This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Re: Unusual rib structure?Hi Ron, Thanks for the feedback. Rib crowned? Interesting. What = characteristics suggest that? (I know very little about soundboard/rib = structure.) I gather that rib crowning is a more recent development in = piano technology? Is there some place I could read a brief history? I measured the ribs for you. I wasn't perfectly exact in my = measurements (didn't have the time), but if you want more exact = measurements, I'll get them for you later. Aside from the tapered ends, = the dimensions are constant throughout the length of each rib. The = bottom of each rib is rounded slightly I didn't measure the lengths of = the tapers. The height and width of the ribs (in mm) are as follows (in = order from treble to bass): rib h w 1 difficult access 2 19 19 3 21 21 4 21 23 5 25 24 6 25 25 7 26 26 8 ? 26 (difficult access) 9 28 26 10 28 26 11 28 26 12 27 26 13 27 26 14 26 26 15 26 26 16 26 26 17 difficult access 18 difficult access You are correct that the bass is rather dark. Of course I like it that = way. Peace, Sarah ----- Original Message -----=20 From: Ron Overs=20 To: Pianotech=20 Sent: Tuesday, May 06, 2003 6:43 PM Subject: Re: Unusual rib structure? Hi Sarah, Its an interesting piano you have. OK, there's something about my piano (1933 Wissner 9') that seems = odd (in my limited experience), and I've just got to ask. My soundboard = ribs have an unusual structure (I think), and I'm uncertain as to the = purpose. Most of the ribs are "tied" together with one of two small = cross-braces. I can't see how the ties can do anything to either enhance the = structure of the board or its function tonally. They remind me of the = tie strap across the bass corner ribs of a model B Steinway, which also = are of doubtful benefit. Counting from the keyboard, high treble end of the soundboard, the = first brace starts around the center, keyboard-end of the soundboard at = rib 8 and continues leftward and towards the tail through rib 13. Then = from the other end of rib 13 (right side of the piano), another brace = starts and extends towards rib 17 in the tail. Ribs 1-7 and rib 18 have = no cross-braces. An 18 rib design, while the D has 17 in the latest offerings at least. Here are some photos: www.wonderfulhome.info/soundboard1.jpg www.wonderfulhome.info/soundboard2.jpg www.wonderfulhome.info/soundboard3.jpg Looking at what appears to be the fifth rib from the bass Sarah (the = rib which in jpg 3 runs to the top LH corner of the image), the rib = appears to be quite deep in the centre. They look suspiciously like they = are rib crowned. Would you mind measuring the overall rib depths at = their centres? I'd be interested to know what they are. The ribs on the cross-brace end are not smoothly tapered the way I = think of most ribs being. Rather, they are reduced in tiers, and the = cross-braces run across the tiers. The rib ends without cross-bracing = are tapered in the conventional manner. So... Why was this done? Was it a way of stiffening the = soundboard? I would speculate that the designer was interested in achieving a = graduation in the sudden reduction of the rib section modulus of a = conventionally feathered rib. The stepped feathering would probably = cause the panel deflection to be somewhat more progressive. Mind you, = this may not necessarily be desirable. For me at least, the 'jury is = still out' on this matter. . The bass on this piano is incredibly rich, powerful, and mellow, = and the sustain is unbelievable. The tiered feathering should allow quite a substantial impedance = reduction in the panel behind the bass bridge. I would expect this piano = to have quite a dark tone in the bass. I'll be interested to hear other observations of others re the = feathering. Ron O. --=20 _______________________ OVERS PIANOS - SYDNEY Grand Piano Manufacturers Web: http://overspianos.com.au mailto:info@overspianos.com.au _______________________ ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/5c/90/9b/ae/attachment.htm ---------------------- multipart/alternative attachment--
This PTG archive page provided courtesy of Moy Piano Service, LLC