Hi Ric, Most interesting figures. I've not believed soundboard moving up and down had much to do with pitch corrections for some years. What I *do not* understand is *why* damppchasers work to ameliorate seasonal pitch change. Clearly they don't have much effect on metal. That leaves the rim and the main frame as possibilities. At 01:12 AM 3/8/2007 +0100, you wrote: >Hi List > >I've been running some numbers and thinking a bit about this traditional >idea that vertical deflection of the strings is the main cause of pitch >change and thought some of you might find this interesting. > >1400 mm length --> -1 cent >1000 mm length --> -1,4 cent >800 mm length --> -1,7 cent >500 mm length --> -2,4 cent >250 mm length --> -4 cent >100 mm length --> -7 cent >50 mm length --> -10 cent > >These examples are simply illustrative of the kinds of things that >actually has to happen if the soundboard rise and fall is to account for >most of the pitch change. I apply all the resulting change on the >speaking length itself and do not account for any friction. This is a >best case scenario. In reality the string will disperse some of any >change in tension caused by a change in vertical deflection... lessening >the frequency change and resulting downbearing... but necessitating even >more vertical change for any give change in pitch. > >I can not help but conclude... looking closer at the consequences.... >that vertical rise and fall of the soundboard simply doesnt have much to >do with the seasonal pitch change at all. > >Cheers >RicB Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T. Non calor sed umor est qui nobis incommodat mailto:pianotuna at yahoo.com http://us.geocities.com/drpt1948/ 3004 Grant Rd. REGINA, SK, S4S 5G7 306-539-0716 or 1-888-29t-uner
This PTG archive page provided courtesy of Moy Piano Service, LLC