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Getting started

Welcome to the Entropy Piano Tuner (EPT). This is a short guide for getting started. For detailed information please download the user manual.

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 select individual keys. 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

Before starting the EPT, connect your microphone and make sure that it works. Make sure that the VU meter responds to the microphone and that the level adjusts automatically. 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 main step of the tuning procedure.

The tuning process consist of three steps:

  • Recording of all piano keys.
  • Calculation of the entropy-optimized tune.
  • Electronically assisted manual tuning of the piano.

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 upper mark and stops when it falls below the lower 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 an earphone a successful recording will trigger 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 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 key 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 and start the calculation. In the tuning curve window you can watch how the tuning process evolves. As you can see, a tuning curve emerges that is represented by the green markers. If there are no major changes any more you may stop the calculation process.

Subsequently you can verify the new tune by playing your MIDI keyboard. Here the EPT synthesizes artificial sounds according to the recorded one, taking inharmonicity into account. If you find that certain keys are clearly out of tune, it is possible to fix it my moving the green markers around with the help of the mouse.

After successful calculation you should again save your project.

3. Tuning

200px-Gtk-dialog-warning.svgPlease note that the tuning of pianos is a highly sophisticated task that requires many years of professional training and experience. Improper tuning may inflict serious damage to your instrument.

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. Please note that you are using this program at your own risk.


If you have questions or comments please use the feedback form or send us an e-mail to info at