have indicated that it keeps the cost down to pin the choice of octaves at the bass end and trim them off from the top down. So if I were to set it to say three octaves or thereabouts I'd have a bass instrument.

I can live with that. As I have mentioned before, for me the best part of playing an ePro was setting it to the bass register and enjoying very playable low frequencies. I can't get that on my etherwave standard or my Enkelaar. I can get a wider spread of high frequencies by the simple expedient of moving closer to the pitch rod. So if the range has to be pinned somewhere I would rather it were pinned at the bottom. And I do like the idea of keeping the price down. So I say that's OK for me.

But... I don't even pretend to be a classical player. So I'm not going to guess if one would feel the same way.

Can I think of any other considerations? Not at the moment. I'll let you know if any occur to me.



(*) Perhaps a one octave theremin would suit a person with shaky hands. I imagine that with the semitones so widely spread the vibrato caused by trembling would be so small as to be imperceptible. (And glissing would be unavoidable.)

[i]"...and now you're making the other sort of mistake. :-) The good Mr Pringle has said on several occasions what he wants of a theremin. He wants it all! I agree with him!" - Gordon [/i]

Thanks Gordon.. ;-)

Unless I get some contrary opinions in the next few days, I will discard the 'bass note limiting' idea and just go for a range selector - what you say makes sense to me.. it is what I have 'ready to roll' and the bass limiting was just something I realized was possible to do without adding cost.

The chip I am designing is a 'universal' component - for a low cost Theremin I use two of them, and use pins normally used for serial messages to instead interface with simple static logic levels - this way these pins can be connected to a simple selector switch or two, and I dont need the digital user interface with its microcontroller, LCD etc.

[i]Doing this will allow me to get the Theremin to market quickly - there is one board for the front-end.. this contains the oscillators and a couple of these chips - it has a connector for the selection switch/es, and this same connector can be taken to other boards and carry the serial data for more advanced(future) Theremins... When in "serial" mode, I will have full control over each of the chips, so (with additional chips on other board/s) it will be possible to "have it all" (for a much higher price) - The idea is to have the core oscillator board upgradable simply by disconnecting the manual selector switch/es and using this connector to connect to the new boards.. This way, those buying 'early' will not lose out when and if I bring out 'higher' Theremins.[/i]

I am still interested in what people want if they can have anything/everything.. This will all be useful information, if not for the simple version, certainly for the higher versions.. There are issues like the user interface (for the advanced versions) which I need to get right.. All fine and well being able to have everything - but (for example) it may be that there are a few ranges people want which can be implemented simply on (say) a rotary encoder.. and that (as with many multi-menu LCD synthesisers) they would not want to program their own custom ranges - even if these could be assigned to 'presets' which were simple to access.

Fred.

OK, playing the hypothetical game, I would like to be able to switch from say soprano to bass in the middle of a performance quickly, silently and without getting confused.

Here is what I envisage happening. I'm playing in the top four octaves and it is time to change. I'm going to keep playing in four octaves because changing that would certainly confuse me. Keeping my pitch hand in place I silence the theremin by bringing my volume hand down and touching the mute button so that I can move my volume hand away from the loop and turn the register knob. With each click I hear the pitch drop an octave in my pitch preview. Exactly an octave. Because I understand octaves. A drop of for example one octave, three semitones and 27 cents would be confusing. Now I an in the bass register and I know where I am. I move my volume hand back to the loop, tap the mute button again to unmute it and carry on playing.

[i]" playing the hypothetical game " ... [/i]

What you are saying, if I understand it correctly, is that you would want to set the range (3,4,5 octaves or whatever) and not want to change this in performance - but would want to be able to move this range up / down in one octave steps, keeping the same position.. as in, dropping by an octave, the position required to play C3 would be the position required to play C2.

The above is not a hypothetical - Dont think I can achieve it on the lower cost unit, but it certainly will be there if I get to building anything "higher" than the most basic unit.

The "mute the Theremin, then change register, then unmute the Theremin" sounds a bit fiddly.. how about the register knob being on the volume antenna? (for that matter, how about if all controls one is likely to change during performance, are 'on' the volume antenna?) ..[i] My volume antenna (being worked on at present as a seperate stand-alone unit - but thats an off-topic for this thread) is unconventional - prototype uses a round circular bathroom light housing.. but will have knobs on it anyway...[/i]

Gordon!!
How can you expect so much from Fred M.??!!
An electronic Engineer's customer input can only go so far before the point of limited returns!
There is a point of limited returns on every investment. Be it emotional, spiritual, financial or creative!!
I do not believe that the features you sought from Fred M. in a Theremin design could be implemented in a cost saving manner.
Stop!
Fred M. is a Theremin Designer/Maker.
Gord C. is a Theremin video/fanmaker.
G.D.L.
tt

Oy ! TT ! Let me jump in here in Gordons 'defence' ! ;-)

I asked for a lot more than I got - What Gordon hypothetically proposed happens to be quite well within the range of attainability - it might not have been .. he could have (and in the context of my "tell me what you want" would have been perfectly within his rights to) proposed that my Theremin read his mind and knew when he wanted a register change..

Gordon has gone out of his way over the last few years, to avoid distracting me from the main objective.. My slowness in getting product to the market is entirely the result of my personality type (disorder? ;)- it is the same mechanism which caused me to leave school at 14 with absolutely no qualifications at all, but then to be teaching electronics in a South African University (Fort Hare - the one Nelson Mandala attended) 3 years later, after having obtained HND's in electronics and become one of the very few people in S.A. at the time with qualifications in colour TV technology (there was no T.V. broadcasting in S.A. - this had only just been agreed by the government, TV was a 'go' but few people knew much about it! ;)

I am always looking for something to excite my mind - and the Theremin has been (is) the most exciting technology I have ever worked on - I never expected it to be - I thought it a mundane old technology I could quickly drag into the 21st century and make some money out of.. But the more I work on it, the more revelations I get.. and this has led to me becoming so distracted with testing my ideas, that little ever gets out the door.

I have no-one to 'blame' but myself.. However, I believe that the delays will be worth it - I think I am *there*.. or certainly at an important 'checkpoint'.. I have been stuck with a high cost, over complex product I could not afford to realize.. I have now found ways to reduce cost and complexity greatly, and make the prospect of getting the Theremins to market far more realistic.

[i]"Fred M. is a Theremin Designer/Maker."[/i] This is one tiny sub-set of what I am.. If I was to put any 'tags' on myself, they would probably be 'explorer' 'inventor' 'pain in the arse'
;-)

[i]"Gord C. is a Theremin video/fanmaker."[/i] If I was to put a 'tag' on Gordon, my first choice would be 'motivator'.

As for you, TT, I cannot think of a 'tag' - But I really appreciate your consistent support!

Fred.