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Use an electronic tuner. Just intonation (beatless freq ratios) on each of the open intervals will land you on a high E that’s 22 cents shy of 2 octaves. 😱 (I do often tune low E and A in a just 5th for power chords.) mathisonian/993526090546135040
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That’s not to say that equal temperament is always the best, but unless you’re playing historically accurate early music, you should probably stick with it. en.wikipedia.org/wiki/Equal_temperament