estebanana -> RE: canon - A stage guitar (Jun. 6 2016 12:25:26)
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I often wondered about the Glenn Cannin really loud guitars and there change to the bridge ...it says like ... ........A continuous lining connects the sides to the top, which creates a much stiffer "drum rim" effect, but without the added weight of laminated sides. This allows for a thinner, lighter top, resulting in a more responsive and bright sound. The bridge patch is replaced by two lattice braces, making the guitar louder and punchier... can a luthier (estebanana) explain the bridge bit , out of curiosity.... Thank you Oh yes, indeed. He is working the cross grain stiffness up while keeping the mass down. Stiff side to side across the bridge gets a loud bright guitar, until it gets too stiff to feel good and too brash. There is a happy medium. The two sticks are like fan brace size and he puts them parallel to the bridge in different places. Probably should not say more than that. The stiff rim thing is anecdotal, it does something, but it has been elusive to prove with any testing other than listening tests, and opinions vary. Stiff rim is an idea that is mainly used for classical guitars and has become a pretty normal thing in modern steel string construction too. The concept is to make the rim inviolate to torsional forces under string tension. The top is more free and independent than a connecting surface meant to stiffen the ribs assembly. The idea s to make ribs and rim so stiff they don't need the top as a plane surface on top of them to add local stiffness when connecting the glue blocks together, this lets top act as free agent without torsional stresses from string tension. This rim/rib torsion resistance is important on designs with fragile tops like Smallman's and Nomex tops that are delicate. The top is not used as part of the super structure of the guitar, but as a pure membrane glued over this solid frame. Think of a snare drum. The system works great if you are looking for brightness, punch, LOUDness and quick tempo response of string recovery. These are all good qualities to work out. The reason I say take it all as anecdotal is because some of the best known concert guitar makers never did this. They worked at these factors from another angle or did not put as much emphasis on them. Or they got similar results with more plain techniques. The famous Hauser guitars often had glue bocks with gaps between them and Romanillos too and those guitars are projectors. I made a guitar with one side super stiff liner and one side gapped glue blocks so I could feel the difference in flex of the rim. After mulling this over for years I came to the conclusion each way works really well and does not sound a great deal different between a solid stiff liner and good glue blocks, provided you build the top and bridge right. I also think that is is possible a bit of flex in the rim might be good for flamenco sound and that some give in the ribs also contributes to flamenco voice. The ribs are giving off some sound on their own and if they are really stiff they will work with some high frequency. If the ribs are super stiff and basically 'dead' , that is not a thing I find useful in making flamencos, I think there something to having thin ribs that are not too stiff and that they absorb some of the energy. That said the continuous solid liner was used by Torres, and even Santos Hernandez, it's not a new idea, but the concept of stiff torsion resisting box is a newer idea that has a lot of proponents around. See the Dominique Field guitar I posted in Harmonic Bars- stiff ribs to the max
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