Ryan, Are you talking about PScale?? If you have that or something like it, you can do the real math.<G> There's probably an easier way to do this, but here's how I did it. I did a scale evaluation with a pitch standard of @A=435cps. (20cents flat of A=440cps). Added all of the tensions of all of the strings, (yes I did the times two for the bi-chords and times three for the tri-chords). Then I changed the pitch parameter to A=440cps. Added all of the tensions of all of the strings and subtracted the first number from the second number. I got just slightly over 500 pounds additional tension...OVER ALL! So, IMHO, a 20 cent pitch raise is pretty common and quite doable. Now, I should say, the whole tension thing is logrythmic! in relation to where you start from and where you are going. If you were to raise pitch a whole tone it is a whole lot more than if you are just doing half tone and that's a whole lot more than just a quarter tone pitch raise and then we get to the criteria I use for declaring that I have to do a pitch raised...that's 5 cents. Anything more than that, I do a pitch raise pass before doing a fine tuning. Am I adding a lot of tension doing a 5cent pitch raise? I'm adding something, but it is of little consequence except that it does torque the plate/case structure in the process....and that's really what we were talking about in the first place. BTW, I'd like to send this on to the list, as I think this info that some really need/want. (hopefully<G>) I'll let you do it, if you feel o.k. with it.<g> Best Regards, Joe Joe Garrett, R.P.T. (Oregon) Captain, Tool Police Squares R I ----- Original Message ----- From: Ryan Sowers To: joegarrett at earthlink.net Sent: 4/2/10 5:44:19 PM Subject: Re: [pianotech] Grey market pianos.....etc. OK maybe I'm figuring this out wrong... I was using PTools and estimating the tension on note a49 based on a hypothetical speaking length of 400mm and a 17 gauge wire. It gave me a tension of 168 pounds. If i changed the note to 50, keeping the length and diameter the same (I figured this would simulate a half step pitch raise) the tension goes up to 189 lbs. That's 21 pounds. Multiplied times 220 strings in a piano, thats 4620 pounds. But I'll admit I don't really know what I'm talking about. I was just messing around with PTools and making generalizations: probably a dangerous thing to do! What's the proper way to calculate the amount of tension added to a piano during a pitch raise? Thanks Joe! On Fri, Apr 2, 2010 at 7:24 PM, Joseph Garrett <joegarrett at earthlink.net> wrote: Ryan, Where are you getting these numbers???!!! They are way off! I took this off list, as I don't want to embarass you, but what you are quoting is hogwash my friend!<G> Joe Joe Garrett, R.P.T. (Oregon) Captain, Tool Police Squares R I --I--- Original Message ----- From: Ryan Sowers To: joegarrett at earthlink.net;pianotech at ptg.org Sent: 4/2/10 4:00:18 PM Subject: Re: [pianotech] Grey market pianos.....etc. I think a half step pitch raise adds almost 4000 pounds of tension. So a quarter step pitch raise (25 cents) should be around 1000 pounds. I should have said "typical" pitch raise not "nominal". But you have a lot more experience with this than I do Joe! On Fri, Apr 2, 2010 at 4:53 PM, Joseph Garrett <joegarrett at earthlink.net> wrote: Ryan said: "A nominal pitch raise can easily add 1500 pounds of tension to the structure of a piano. I'm not guessing how much or in which ways the structure moves around, but we certainly know that it does." Ryan, The first statement is NOT true! Of course, you're idea of a "nominal pitch raise" and mine can be worlds apart. If you were raising pitch, on a modern piano, from A=435cps to A=440cps, you would add a little more than 500 pounds overall tension. That I would consider, a "nominal pitch raise". As for the structure moving, that is an established fact, that can be proven time after time. How it moves is a whole nuther thang.<G> Joe Joe Garrett, R.P.T. (Oregon) Captain, Tool Police Squares R I -- Ryan Sowers, RPT Puget Sound Chapter Olympia, WA www.pianova.net -- Ryan Sowers, RPT Puget Sound Chapter Olympia, WA www.pianova.net -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100402/383925ba/attachment.htm>
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