I suspect that if the 2:1 octave is tuned beatless then the double octaves will sound flat. -Robert Scott If you mean two contiguious octaves it depends on various parts of the piano whether the double octaves will "sound" flat. Piano tuninig is done first and last by beats, not by sound or intonation. Of course "the sound" has to be agreeable after the tuning. When aurally testing double octaves, the 4th partial of the bottom note will sound with the 1st partial of the upper note. How sharp the 4th partial is, is how "sharp" the 1st partial will be when "in tune". This is what the theorists call "stretch" but not piano tuners. We realize theory says because of inharmonicity a beatless octave may indeed be "stretched" from mathematical perfect ratios. Stretch for tuners is how many beats sharp an octave can be before it becomes "objectionable", or what is needed to satisfy asthetic concerns. This of course is a judgement call and why some call tuning an art. After all, what is art but producing what other people will appreciate? ---ric
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