"Pure": I meant clean single octaves. I normally stretch to a clean third octave. In this case, stretching that much will cause a Steinway vertical to creep too sharp in the treble. Unisons - defined as pure when all coincident partials are aligned, and/or the three strings (or the two strings in a bichord) aurally sound "clean" when played together. So, for the Steinway vertical, when you set the pins for the octave or for the unison, set them coming from flat of "clean", not sharp of "clean" Nomenclature, nomenclature. Sorry for any confusion. Boaz
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