Seems there are two separate questions: one of efficient and permanent coupling of the bridge to the board, the other is the mechanics of the how the sound is transmitted. Given a reasonably tight coupling of the bridge to the soundboard with screws the acoustics would seemingly not suffer, at least not audibly and not as long as the joint remained tight: as the bridge moves so does the board. Whether there is, without the benefit of a rock solid glue joint, some even fractional movement (friction) in which some of the energy at some frequency(ies) might not be dissipated in the form of heat is for more refined measuring devices than our ears will surely deliver. That we aren't able to discern the loss with our ears doesn't mean there may not be some. Some answers are complicated, especially those that lead to other questions, and I don't think denigrating legitimate inquiries is a very good path to knowledge. Needless to say, it's best to glue the bridge to the board. David Love www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Ed Foote Sent: Thursday, January 31, 2013 6:06 AM To: pianotech at ptg.org Subject: Re: [pianotech] Totally glueless Ron writes: People have an absolute genius for complicating anything and everything and feel compelled to invent detailed explanations whether they have any facts or logic to work with or not. It's intuitive, instinctive, and fundamentally irrational. It's also nearly universal. "I've heard", "I was taught", "I believe", "it's obvious", "simply", and "stands to reason" are the enemies. Innate contradictions like the glue joint blocking sound, while a loose joint not passing vibrations because there was no glue with the screws, should be questioned.>> Ok, a question, then. Do you glue your bridges to the soundboard, and if so, why? I don't think a pair of screws couples the bridge adequately to the soundboard, either mechanically or acoustically, but if there are reasons why that coupling isn't worth questions, I would love to hear them. Regards, Ed Foote RPT http://www.piano-tuners.org/edfoote/well_tempered_piano.html
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