D. B. Stang stangdb@voyager.net wrote: I am kind of a newbie, so if this topic is a dead horse that's already been beaten a few times, forgive me. What I would like to do is briefly describe my understanding of stretch and ask for comments about whether I am getting the idea or not. <snip> Hey, welcome aboard, D.B. (any name you'd care to share?) It sounds like you have a good idea of the basics...... Try and picture this: Each and every string has a ladder of partials that vibrate when a string is struck. The partials are: 1. fundimental (the one our brain tells us IS the note) 2. octave above 1 3. octave plus a fifth above 1 4. two octaves above 1 5. two octaves and a major third above 1 6. two octaves and a fifth above 1 (that's enough for now....) Now, just as a ladder has rungs spaced out, these partial ladder rungs are spaced out, however, not in the mathematical, whole number progression that was origionally thought. That's inharmonicity. Each of the higher partials vibrates a little sharper than predicted. In addition, the spacing of the rungs will vary from note to note. This is why there are many different solutions to the piano tuning puzzle. When trying to come up with a tuning that 'matches' a piano, the problem comes when trying to match up rungs from multiple notes.... because the spacing of the rungs is different, they can never match up at all the partial ladders. Enter RCT. (and other machines) There are different stretch options to try to match technicians' own tuning preferences. Some people may prefer to have purer single octaves, when matching a particular interval, (ie. 2:1 or 4:2, or 6:3) at the expense of the double and triple octaves. Conversly, other techs may choose to try and get the best double and triple octaves, while letting there be a very slight beat to the single octave. There are some pianos that there are substantial differences at the single octave level between the 2:1, 4:2 and 6:3 octave types. In effect, there is no place that will make the single octave pure. Sometimes it becomes a choice to find the place that will make it the "least bad". These are the type of pianos that are the most challenging, especially with the older tuning gear that only focuses on a single partial when tuning. So yes, you are on the right track...... Ask more, search the archives, hopefully it will make sense! Ron Koval Chicagoland _________________________________________________________________ Tired of spam? Get advanced junk mail protection with MSN 8. http://join.msn.com/?page=features/junkmail
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