The pitch preview display -- how it should be

I'm two steps away from designing a built-in pitch preview display. It will incorporate 12 LEDs for note name and 8 LEDs for octave number.

At each time a pair of LEDs will indicate the current pitch.

So the question is: How best to arrange the LEDs on the front panel. Below is the two variations I prefer (also I hate the rainbowing, the maximum is two colors):

Are you not having any quantitative indication of pitch error? Or are you going to fade from one LED to the next, so that for example, of the 'note' played is mid-way between 2 semitones (50 cent error) both LED's will be equal brightness?

IMO, the major problem (and reason why audio pitch-preview is required) is not so much that thereminists dont know / cant find the correct note (would need to be real terrible player to be off by 45 cents) but that they cant tell if they are off key by say 10 cents. Another string of say 10 LEDS, and one to indicate flat or sharp, could show pitch error in 5 cent steps.

Out of the 2 arrangements you show, I prefer the circular.. I would have another 11 LEDS horizon row inside this to show cent error. (0r an inner circle with 20 LEDS)

Fred.

I think you shouldn't have any kind of independent sub resolution display - too hard to interpret on the fly.  Use PWM to show where you are between notes.  I have some ideas along these lines over on my digital Theremin thread.

It may sound heretic what I'll tell now...

Have you ever seen a trombone, a violin or an ondes martenot (or any other instrument with continuous pitch) with visual pitch control?

People who have not the musical ear to hear when they are off key should IMHO rather choose a different instrument such as the piano (fixed keys) or the guitar (frets).

It's always a good thing when engineers think about new solutions, but in some cases these ideas which are technically brilliant tend to be far away from musical reality. Things like musical talent and giftedness cannot be built as circuits.

"I think you shouldn't have any kind of independent sub resolution display - too hard to interpret on the fly.  Use PWM to show where you are between notes.  I have some ideas along these lines over on my digital Theremin thread." - Dewster

You are probably right.

But my personal opinion is that, for the theremin, pitch preview display of any kind is not a great idea. I feel that playing requires (or certainly does for me) the kind of concentration and listening which any distraction impedes.. For me, finding the note (when using audio preview) is not the problem.. the "problem" is about getting this notes fine tuning and vibrato depth right - And for me the only use of a visual display would be within +/- 20 cents of the note - perhaps 20 LEDs in 2 cent steps, 10 either side of the green LED in the centre which indicates perfection (and would rarely illuminate, LOL ;-)

But I have no idea about whether a display like this would be of any real use. To be honest, I think that any possible "gain" would be lost due to lack of concentration on listening which (for me anyway) will result from looking at the display.

For me, listening "deeply" is a function I "do" far less "well" if I have any visual "distraction".. If I want to listen to the MUSIC on say you-tube, I close my eyes.. I often play my keyboards with my eyes closed so that I am not distracted by thinking about what keys to play - And I think that this is a possible reason why I cant sight read music and play, even though I can read and comprehend it.

Fred.

LOL ;-) We posted at nearly exactly the same moment Thierry - My internet connection is slow at present, it might even have been exactly the same instant ;-) .. If I had seen your post I wouldnt have bothered with this one - I agree with you, and this time you said it with a sulpherous "tang" not me! ;-)

As far as I know, I was the first thereminst to use, and actively promote, the audio pitch preview. Ever since I began playing the theremin in 1996, I was bothered by the need to "pitch fish" for the starting note. To me, it was unthinkable that any musician would have to disturb the audience and/or other musicians by audibly searching for the starting note. 

The first thing I experimented with was the visual preview. The late thereminist, Robert B. Sexton, author of the book METHOD FOR THE THEREMIN (available from Amazon), described in detail how to add a visual preview to the Etherwave theremin. His idea was to use the SABINE ST-1100 AutoTuner.

http://www.musiciansfriend.com/accessories/sabine-stx1100-chromatic-autotuner

I purchased one of these and connected it to my Etherwave theremin. It worked as it was designed to work, but there were two problems with it. It was too slow, and it was distracting to have to pay attention to visual signals when all my concentration was focused on SOUND. The visual signals may be fine for some types of theremin playing, but for precision playing it was useless.

That's when I switched to an audio preview. 

The visual preview may work for those who are playing at the beginner level, but it is totally useless for advanced precision thereminists.

Just a couple of personal observations about pitch preview.

I'm not great with perfect pitch but my relative pitch is pretty good, which means that once I have a starting note I can usually take it from there.

Searching for notes on a visual display with many things to look at is not as easy (for me) as trying to match a note.

Indeed in orchestras the tuning note is taken from a played instrument (is it the clarinet or oboe I canny remember?) and all instruments are tuned to this by ear (aye ok, not by ear but by fingers, for the pedantic!).

My earliest tuning aid for my fiddle was a tuning fork.

I suspect I'd be with coalport on this one and suggest that a sound pitch preview would be much more useful than a visual pitch preview.

R

"I suspect I'd be with coalport on this one and suggest that a sound pitch preview would be much more useful than a visual pitch preview." - RoyP

As would I. .. As to whether visual feedback would be helpful for some beginners, I could not say - but I have my doubts..

"I'm not great with perfect pitch but my relative pitch is pretty good, which means that once I have a starting note I can usually take it from there." - Roy

Someone with good reletive pitch should be able to play the theremin IMO, and if one has good reletive pitch, you only need one "perfect" pitch on which to reference this.. So if, for example, one had 3 LEDs, the centre one which came on at 440Hz +/- say 2 cents, and the other ones coming on when pitch was above or below this, one could obtain a reference point using audio pitch preview (and when on 440Hz, could enable this pitch for other instruments to tune to) and, as I see it, you have all that is needed.

Anything more than the above (unless visual preview is of benefit to beginners) is likely, IMO, to be of little benefit.. And even the above may well not be worth including IMO - Most people have a keyboard or other reference pitch they can use - Adding an audio input to your theremin so that this can be mixed with the preview / monitoring section IMO is probably far more useful - But I probably only say this because I am doing it LOL ;-) - I have a sub-mixer for the headphones which mixes preview, main, and external to taste - one gets the "reference pitches" from the input audio.. and can play the whole theremin through headphones without losing preview.. 

However - Visual tuning "preview" could look good, and perhaps could increase sales if it didnt add too much to the cost.. Wheras adding a monitoring mixer probably adds more cost, and is less "cool".

Fred.

I've had visual pitch preview on my prototype almost since it started making its first noises and it has been a tremendous help with development.  You can literally see how linear various ranges are.  As a lay singer / guitarist my pitch sense is pretty good, but IMO the visual preview takes things to a higher level, particularly when playing without accompaniment where everything tends to get wishy-washy on an essentially referenceless instrument like the Theremin.

When people think of pitch preview they probably have slow / inexact guitar tuner behavior in mind.  My preview reacts as quickly as the pitch itself, because it uses the same numeric value that produces the pitch (~2ms response time).  Not trying to sell anyone anything they don't want, and not trying to blow my own horn, but from my limited experience it seems like a very positive thing to include if it isn't too expensive or too much trouble. 

Ironically it is perhaps too analytic, exposing phase noise, dither, and other pitch issues that aren't necessarily audible, particularly at low frequencies, but that could encourage negative listener bias.

Dewster,

1.) I fully accept that for development work, visual pitch display is essential - I have a modified guitar tuner and frequency counters showing audio and RF frequencies running when I do development, ans often have these logged so I can go back and analyse results.

2.) I agree that, if useful, the pitch display needs low latency - Not as fast as 2ms (the eyes response is  slower than that!) but perhaps 10ms.(I think about 15ms seperation is the shortest interval someone is likely to see, 69Hz if I remember correctly was the frequency at which flicker was discernable to one candidate at the Royal Free Hospital when I built a flicker fusion kit for a research project at the Medical School - this used LEDs pulsed at 50:50 duty cycle - most people lost it below 60Hz - above this frequency candidates saw the LEDs as continuously on - 10ms [100Hz] is certainly above this threshold for most humans.. Tests were conducted void of any interfering modulated light sources! Most flicker seen on displays etc is the result of beat frequencies with other modulated light - flourescent tubes etc... Real optical theremin stuff, complete with optical heterodyning!  Quite possible to implement with a couple of LEDs sharing a photo-sensor! LOL ;-)

3.) "particularly when playing without accompaniment where everything tends to get wishy-washy on an essentially referenceless instrument like the Theremin." - Dewster

Yes, I suspect this is valid - and is perhaps the only reason I can see for some form of visual cuing.. But surely all one needs to see would be when one was on key? Is, for example, display of octaves required? If you cant hear what octave you are playing, I doubt one has any chance mastering the theremin..

I suppose it may be true that the theremin is a somewhat different case to the trombone or violin or odes in that there really is no place for "muscle memory" due to its variability and invisibility (even if not deliberately marked, there is visual feedback on all these other instruments, Our visual perception is often excellent, so the positions related to pitches is likely to be visually encoded in a way which will make these instruments easier to play) and absolutely no feedback of any kind other than audio.

But I still doubt the usefullness of visual pitch preview - particularly if overcomplicated.. The following for me would probably be at the edge of overcomplicated.. 12 leds for the notes, with them going green when within say +- 3 cents, and red when within +/- 50 cents but not within +- 3 cents - and perhaps an amber range,say +- 10 cents..  and a few LEDs,in a seperate row, to show actual deviation from the highlighted note - say 4 either side of a green, or something like that, which indicate +/- 3 cent deviation steps with the extremes showing you are more than 9 cents off key.. Just by way of an example.. Or even just 12 notes, going green within say +/- 5 cents, that way one could keep from drifting too far from the original starting pitch.

But I have never tried playing anything lengthy without accompniment - I suspect that I might wander off by several semitones over a long piece if I did that.. And I can see that, if one wants to play in that way, visual cuing may be essential for me and probably others.

Fred.