TherAsynth - New product under development - What do YOU want?

[i]With regard to extra functionality. Your design sounds very modular - separating the functions of distance location and tone generation, for example. My preference would be for a very straight-forward device with all the design effort going into making it a practical, solid working tool to start with.[/i]

You may well be right about this Gordon - Open hand time again.. My reasons for wanting to package a comprehensive analogue synthesiser with Theremin interface are that I have more love for synthesis and rich tones with harmonic sweeping etc (sounds like the Mini Moog produces) than I have for the classic theremin sound.. I know that saying this here is probably tantamount to blasphemy - but its the way I feel + what I like.. It is difficult to think about 'downsizing' when I have this clear idea about my perfect instrument... But I may be forced to, or at least wise to.

Well, I think it is fair to say that there are some differences of opinion on this subject amongst the theremin community, and a healthy smattering of blasphemers.

Here are a couple of people who have come to the theremin from a synthesiser background and are making (in my opinion) great music with it.

http://www.myspace.com/kkissinger

http://www.myspace.com/alexanderthomasmusic


And of course, no discussion of experimental thereminnery is complete without mention of Pamelia Kurstin. What she does with an ePro, a couple of loopers and an Electro-Harmonix Micro Synthesiser has to be seen to be believed. Fortunately, if you have twenty minutes to spare, you can do just that...

http://www.sr.se/cgi-bin/p2/program/artikel.asp?ProgramID=3029&Artikel=1816714

(Click on the thrid picture down, the young lady with the etherwave pro.)


However, I think it is also fair comment that what first attracted the overwhelming majority of thereminists to the instrument, including us electronica-heads, was the original sound of the instrument.

[i]Gordon C : "From the description of Fred's proposed instrument I suspect linear/logarithmic could be a user selectable option, as it is just a software mapping."[/i]

This is essentially correct - in fact, the 'mapping' is not done exactly as my description would indicate - there is not enough memory to store a 16bit x 16bit lookup array, or enough time to compute this - the output value is computed from a formula (function) each 10ms, and this function takes 3 arguments - Max value, min value, and current value - Change the formula, and the output law can be changed from linear to some other relationship..
Also, if conventional non-directional antennas are fitted, it should be possible, if I have the relationship (law) of other Theremins, to copy their charactaristics exactly..

So - What is the most popular relationship? Is there a source of information on these relationships (can anyone point me to the curve or formula for say the original Theremin, the RCA, or for that matter the Etherwave or EPRO?)

To implement a sensor which could switch between different profiles I will need to go for a bigger processor (I am using an 8 pin PSoC in my present sensor, and have no spare pins!)..

This is definately something I will not attempt right now - but could be well worth doing in future - particularly for a simplified classical Theremin.. Having a switch which allows selection of which model one wants to play (this could also signal the sound generator, so that the sound is the same as the selected Theremin - or alternatively, sound and profile could be independently selected, so one could play say an EMI clone sound with some other instruments control profile) might be something people would like.

[i]"However, I think it is also fair comment that what first attracted the overwhelming majority of thereminists to the instrument, including us electronica-heads, was the original sound of the instrument."[/i]

Dont get me wrong - I love the sound of the Theremin - However, I believe that most of the appeal of this sound comes down more to the human vibrato and portamento than as a result of the waveform - It is the ability that competent players have to frequency and amplitude modulate the waveform, and the fact that this is human and not the result of modulation from a LFO, which makes the sound so special (in my opinion).. There is no way to achieve anything remotely close to this using modulation wheels, joysticks, or any other controller I have come across.
So, whilst I love the sound, I think (and my limited experiments, for me, back this feeling up) that being able to play with a harmonically rich waveform, and do human modulations not only on pitch and amplitude, but also on VCF frequency and Q, will produce the best of all worlds - I remember the first time I heard a synth (the Mini Moog) and it changed my life - I probably would be a biologist instead of an electronics engineer had I not heard it, LOL! (and probably be a lot wealthier.. ): I would really like to make an instrument which puts humanity back into synthesisers - makes playing fun and easy, is accessible to people who have no musical training but have music in their head which they want to get out, and play.. The first synth I made, as a teen, had a probe and a carbon strip as its 'keyboard' - It took me years to play a real keyboard well - but I had mastered the carbon in a few hours!

GordonC, You pointed out an extemely important aspect of the playing fields with your question:

Thomas - if I have understood correctly, the playing fields are shaped roughly like the cone of light from a torch, extending from the sensor (antenna). It should be easy to produce a very clean, short attack or release by moving your hand in or out of the field at right angles to the direction that the sensor is pointing, whilst moving towards and away from the sensor for expression.

What I wonder is, what happens if your pitch hand wanders out of the side of the pitch cone?
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FredM, I echo GordonC's question here. Mainly because I'm legally blind, and have no depth perception. If the field is too tight, it might make it difficult, if not impossible for someone who has low vision, or is totally blind to play. However, if the fields are on the order of say, 70, to 90 degrees, or evin wider, then the instrument becomes much more playable.

As it stands, how many degrees wide are the cones?

It could be a performance disastar if I were performing, and became distracted to the point of unintentionally taking my pitch, or volume hand out of the cone of detection if the cone is too narrow.

[i]To implement a sensor which could switch between different profiles I will need to go for a bigger processor (I am using an 8 pin PSoC in my present sensor, and have no spare pins!)..[/i]

I shouldn't think the ability to switch from linear to logarithmic mapping mid-performance will be a terribly useful facility for the majority of players. It's more like something you choose once and stay with. Which set me thinking...

I noticed that PSoCs are USB savvy. Will there be a facility to update the firmware from one's computer?

And, going one step further, will you be publishing an API?

Fred,
I think with, Gordon and T.Grillo, that you have finally attracked some of the two extremes here at Theremin World. Listen well!
Good Luck!

teslatheremin

[i]Sorry - what I meant was would a 1cm travel from max volume (0db) to min volume (-88db) be sensitive enough - all I am doing is changing the amplification applied to the CV - the CV goes from 0 to 10V over (say)30cm - so amplifying this by 30 will give 0 to 10V over 1cm[/i]

1cm is barely moving the hand! I think that a 30cm range from quiet to maximum volume would be excellent. However, the option should exist to make maximum a small distance (1cm is plenty small!) to allow for staccato playing.

[b] Sensor fields + Sensor design / possible changes: [/b]

[i] Thomas Grillo: “I echo GordonC's question here. Mainly because I'm legally blind, and have no depth perception. If the field is too tight, it might make it difficult, if not impossible for someone who has low vision, or is totally blind to play. However, if the fields are on the order of say, 70, to 90 degrees, or evin wider, then the instrument becomes much more playable. As it stands, how many degrees wide are the cones?”

Jeff S: “I do see how the relatively narrow "cone" of a capacitive sensor could be a problem for some people. It could be a problem for everyone if it is too narrow.” [/i]

The sensor development is far from complete, and I have not done real measurement of the field shape.. All that I have really done is to confirm a linear relationship when the hand is moved towards / away from the sensor and is positioned directly in front of the centre of the sensing plate. I know there is a sharp cut-off for any object behind or at the side of the sensor, and that as one moves ones hand forward at in a line from the edge of the sensor, detection is noticed quite quickly (at about 1-2 cm).. However, I have a few experimental builds and have been a bit sloppy (got a bit muddled over notes relating measurements against sensors ):

However – I think the field sensing area is not highly focused – I am going to need to redesign the sensor to increase its sensing distance anyway, and am (as a result of the valuable feedback from you all) looking into what I could do to make the sensor field user adjustable.. In its present form the field focus an be widened simply by sticking conductive tape (aluminium foil) over the whole sensor face – this undoes my careful shaping of the sensor pad vs its outer earthing “focusing” ring – and the processor takes care of the capacitive change, so the range is not affected… One could wrap the whole sensor in foil, and make it omnidirectional.. I am looking at whether I can do a more elegant solution though…

[b] What follows here is quite technical, and probably only of interest to DIY builders, Theremin modifiers, and my competitors! LOL! [/b] [i]Also – I have 2 different sensor technologies.. Some of my earliest plans were to have both sensors as horizontal pads inside the top of the box – and at that time I was having problems with large capacitances from the earthing of the box – I developed a means to overcome this for which I filed a patent application ( I was dubious about whether this was worth doing, as I thought the prior art of having a guard ring on the input to a sensitive input may well make the application fail) – The search came back, and I found that someone else held a patent for exactly what I had done (What I was doing was to have a 3 layer sensor – top layer was the sensor, 2nd layer was a plate driven by an amplifier getting its input from the sensor, so that it acted like a low impedence screen and did not present any loading to the sensor, and third layer was ground, which was invisible to the sensor plate) – this scheme works superbly (I present it for any DIY builders out there – it is ideally suited for conventional heterodyning Theremins where background capacitance can cause problems – a fast unity-gain non-inverting amplifier with high input impedence and low output impedence, connected in this way, makes screening invisible to the sensor plate, and makes a simple directional antenna) [/i]

[i] Gordon C: “Thierry - the impression I got was that field size and pitch range are independently variable - if you want one octave over 30cm, that's fine, you can have it; if you want ten octaves over 10cm, you could have that too.” [/i]

The above is not completely correct – The field size is not adjustable, it is fixed by the maximum distance that consistant capacitive change can be monitored, and this is fixed by the physics (area of the sensor ‘plate’ or ‘ante

[b] Updating[/b]
[i] Gordon C: “I noticed that PSoCs are USB savvy. Will there be a facility to update the firmware from one's computer?”[/i]

[b]NO! [/b] – There are lots of reasons, including the fact that USB PSoCs (and the hardware required) adds extra cost.. but main reasons are:

I HATE equipment which one must update – In the main, it is a means for manufacturers to release products which they have not engineered well in the first place – When I buy something, I expect it to work out of the box – FULLY – With no “Oh yes, there is an issue with this – we are fixing it, and you will be able to download the fix shortly” .. I have had this happen with several products (Free-view decoder and USB DVDRW being the last examples) – When I tried to return the items for refund BECAUSE THEY DIDN’T **** WORK! I was forced to go via Trading Standards + CAB, wasting hours, to get my money back..

When my product goes to manufacture, it will not have any ‘grey’ software – If someone wants something special done involving change to the processors, I will do this and send them the replacement processor – They can then send the old processors back so it doesn’t get used in a ‘bootleg’. I am using normal (not SMD) parts so swapping processors will be simple…

[b]But I really intend to have everything exactly as the customer wants before the instrument is shipped, and for there to be no reason at all for ever needing to update anything![/b]

One other reason I will not provide downloadable software updates is that the sensor has been my major effort – I have spent about 500 hours on its development so far – I have only given the skimpiest details about what is really going on inside this sensor.. only scratched the surface.. It is the component which sets my instrument apart from the rest – so giving downloadable material which might help a competitor to work out what I am doing, and copy it, is not an option!

[b] Linearity[/b]
[i] Jeff “The importance of linearity depends largely on what you want to use the Theremin for. Personally, I feel it is of great importance. I play using hand shapes. My hand is one fixed length, so linearity from the upper to lower octaves is important to me.

Since there are, as yet, no Theremins with a truly linear field, we've all had to adjust to playing in a nonlinear field, whether we like it or not. Since that is the case, there are other factors that also influence our choice of instruments.”[/i]

I am very much inclined to agree with everything Jeff says here (but then I would be.. ! ;) The salient point to me is [b]“there are, as yet, no Theremins with a truly linear field”[/b] – Until such a unit has been evaluated, the jury has nothing to go on… My feeling (and hope) is that a linear instrument will make Theremin playing easy and accessible to people (particularly young people) who are impatient and less ‘controlled’ than today’s Theremin masters.. I am one of these people (not a Theremin master – one of those impatient people who wants to be able to play a reasonable tune after a couple of hours on any instrument)..

However – I may be wrong.. Perhaps there are reasons why some non-linearity is desired or perhaps even required for virtuoso playing.

After thinking about the issue, and the possibility of providing software to implement non-linear functions, I got an idea – I will not elaborate, but I can now implement a sensor having 2 processors which has a control knob – at one extreme, the output would be linear, at the other extreme, the output would be what one would get from a cheap RC Theremin, Centre position would be the response from a standard LC Theremin, and between centre and the linear extreme, one would get progressively more linear, and should be able to get something similar to the response from the EPRO. (the second processor etc could be fitted as an option)