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Guitar pickup on the midi music box comb/tines = rhodes in a box (nearly)
kaisersozehongbatemp Posted: 16 Jan 2020, 03:01 AM

Posts: 4
Joined: 16-January 20
Might just work with a guitar pickup, might have to custom wrap a coil around a long enough magnet, maybe around the actual comb - but *as it's electric, it won't pick up acoustic noise* - might need electrical sheilding from motors. No velocity control (an all-note off/variable softness mute worth pursuing?), but plug it into an amp ( just one more 1/4" jack socket on minimalist box) and it might sound quite a bit like an electric piano. Isolating the pickup from the acoustic resonator, picking up the tines via magnetic flux, isolates it acoustically, and this opens up electro mechanical possibilities - using the note reset motor as a mechanical lfo oscillator (can you speed that up any more, the reset time?) like a vibraphone - via an off-weighted flywheel on the end of your belt drive, mounted through a mounting screw for the comb, or amplifying the signal and then feeding it back into the comb via a coil - like an ebow - interesting line signal from an acoustic instrument, anyway.
Could you cut your own tines with the laser cutter, have an array of combs, stack them, customise the spacing?
Some really brilliant ideas here, man, loving your work, thanks for sharing it.
Side note - just because you have a box anyway - a cheap upgrade might be stetching a couple of springs around, from the base where the comb is coupled to the middle of the box panels, for a quick acoustic reverb/amplification. No using a pickup near a speaker then, though.
EDIT: Instead of a pop-up ballerina, any uplit rotating form projected onto the inside of the upturned lid. A zoetrope! with monochrome transparent LCD panels that play silent movies and movie archae as it rotates. Just a thought.
Sorry if this is a ballache to read, but I'm really thinking - you could make a tuned resonator. You arrange the servo extensors such that they bypass the plucker and instead mute and unmute the tines by direct contact. you feed an external signal into the ebow, play your tines and hold them open without muting, they resonate where other don't...
Or using a speaker coil and a contact (or a loud speak ouside th box) to mechanically oscillate the tines and pick up the signal electrically using the pickup.

Last edit by kaisersozehongbatemp at 16 Jan 2020, 04:01 PM

mit Posted: 21 Jan 2020, 08:01 AM
yeah whatever

Posts: 232
Joined: 4-May 16
Wow, that's a lot of ideas.

No, never tried a guitar pickup on it. I have no idea if it would be possible or how well it would work, but I'll give it a go at some point.

Cut tines with laser cutter - I thought about this. I can't do it with my laser because you need a lot more power to cut sheet metal cleanly, but it's not too expensive to order it from various companies.

I changed the musicbox since making the video to use a belt drive for the last motor, doing that has made a big difference to the sound, but now the other servo noises are more noticeable.

I've been playing around with all kinds of ideas to build a better music box. The most promising one is to take a mechanism similar to how a harpsichord works, in order to have it pluck in one direction of the stroke but not the other. Another thing would be to use bowden cables to move the servos out, with enough space between them we could use nearly-silent solenoids instead.

kaisersozehongbatemp Posted: 22 Jan 2020, 02:01 AM

Posts: 4
Joined: 16-January 20
EDITED TO HIGHLIGHT MOST APPOSITE POINT - I think a pickup will work, and sound like an electric piano, because this is how, essentially, electric pianos work. You'd need steel tines, obvs.
*or a ferric (guitar string, magnetised composite?) part on/in the tine - oscillating at the fundamental, perhaps just on the end - this would alter the tuning, obvs, but if you need a mount - a thumb piano-style bridge would allow you to tune the tines...but then lining them up...
Can you cut another material that could be used to make a comb - i suppose plastic will distort - thumb pianos would use anything - bamboo and thin strips of wood - and then stick a square of magnetised plastic on the end? - I don't know what might be suitable.
I just happened across an old wintergatan thing about music boxes with interchangable discs, a proto jukebox. They had two combs actuated by the same rotating plucker. Louder (1db?) and a "unison flanging" - that would be an easy add now, compared to a harpsichord action.
Overkill but tuned resonators - if you're cutting and separating them enough to have solenoid actuators without the cables - each tine could have a tube cut to resonate at the fundamental - a stopped tube would be half as long, but quieter - the tubes can be flexible and lead anywhere as long as they maintain length, so you could fold them up with the lid, end them in horns pointing in every direction. You might be able to split the resonators between two combs and still squeeze them in above and below - really small diameter tubes should work as well - NB - you can tune it by blowing over the top, a bit of close fitting extension tube would help with fine tuning. A thinner end would help get close to the tines. Worth cutting one and experimenting with placement, see if the amplification and tone is worth it - it should really really ring.
I think any resonator fixed to the mounting block will work - you could just hedgehog closed and/or open tubes of the right lengths all over it - but holding one open end over the oscilating tine should work more effectivly, produce a different tone and the sound is more malleable. Possible to do both in addition. You would even get mileage out of sympathetic strings, if you have the room and the inclination. Simple tuning pegs, you can ignore connecting to the baseplate directly. You can spread the tensions out because a player doesn't need access, but you might need to strengthen the box (or the lid?).
Serious overkill but the belt drive could rotate stoppers between the tines and the resonators, like an actual vibraphone, but that idea of rotating off-center weight on the combs might be easier, maybe encase a rotating 'periscope' reflector/opening a la leslie speaker. Having a rotating thing just cries out for something.
Sorry about the brainfart, bit inspired by your work, tbh. I was rounding in on that midi controlled electro acoustic tuned resonator in a box idea - I think that has legs, if you want me to elaborate...

Anyhoo, genuinely exciting work you're doing, this project intersects a really interesting place. nice one!

EDIT - if you're adding solenoids, you could have percussion channels that knock the sides of the box. Different positions produce different tones. Different mallet end shapes and materials. Could strike metal or felt fixed against the inside of the box. You could stretch a snare to rattle against one panel - use a joint as a castanet/clave - the box as a midi cajon.
Also, a solenoid activated mute for the whole comb might be musically useful, if again further removed from the music box sound, but a soft mute could be left 'on' to change the tone.

You could add formant, vowel filters to the resonating tubes, so each note gives an oo, oh or aah, use differing vowels on two combs playing same note, or use the motor to deflect between two formants at 60 degrees to the tine.
Or several masters for the whole box, one per vowel, popping out of the lid, opened and closed by midi. Opening one as you close the other might give you dipthongs. A singing music box!

Thinking on this, with a bit more creative percussion going on, rotating shakers for sibilants and fricatives, using different beater/beatee materials to change the perceived transient of a note played simultaneously, and you're not far off an acoustic/midi speech synthesizer. Or a pallet that's musically useful, extended from that idea without actually needing to reproduce intelligble speech. I saw (grainy) footage of a real time, human operated machine that did manage this electromechanically, early mid 20th century at a worlds fair...

wintergatan playlist with this music box player and other musical automata(?) from a collection in Utrect!
One thing that keeps coming up in this playlist - inventors converging on a solution of halving the note reset time by having two actuators per note - to allow for the mechanics of the first to reset, the second actuator plays the next note, then alternating. If this is an issue with solenoids, this solution doubles your actuators, which is a PITA, but (bonus) allows that unison chorus effect with a harpsichord-like plucker, you just need a coding solution so notes are played in unison on two combs by two actuators, but note repeats that arrive too quickly fall into an alternating pattern, although you'd need to make that decision when you play the first note. I dunno if that's an issue, but hey...

EDIT2, final, possibly stupid idea. I saw "look mum no computer" of Furby organ fame, make a MIDI operated furry 3D animated face - rotating ball eyes that followed pitch, eyebrows that upturn with the filter, percussion opening the joke-shop teeth, that sort of idea - and it was surprisingly simple for someone of your expertise. A MIDI controlled music box is, I suppose, quite a steampunky aesthetic - futurist anachronism?!?!- It looks like an opportunity to do something exploring the automata that came with musicboxes - a 2D, paper theatre, Terry Gilliam Pythonesque version of LMNC's idea, replete with rolling eyes, rotating edwardian moustaches and colourised victorian patent applications. Not a foot on a pole, something that looks like it was originally run off a punch card, but has some contemporary (well, MIDI) sophistication. A riff on a ballerina?
Just a thought...there's something of potential in there somewhere.

Last edit by kaisersozehongbatemp at 30 Jan 2020, 06:01 AM

kaisersozehongbatemp Posted: 29 Jan 2020, 04:01 AM

Posts: 4
Joined: 16-January 20
Nobody's asked, but here is the midi tunable acoustic resonator idea
If you hold open the sustain pedal and sing into the back of a piano, the piano sings back.
If you shout, the piano resonates with the chromatic notes in your shout.
If you hold open a chord, and shout - the piano only rings with the notes in the chord.
If you could wrap a pianos strings in a coil, like a guitar pickup, and played a loud acoustic signal through the piano, the 'pickup' would capture the oscillating magnetic flux of the strings moving *without picking up the sound* - so you could play music through a speaker next to a piano, finger chords, and only pick up the singing of the piano strings.
Complex achieving such a thing and a hulking great result, but consider a portable cathederal - a spring reverb - an electrical to mechanical transducer amplifies the incoming signal into a mechanical/acoustic oscillation of one end of a spring(s), like a speaker. The springs, excited resonators, resonate. At the other end of the springs is a mechanical/acoustic to electrical signal transducer, like a microphone. This signal is then amplified, maybe some of it is fed back to the input, perhaps 180 out of phase, and the signal is sent out.

Here, we have a choice of ways to excite the resonator in isolation - something I've seen used to excite resonance in objects for impulse response is essentially a speaker with the cone replaced with a rod held against the resonator - or a coil around/in proximity to the resonators - like an 'ebow' or the string exciter on a roland guitar synth, but fed with your (amplified) signal.

A simple piezo on the baseplate, or a loudspeaker outside the box would work where you don't care about acoustic isolation.

The resonator is a midi operated musicbox comb, where the actuated notes, instead of (alternate to) plucking a note, lift a stopper, allowing a tine to ring. Needs note off/on, per note.

To get an electrical out signal ('e-piano' sound), use a guitar pickup - a coil wrapped around a magnetic core held next to the tines, or just a coil around the tines - not too dissimilar to the ebow arrangement above - in reversing the same idea, in an analog with using a speaker as a microphone, it might be possible to use the same rig in either role.

Or, where you have cared about acoustic isolation, want the acoustic tone you've created, a microphone (or both).

A midi tunable resonator in a box. You could send any audio to an (electro)musicboxifier effect and harmonise it on the fly. You could make multiple passes at different speeds to extend the range and get different (formant) resonances and *automate that process*. Backwards, 'predelay' the midi etc.
If you were going to have a midi operated music box, perhaps one with a guitar pickup, this might be a parallel, additional perk option, increasing the functionality of the original project, but adding the 'cost'/complexity of note mute off/on to a harpsichord action and a couple of transducers. You wouldn't perhaps build one from scratch, but you're already a good way there.

Last edit by kaisersozehongbatemp at 30 Jan 2020, 06:01 AM


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