Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at [aritrakdebnath2003]’s MIDI THEREMIN, we see it works differently, but it does play in the manner of the exotic radio instrument, so we suppose it can use the name.
The MIDI THEREMIN is purely a MIDI controller. It sends note data to a computer or synthesizer, and from there, you can get whatever sound at whatever volume you desire. The device’s brain is an Arduino Uno, and MIDI-out for the Arduino has been a solved problem for a long while now.
In fact, we’ve seen Arduino-based Theremins before, but where this project differs is in the use of TOF sensors over the traditional ultrasonic sensors. In this case, the instrument uses VL53LOX TOF sensors controlled over I2C, along with an Adafruit library to interface with them.
As with all theremin-style instruments, distance from one sensor manages pitch and the other volume. Time-of-flight optical sensors are designed to provide a smoother, more precise, and more stable output than ultrasonic ones, and this tends to be the case in our experience. According to [aritrakdebnath2003], this makes the instrument more playable, and we believe it. You can download a demo video as an MP4 from the project at Step 5 if you want to hear it in action.
If you haven’t gotten enough theremins yet, we’ve covered many over the years–including one based on a Commodore 64. Be warned. If you want to build this one, you’ll need a lot of bread.
i mean there’s no denying it’s a hack! a demonstration of how easy it is to use these TOF sensors.
but every one of these music instrument projects seems to highlight the fact that the hacker didn’t understand or appreciate the musical qualities of the instrument, which always jumps out at me anyways.
everything musical about a theremin comes down to its analog nature. it hits the in between frequencies as you move. and it is instantaneous. this creates both its signature “spooky” sound and provides a tight enough feedback loop that people are able to learn how to control it like it was a part of their body.
since this is not only a digitized sensor, but also MIDI, it is quantized all to heck. and the delay is extraordinary — the sensor’s fastest mode is 20ms, but “high accuracy” mode is 200ms, and the demo video seems to have at least 200ms of latency. and the sensor is not the only delay — it has to sense, decode, communicate, synthesize, and then DAC. each one of those steps adds latency and it really adds up. in my experience, 20ms is about the limit of a delay where it becomes noticable. 50ms of delay is enough to be obnoxious and 200ms is well into “unplayable” territory.
it doesn’t make the spooky sound. it doesn’t provide the kind of instantaneous and precise feedback where you can train yourself to use it delicately. so it can’t really have the strengths of the theremin. it can only have the weaknesses of the theremin, which is basically the worst music instrument user interface ever designed.
there would be downsides, but if you actually wanted to make a theremin out of a TOF sensor, you would do it the exact same way as the radio sensor: analog all the way! the last thing you want is to quantize it to I2C or MIDI.
shrug just my two cents as someone who cares about musical instruments. probably, in defense of the project, it was never meant to be a music instrument :)
I agree, it indeed is not a theremin, or a usable musical instrument at all. Still it was probably a fun build for the creator
I think you are right about the original theremin. Still, digitized controllers can be useful. I agree that latency is a concern, especially if you want to play along with other musicians. In my own related project (lalelu_drums) I work with an update rate of 100 Hz and could measure a latency (player movement to audio out) of 20ms, which I would claim is acceptable.
Here is my project:
https://hackaday.io/project/194264-laleludrums
and here is the latency measurement:
https://hackaday.io/project/194264-laleludrums/log/239700-log-17-latency
I bought a cheap ebay theremin with a bunch of voices built In , they cost about $30 . It is a worthless toy at best . Due to latency. I have a moog etherwave and a stylophone theremin and they are very fun and play great. Also have an Obamatone delux though not a theremin it is very fun and responsive to play with a bit of a theremin flavor to it. The thig here is that if it has latency, it’s not a musical instrument. It’s an expensive toy that will end up making you angry and wanting to smash it . And as a word of advice, never buy junk musical instruments for a Child. Unless you want to discourage them from learning to play an instrument.
Where are the sharks?
Haha II was thinking to do the same things!