Someone told me George Van Eps computed the number of chord combinations in his book “Harmonic Mechanisms for Guitar” and it came out to 364 million chord possibilities. I found that Ted Greene made a reference to it in an interview with GVE linked below, but it is only mentioned in passing.
I attempted some of my own calculations, but it misses the mark. I even tried if Greene confused million with billion.
If I assume 24 frets on a 6-string guitar, plus open strings and muted strings adding two more notes, it should be 26^6 = 308,915,776 = 308 million.
If I assume the result should be 364 billion, on an 8-string guitar you might calculate 26^8 = 208,827,064,576 which is around 209 billion.
So none of these results suggests 364 million or 364 billion.
I also tried to think in terms of piano/guitar. There are 88 keys on piano, and if you were thinking with the limits of 6 notes from 6-strings on guitar, you might try 88 choose 6, but that is 541,931,236 or around 542 million.
I'm not sure if what he had in mind was specific to the guitar or not, but he wrote books for 6-string guitar and played a 7-string guitar himself. I can't think of any other combination that might be meaningful musically.
Can anyone elaborate on how GVE came up with the figure of 364 million?
