Emulating accordion bellow shake for Synth keyboards...

[jjj]

My Tyros got nice accordion sounds, but I wished I could somehow add that missing bellow shake. I was thinking that might somehow be possible? So, far my limited electronics knowledge led me to think of achieving it in one of these ways:
Roland accordion's "Innovative Dynamic Bellow" has it, too. I wonder how they created it?
- It might be possible to do it with the 3-axis accelerometer, because it can be adjusted to volume control of the Kbd. So, by shaking the hand this effect can be created and varied? Important is that the effect changes start (like reeds) from "0" and has steep envelop patterns; almost like a tremolo. i wished to find out how the Roland bellow control works?

My two project ideas are:
1) It might be possible to create that "sawing type" of bellow shake via LDR light variation or via a pressure sensor?
My old Elka49 organ had such a foot volume pedal. It had a little black box. Inside was a division wall with a width increasing slot, through which a bulb light beam was directed at an LDR. One one side was the bulb light and on the other side was the LDR. So, when the slot size increased, more light hit the LDR and the organ volume increased!
This process could be RF controlled via a finger mounted ring gadget, like in HotHand. The light slot slider could even trigger a slightly different filter, emulating minute timber change of reeds. So, the idea of a light controlled gadget with remote control is not a bad idea, after all...

2) My other, an even better idea, is to use a Mini Mercury switch on a finger ring to control the on/off chord volume via a tiny RF transmitter. This switch could also control a little circuit, which tailors the sound's envelope; i.e. for instance filter the sound every second shake to compensate the slight reed changes. A tiny low voltage filament bulb (not LED) has a small turn on/off drag, simulating accordion reeds. This bulb then sheds its light onto a sensitive LDR, controlling the Tyros Kbd. chord sound. I also got that Yamaha MFC10 MIDI controller and parallel wired its high quality 10K foot volume/expression pedal. So, any LDR responds perfectly.

So, what's your take on that? Since your electronics knowledge is able to think of even better solutions, I would be delighted if you could kick me to success. I'm a young pensioner (75) and enjoy playing wonderful sounds and melodies. Adding that bellow shake variations would enrich any melody in many ways. I attach some interesting data, which might help to pinpoint what I'm after:
https://app.box.com/s/brj4xktxo1tv3xa8m832nbnr4hx0fnoz

[Enzo]

I don't do squeeze box, so help me. How is this effect different from tremolo?

In the world of tremolo, we have the LFO, which is commonly a sine wave, or even a triangle wave, but for attack you could easily change that to a sawtooth wave.

Are you a stroller? Or do you stand fairly still in front of a microphone? Myself, I'd much prefer a simple foot switch, like a keyboard sustain pedal over som,e RF mercury switch thingie.

My experience is mostly limited to the Iorio Accorgan, I had a couple customers with those, and I saw one Cordovox years ago. The generator cab was as large as the amplifier cab.

[Mick Bailey]

For a pressure sensor I've often thought of experimenting with quantum tunneling material as an alternative to LED/LDR combinations. A few years ago I built a wah for a guy who'd lost the use of his legs and I used an LDR to control the filter - you cupped it in your hand and it swept the filter according to how much light was blocked off. It could be mounted on a trem and had far better control than a regular wah. I thought then that a quantum tunneling pill could be integrated into a plectrum to do the same thing - the harder you pinch, the more wah sweep, or whatever you wanted to control. Maybe this could be a starting point.

You've already identified that there's more to this than tremelo, but that would be my starting point. If you can get the trem control, then you can take a modular synthesis approach, but this limits you to processing analogue signals. Maybe some of the DSP effects packages are capable of more sophisticated and easier implementation with fewer components.

[jjj]

I don't do squeeze box, so help me. How is this effect different from tremolo?

Hi Enzo, you good rescue angel! You have a lot electronics knowledge and that's the thing I admire, but personally lack. All I can do is to search for circuits, which might deliver the goods I'm after.
Yes, "bellow shake" is different from tremolo, in that each beat can be manually varied in length and intensity. Check it out on YouTube. It truly is very different from a tremolo. My Tyros got echo reverb settings, which create some resemblance to a bellow shake, but it's automated and so, doesn't sound genuine, because feelings cannot be automated.
I like it so much, because it brings alive any electronic Synth melody. I got to know its advantage while playing the accordion for years.
My second idea, that of using the Mini mercury switch to activate the filament bulb, might be the shot. I got to experiment with it. Yet, this mercury switch could do so much more than that: it could activate an envelop filter circuit etc. - I wonder how Roland did it so wonderfully in their electronic accordions?

[jjj]

Greetings Mick Bailey,
The Tyros's pressure sensor tape (of after-touch) is a bit hard to activate. I adjusted it to "light", but it's still far to hard to activate don't use it.
I could disconnect it and change it for a more sensitive tape, which controls a dedicated "bellow shake" circuit. That would be even better than my "RF finger ring/ mercury switch" idea. I wonder that no-one ever brought up this idea adding the useful bellow shake effect in electronic keyboards?
It's truly amazing how it brings alive any boring electronic sound! That's why electronic organs use Leslie effects. Yet, the bellow shake effect offers players even more expression of personal feelings... and isn't that what musical creativity is all about?
Now Roland accordion players apply this effect to all their voices and that's why it sounds so good.

[Enzo]

OK, then how about a tremolo circuit but instead of a steady LFO controling it, we have some motion capture in place of the LFO?

I don't know much about them, but there are motion capture things in like Nintendo Wii games and similar. Mercury switches would depend upon always being upright, otherwise you bend over and the mercury ball just lays against a contact.

I understand your description. In my band days we used to practice singing together, so we could tremulate as one. And on some songs, the tremolo was not a steady thing, it varied expressively, which we still wanted to do as one voice. IN a way a sort of aftertouch effect. ON some Yamaha keyboard I press on the keys harder to engage a tremolo, and I can fade the effect in and out of intensity by pressure.

[jjj]

OK, then how about a tremolo circuit but instead of a steady LFO controling it, we have some motion capture in place of the LFO?
I don't know much about them, but there are motion capture things in like Nintendo Wii games and similar. Mercury switches would depend upon always being upright, otherwise you bend over and the mercury ball just lays against a contact. ON some Yamaha keyboard I press on the keys harder to engage a tremolo, and I can fade the effect in and out of intensity by pressure.

The mercury switch is very small and mounted on a finger ring it could be shaken (like the "Hot Hand" gadget) and so, triggering either a filament bulb shining onto an LDR for volume variations.
As mentioned, the triggering could preferably be done via the Tyros's after-touch. I.e. I could disconnect and change it for a more sensitive after-touch tape, which then (when activated) controls a dedicated "bellow shake" circuit. - That would be much better than my "RF finger ring/ mercury switch" idea.
So, now I would have at least a trigger signal, which could drive a filament bulb at less than half its capacity (to make it last) and its slow start would offer me the welcome sound curve, similar to the responds of accordion reeds. An even more sophisticated circuit could be created by electronic wizards. So, from what I gather, the project consists of two steps: 1) triggering and 2) envelope shaping.
The shape of the wave form can be easily traced, but I wouldn't know how to create from that a trigger-able active volume envelope or maybe even filter to perfectly emulate the bellow shake? - Well, Roland's engineers mastered it perfectly.

[Enzo]

What mercury switch have you in mind? I think of something like this:


Inside the bulb are two wire contacts, and a ball of mercury. If the ball rolls over to the two wires and touches both, the switch is ON. But you can see that the switch has to be horizontal to tilt back and forth. If it stood on end, it would be always on (or always off). SO me fear is that wearing it as a ring means you can't drop your hand ever. And that would include expressive motions dancing around the stage.

[nickb]

I think the most appropriate sensor would be an accelerometer. It would require a single chip (a micro) to convert the output to analog control signal.

Is the effect purely volume or is there a pitch component?

PS: Suitable module or just use a chip
Link analog output from micro to control digipot for volume control

[jjj]

What mercury switch have you in mind? I think of something like this: Inside the bulb are two wire contacts, and a ball of mercury.

Yes, its that lousy little bulb-like switch!
Yet as mentioned, I'll be better off triggering the Tyros's after-touch. I.e. disconnecting and changing it for a more sensitive after-touch tape, which then (when activated) controls a dedicated "bellow shake" circuit.
Alright, now I at least got a step further... knowing how to best trigger this bellow shake effect via after-touch on each of the 61 keys.
Now the even bigger question if the triggered filament bulb & LDR is going to deliver the goods? Will it be sufficient to just keep pressing the chord keys at the desired rate to create that authentic bellow shake. Remember, it cannot be automated, because then it loses its "human touch", turning into a robot. Thus, my innovative idea serves to enrich musical electronic creativity.

[jjj]

I think the most appropriate sensor would be an accelerometer. It would require a single chip (a micro) to convert the output to analog control signal.
Is the effect purely volume or is there a pitch component?

Thank you nickb for that kick! - Yes, that would be another trigger angle to consider, provided it fits onto a finger ring and it would need transmit its trigger signal to a stationary unit, which I could accommodate inside the Tyros. Pretty complicated! - That's why I thought to forget about finger ring controls and rather triggering the Tyros's after-touch. I.e. disconnecting and changing it for a more sensitive after-touch tape, which then (when activated) controls a dedicated "bellow shake" circuit.
Its effect is purely volume, but when you listen to accordion players (on YouTube), performing the bellow shake, you'll notice that their chord has accented volume levels. Yet, I think I'll be able to accent it to some extent via the foot pedal volume control.

[jjj]

Now, since I successfully MIDI-fied an old 120-button accordion bass (bass section only), I thought of adding a 6-row Janko adapter and place it over my Tyros 3 keyboard. I then can play it like a Janko accordion. - The only thing I'm breaking my head about, is ... how to emulate that genuine accordion bellow shake, because it adds realism to any melody. I thought of switching it by (spring-) suspending one side of the accordion bass and pressing/shaking it up/down. In that way I can manually vary the bellow shake's speed.
My Tyros 3 doesn't offer me anything resembling an accordion bellow shake. - After trying out and considering several ways of achieving this object, I came to remember an old "Dr.Boehm" organ accompaniment (called "Boehmat"), in which little black carton tube contained a tiny bulb and a longish LDR. As the bulb worked on very low voltage, it was virtually indestructible and since its turn-on/off envelope compares to the actual below shape sound envelope... "it should" offer me the desired result (?) Here's my circuit idea of it. Since I depend on experimenting, please correct my circuit idea I designed here: