Stretch Tuning vs. Equal Temperament Tuning: The Proper Way to Tune Your Rhodes, Wurlitzer or Clavinet.
What is the difference between Stretch Tuning and Equal Temperament Tuning? And why can’t you tune a piano with a guitar tuner?
If you took a high school or university physics class that had a unit on the physics of sound, you may recall learning that notes an octave apart have a frequency ratio of 2:1. These are the place holders for the two ends of a scale. Taking this basic knowledge, it may seem reasonable to take the twelve notes of the scale and divide the octave into even portions. If this were the case, over the course of several octaves as on a piano’s keyboard manual, the harmonies would begin to sound dissonent. But why? In the most simplified terms, this is because as intervals move further apart, the human ear finds the beats generated by the two or more frequencies unpleasant. Luckily, there are alternate methods of tuning that produce more appealing harmonies.
When two intervals are played together, the combination of the two or more frequencies produce beats. The rate of the beats is a function of the differences in frequency of the two pitches, which is one of the components of how the human ear interprets harmonies. In order to produce the most appealing harmonies in a piano or ensemble, a number of tuning philosophies exist that create more pleasant beats, and can even account for inharmonicity within the instrument (more on inharmonicity in a later post). The philosophies typically use more pure major thirds, minor thirds, fourths, fifths—you name it—some temperaments even go as far as taking into account the specific key signature that will be used.
Side Note: Even the Greek philosopher and mathematician Pythagoras conjured a superior tuning methodology that resulted in tuning that is close to tuning to perfect fifths (on a ratio of 3:2). Each tuning methodology has it’s strengths and weaknesses, and unfortunately for Pythagoras, the most dissonance that results from his tuning methodology is on the major and minor thirds that results in dissonant major and minor triads.
Without getting too detailed into the technicalities of these tuning paradigms, the fundamental philosophy of stretch tuning is to make up for the frequency ratios of various harmonies within the scale (or targeting inharmonicity of the instrument) of an instrument by compensating for the variance of the harmonic tones produced by a string, tine, or reed. In its most basic form the solution is to ‘stretch’ the lower octaves to be ‘flat ‘and the upper octaves are a little ‘sharp’ compared to equal temperament tuning in 440hz.
Most guitarists that use digital electric tuners may recognize 440hz as the frequency that they set their tuners in order to sound in tune with other instruments. But if you tune an entire piano to 440hz the result will be that notes played within the same octave will sound relatively in tune whereas notes spaced further apart or paired with other instruments will sound dissonant and as if they are out of tune. This is why you can’t tune a piano—or electric piano—with a guitar tuner.
Notice: at each end of the chart for stretch tuning of an 88 key piano that notes are tuned to roughly 13 cents flat and sharp (or 13/100ths of a half step) which is offset more than 10% “out of tune” from equal temerament.
In order to do this with an electric tuner, you will need a much more accurate tuner than a common chromatic guitar tuner. For instance, The Chicago Electric Piano Company uses the precision of a strobe tuner that is rated accurate to 1/10 of one cent (or 1/1000 of a half step). It also visually represents the series of the overtones produced by a piano adding to its precision. Strobe tuning also allows you to offset equal temperament tuning by intervals of 1/10th of a cent so you can accurately set the tuner to account for the tuning methodology of your choice.
For more on the tuning methodology specific to Rhodes and Wurlitzers, please stay tuned for our follow up post on inharmonicity of electric pianos.
The Chicago Electric Piano Co. is the Midwest’s electric piano tuning expert for Rhodes, Wurlitzers and Clavinets. After studying and comparing the outcomes of various tuning methodologies, our shop endorses a stretch tuning methodology that is used industry wide by the most reputable piano tuners. If there is an alternate or historical temperament that is called for, we can tune to any temperament of your choice with the highest level of precision–guaranteed. Our goal is to provide the most accurate electric piano tuning to recording studios and musicians nation wide.
What is stretch tuning? How to tune a piano. Tuning philosophies. Strobe Tuners and Chromatic Tuners. Can you tune a piano with a guitar tuner?