There is a community near me of New Age/Eastern Mysticism folks. One of them asked me about tuning their Boston grand to 432. Here is the reply I emailed to them. Feel free to copy.
Hi Xxxx,
Short answer: I can, but it is not recommended.
The longer answer has three sides to it.
First, the belief in a connection of that frequency to a spiritual harmony. I can't really speak to that, as that is a spiritual decision you will make for your own reasons, or not.
Second, I am aware of the article that started much of the conversation about 432 versus 440. I have also seen materials that question the sources used in that article. Some presume mathematical numbers based on celestial orbits and diameters which have since been accurately measured to be different those used by the older sources quoted in the article. 432 is not a factorial of the newly accepted numbers.
Third, the piano is specifically designed to function best at A=440 Hz. The tension of the wires is optimized at a certain percentage of the breaking tension; for tone, for enharmonicity (the relationship of coincidental partials, how the notes relate to each other), for the amount of down bearing on the bridges, for the overall stress on the structure of the instrument.
On the plus side tone wise, the piano will sound deeper, perhaps richer, less strident. On the negative side, it will lose its brightness, power, and some of its dynamic range.
There are even more complicated mathematical questions that arise if 432 is an absolute goal. Pianos are enharmonic rather than harmonic. The upper partials of a struck string do not create the theoretical frequencies; 27.5, 55, 110, 220, 440, 880 and so on. Bowed strings do create harmonic frequencies. So, if I do tune a piano to A4=432, the upper and lower octaves will not necessarily fall into the same harmonic/mathematical schema the above mentioned article describes.
A side note: A has been defined in the past as anywhere from 385 to 485. 435 was used as well as 440 in the US until the early twentieth century, when 440 became the accepted standard. European orchestras commonly tune at 442, 443, sometimes as high as 444 or 445. There are many apocryphal stories about the favorite pitch of Bach, Mozart, or whomever.
If you should wish for me to tune at 432, it will take extra effort to tune it and then re-tune it. Returning it to 440 will take the same extra effort. It won't damage the piano, but it won't be as stable until it has been tuned a couple of times at the frequency of your choosing.
Please let me know if you have any other questions.
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David Stocker, RPT
Olympia WA
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Original Message:
Sent: 12-07-2025 16:06
From: Patrick Greene
Subject: A432
A client called me and said she would like for me to tune her piano to A432 and she wants some other instruments (dulcimer, hammer dulcimer, guitar) tuned to A432..I am thinking she wants a really "old fashioned sounding" Christmas. I have never tuned a piano to A432 and since I tune aurally, could I just find an app that would transmit that tone and I would tune the piano down to it? In 38 years, no one has ever asked me to do this and I tried to discourage her a bit on it, but she seems determined.
What do you all suggest? I may decline to do this as I do not want to mess up her piano.
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Patrick Greene
OWNER
Knoxville TN
(865) 384-6582
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