Is it possible to use 2 or 3 Altura’s together?

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  • #29548 Reply
    Russell Thomas

    I would like to create a dual 2D (X-Y) or 3D (X-Y-Z) configuration, using two or three Alturas, with modified hardware for the speaker and microphone.

    This would be purely for CC controls, where each hand is sending two or three rather than one. However, I might use it for controlling sound effect patches or pads or sound layers. I even imagine wearing plastic spheres around each hand for good reflectivity and to allow freedom of movement of the hands and fingers.

    I imagine the following configuration:

    Altura #1 mounted on a pedestal, about chest high, with the normal board and case except that the speaker + mics are at 180 degrees, pointing straight out left and right.

    Altura #2 would be mounted on the table, about belt high, but with separate housing for left and right speakers + mics, spaced about shoulder width or a little wider. They would be both be pointing straight up from the table.

    Altura #3 would be also mounted on the table, but their left and aright speaker + mic sets would be pedestal mounted at shoulder width and about arms-length away in the Z direction.

    There would be no need for all three to communicate digitally, since they could independently send their control information via their own MIDI outputs.

    Thanks to the kit and instructions, it shouldn’t be hard to create “remote speaker + mic housing” to add longer wires to the PC board.

    The only barrier I can think of is the sound frequency of the sonar. If it is the same for all three Altura, then it probably creates big problems. But it would seem that a simple solution would be to have customizable frequencies for each, far enough apart to avoid interference.

    Am I missing something? Is this possible? Has anyone tried it?

    Thanks and keep up the good work,

    Russell Thomas


    #29549 Reply

    Russell, you are my new favorite. Yes, you can use 2 or 3 Alturas together, BUT — you are right, the sensors all listen for the same frequency chirp: multiple Alturas, if not positioned carefully, will cross-talk. This is why whenever we turn on the display Altura in the showroom, the doorbell chimes. Each speaker is speaking the same chirp, then waiting a few milliseconds for an echo to appear at the microphone. If there are several Alturas all chirping around in the same environment, a microphone will not distinguish its own speaker’s outbound chirp from a chirp coming directly or indirectly from a different speaker.

    That said, your plan is still sound. Please note that in Funcion 6 (X-Y), one Altura is sending two completely independent streams of MIDI CC data — granted they are on one transmit channel, but two different CC #’s on one channel are easily mapped and routed out to any MIDI device. Thus you only need 1-1/2 Alturas to provide X-Y-Z control!

    All of your reasoning concerning long wires and sensor mounting and orientation is sound. Yes you can do this; yes others have gone before you. Some other things to consider as you develop your setup:

    Sensors emit a chirp in a cone-shaped pattern that is about 70 degrees wide. You have to picture that cone in the air as you adjust your setup. Cones should not overlap.

    Sensors oriented horizontally and then set on a tabletop will have problems. As you move your hand toward the sensor, the chirp has multiple paths by which to return to the microphone: the short, direct path, plus others that reflect off the tabletop. The result is erratic behavior.

    Sensors oriented vertically, such that the axes of the sensor cones are parallel, can be tricky, because a chirp strikes the floppy shape of your hand and then scatters; so a hand in one cone can reflect a chirp back to both sensors. This is why we settled on the diagonal orientation of the stock Altura.

    All that said, you should TOTALLY go for it. Find longer 4-conductor cables with which to plug in the sensors, or hardwire the sensors to the board with your own length of ribbon cable. Devise a holder for the sensors that you can easily aim.

    One last consideration: I cannot quite picture the “plastic spheres around {your} hands for reflectivity.” As I discuss at about 5:20 in the Altura tutorial video:

    the sensor wants a flat reflective surface, like a paddle, a fry pan, or a paper plate. Plastic spheres would scatter chirps all over the room, with chaotic results — which sometimes might be just what you need!

    Good luck! Do it! Post videos!


    #29550 Reply
    Russell Thomas

    Hi Glen,

    Thanks for your detailed response. Being your new favorite person, even for a day, means I can die happy. ๐Ÿ™‚

    To clarify: I’m looking to set up TWO X-Y or X-Y-Z sensor fields, one for each hand, moving independently. This would yield 4 or 6 independent CC signals on some number of MIDI cables (don’t care).

    I took a long walk and was thinking about all this.

    First, it was clear that I needed audio isolation – at least between left and right, and maybe more. Since these are high frequencies (I presume), then acoustic foam should be useful.

    About the “hand globes”, I now see that spheres won’t work. They would need to be cubes, with each side facing a speaker + mic pair. I will adjust the rest of my costume to fit that motif. Maybe neo-Devo?? ๐Ÿ™‚

    I also realize I won’t get full X-Y or X-Y-Z coverage in each arm if I use just one speaker + mic for each dimension, since they would be positioned in the middle of the plane. I don’t think I need full range on all the CCs at once, or if I do, I can write a script in the DAW (Reaper) to do the conversion.

    Sensor frequency and sensitivity to reflections seems to be the main issue to deal with in design phase. Dusting off my decades-old EE degree, I wonder if there isn’t some way in HW + SW to make each Altura more selective in frequency, so that they reject signals from other Altura’s even if they are in range.

    Acoustic treatment seem like the best way to cope with unwanted reflections. Heck, I may just make a stand for all of this, so there is no table for sound to reflect off of. I imagine this to be a fairly athletic activity, rather like conducting an orchestra, so making it a stand-up rig makes sense.

    Thanks for your encouragement, and yes I will make videos of the project if I dive in. I have some other basic hardware stuff to sort out first.

    Russell Thomas

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