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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!
glen
Sebastian, I am very sorry to report that your post got swept up and away by a routine, automated spam sweep. The post appears to be lost. I am very sorry for the inconvenience, but you will have to re-post. This thread seems safe, so just reply here.
GlenDerek, sorry for the late reply. No, the resistor value has no influence on the tome. The tone is generated digitally by the microcontroller at a frequency hard-coded into the software. You can lower the value of the resistor on your bum key by adding that second resistor in parallel. This will lower the resistance across the key. You can try this by just holding the leads in place across the pads. Tricky, but a quick check. If you want to increase the resistance, you will have to pull out that resistor again and replace it with a higher value. You can’t hurt anything with different resistor values, and the magic number may vary from unit to unit, so experiment.
Roy, this is tremendous! Thank you for your detailed comments, and your theremin patch! You are my Favorite Customer of the Week!
Concerning note-on/note-off lead-or-lag: Yes, the Altura always kills the old note before triggering the new note. There is no specific delay involved. The two messages are usually tossed into the MIDI Transmit Buffer on the same cycle of the microcontroller. The OFF simply arrives first in the queue and is processed by the synth ahead of the ON message. We did it this way after extensive testing in development. Sending the messages in the other order resulted in hanging notes in a lot of situations.
The MIDI spec–especially 1.0, which has been on the books from about 1972 to 2019–is a wide-open, very loose environment for developers. There is no one way to implement portamento. We have seen synths handle it in many ways. (Many synthesis technologies do not lend themselves to this technique at all, and portamento is not implemented.) While some synths behave just as you described — play staccato and you get no glide — many if not most others behave differently. One of our Alesis modules is the opposite: play staccato for glide, legato for no-glide! One thing to bear in mind is Release. We developed the Altura assuming its use with a patch that has a non-zero release time. We assume the sound will linger, if only for a moment, while the next note sounds. This helps smooth out the theremin glide considerably.I notice our documentation is a little skimpy with MIDI implementation. When you set the Altura to Mode 5 – Portamento and stick your hand over the left sensor to set Portamento Time, as soon as the device gets its first non-zero reading I think it sends a CC65=127 message to switch Portamento ON, followed by a CC7=n message to set portamento time, where n is the value it picked up from your hand position. When you manipulate the controls to send a Portamento Time = 0 (CC7=0), the device also follows this immediately with CC64=0, Portamento OFF.
Now here is something that may be missing from your understanding of the Altura’s functionality. You can indeed manipulate notes and volume in portamento mode. Set Function =5 and use your left hand to set a nice portamento time. Remove left hand and set Function = 4, Channel Volume (CC5). Now Portamento remains active, right hand sends notes, and left hand manipulates vlolume. I like to go one step further: remove left hand, set Function = 2, Modulation (CC2). Add a little vibrato, remove left hand, switch back to Function 4. In this way you can sculpt a very convincing theremin sound.
Finally, here’s how we chose to implement portamento on the Macchiato. Since the Macchiato uses Pulse Width Modulation (PWM) synthesis, we are working directly with the waveform and frequency of the sound. When the Macchiato recieves a Portamento ON message, it stores whatever note is currently playing as the START frequency. When a NOTE ON is received for a different note, regardless of the on/off status of the old note, the new note starts from START frequency, and glides up or down to the new note frequency over the time set by Portamento Time. So you ALWAYS get a glide, whether playing stacatto or legato. If you use a long portamento time and then play a run of notes quickly, the oscillator may wander about without ever reaching a particular note — until you stop moving your hand.
— Glen van Alkemade
Joseph, we think this behavior is most likely due to software corruption, for which the solution would be to re-flash the microcontroller. This is wasily done with a USB-Tiny programmer and our free Updater App for PC. Before taking this remedy, however, you can check the functionality of the RELEASE pot.
1. Use your volt meter to test the voltage on the center pin of the pot, with the unit powered up, as you sweep the knob. The voltage should range from 0-5 volts. If the voltage is constant at zero, it is not sodlered properly somewhere. If it is static at some non-zero value, or fluctuates erratically, the pot is damaged and we will send a replacement.
2. Check for continuity between the pot center pin and its corresponding pin on the microchip. Consult the schematic at the back of the manual to determine which pin the pot is connected to. Or you can gently run one test probe across the tiny pins on each side of the MCU, listening for a beep. Carefully isolate the beep until you are confident which pin it is coming from. If there is no beep, the pot is not physically connected to the MCU.If the pot passes these tests, then the only remaining possibility is software.
Hmm, lemme think about that one. In the meantime, you can carefully inspect the soldering of the Release knob. You may want to reflow the connections. Obviously, if it were not soldered well, it wouldn’t work; but transferring that functionality to another knob, now that’s a bit puzzling. I’ll discuss with my partner and will re-post here.
JB, thanks for writing! This is a new one. There are four knobs that all modify the filter in some way: wave shape, rate, depth and cutoff. Which one(s) seem to also influence the release time? All of them, or just one? Does that knob seem to have the expected effect on the filter, as expected, plus the added bonus of fiddling with the release time, or does it ONLY adjust the release time? And finally: lets’s say RELEASE is all the way to the left, for very short release, like an organ. Now let’s say you make a filter adjustment that results in a very long release time. If you nudge the RELEASE knob just a hair, does it re-set the release to a very short time, as expected? And does nudging the misbehaving filter control switch it back to very long release? Let me know.
glen
That’s the correct, latest firmware version.
I’m sorry about that flaw in the cabinet tempate. We were aware of the error, but I did not think any bogus templates actually made it into circulation. The revision of Oct-29-2019 has the correct hole arrangement. In that template, you are looking at the inside of the cabinet: all folds bend upward. The group of three holes in the lid should be on the opposite side of the large MIDI hole in the cabinet back, not on the same side. If you eamil me at info(at)zeppelindesignlabs dot com, I’ll send you the PDF of the correct template. yes, you could salvage your PP pattern by slicing off the lid and flipping it around, reattaching it with a hinge.Glen
By Jove, you may be right! Thank you! We are currently shipping software v2.4.3, but this bug likely persists in that version as well. I will incorporate this fix into v2.4.4. We are having some trouble supporting our nifty Updater App, so distribution of future updates will probably be via download direct from the product page. Sign up for our newsletter to stay on top of developments. And thank you!
Glen
“Breaking” news!! Break the Machine will soon be stocking the VPM-1 standard kit. Please let them know about your interest.
OK, the built units are nominally sold out,but I think I have a floor model or B unit I can fix you up with. I will contact you directly.
One thing to check regarding No MIDI Out. This kit has two nearly identical 16-pin ICs. If they are installed in the wrong locaction or wrong orientation, the MIDI out will not work and the display will go funky. When the PCB is upright, with the row of pots at the bottom, the two ICs are to the left of the display with the divots pointing down, toward the pots. The IC on the left is labelled CD4050BE and the one on the right is SN74HC595N. Humor me and verify these are installed correctly.
