Idea for Theremin Staccato Pedal

Christopher - I like your "dan bau" sound very much. It's the sort of sound I have in mind. :-)

Gordon thank you, a complement coming from you, the man of reason, is special.

Theremin meets the dan bau .mp3   500kb

I should have a prototype with a PDF iron on made board in a few weeks or so. The results were unexpected, the board does have a switch to reverse the popping on, to the sound popping off, no telling what that will sound like. Hey engineers, Mouser no longer carries a through hole LM386. The board has an amplified pitch preview and a line level attenuator to soften the EWS output into a guitar amp. Uses ¼” input output jacks and a 3.5mm earphone jack.

Board size 2.7” x 3.5”. Layout was fun!#$%, Gordon can you assemble and solder a board if it is paint by number?

Something else the board will do which is not obvious, and it might fulfill my new design of Paul’s Box. Horatio guess who is talking these days. (-'

Christopher

He Gordon,

to achieve a maybe quicker staccato something like a data glove might be also an idea. It all would be kept in the volume hand, with the disadvantage of either extra cables or – if being designed fancy – the need of a transmitter and receiver (optically or whatever). Those FSR strips change their resistance by bending.

FSR strip link 1

FSR strip link 2

Dominik

Aha! the forums are fixed. Took me a while to notice - d'oh. 

Christopher, technically I can solder, but it is not one of my strengths or something I can do with enthusiasm, so constructing a kit would not be my first choice.

Dominik, it's a reasonable suggestion - Wilco Botermans uses something similar to control his moogerfoogers - but I  want to explore the idea of using the foot and discover how it works out in practice.

... and I see we spawned a spin-off thread while I was gone. 

Fred wrote: 

Over on the Plates, Shielding, Spread Spectrum, etc. thread, Dewster proposes a (IMO) clever capacitive solution that "overcomes" thermal issues -

I think that with this, or some variant thereof, a simple non-moving (no requirement for mechanics / compression or suchlike)  capacitive sensing pedal which achieves the objectives simply, could probably be implemented.

And on the Plates, Shielding (etc) thread:

"To me, the staccato pedal is more of a crude, snappy action, short range controller - as opposed to a precision, continuous action, long range controller.  ......  If the plate-to-plate capacitance varies 10% over temperature, who cares?  Any variation in response will likely be more than offset with a substantial dead zone ... " Dewster

Ok - I see what you are saying..!

Perhaps the relevant parameters for the pedal are more to do with attack 'velocity' and release 'velocity' - and these can be determined regardless of any slow drift in actual capacitance sensed by the pedal - in fact, even mains hum would have only minimal effect if the attack and release velocities were 'strobed'.. (one would perhaps be looking at a change in capacitance from movement of the foot of 1cm, which would be quite substantial - this 1cm could be anywhere within say a 2cm field from the plate - and this 1cm change in capacitance would swamp any changes caused by thermal or induced effects)..

And the driven-shield capacitively coupling to the sensor plate could be the best way to implement this.. (in fact, a small PSoC CapSense IC has everything needed to fully implement this - shield drive, sensor, ready-configured "User Module" and API's to derive capacitance delta, DAC's  or PWM or UART to output the data, or perhaps even MDAC so one may not even need a VCA)

Yeah - all the problems go away if you arent looking for an absolute measure, but are just looking for a "large"  change - and are effectively only using that... Or if you have the "sensing zone" "floating" above the plate and dont need to worry too much about its absolute position or say 10% variation of this position.

 

Dewster: "a crude, snappy action, short range controller"

Yes! Ha - before I started this thread I thought it was a simple idea, because it seemed that everything I wanted from the foot plate was everything that theremin engineers had to work hard to avoid - snappiness and short range.  Oh, foolish me. But pleased to see that we are starting to home in on what I am looking for. Keep it up, guys. :-)

Hello Gordon,

I would like to see what the engineers come up with, they make me so jealous, all that capacitance stuff. (-' I used the radio audio to demonstrate attack on the volume of the sound in this Sample.mp3  This is a converted $5 bathroom nightlight.  A finger moves faster but I guess a twitchy foot could have affect. What confuses me of what you want is, you want a pedal that changes the behavior and response of the volume loop or does your foot just do its own thing with rapid foot tapping?

The above has two different methods that can give the effect, both could be down at the foot (but why?), the dan bau is a third and is different with a more complicated construction. I am constructing both currently, should have results later next week.

Christopher

Hi Gordon,

"... and I see we spawned a spin-off thread while I was gone. "

Yeah ;-(  .. Sorry 'bout that - It seemed like a good idea at the time - But with this thread now operational again its just redundant (and possibly confusing) - I would delete it if I could, but I cant.

Fred.

Christopher. The foot plate and the volume loop should operate independently of one another - two separate controls lined up in series along the audio chain.

One of the key concepts I learned from my time spent programming in Forth is "factoring" - identifying distinct functionalities and separating them so that they can be recombined in different permutations. Consider a sequence of staccato notes which are increasing in volume (crescendo) - this would be one way of combining the functionality of the expression loop (to shape the crescendo) with the functionality of the foot plate (to make the notes distinct by interspersing them with brief silences.) 

Gordon,

If we assume that only "attack" and "release" velocities are derived, what function should these two variables implement?

Should these be used as parameters to control an envelope shaper (actually translate to "attack" and "release") ? - does this actually need an EG, or would the natural attack / release (which would be fast as its the travel over say 2mm max) be usable - or should this "natural" be "stretched" (for example, lets say the slowest "physical" attack one could reasonably manage was 10ms, and the fastest was 5ms, would one want this to translate to say a fastest (audio) attack of 3ms and a slowest attack of 50ms.. numbers just sucked out me thumb, as I have no idea about real ones)

Fred.

Hello Everyone,

Back in the day at work I had a good friend of the younger generation that was a guitarist. He always spoke of getting a pedal for this and that effect and I never knew what a pedal was until I came to TW and learned from the masters. I really am naive to music and have mentioned before that I don't even own music CD’s.

Too me the feet move too slowly for much other than to switch a circuit on & off.

Below I reveal a forth early staccato method. I can hardly remember what I was doing but for sure it is done with the hand, as what is heard is real-time octave shifting, no clumsy switches.

All of my volume control methods rely on electro-magnetic radiation, there is no latency because they mainly work at light speed demonstrated in reality!  This should be a fun staccato sound for the experimental Thereminist to study. Just how exactly does he do this?  The theremin needs to move beyond a puny whistle buried in reverb, designers need to wake up to why the public is losing interest!

Staccato2.mp3

Christopher

Refreshing, a roll-over next post!