DIY Eigenharp - Keys Hardware?

When I was in college I dreamed of one day being able to afford an Eigenharp Alpha or Tau, and now that I have the cash, I’m seemingly out of luck for now unless a used one comes available onto the market (the online store doesn’t seem to work, and my emails have gotten no responses).

There are some other nice instruments on the market now like the Linnstrument and the ROLI Seaboard Rise 2, but I’m feeling so inspired by the form factor and ergonomics of the Eigenharp keys/neck that I’d like to try my hand at potentially building a DIY version of it, and hook it up to the open source EigenD software.

Has anybody had similar thoughts toward a DIY Eigenharp?

Has anybody done a teardown of the Eigenharp hardware to see what components are at play for the physical keys, specifically?

I have enough electrical engineering background to probably handle a lot of the rest of the pieces (at least enough for a personal DIY-quality attempt), but I’d love to know more about the hardware being used for the physical inputs, since I think that’s where a lot of the magic as far as expressivity is.

indeed, the special thing about the eigenharps are the keys due to the way they are implemented… they are extremely sensitive, and have virtually no latency (being light based)… its truly surprising how responsive it is when you first touch it.

not sure how viable it’d be given its entirely custom components, and based on alot of precision.

I should also point out, whilst EigenD is open source, the firmware for the eigenharps is not… and that firmware is what does all the calculations for the waveguide, and handling things like noise/calibration etc. which I suspect is non-trivial.

overall, id say, perhaps it can act as inspiration for a diy project, rather than being something you’d likely be able to replicate.

Welcome @jemc to the forum :wink:

Thanks for the video!

Oof, yeah - I had seriously underestimated what was going on in there. I had hoped the key hardware was something I may be backed by something I could find on DigiKey or Mouser plus a bit of 3D-printing, but it really seems like they did years of ground-up engineering to produce something truly unique, even just in the keys.

At least he gave a hint about the Honeywell breath sensor if I wanted to try to replicate just that small piece of it.

I may still try to poke around a bit and see if I can find something off-the-shelf I can try to use, even if it will pale in comparison to the custom engineering of the true Eigenkey. Let me know if anyone has any ideas on that.

I do hope that Eigenlabs will eventually decide to either start selling instruments again, open-source the hardware/firmware/VHDL, or license the core designs to another entrepreneur who wants to continue the legacy (maybe Roger Linn or ROLI?). I truly do believe, even having never held one myself, that the Eigenharps are the most compelling instrument of our time and hope that they can achieve their rightful place in the future of music.

Such hopeful decisions assume Eigenlabs still has business interests. They still exist on the books, but there has been no activity from them otherwise.

Neither Roger nor Roland are likely to continue the Eigenlabs legacy since they already have their own products, and the Eigenharp product line has proven to be a commercial failure. It will take a highly confident entrepreneur, moreso than John, to revive it.

Compelling to hackers and tickerers at best. No one will want to buy a product that has long ceased receiving support or attention from the parent company. If you need a hard reminder, take a good look at the Sensel Morph, and if you want more MPE hardware controller examples, I will be happy to provide them as additional references.

yeah, the tech is impressive … and the results show,
still today, only the continuum can match the Eigenharps sensitivity and responsiveness… and of course, thats a very different surface, the eiegnharp remains unique.

but yeah, Id not recommend anything thats out of production/getting official support to anyone other than an ‘enthusiast’.

the good news of the Eigenharp is that we have a strong community, and the high quality engineering means we hear of very few failing… so the future is fine for a while. … so many of us (including musicians ) still enjoy the Eigenharps :slight_smile:


I have high confidence in the hardware, and because of community efforts the software side is also in a healthy state. I’m less worried about the Eigenharps’ future now than I was when I decided on getting one 8 years ago or so. So there’d be at least one willing to buy them today! :slight_smile:

As for the commercial viability of a relaunch today, the Eigenharps were very early (too early?). The MPE standard didn’t exist, suitable synths were very slim pickings, and a consumer interest in these types of products are very different today than it was in 2009. I agree it is highly unlikely to happen, but I’d argue the opposite of them being “a proven commercial failure” (even though technically true). Eigenharps are still being actively used, with an active and very commited community, there is still nothing else quite like them out there and people are still wanting to buying them. To me, they have proven that EigenLabs got a lot right and that the potential is there. But yeah, this is all hypothetical, unfortunately…

Anyways, welcome @jemc! Your thoughts on the Eigenharps are not too far off my own. There is a certain magic to playing an instrument this well designed. It just feels “right” to me, in a very satisfying way. Used Eigenharps have been showing up for sale once in a while over the years, so with enough patience I wouldn’t dismiss the possibility of being able to buy one, if you so decide.

I barely used my Pico for a long time, but that has recently grown a lot on me. I now see less its limitations and appreciate what I actually can do with it. I doubt it can be that hard to track one down, so perhaps still worth some consideration to get a feel for the keys, EigenD, etc.?


They were unfortunate in terms of timing (eg MPE) but the problem was even more fundamental. To be a commercial success requires a certain scale of sales, and they clearly came nowhere close to a sustainable leve of sales. It doesnt matter that there are dedicated fans out there and occasional willing new customers, you have to demonstrate that there are a great quantity of them and plenty of new customers over time.

As an outsider it seemed to me that they gave up commercially within a relatively short space of time after the Pico launched. They probably needed a far higher volume of sales of those units than was achieved, they needed them to be some kind of mass market success. And so the game was quickly up once they discovered the sales volume reality of that product, with large amounts of money that was invested in this venture written off.

Commercially the MPE controller business is not easy. Very small entities can manage to sustain it if they are not expecting huge sales volumes and arent desperate to provide a return on investment and the covering of all R&D costs. Only time will tell whether Osmose can manage to be sustainable as a full on commercial entity with ambition (and some venture capital backers). On paper its got the best chance because the fact its a keyboard makes the potential sales base greater, people arent put off by an exotic form factor. ROLI were not a good test case because of the extreme amounts of money they spent, based off of very high levels of investment and running the whole thing as if it were an internet tech startup.

I would say theres been no prospect of Eigenharps thriving for over a decade, no reason to put hope there. The only hope I can think of would have been if someone who was happy to lose millions of pounds was a fan of their instruments and wanted to keep things going for the sake of it.


All true, I’m sure. But I was not talking about running a startup, but if it could hypothetically make financial sense to do a new Eigenharp production run (and then offer support, obviously).

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I was brainstorming a bit last night about how one might approach hardware for the keys of an Eigen-like instrument from a small scale hardware-hacker/DIY perspective.

A general outline in my mind has begun to form.

I think the optical tech they used in the true Eigenkey is definitely going to remain out of reach for the hobbyist, at least for now. Even among industrial control hardware, I only found one example that was even in the same vein, and that one appears to be a prototype produced in 2017 that has been inactive since then. Eigenlabs beat them to the punch by a decade.

If I set aside the idea of using optical tech, I think the next best bet is hall effect sensors - the underlying tech for high-end gaming controllers that want to avoid the “stick drift” that plagues potentiometer-based joysticks. With something like the TMAG5170 or TMAG5273 IC, you can measure changes in magnetic field across three dimensions, and this is often used for joystick-like applications.

Because it’s a 3d hall effect sensor, you should be able to pick up not only the pitch and yaw (like a typical thumbstick on a game controller), but also overall downward travel as the button is depressed downward (which is not a typical motion that game controllers are built to capture, but the Eigenkey is).

At this point, the trickier next step would be to design a DIY-3D-printable key housing for the magnet that facilitates proper movement and return of the key within the instrument neck. This could potentially be done with mechanical springs, but perhaps it’s worth trying to use magnets for this as well, taking inspiration from Riskable’s “void key” design for magnet-levitated computer keyboard keys. The 3d models for these are generated from OpenSCAD files which Riskable open-sourced here.

In the “void key” design, each key uses 3 cheap magnets to provide springiness and tactile feedback - one in the movable key, one below that repels it from the bottom of its travel, and one above that attracts it back to the top of its travel. An Eigen-like key has more degrees of freedom, so it probably needs some more magnets involved, but it still seems tractable - one can imagine a key that is more or less free-floating inside its housing (not constrained to a single axis of travel), and the only thing that causes it to return when the instrument player is done depressing it is a magnetic force that snaps it back to its inert position.

The other nice thing that lends simplicity and elegance to the “void key” design is that the same magnet(s) in the key that are used to return it to its position can be measured by the 3D hall effect sensor to measure how much the key has been displaced from its neutral position - so the magnet is serving “double duty”. And indeed, in the computer keyboards that Riskable has built with the “void key” design, it is a hall effect sensor that detects when the key is depressed - so there is precedent for this “double duty” design.

To calibrate the magnetic measurements, you likely want the key housing to have a sort of “funnel” at the top and bottom for the free-floating key to settle into when either fully released or fully depressed, so that you have two precise/repeatable places to measure as the min and max travel.

One thing to be worry about is “leaking” of magnetic field changes from other nearby ‘active’ keys affecting the hall sensor for a key that is supposed to be ‘inactive’. You could try to compensate for this in software/firmware, but you risk making the keys less responsive, so it’s best to try to eliminate the effect in the physical design as much as possible first.

Definitely seems like an interesting project to take on. It won’t match the incredible engineering of the “true” Eigenkey, but it may be responsive enough to be cool to play as an instrument. Perhaps interest in DIY Eigen-like instruments would drive consumer and commercial interest in the high-end “true” Eigenharps as well.

Seeing the Striso also suggests that maybe a silicone-based key (which can be sort of 3D-printed, via a 3D-printed mold) could be an appropriate solution - the magnet for the 3D hall effect sensor could be embedded in the flexible silicone, which would spring back to its inert position without need of any further magnets to attract or repel it back into position.

Honestly if just the Striso design could probably be adjusted physically to be a more Eigenharp-like key layout and ergonomic form factor (lined up along the neck of an instrument), that would probably go a long way.

Probably the “void key” design is a bit more physically responsive than silicone would be though? I imagine that silicone would take more finger force to depress. With the “void key” magnetic design, the distance between magnets can be calibrated to adjust the amount of force needed (as shown in the “void key” video I shared), whereas the silicone design will always likely be fairly “stiff”, leading to a different kind of playing style.

Continuum (and now Osmose) use Hall effect sensors.

I think this was talked about a little bit by Lippold Haken at a past Continuucon
(I think this video… but I may be wrong…)

it may be there is also documentation on this elsewhere…
(Im pretty sure Ive seen diagrams of the continuum somewhere)

obviously a very different form factor though, an Eigenharp needs to be light as its main use is to be held… Eigenlabs were keen to have a performance instruments, in a similar vein to guitar.

one interesting point, that Ive heard from Lippold and others, is that getting the right ‘feel’ thru the surface is pretty tricky, and time consuming…
also you have to be careful with things like temperature, to not throw off things like calibration.
… these things are so sensitive, and to be useful they need to accurate!

look at the discussion on this forum about Embodme Erae Touch , and issue users have had, and you’ll see its non-trivial.

frankly, this is an area where ‘cheaper’ mpe controllers have a nasty habit of being ‘wanting’…

I’m not sure what sensor tech is used for the Striso - perhaps @pierstitus would give some info?

this may be the way to go, as the Striso is fantastic…
perhaps even work with Piers, he spent many years working on the Striso… perhaps he can make something ‘custom’ … alot easier than reinventing the wheel :wink:

After months, it has just dawned on me that Eigen-folk want the guitarish feel and play, which is almost completely foreign to me. I see it on the GeoShred, but after a month or two with the Striso (Wicki/Hayden layout) I can’t imagine anything simpler for playing “whatever I can hear” in 'most any key. That layout is only “odd” for a few weeks, but obviously is not like a guitar neck. Maybe Piers will “stretch” one out for a custom product, as thetechnobear suggests.

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I think a circle-of-fifths-based layout like the Striso is really nice for chords and chord progressions - I think there’s no better layout for that.

But for leads/melodies I still prefer sequential layouts (like a keyboard or guitar, though a guitar-like layout has the added advantage of letting you skip an interval up or down along the other axis of the grid). Eigenharp takes it up a notch over other guitar-like instruments in melodic ease of use by letting you select a key and omit all the chromatics in between if you choose - so you save yourself the mental attention bandwidth of avoiding undesired chromatic flubs. Despite the Eigenharp being daunting to novice in its flexibility and tinker-heavy focus, I think the diatonic orientation gives this kind of key layout the potential to be very approachable for musical novices (or for those who just don’t want to expend their mental bandwidth on diatonic scale shapes over a chromatic layout). And the chromatic layout is always configurable as a fallback if you want to use chromatics.

If I were designing my perfect instrument it would probably be a bit of an Eigen/Striso blend, with a Striso-like circle-of-fifths layout for the left hand (high on the neck), and an Eigen-like grid for the right hand (lower on the neck), probably with some drum/strum-oriented buttons like the Eigenharp has.on the bottom (in this case, just below the melodic key layout, so you can switch from melodic focus to strumming with a short jump of the hand).

Silicone’s responsiveness largely depends on its durometer, which is typically based on Shore Type A. The LinnStrument (128)'s silicone playing surface, for example, is 40 durometer. The lower the durometer, the more easier it becomes to compress, at the expense of easier indentation.

It’s spooky, I think I said almost this exact thing to John when I first discovered the Eigenharp (too late, in 2020). By that time he was not very responsive and the few other people I could track down had moved on long before.

The Eigenharp was enormously ambitious and succeeding would have required an enormous investment. It’s amazing they got as far as they did, but opening it up totally (hardware, CAD, process, everything) was the only chance it had of becoming an established instrument. They open sourced the software too late and then stopped there. The software is also very complex and customizable, which again, requires a lot of engineer hours to fully develop so that it is intuitive and reliable.

The problem is, to last you need prominent musicians to get very proficient and demonstrate what it can do, and they never had that. Example: Jordan Rudess got a Continuum and then integrated it into his rig. He got an Eigenharp, made a couple videos, and that was it.

It’s a hard sell to get such a person to put in the effort to get good at playing a unique proprietary instrument that depends on one small company for its existence. Imagine if only one company could ever make electric guitar pickups, it would have gone nowhere.

TLDR; it was too ambitious and John was reluctant to open up his labor of love the way it needed. In the early days of FLAC I had to confront the same tradeoffs, and that was just a software project; it would have gone nowhere as closed-source/licensed/patent-encumbered (remember Monkey’s Audio?).

If he dumped the whole enchilada now onto a public server, someone might pick it up and run with it, otherwise it will have to be someone like you to start fresh with the idea. And I wish someone would, because it was a great idea.


I’ve also thought about the idea of a DIY Eigenharp. What I partly like about it is the sheer size and presence, like a cello or a bass clarinet. Having a large number of complex mechanical keys would make it an expensive project though. Multi-axis squishy buttons like the Exquis or Striso are certainly one way to go.

You might find some more tips in this thread.

This includes a link by Piers to a discussion on the Axoloti forum where he described a version of the mechanism, but the link’s not working. IIRC it described a criss-cross array of strips of velostat. There’s also a bit of info in section 6.1 of this doc:

I found quite a promising and affordable combination of keys and sensor for a Hall-effect key mechanism, but not a multi-axis one. Could be useful for velocity or Lumatone-like expression though.



Wooting Lekker with OH49E.

The Wiggler also uses Hall effect.

Joysticks are potentially something to consider as well. They were notably used on an MPE hardware controller called the Joyst JV-1.

I found the details of the Striso hardware published here (specifically, section 6.1) - each button uses a triangle of exposed pads on the PCB which get bridged during button press by a material that has a pressure-dependent resistance. Then those get sampled by an ADC - about as cheap and simple as you can get (more or less the polar opposite of the intense engineering of the Eigenkey).

The Striso paper also links to an instructable which was probably the inspiration for the idea.

That kind of solution is definitely within reach for a DIY hobbyist - though I’m still “attracted” to the idea of using a Hall sensor instead (if you’ll forgive the pun) because it seems likely to be capable of more expressivity with less finger pressure.

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