>How is the length and position of the cutoff bar calculated? > >David Love >davidlovepianos@earthlink.net By standing at the instrument with tape measure in hand and taking an overview of the actual sound board 'acreage' as it stands, the proximity of the long bridge to the concave curve of the outer rim and belly rail, and trying to arrive at a curve which will place the long bridge approximately in the centre of the belly. However, there is considerable variation in the distance from the long bridge to the concave curve of the rim. I use the note C52 as my primary reference note when taking measurements. Designs from the '70s, say a Yamaha G2 might have 280 mm from C 52 where it crosses the bridge to the concave curve of the outer rim. This figure has been gradually increasing with more contemporary designs. The Baldwin SD-10 and the Yamaha C7F are about 350 mm to to the rim, while the Steinway D is about 330. In instances where C52 to the rim is only 280 mm, it might not be a good idea to set the cut-off such that the long bridge is in the middle of the panel - 560 mm may not be enough effective sound board 'width'. But you do need to take a look at each design and try to make an educated guess. There's no magic formula, just experience. On the other hand, we don't need half a football field of sound board acreage from C52 to the rim as some makers seem to think. Big is not necessarily better. Bigger might be better for the low bass up to a point, but the sound board area adjacent to the bridge should gradually decrease as we go from bass to high treble. A sound board without a cut-off completely flies in the face of good piano design, even if it is only a short piano. A slab of spruce attached to the sound board panel across the bass end corner but not the back beams is not a proper cut-off. This is merely the 'Claytons cut-off' which we see too often amongst the commercial outpourings of makers who should know better. Maybe they do know better but just don't care? Maybe I don't know what I'm talking about? We just have to keep thinking about it as we get older. Answers will appear by and by. Best, Ron O. -- _______________________ OVERS PIANOS - SYDNEY Grand Piano Manufacturers Web: http://overspianos.com.au mailto:info@overspianos.com.au _______________________
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