Hi JD: Thanks for your further comments on top of Del's. Many of the old Chickering grands had low bridges at heights in the range you describe, and not a particularly powerful or satisfying tone - they can sound a bit flabby to me. The why of the taller the bridge is what most intrigues me. All else being equal, the taller bridge will have more mass. I think we probably have a better understanding of the role of mass in the bridge than we do stiffness. Our R,C, & S bellymen who regularly mass load bridges to targeted levels to fine tune the performance of the soundboard can attest to the importance of that from their own experience. But that taller bridge is also going to be stiffer - how much does that add to the improved performance of the soundboard? How much stiffness do we need to achieve optimal performance? I recall reading in " Piano Tone Building" about experimental bass bridges which were made out of Vanadium instead of maple or beech. These bridges were much stiffer than the wood ones, and had a dramatically longer sustain times - but not a pleasing tone. Still, it points to the potential value that added stiffness might have, particularly in this modern age of composite structures, where various materials are combined to achieve a blend of properties. Will Truitt -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of John Delacour Sent: Sunday, March 22, 2009 4:18 PM To: pianotech at ptg.org Subject: Re: [pianotech] Increasing bridge height At 15:21 -0700 21/3/09, Delwin D Fandrich wrote: >I don't really like treble bridges that are 24 to 25 mm tall. I want >to end up with a bridge height of at least 30 mm at C-88. I'd say that is very conservative. In 1916, Wolfenden wrote:- ______________________________ "For many years, both long and bass bridges were cut out of 1 in. [25.4mm] beech, and were often finished under 7/8 in. [22.2mm] in height, but of late the long bridge, by general tacit consent, stands at 1-15/16 in. [33.3 mm] to 1-1/2 in. [38.1mm] above the belly, and the bass bridge from 3/4 in. to over 7/8 in. higher still. No definite proportion between the tension of the strings and the height of the bridge has been discovered. It would not be surprising were it to be found that a further increase in height was of advantage." ______________________________ In fact one English maker had already been building uprights and grands with a bridge 42 - 44 mm in height for nearly 50 years before this was written, having changed from a 1" bridge as soon as the low tension pianos were discontinued in favour of the modern scaling with the new wire. And these pianos are, without exception in my experience, powerful, clear and subtle with excellent sustain. I would go so far as to guess that, all else being equal, the taller the bridge the better. The few pianos I have, both upright and grand, that have bridges over 35mm in height, all have well-designed string scales with moderate tensions (ca. 160 lb.), and all of them are outstanding. JD
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