Let me try to do a maths here.We all know the formula for string frequency, f=1/2*l(T/u)^1/2, here f is frequency,T is tension,we can change it to T=4*l*l*u*f*f, For note A440,assume the piano is on pitch, T(440)=4*l*l*u*440*440, if we raise the pitch by 4 cents(1 HZ),the tension is going to be T(441)=4*l*l*u*441*441 T(441):T(440)=1.0045505,that means the tension for A440 is going to raise 0.455% after 4 cents(1 HZ) pitch raise. we can do the same(similar)calculations on all the strings of a particular piano and all should have the same results(percentage of tension increase). Conclusion: the whole tension of a piano will raise by 0.45% after 4 cents(1 HZ for A440) pitch raise. If i remember correctly,the tension for grand piano could be more than 15 tons(30,000 pounds),that means one Hertz pitch raise can change the tension by 135 pounds. Baoli --- John Delmore <jodel@kairos.net> wrote: > Okay, it's mass only. If someone can give me a > typical scale description > (gauges and lengths, including wound strings [with > total diameter and core > diameter]), I think I can come up with a general > figure, per cent pitch > raise, pretty quickly. > > _____ > > From: pianotech-bounces@ptg.org > [mailto:pianotech-bounces@ptg.org] On Behalf > Of John Delmore > Sent: Wednesday, December 21, 2005 8:18 AM > To: 'Pianotech' > Subject: RE: How to explain a pitch adjustment > > It is an interesting question. The difference in > tension needed to cause a > one cent difference in pitch is going to vary > according to the mass (and > possibly the stiffness) of the string (I'll have to > check my old physics > books tonight). So, to get a general value for > added tension per cent PR, > you'd have to consider, also, the size of the piano, > i.e. you'd have > different values for a spinet, a large upright and a > large grand. > John (finally a bona fide member) Delmore > > _____ > > From: pianotech-bounces@ptg.org > [mailto:pianotech-bounces@ptg.org] On Behalf > Of jonathan stuchell > Sent: Tuesday, December 20, 2005 9:37 PM > To: Pianotech > Subject: Re: How to explain a pitch adjustment > > Thats good, I want to know the tension per cent > . That is a good > constant, useful for many applications. > ----- Original Message ----- > From: Geoff Sykes <mailto:thetuner@ivories52.com> > To: 'Pianotech' <mailto:pianotech@ptg.org> > Sent: Tuesday, December 20, 2005 5:44 PM > Subject: RE: How to explain a pitch adjustment > > That raises an interesting diversionary question. > What's the amount of > tension per cent? How many cents of change, over the > entire piano, would > create a ton of tension change? > > -- Geoff > -----Original Message----- > From: pianotech-bounces@ptg.org > [mailto:pianotech-bounces@ptg.org] On Behalf > Of Cy Shuster > Sent: Tuesday, December 20, 2005 2:24 PM > To: Pianotech > Subject: Re: How to explain a pitch adjustment > I measure pitch on all the A's before I start, and > record this for the > customer on a graph on the invoice. This gives them > a great visual about > what work is needed. The graph indicates "fine > tuning" range (+/1 eight > cents for me). > > The analogy I use is sanding: if wood is very rough, > you can't start with > the 1000-grit paper; multiple passes are required. > Same thing for painting: > with regular maintenance, one coat covers, otherwise > you may need several. > > A description of the forces involved helps: 15 to 20 > tons of tension > overall; a pitch raise can add a ton of tension > (right?), yet a fine tuning > requires < 1% accuracy. No wonder it doesn't last! > > --Cy-- > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
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