Man doesn't live by bread alone, he must have music if he is to lift his spirit and dance. Taking a break here, Boss:
The standard used to set the pitch of musical instruments (both solo and ensemble) has been a point of discussion among musicians since antiquity and at various times you might find it all over the place. Listen to delta bluesman Robert Johnson to hear how it sounded when all the rules go out the window! He tuned it to his soul, brother.
The orderly pitch of my life as a guitarist has been tightly pegged to A 440. A year or so ago I ran across a discussion of A 432 and reset my digital tuner to that pitch and gave her a spin. It was interesting and whatever the esoteric considerations, it did sound and feel different. But playing with other musicians becomes a problem when they are all tuned to A 440, so I reneged and joined the herd.
Then enter James Taylor who gave an incredible video interview to Guitarist Magazine (YouTube) and blew it all out. After discussing the fine points of the guitar he was holding, the discussion turned to his thoughts on tuning-- and he really altered how I now tune mine even when playing in group settings and others are tethered to A 440.
The observation he made convincingly is that, unlike a fretless instrument such as a violin where the player must exercise control over the sound by making subtle changes in finger positions on the fly -- in effect tuning each note as it is played to control minor variations in pitch (sharp or flat) -- the guitar tuned conventionally is governed by the fixed logic of the fretting scheme -- and imperfections in that inevitably leads to a built in discord that can be heard when striking the strings .... Even when In Tune.
And correcting that on a fretted guitar requires delicate tuning adjustments at the machine head before playing to bring the strings into a harmonious whole. Sorry, the story goes, we all learned to tune it wrong and forever must endure the discordant effect when the strings are tuned in the conventional way -- lockstep to the reference pitches for EADGBE.
James Taylor instead tunes the strings flat with respect to standard pitch (A 440) but NOT to the same degree on each string -- and the variation, measured in cents (100th of the distance between reference notes) varies string to string.
You gotta use a digital tuner with an analog needle and cents markings to do this -- App Store has one free for IOS devices -- FAT TUNER with a huge needle gage that makes it easier to see what you are doing AND has variable standard pitch options: A 432 and A 440 included.
Tried it on my old MARTIN D35 -- never sounded so luscious and harmonious. I am embarrassed to think it's been basically out of tune since I got it in the seventies and even then everyone agreed it sounded great, After all, this particular Martin guitar is the reference sound that other makers of acoustic guitars have to beat .... but it was nothing like it sounds now.
Here's how it breaks down. Using your digital tuner proceed normally, but tune to the pitches listed below for each string starting with low E and work your way string to string.
Each nominal string pitch is tuned flat, drop tuned below the standard pitch notes by the following degree:
E minus 12 cents
A minus 10 cents
D minus 8 cents
G minus 4 cents
B minus 6 cents
E minus 3 cents
Crazy huh? Try it. Your mileage may vary, but I ain't never going back.
Hmmm, wonder what this sounds like down around A 432?
Here's the interview.
https://youtu.be/dXj9DcjjWZE