Alternative key layouts have popped up in commercial hardware and now iPad apps and such, but there’s nothing like trying to build something to grasp how it works. An intrepid group of makers who call themselves Louisville Soundbuilders are working now to clone the C-Thru Music AXiS-64. The goal: their own, original instrument that uses the isomorphic array of keys the AXiS does, which by organizing notes by harmonic interval makes complex melodies and harmonies much simpler than on traditional fretted instruments and keyboards.

You can see results in the video. (It doesn’t make sound until the very end. This is how instrument building goes — dedicate months to build, then months more to practice!) The discussion of how it’s made is especially interesting, and offers some tips to people who are building entirely different devices – check out what they learned about switches and velocity sensing. See the forum:
Soundbuilders Discussion

Thanks, Nick Sturtzel, for sharing your work.

And that really brings us to the value of cloning.

To me, the presence of these DIY boards shouldn’t detract from the value of C-Thru’s product. C-Thru’s gear is superb, and clearly, a lot of their market wants a pre-built project and not a few months in a local hacklab. In fact, clones could add value rather than subtract: by putting these instruments in the hands of people who can’t afford the C-Thru, the project helps evangelize isomorphic layouts. The real challenge for clever key layouts has been that their use is so limited, which means you never get a chance to build a scene and a practice around their musical application. Lastly, as the exploration of switches and velocity shows, building a clone of something else and getting involved in how something is made can yield entirely new designs – especially since this is a group of hacker musicians, not a factory making knock-offs.

I’ll be interested to see how this goes … and now I’m curious to build something like this.

Bonus points to this group for being from my hometown, Louisville, Kentucky. (I was born and raised, before moving to New York. If I ever move to Baltimore, I’ll have the Triple Crown.) For the correct pronunciation, think not how the French who settled it would speak, but instead imagine stuffing a pile of these keys in your mouth, and try to say “Louisville.”

In fact, that “” domain isn’t really even some hacker thing. “lvl” is probably the proper way to spell what people in Kentuckiana actually say. Hope I get to come visit folks in Louisville soon; it’s always good to come home.

  • Em Wilson

    If I ever win the lotto, I'm buying the world a tripod. Awesome project though, Thanks for sharing!

  • Human Plague

    Be my Renoise fantasy?

  • Random Chance

    If it's an isomorphic keyboard, what's it isomorphic to? And why exactly does the article have to mention the iPad in the first sentence? Isn't this a hardware device best compared to physical keyboards as oppoosed to a simulation on a screen? What this site needs is a signature for all the posts that reads "Posted from my iPad." ;-)

  • Spazmatron

    Well, the iPad is one of the few places to find this hex layout, so I'd say it's totally relevant. As far as hardware, the axis is really the only comparison, and it is referenced in the article. 

    I've been considering the axis 49 for a while, but I want to use it with hardware synths via midi(it only has USB). Does anyone know a way around this without going though a computer?

    -posted from my iphone

  • Spazmatron

    Isomorphic, in this context means that the fingering shapes/patterns are the same for all the scales and chords, no matter what position your at on the keyboard. 

  • Jordan Colburn

    Great to see this on CDM!  I was out at one of their soundbuilders meetings a few months ago and they had a few pcbs and prototypes made.  A lot of hard work, and a interesting design.  Very cool to see this progressing and getting some exposure!

  • psioniclabs

    Thanks for the interest! Apologies about the amateur camerawork. This video was meant as a quick demo of a work *in progress*. We didn't really anticipate that interest at this early stage would be as big as it has been.

    Some more photos here:

    Check back for more progress as this hardware evolves! 

    As suggested in the write-up, if this alternate keyboard design intrigues you; check out the Axis controllers. This project's appeal is the technical challenge of designing an isomorphic keyboard with velocity sensitive keys for expressive playing. If you just want to play around with an isomorphic keyboard layout, Axis has their product ready for purchase. 

    But… if you're interested in the technical challenge, feel free to ask questions! We love to share what we've learned.

    Thanks again!

  • Jim Aikin

    The trouble with the Axis-64 is that its keys are mapped to MIDI notes in a fixed manner. The Axis-49 has a "selfless" mode that outputs MIDI note numbers 1 through 98; you can remap these through Pd to produce whatever harmonic grid you like — but as an isomorphic layout tends to have redundant note assignments, you'll end up with a lot fewer than 98 keys on your keyboard.

    My fervent hope is that this new design will have user remapping of any key to any MIDI note on-board or in a dedicated software interface.

  • Barry Wood

    @Spazmatron: The iConnect MIDI device ought to do the trick for you, it will allow you interface USB, MIDI, and iOS devices.&nbsp ;

  • Peter Kirn

    @Random Chance: Isomorphic keyboards are not isomorphic to something else; it's the idea that harmonic shapes are isomorphic to one another when transposed. Wikipedia has a reasonable explanation:

    Since this impacts your fingers, it means that these shapes are not only isomorphic, but that fingers are invariant. Not having to change fingerings when you transpose is a pretty big idea.

    You seem to think the iPad is more relevant to this discussion than I do, but even in spite of me being an enormous iPad fanboy (yep, those are chuckles you're hearing in the background), I'll say this — this kind of layout only really works with physical buttons, because you need the differentiation to feel the benefits of those isomorphic fingerings and having velocity sensitivity to many of us is a big deal. Touchscreens in general, with or without various velocity sensitivity and "tactile" feedback tricks, just don't hold up to that. They might work well as a prototype for a hardware device, but eventually for this I think you will want hardware.

  • WalterSear

    As a never-going-back harmonic table (aka isopmorphic keyboard) user, I am really stoked to see these latest developments. First Roger Linn and then this DIY project. Both ends of the market at once! Very cool.

    It really is a better, easier to learn, more comfortable layout for a keyboard.

  • Brother

    LOUISVILLE!!!! You guys are awesome thank you for showing these people to me. Time to get mah hack on. :D

  • psioniclabs


    We're using the Midibox Core for the system board and, yes, you can map the keys anyway you like. In fact we had to do just that. ;-)

  • V²

    Nice, having two of these facing with their backs towards eachother makes a great digital "trekzak" (Accordeon/Bandoneon)

  • Automageddon

    I'd really love to see more of these, the C-thru is way too expensive and the disposition not really user-friendly, but something like the Linn-stument with the Wicki-hayden layout or the hack in the article would be awesome.

  • leakeg

    love these isomorphic layouts. Why oh why is the piano keyboard so ubiquitous when it's so unintuitive?!

  • cobaltage

    Isn't this just a kind of layout similar to the chromatic or Bayan accordion, but positioned in a less playable orientation?

  • psioniclabs


    Your rhetorical question may be technically accurate, but unfortunately you have missed the point entirely. No points awarded.

  • WalterSear

    @Automageddon – the Axis unit is ~$400. For a small scale hardware production run, you aren't going to get it for less.

    That said, you will eventually need two if you are going to use them exclusively: one for each hand. And some kind of pitch bend wheel/continuous controller

  • cobaltage


    While I can always appreciate a defensive, condescending, and needless response to an honest attempt to confirm something, let me try to extend this useless interaction by being more explicit.

    I'm just trying to confirm that the principle of this layout is the same as that of the chromatic accordion, because Peter refers to it as an "alternative key layout" modeled after the AXiS 64, writing that it "makes complex melodies and harmonies much simpler than on traditional fretted instruments and keyboards." However, having just watched videos of this fellow play the accordion very recently (as in the following linked video), what occurs to me is that this layout in a horizontal position — as it would be on any touchscreen, because there is no tactile input, or on the AXiS or Linn's new instrument, for instance — could not possibly allow for the speed of playing that can be achieved on the accordion. That leaves me wondering why someone would use the key layout in this flat orientation, when it is so obviously non-ergonomic relative to the orientation of the keys on the accordion. I can see why an alternative orientation on a touch interface would not be possible, but a tactile set of keys — such as the one being developed in the project described in the article — could have a different orientation.

    I'm sorry if you thought I was attempting to take a stance of superiority in my previous comment. I admit that my thought process was not completely clear. I hope I have been more clear.

  • ns

    I don't think playing a keytar is any faster than playing a piano.

    The button layouts are very different. The AXiS 64 uses a harmonic table layout, like this:

    where as chromatic accordions use the "C-system" layout, like this:

  • psioniclabs


    Ah I see. At face value I took that comment as an off-hand dig. Truce? Let's be friends.

    The context here is that we're a small group hobbyists engineering this from the ground up. And we're kind of making this up as we go along. We're using a stacked circuit board layout to hack together velocity sensitive keys. Lacking a manufacturer's fabrication resources, we're dependent on existing hardware. We have to use Cherry switches, which have a key stem that plunges below the mounted PCB in order to get a secondary switch strike for velocity sensitive capabilities. Those switches come in a single width, and in order to get usable number of keys the PCBs are kind of huge. I think you're on to something regarding the orientation, but standing it vertically (accordion style) would be kind of cumbersome. Imagine playing a 3x sized novelty accordion and you'll get the idea.

    But maybe someone could take the velocity-sensitive key hardware technique we're using for something like you're suggesting. I suspect it'd either be restricted in the amount of usable keys or need some alternate octave selection. But I'd love to see someone give it a shot!