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System Self-Calibration


The Yamaha Disklavier is considered the most accurate player piano in the world. To achieve this level of accuracy, 3 things are required:

   1. A well-constructed acoustic piano that is built very consistently and accurately.

   2. A sophisticated record and playback system, where the sensing system of the piano is fully integrated with the playback part of the system.

   3. An automated calibration system that incorporates both the sensing system and playback system in the calibration process. Disklavier pianos are the only player pianos to have such a calibration system.

SYSTEM SELF-CALIBRATION – Goals

An accurate “capture” of a piano performance requires the ability to precisely measure and record the speed of the keys, hammers and pedals during the recording process. The speed of the hammer right before it hits the string is what determines how loud or soft the note is played. The Disklavier PRO is able to capture 1024 levels of velocity of the hammer. In addition, pedal movement must be accurately detected. Disklavier PRO systems capture 256 steps of incremental pedaling.

To accurately “play back” a piano performance, the solenoids have to throw the hammers to the strings with the same velocity as what was captured during the recording. Pedals playback exactly as they are recorded.

SYSTEM SELF-CALIBRATION – Why is it important?
1. Acoustic pianos are made with many wooden components that change in dimension due to humidity. The way a piano feels and performs is affected by slight changes in the dimension of the action.

2. Piano actions have felt and buckskin attached to their wooden components. Combined, the keys and action alone have nearly 10,000 individual parts. The various felt bushings wear as the piano is played, also affecting the way a piano feels and performs.

3. Piano technicians “regulate” the action of the piano to compensate for the variations caused by humidity and wear. System self-calibration allows the keys and action to play with the highest level of repetition and power, and to play evenly, from key to key.

SYSTEM SELF-CALIBRATION – What is it?
Disklavier pianos have utilized system self-calibration since the original Disklavier grand was introduced in 1989. In the Mark IV, E3 and Enspire Disklavier systems, calibration consists of key/action sensor calibration, pedal calibration and drive system calibration. Each of these calibrations incorporate the performance of the drive system solenoids with the sensing system monitoring the performance of those solenoids, at many different velocities.

The service technician is able to access special service modes in the Disklavier that are not seen by the owner. The technician accesses these service modes by powering up the Disklavier and pressing a specific button to begin the calibration. Keys, hammers and pedals start going up and down in a complex series of patterns and at a wide variety of velocities. This calibration gets pretty “noisy” as solenoids go from playing very softly to playing quite loudly. The entire calibration process can take as long as 25 minutes.

During the calibration process, new “table” data is created from what the sensing system is detecting. A simplified explanation of what is happening is as follows: Let’s say that the playback system is called upon to play middle C, attempting to move the hammer at 80 miles per hour (MPH). If the hammer moves through its stroke, and the sensing system measures the hammer movement at 82 MPH, then the system creates a table offset for middle C, so that when the solenoid is called upon to move the hammer at 80 MPH, it does it by very accurately reducing the amount of voltage for that specific velocity and saves this information to a new data table. If the hammer moves through its stroke, and the sensing system measures the hammer movement at 80 MPH, then no offset is created for that specific velocity for middle C.

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Written by Bill Brandom:

Bill Brandom began his career in the music industry as a pianist and a piano technician. He attended a piano tuning school and opened his own shop in Kansas City before being asked to join the Yamaha team in 1980. His first role was to manage the service department for the Everett Piano factory in Michigan, which was owned by Yamaha at the time. He later moved to the Yamaha corporate headquarters in California and joined the Yamaha piano service department. Bill served as National Piano Service Manager for over 20 years, where he played a vital role in the development and promotion of Disklavier products. Bill was Disklavier Marketing Manager for several years and later became Senior Technical Manager before his retirement in 2010.