There is no such thing as a pure octave as it will depend on the coincident partial you are using to compare the two notes. There is built in stretch when you tune aurally depending on which type of octave you use. A 2:1 octave will be less stretched than a 4:2 or 6:3 or 8:4 (progressively) owing to the phenomenon of inharmonicity. Similarly if you use a P12 as a check that will also stretch the octave. So depending on the checks you use and the way you manipulate the way those checks compare you can build in a stretch factor. There is no one style that fits all, each piano or each tuner. David Love www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Duaine & Laura Hechler Sent: Friday, November 13, 2009 7:26 AM To: pianotech at ptg.org Subject: [pianotech] ETD stretch vs pure (octaves) This may seem like a silly question but .... At least Cybertuner has stretch factors built-in. Do you aural tuners do stretch factors? How do you tune "pure" octaves with a "stretch" factor - this seems oxymoronic. Duaine -- Duaine Hechler Piano, Player Piano, Pump Organ Tuning, Servicing & Rebuilding Reed Organ Society Member Florissant, MO 63034 (314) 838-5587 dahechler at att.net www.hechlerpianoandorgan.com -- Home & Business user of Linux - 10 years
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