I have a friend and an uncle who both have similar spinets. My uncle's is a 1970s or 1980s Thearle (I think -- that's the name on the fallboard and plate) 36" spinet, and the other friend's piano is a 1950s to 1970s vintage Wurlitzer 1170 series piano. Both have the same stringing arrangement (A1 - A#14 = double-wrapped monochord, B15 - G35 = single-wrapped bichord, bass/treble break = D30/D#31, G#36 to C88 = plain triple-string unisons. Until I opened up the pianos, I thought the mono/bi break was around G#12/A13 or something like that and the bi/tri break was where the bass/treble break happens to be. On my mother's PG-150, I can easily tell where the bass/treble and monochord/bichord breaks are, but I have to look to see where the bichord/trichord break is. --- John Delacour <JD@Pianomaker.co.uk> wrote: > At 12:54 18/09/01 -0500, Ron Nossaman wrote: > > > >No, I'd expect the tensions to be climbing as you > go up scale, from, say, > >328lbs at #12 in an example I have at hand, to > 175lbs each at #13. The > >monochord is at 54% with 0.048"core, and the > bichords are at 34% with 0.44" > >cores. This hardly strikes me as unreasonable or > unacceptable considering > >the original figures were 343lbs @61% for #12, and > 233lbs @41% for #13. My > >choice in core diameters in this instance isn't all > that huge a jump > >either, being 0.004" rather than the acceptable > 0.003". > > Well, we clearly have very different experience. > You say you'd expect the > tensions to be climbing as you go up scale -- so > would I through the > singles of a 6 ft. grand but only because of the > length of the piano. In a > concert grand I would expect the tension on the > singles either to be > roughly constant or even to fall somewhat towards > the transition to > bichords. The only reason the tension tails off to > the bottom on uprights > and smaller grands is because we have not the > length. > > As to your 328 lb., I would say such a tension is > dangerous on a No. 22 > core and would not exceed 307 lbs if I wanted it to > last. To achieve such > a tension you have jumped two whole sizes. That is > fine -- I usually jump > at least one and a half sizes -- but I would then > say that your 175 lb. > could be rather low for a No. 20 core. At any event > I would be likely to > spin the top single for 270 lbs on a 21 core and to > first bichord for 180 > lbs on a 19.5 core, presuming it's an average grand > or large upright, > though I'd need to see the lengths as well. This is > not just my crazy way > of doing things; Over 25 years of restringing > pianos and making strings > for the trade, I've had the opportunity of analysing > the best and the worst > of pianos. By and large, the best pianos seem to > have been designed along > similar lines, with a few notable exceptions. I > would need to hunt for > quite a while to come up with more than a couple of > scales that would agree > with your practice. > > > >As to "blending the tone", by which I understand > matching as far as > > >possible the harmonic balance of the adjacent > break notes and not merely > > >avoiding the most shocking of breaks, here the > actual design and details of > > >manufacture of the strings also plays an > important part. I heard someone > > >say not long ago in front of an audience that a > piano needs to be 9'6" long > > >in order to achieve a satisfactory break between > steel and covered strings! > > > >Whatever blending the tone means, I've produced > pianos in which pianists > >and technicians couldn't find the > monochord/bichord, bichord/trichord, or > >bass bridge/tenor bridge transitions without > looking. All well under 9'6" > >long, incidentally. It's doable, but you have to > give up the old soundboard > >and bridge configuration in favor of one that > works. > > I thought I made it clear the 9'6" thing was not > serious, though clearly > the man who said it thought it was. To me it was a > joke. Without changing > any bridges or anything, a perfectly acceptable > break can be achieved on > any reasonable-sized grand or upright simply through > good string scaling, > which like all piano things involves a good deal of > the intuition of > experience besides the "science", much of which is > contradictory and > devised by acousticians who play the trombone or > something. There are, of > course, cases where I would love to reshape the long > bridge if the job > would stand it, but if a piano has lasted 100 years > sounding good with a > less than perfectly shaped bridge, I reckon it > deserves to carry on for > another 100 or so without losing its defects of > character. For example, it > is the high tension in the tenor of a Blüthner and > the unusually thin cores > or the monochords that help to make up the "Blüthner > sound". > > JD > > > > __________________________________________________ Terrorist Attacks on U.S. - How can you help? Donate cash, emergency relief information http://dailynews.yahoo.com/fc/US/Emergency_Information/
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