At Hack a Day, we don’t throw the term genius around lightly. We’re obligated to bestow that title on [Don Gilmore] for his amazingly simple self-tuning piano. To appreciate [Don]‘s build, you need to realize that just because a piano has 88 keys, that doesn’t mean it has 88 strings. Treble notes have three strings per key while tenor and bass notes have one or two strings each. This usually comes out to more than 200 strings per piano, and [Don] can bring them all up to tune in under a minute.

[Don]‘s system needs to perform two functions. The first one is sustaining the strings so the computer can ‘hear’ the strings. He does this with a magnetic sustainer that is a lot like an E-Bow. To bring the strings up to the right pitch, there are small heaters underneath the pin block. Running a little bit of current through these heaters allows [Don] to decrease the tension of each string and lower the pitch.

This tech reminds us of the Gibson Robot Guitar, a self-tuning guitar that does it’s trick with motors in the tuners. The Gibson didn’t do well on the sales floor, given that everybody and their mom can tune a guitar. Pianos, though, are another story. [Don] is looking for investors to bring his idea to market, and we hope to see it on the floor of a music shop sometime in the future.

Yes, an REO Speedwagon reference. Only slightly ashamed, if you’re wondering.

Sometimes you just don’t have space for a baby grand. [Abdullah] got around this problem and built a virtual wireless MIDI piano. Unlike it’s inspiration, it’s not bad but we still love it.

[Abdullah] got his hands on some flex sensors and attached them to a glove. These resistive sensors are put through a voltage divider and sent to a microcontroller (a PIC16F778, we believe) and corresponding MIDI notes are chosen. These MIDI notes are sent to a computer and played over a speaker.

Right now, only a single arpeggio is coded into the microcontroller. Depending on which finger is bent shifts this arpeggio up and down the keyboard. That being said, the firmware can be easily modified to recognize standard piano fingering so chords can be played. The only issue is moving the hand up and down the keyboard.

[Abdullah] is planning on making his glove completely wireless with a microcontroller and battery sewn into the glove. Here’s to hoping he’ll keep us posted.

Check out [Abdullah]‘s demo after the break.

[Todd Harrison] recently wrote in to tip us off on his submission to the Tektronix oscilloscope contest – using a scope to tune a piano. In his video he demonstrates how a Fast Fourier Transform can be used to determine the fundamental frequency of the note being played. This is a quick and easy way to determine if that key is in tune, and if not, how far off it is from the desired frequency and in which direction.

He goes on to explain that a scope can only be used as a starting reference point since “mathematically correct” tuning on a piano doesn’t sound right to the human ear. It turns out that when struck, the stretched wires in the piano behave less than ideally. In the case of a piano, the overtones (the other peaks shown on the scope higher in frequency than the fundamental) are actually slightly sharper (higher in frequency) than the expected harmonic whole-number multiple of the fundamental frequency.  As a result, the frequency ranges of each octave must be “stretched” in order to accommodate this and sound correct when multiple notes are played together across octaves.

Typically, only the A4 key is actually tuned to its correct frequency of 440Hz and all of the other keys are manually tuned off of this baseline. The amount of necessary stretch applied to each octave increases as you get further away from this initial reference point in either direction and is unique to each and every individual instrument – thus there is no universal device capable of perfect tuning. Although [Todd] admits that he won’t attempt to tune the entire piano himself using this technique, he finds it a convenient way to keep the most heavily played center sections of the piano closer to true between professional tunings.

If you have any interesting or unique uses for your Techtronix scope, you can enter the contest here. Just don’t forget to tip us off too!  Thanks [Todd]!

[Joren] likes his digital piano, but it was missing one key component that he wanted to use: the ability to produce vibrato while playing. Vibrato can be done in several different ways on regular pianos, but it seemed as if there was not a lot of consideration given to the effect when designing digital pianos.

He enjoys playing all sorts of music, including solos from Franz Liszt which suggest using vibrato at times, so he decided to build himself a vibrato box. Constructed with a bit of assistance from the friendly folks at Hackerspace Ghent, his “Pidato” incorporates an Arduino and three-axis accelerometer to get the job done.

The Arduino is connected to both the MIDI output of the piano as well as to the accelerometer, which he has mounted on his wrist. While playing, all he needs to do is simply move his hand rapidly to produce the vibrato sound as you can see in the video below. The Arduino code filters out any other sorts of movements to ensure that he does not accidentally trigger the effect when it is not desired.

Check out the video below for a quick demonstration of the Pidato box.

[Sebastian] is trying to improve the responsiveness of an electric keyboard. He was unsatisfied with the lack of adequate sensitivity to keystroke. The first step in his process was to measure how fast the quickest keystroke actually is. By setting up an LED and phototransistor and taking some measurements he found that sampling at 1 kHz would be more than adequate.

With initial testing complete he ordered some CNY70 transmissive/reflective light sensors that can be place below the keys. He measures the sensor with the ADC on an ATmega16 microcontroller. Running at 16 MHz he can sample each of the eight analog-to-digital converter channels at 1202 Hz. After doing a bunch of math he put together some lookup tables that are used to translate the ADC data into midi signals. We’ve embedded a video of one sensor controlling the midi program PianoTeq. [Sebastian] also sent us a schematic of one node in the sensor network (see it after the break).

When everything is said and done he plans to use eleven ATmega16 microcontrollers to address the 88 keys, with an additional microcontroller to act as the master using a two-wire interface for communications.

Update: [Sebastian] put up a webpage with a fairly verbose description. Reading it straight from the source really clears up a lot of questions.

[Diego Stocco] makes music with instruments he assembled. For instance, his Bassoforte uses piano keys, the neck and strings from an electric bass, and what look like some cymbals. Throw in a hammer from that piano and a double bass bow (plus heavy use of audio software) and he’s in business. Big business actually, his work has been in video games such as The Conduit and in feature films like Sherlock Holmes where he worked with Hans Zimmer. Bassoforte isn’t his only invention, he’s got several more including the Experibass string family on one instrument, the Light Controlled Oscillator, and sand music using the fine aggregate along with some piezoelectric film transducers.

[Thanks LuciusMare]

The MIDI piano instructor is a tool aimed at those who wish to learn to play piano, but don’t want to take lessons. The LED bar mounted above the keys lights up to show you exactly what key to press and when. We’ve seen this available in some electronic keyboards for some time, but this unit would be able to fit any standard sized keyboard.  Check the page for schematics and pictures.

[via Flickr]

We always wondered what happens to ancient pianos when the internals can no longer be kept in a playable condition. [Jean Philippe Roch] gutted his elderly upright and fit a Korg Triton inside. After the break you can watch a few videos including a slide show of the work log.  [Jean] separates the Korg keyboard from its case and places it in the empty upright piano rank. He then mounts the Korg’s controls in the front panel and adds motorized control to reveal this hidden secret. The project is finished with speakers in the bottom portion of the upright and blue LED lighting effects.

The result is a pretty nice show-piece. It’s not as hacky as vocoding, but we really love the finished look.

Construction log

Case automation

Playing demonstration

[Thanks poisoMike]

Reader [Philippe] tipped us off about this video showing a set of subway steps being turned into a piano keyboard (english translation). The creators wanted to make taking the stairs rather than riding the escalator a bit more fun. They added pressure sensors to each step, then covered them with white and black keys to resemble a keyboard. When a passenger puts their weight on a step, the corresponding pitch is played out loud.

We may have lied in the title as this doesn’t really compare to hearing Josh Bell play for pocket change at your train stop. But coming across this setup on an otherwise mundane commute would really brighten up our day.

This really cool project allows a grand piano to “speak”.  We don’t know any details about its construction but we had to share. The keys are being hit by solenoids in a manner to replicate human speech.  Click through to the video, it’s worth it. You may have to allow the popup to see the video, and it is in german, but the piano is clearly speaking english. We want one to keep around the office. It could read our emails to us.

[via matrixsynth]

For their final project in ECE 4760 at Cornell, [Christina] and [Joe] made a small single octave keyboard using LEDs as the input. They used a total of 63 LEDs to make the keys. Each key consists of 9 LEDs, with the center one acting as a sensor. When you lay your finger on it, the light reflects off of your finger and is picked up by the center LED. An ATMega 664 runs custom code to play a sound. You can find out more details about the construction as well as download the source code on the site. You can also download an example movie of it in action ( 7MB .mp4)

It’s construction is relatively simple: an Arduino, several infrared sensors, and LEDs corresponding to the notes make up the device. It doesn’t have any built-in audio hardware at all, so it’s most basic use is as a MIDI controller. Still, it is essentially an unspecified input device, so it could theoretically be used for other purposes. For us, it’s fun to just watch the AirPiano in action.