Repairdown: Disklavier DKC500RW Control Unit

If you’ve been kind enough to accompany me on these regular hardware explorations, you’ve likely recognized a trend with regards to the gadgets that go under the knife. Generally speaking, the devices I take apart for your viewing pleasure come to us from the clearance rack of a big box retailer, the thrift store, or the always generous “AS-IS” section on eBay. There’s something of a cost-benefit analysis performed each time I pick up a piece of gear for dissection, and it probably won’t surprise you to find that the least expensive doggy in the window is usually the one that secures its fifteen minutes of Internet fame.

DKC500RW installed on right side.

But this month I present to you, Good Reader, something a bit different. This time I’m not taking something apart just for the simple joy of seeing PCB laid bare. I’ve been given the task of repairing an expensive piece of antiquated oddball equipment because, quite frankly, nobody else wanted to do it. If we happen to find ourselves learning about its inner workings in the process, that’s just the cost of doing business with a Hackaday writer.

The situation as explained to me is that in the late 1990’s, my brother’s employer purchased a Yamaha Mark II XG “Baby Grand” piano for somewhere in the neighborhood of $20,000. This particular model was selected for its ability to play MIDI files from 3.5 inch floppy disks, complete with the rather ghostly effect of the keys moving by themselves. The idea was that you could set this piano up in your lobby with a floppy full of Barry Manilow’s greatest hits, and your establishment would instantly be dripping with automated class.

Unfortunately, about a month or so back, the piano’s Disklavier DKC500RW control unit stopped reading disks. The piano itself still worked, but now required a human to do the playing. Calls were made, but as you might expect, most repair centers politely declined around the time they heard the word “floppy” and anyone who stayed on the line quoted a price that simply wasn’t economical.

Before they resorted to hiring a pianist, perhaps a rare example of a human taking a robot’s job, my brother asked if he could remove the control unit and see if I could make any sense of it. So with that, let’s dig into this vintage piece of musical equipment and see what a five figure price tag got you at the turn of the millennium.

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3D Prints Turn Any Keyboard Isomorphic

In the history of weird musical instrument interfaces, isomorphic keyboards are a favorite. These keyboards look like a grid of buttons, but when you play them, the relative shapes of chords are always the same. The benefit? Just say no to five hundred years of clavier tradition. It looks cool, too. Theoretically, it’s easier to play independent of whatever key you’re in. [John Moriarty] has built one of these isomorphic keyboards, and unlike everything we’ve ever seen, there are no electronics. It’s all 3D printable and turns any MIDI keyboard into an isomorphic keyboard.

We have seen isomorphic (piano) keyboards before, from a slew of Cherry keyboard switches to a bunch of arcade buttons. There is one downside to these builds, and that is that it’s really just building a MIDI controller. [John]’s build is simply a 3D printable overlay for a traditional piano that turns any standard keyboard into an isomorphic keyboard. The advantage being that this is really just a few pounds of plastic to be printed out and not a mess of wiring and electronics. Simple, removable, reversible. Not bad.

This keyboard effectively adds two differently colored keytops to each key on a keyboard. The best explination of how this keyboard works is in this video, but the basic idea is that all the note names are grouped together by color; C flat, C natural, and C sharp are all blue, for example. This means a third interval is two colors away, and a minor third is two colors to the right and one ‘row’ down. Yeah, it’s weird but that’s what an isomorphic keyboard is.

Since this is just a bunch of 3D printed parts meant to fit on any piano keybed, this is something that’s extremely easy to replicate. All the files for this keyboard overlay are available on Thingiverse, and [John] is offering to print these key tops for others without a 3D printer.

DIY Piano: Look, Ma, No Moving Parts

[Michael Sobolak] has a penchant for pianos, concern for capacitive touch, and special sentiment for solid state. This alliterate recipe results in a DIY PCB piano that leaves out the levers and is barren of buttons unless you count the stock RESET button on the Teensy. A real stickler might point out that speakers have moving cones. Beyond these tangential parts, which have motionless options, it is an electronic instrument with no moving parts.

The heart of the project is a Teensy 3.2 which natively supports twelve capacitive touch sensors. The infamous demo board is mounted to a homemade PCB featuring twelve keys but is actually an incomplete octave plus another key one octave above the first. If you look sharp, you already noticed the missing and extra touchpads. PCB traces were made in Illustrator because if you have a familiar tool, you use what you know and you cannot argue that it works. The design was transferred to a copper board using the old magazine page trick that we love and reliable old ferric acid.

We couldn’t help but notice that the posts of the Teensy were soldered to the top of the board, rather than drilling through, IMT-style. Again, the results speak, even if there is room for improvement. Reportedly, there is a second version on the way which includes every expected key.

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Simple Hack Completely Changes The Sound Of This Piano

We’re partial to musical instrument hacks around here, mainly because we find instruments to be fascinating machines. Few are more complex than the piano, and, as it turns out, few are quite so hackable. Still, we have to admit that this ragtime piano hack took us by surprise.

We always thought that the rich variety of tones that can be coaxed from a piano, from the tinny sound of an Old West saloon piano to the rich tones of a concert grand, were due mainly to the construction of the instrument and the way it’s played. Not so, apparently, as [Measured Workshop] demonstrated by installing a “mandolin rail” in a small upright piano. The instrument had seen better days, so step one was disassembly and cleaning. A wooden rail spanning the entire width of the string board was added, with a curtain of fabric draping down to the level of the hammers. The curtain was cut into a fringe in the same spacing as the hammers – marking the hammer locations with cornstarch was a nice trick – and metal clips were crimped to each fringe. The completed mandolin rail can be raised and lowered using a new foot pedal, completely changing the tone as the hammers hit the strings with the metal clips rather than their soft felt heads. It makes the piano sound a little like a harpsichord, or the aforementioned saloon instrument, and at the touch of a foot, it’s back to its original tone.

Most of the piano hacks we offer tend toward the electronic variety, so it’s nice to see a purely mechanical piano hack for a change. And if the hacked piano doesn’t work out as an instrument, you can always turn it into a workbench.

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Recycled Piano Becomes Upcycled Workbench

Pianos are free, in case you’re not hip to the exciting world of musical instrument salvage. Yes, the home piano, once the pinnacle of upper middle class appreciation of the arts, is no longer. The piano your great aunt bought in 1963 is just taking up space, and it’s not like the guy on Craigslist giving away a free piano has a Bösendorfer.

It’s out of this reality of a surplus of cheap used pianos that [luke] built a new desk. He got it a while ago, but after getting it into his house, he realized it was too old to be tuned anymore. Or at least it was uneconomical to do so. This piano became a workbench, but after a while [luke] wanted something with a little more storage.

The process of converting this piano to a desk began with taking a few photos and putting them into Fusion 360. A series of panels and brackets were modeled in box jointed plywood, and the entire thing was cut out of 6mm Baltic birch plywood at the Vancouver Hack Space.

There are a few nice features that make this desk a little better than an Ikea special. There’s a Raspberry Pi mounted to the shelves, because the Pi still makes a great workbench computer. There’s a power supply, and hookups for 12 V, 5 V, and 3.3 V from an ATX power supply. This is controlled with an awesome antique power switch mounted to the side of the piano. Slap a few coats of black paint on that, and [luke] has an awesome, functional workbench that also has out-of-tune sympathetic strings. Not bad.

You can check out the entire build video below. Thanks [Jarrett] for sending this one in.

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Piano Genie Trained A Neural Net To Play 88-Key Piano With 8 Arcade Buttons

Want to sound great on a Piano using only your coding skills? Enter Piano Genie, the result of a research project from Google AI and DeepMind. You press any of eight buttons while a neural network makes sure the piano plays something cool — compensating in real time for what’s already been played.

Almost anyone new to playing music who sits down at a piano will produce a sound similar to that of a cat chasing a mouse through a tangle of kitchen pots. Who can blame them, given the sea of 88 inexplicable keys sitting before them? But they’ll quickly realize that playing keys in succession in one direction will produce sounds with consistently increasing or decreasing pitch. They’ll also learn that pressing keys for different lengths of times can improve the melody. But there’s still 88 of them and plenty more to learn, such as which keys will sound harmonious when played together.

Piano Genie training architectureWith Pinao Genie, gone are the daunting 88 keys, replaced with a 3D-printed box of eight arcade-style buttons which they made by following this Adafruit tutorial. A neural network maps those eight buttons to something meaningful on the 88-key piano keyboard. Being a neural network, the mapping isn’t a fixed one-to-one or even one-to-many. Instead, it’s trained to play something which should sound good taking into account what was play previously and won`t necessarily be the same each time.

To train it they use data from the approximately 1400 performances of the International Piano e-Competition. The result can be quite good as you can see and hear in the video below. The buttons feed into a computer but the computer plays the result on an actual piano.

For training, the neural network really consists of two networks. One is an encoder, in this case a recurrent neural network (RNN) which takes piano sequences and learns to output a vector. In the diagram, the vector is in the middle and has one element for each of the eight buttons. The second network is the decoder, also an RNN. It’s trained to turn that eight-element vector back into the same music which was fed into the encoder.

Once trained, only the decoder is used. The eight-button keyboard feeds into the vector, and the decoder outputs suitable notes. The fact that they’re RNNs means that rather than learning a fixed one-to-many mapping, the network takes into account what was previously played in order to come up with something which hopefully sounds pleasing. To give the user a little more creative control, they also trained it to realize when the user is playing a rising or falling melody and to output the same. See their paper for how the turned polyphonic sound into monophonic and back again.

If you prefer a different style of music you can train it on a MIDI collection of your own choosing using their open-sourced model. Or you can try it out as is right now through their web interface. I’ll admit, I started out just banging on it, producing the same noise I would get if I just hammered away randomly on a piano. Then I switched to thinking of making melodies and the result started sounding better. So some music background and practice still helps. For the video below, the researcher admits to having already played for a few hours.

This isn’t the first project we’ve covered by these Google researchers. Another was this music synthesizer again using neural networks but this time with a Raspberry Pi. And if our discussion of recurrent neural networks went a bit over your head, check out our overview of neural networks.

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Listen To A Song Made From Custom Nintendo LABO Waveform Cards

[Hunter Irving] has been busy with the Nintendo LABO’s piano for the Nintendo Switch. In particular he’s been very busy creating his own custom waveform cards, which greatly expands the capabilities of the hackable cardboard contraption. If this sounds familiar, it’s because we covered his original method of creating 3D printed waveform cards that are compatible with the piano, but he’s taken his work further since then. Not only has he created new and more complex cards by sampling instruments from Super Nintendo games, he’s even experimented with cards based on vowel sounds in an effort to see just how far things can go. By layering the right vowel sounds just so, he was able to make the (barely identifiable) phrases I-LIKE-YOU, YOU-LIKE-ME, and LET’S-A-GO.

Those three phrases make up the (vaguely recognizable) lyrics of a song he composed using his custom waveform cards for the Nintendo LABO’s piano, appropriately titled I Like You. The song is at the 6:26 mark in the video embedded below, but the whole video is worth a watch to catch up on [Hunter]’s work. The song is also hosted on soundcloud.

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