DIY touch-sensitive grid keyboard (Linnstrument inspired)
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- čas přidán 11. 05. 2023
- A walk thru of my new DIY midi controller, which is inspired by the Linnstrument, spans all 128 midi notes, and is inexpensive to make.
It's also friendly to microtonal /xenharmonic tunings, and has polyphonic aftertouch.
Some thoughts I didn't mention in the video:
This instrument has velocity sensitivity, and polyphonic aftertouch. It's not MPE compatible, and doesn't have the other dimensions of expression that you get on a true Linnstrument (per-note pitch bend on the X axis, other controls on the Y and Z axes, etc. and there aren't any lights to help you identify notes. I just focused on creating a big grid of note pads that would be sensitive enough and respond fast enough for a musical instrument. Roger Linn's site has fascinating information on how the Linnstrument's hardware is built, and boy howdy is it cool! I could never create something with that amount of complexity, but using the materials to do something simpler turns out to be really feasible!
The Linnstrument is patented, but the information I used to come up with this was freely available, and I'm not selling anything, so I don't think there's any harm in using or sharing this stuff w/ the DIY community.
The Velostat material that makes this possible is very affordable, and unbelievably useful. You can use it to make pressure-sensitive pads, XY touchpads, ribbon controllers, and so on. I got my 2 sheets from adafruit.com for less than $10.
The microcontroller that does all the computing and reading is a Teensy LC. They are probably going to be discontinued, but there are even more powerful successors to the Teensy LC at pjrc.com.
The velostat is a single solid sheet, in between a set of 16 rows of copper tape and a set of 16 columns of copper tape. The microcontroller sends some voltage through the row strips one at a time, and reads how much voltage passes through the velostat and into the columns one at a time. The harder a finger is pressing on one spot, the higher the voltage is read.
Man, I should probably just write a blog about the technical stuff.
Disclaimer: I don't have a ton of free time these days, and I'm not a great video producer, so I'm focusing my time on projects rather than making great videos. I really want to share the stuff I make, especially when I think it might appeal to or help other folks though. So I hope you don't mind my videos being simple and raw! I'm not on CZcams to make money or grow a big subscriber list. - Hudba
I would love to see a video with more info on how you did this in the details.
Thanks for watching! Yeah, I think I'm going to tackle this by building another one, with a few tweaks for simplicity. I'll document that process and probably share it here in video form.
Fascinating stuff. I hope to see your video on how to make it. And I hope for that one you put your camera into landscape mode. I feel like I’m watching genius through a crack in a wall. :)
I know, one thing I gotta do is figure out a camera mount.
Thank you for your comment! I'm still working on the next video on this project. It'll be long and I'll try to include all the little bits I've learned so far, but it won't be a step by step guide.
@@markfdesimone I’ll await it with interest. Good luck with the project!
Wow. Very cool project. Lots of cleverness both in idea itself and the execution. I have a Linnstrument, along with Akai Ewi and other wind controllers, and I'm starting to experiment with DIY controller building. Looks like yours would be a fun project. How are the pads/keys (and/or the cushion layer) attached to the velostat? Similar with Borgophone instrument, curious about what exactly you used for those metal keys on that one , and special kudos for the brass-oriented fingering design, haven't seen anything quite like that before; hope to get some ideas from your github project on how you've applied/extended J. Berglund's note identification algorithm.
Thank you! I hope you find as much fun in DIY controllers as I am! It's pretty frustrating at times, but also hugely rewarding when something you made works, and does something unique.
All those brown squares are 3d printed shapes I came up with. I didn't use them the way I meant to in the end, and I wouldn't probably recommended going to the trouble of printing all those. There are other cheap options out there that take less time to make. I'm working on a followup video with more details; not sure when it'll be done but I'm going to try and talk about keys, because I think that's the most important part of the whole thing. In another attempt at making keys, I just used some thick 1/4 inch closed-cell foam from an arts & crafts store; and cut it into squarish shapes, which I glued down to some thinner foam. That's working pretty well, and I wish I'd found that material sooner. Still it's not perfect, and I made both of these prototypes with a smooth surface, to which I'm attaching sheets with the buttons glued on. This lets me try different things without having to mess with the circuit or any of that hard work.
So on my Borgophone, for the first few versions I used copper tape, which is easy to get. I stuck it to clothes buttons to get a 3d texture, and soldered wires to the pads. They use capacitive touch. For the newest one, which I don't think I've put up here yet, I used cherry-style keyboard keys because I wanted the physical feedback of pressing a button. They work better than expected, and I personally prefer them over the touch pads. They're more costly than the copper tape materials-wise though.
Do you plan on sharing your endeavors anywhere? I'm always wanting to see other projects like these! Thanks again.
@markfdesimone Interesting, I'll look forward to your next video. I wonder whether your grid has resolution to at least get some expressiveness on x and y axes of a pad. Wouldn't need in any way to have 0-127 that Linnstrument gives in those dimensions, seems like even a bit would help, e.g., for vibrato. Resolution of your full grid is at the very least 16 x 16. How much beyond that do you think it goes? RE: foam, I do know some Linnstrument devotees think a big part of why they like Linnstrument is the hard surface. I'm not sure.
Cherry keys on Borgophone make me think of the Samchillian device. If you don't know that already I bet that's a mode you'd like to build in. I plan to include it on my device. Search youtube for 'Samchillian demo at Harvard Reunion', and 'Eventide Misha, a Totally Unique Interval Sequencer'. Maybe it's not just a coincidence that both those devices have light ring displays like Borgophone. Unrelated, but I also ran across interesting 'UDAR - Amazing musical invention' on youtube.
Thanks for the recommendation, I'll have to look up this samchillian device. I love the idea of being able to add new modes of functionality just with code updates :)
And regarding x and y expressiveness, although the resolution is a discrete 15 x15 columns, a friend has given me some advice on how to approach some logic to detect vibrato and pitch bend with code. I'm planning to try this at some point, when I've got the second version with faster microcontroller working solid. I didn't intend to add x or y axes because I was mainly hoping to have a velocity sensitive isomoephic keyboard with lots of keys, for exploring microtonal tunings. The Roger Linn Design site has some really interesting technical info about how Mr. Linn achieved the Linnstrument's many axes of expressiveness, and that approach is far out of what I could try. Also, he does have a patent that I want to respect. I'm not planning on selling any though.
I think the hard playing surface has got to be the best approach. I am still trying to brainstorm how to create one. It needs tactile landmarks that help your fingers delineate the keys, as well as the orientation of the xy grid. A totally smooth surface feels like trying to play refrigerator. But while the soft foam feels nice, it ends up being inconsistent in several ways. I think it's probably got its uses though, and I think being able to swap different sets of keys in and out will be a great feature. I can color code the keys for different tunings, or use the foam keys if I want smushy notes, for ballads maybe?
@@markfdesimone The Samchillian/Misha type device is friendly toward microtonal use, I think you'll like it.
And re: velocity sensitive isomorphic keyboard, yes, that's very useful in itself, and is all many Linnstrument players use it for. Jesse Washmon has some amazing Linnstrument videos, and that's all they use. And adding non-polyphonic vibrato or expression with breath controller while playing grid keyboard is also useful.
"promo sm" 😩