Why 432hz Tuning?

Several piano tuners have told me that my circa 1900 Mason Hamlin upright piano will never be able to be tuned at 440hz. It’s just the way it is. Embrace the inconsistencies of tuning. Be flexible when you tune your guitar, banjo, fiddle or electric bass. As long as everybody is playing at the same reference pitch it’ll sound just fine. Enjoy the differences in sound quality the different tunings convey.

Lots of Folk/Old Time fiddle music is played on a fiddle that is either "Cross-Tuned" (AEAE, GDGD etc.) or "Black Mountain-tuned", cross-tuned but with the high E string further tuned down so it is a Third above the A string. These alternate tunings certainly limit the instrument’s flexibility to play in different keys, but they convey a wonderfully folky/primitive flavor and easily allow for magical harmonies and unisons. In other words, a whole world of music opens up when you stop obsessing on perfectly 440 pitched music ensembles. Let a thousand flowers bloom.

@frogman 

It's a simple matter of practicality. A lot of G and D fiddle strings simply cannot take the tension it takes to tune to the necessary A and E pitches.  I've had more than my share of G and D strings snap. It might happen immediately. Sometimes you'll open the fiddle case, the next morning, to find it happened some time during the night. Once or twice I'd put my fiddle away in AEAE (what is known as cross-tuning) and open up the case the next morning to find the neck had detached itself from the fiddle's body. I remember having my kindly old German luthier tell me "zeese sings happen" when I took the fiddle to him to have the neck glued on again.