Entropy Piano Tuner

Quickstart Guide

Welcome to the Entropy Piano Tuner (EPT). This application allows you to test a new electronic method for piano tuning which minimizes the disorder (entropy) of the frequency spectra. This is a short guide for getting started. For detailed information please download the user manual.


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Hardware requirements and installation

Computer: The EPT runs on most laptop and tablet computers and even on mobile phones.

Microphone: To operate the tuner one needs an external microphone of good quality. We recommend a low-noise condenser microphone with a linear frequency response. Inbuilt microphones of tablets and smartphones may be used for testing but they may fail at low and high frequencies.

Headphone: Optionally an ordinary headphone will be useful to check the recorded tones. If you do not use a headphone you should mute the loudspeaker of your device in order to avoid unintended feedback via the microphone.

MIDI keyboard: Optionally you may connect a MIDI keyboard to your device which allows you to play and hear the computed tune in advance. However, a MIDI keyboard is not required for tuning.

Installation: The Entropy Piano Tuner is available for OS-X, IOS, Android, Windows and Linux. Please visit our Download page.

First steps

Connect your microphone and start the EPT. Make sure that the VU meter responds to the microphone and that the input level is automatically adjusted. If you tune the instrument for the first time, choose File-New, specify the concert pitch, and provide the necessary information. The left toolbar allows you to switch between four different operation modes which can be selected by mouse click or by using the TAB key. These operations modes correspond to the three main steps of the tuning procedure:

1. Recording

Select the recording mode and strike all keys of your piano subsequently from the left to the right in order to record the keys. The recording starts whenever the VU meter passes the 'on' mark and stops when it falls below the 'off' mark. The pressed key is recognized automatically. Above the keys you will see the frequency spectrum with the partials as a red line.

Please keep the piano key pressed until the red recording symbol disappears and wait until the data has been processed. If you use a headphone a successful recording will acknowledged by a brief echo of the same pitch. The corresponding key will be marked by a green tick.

If you decide to record a certain note again select the corresponding key by a mouse click or by using the arrow keys. If the key is not correctly recognized, e.g. in the bass or in the treble, it is possible to force the recognition by clicking the key twice or by hitting the enter key.

After each recording the EPT displays the quality of the recorded signal. There is no need for this quality to be maximal, but it should vary smoothly from key to key. For tones with several strings it is recommended to record only one string while muting the other ones.

During recording two curves will emerge above the spectrum. The blue markers measure the pitch relative to the equal temperament. Contrarily, the gray markers quantify the inharmonicity plotted upside-down. Apart from a jump between the two diagonal string sections, the inharmonicity levels should vary smoothly. The inharmonicity is not measured in the topmost octave.

Once all keys are marked by a green tick please save your work (using File-SaveAs....). With a MIDI keyboard it is possible to verify the recorded keys acoustically.

2. Calculation

Go to the calculation mode, select the entropy minimizer and start the calculation. In the tuning curve window you can monitor how the tuning process evolves. As you can see, the algorithm creates a tuning represented by green markers. If there are no major changes any more you may stop the calculation process.

Now it is possible to test the calculated tune by playing on the MIDI keyboard. Here the EPT synthesizes artificial sounds according to the recorded ones, taking inharmonicity into account. If you find that certain keys are clearly out of tune, you can correct them by moving the green markers around with the help of the mouse.

After successful calculation you should again save your project.

3. Tuning

Now switch to the tuning mode. Here the EPT works in the same way as an ordinary tuning device. However, since inharmonicity is taken into account, it works only with the same instrument that was recorded.

To tune a string simply try to bring the rectangular marker in the Analyzer-Window to the center. Alternative, try to move the red markers to the region in the center which is highlighted in green color. For keys with several strings per tone it is recommended to first tune one of them and then to tune the other aurally relative to the first one.

In the tuning mode the EPT recognizes the tuned key automatically. At the same time a synthetic sound is generated in the headphone which should coincide with the sound of the string. Again it is possible to select a particular key and to force its recognition.

License / Disclaimer

The Entropy Piano Tuner is completely free of charge and may be used for private as well as for professional purposes. It is published as an open source software under the GNU-GPL license. We would like to point out that the tuning of pianos is a highly sophisticated task that requires many years of comprehensive professional training. Improper tuning may inflict serious damage to your instrument. Please note that you are using this program at your own risk.

Feedback

If you have questions or comments please send us an e-mail to info at piano-tuner.org or use the contact form on our website.