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Old 01-02-2018, 07:16 AM
hat hat is offline
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Quote:
Originally Posted by Alan Carruth View Post
Louie Atienza wrote:
"I believe the reason the saddle is as far forward is because that's what allows the strings to "apply" the most "torque" on the bridge for the given string height off the top."

Ummm....

I think you could say that the further the back edge of the bridge is from the centroid of rotation the lower the maximum stress is on the back edge of the glue line holding the bridge to the top. The centroid is not at the saddle location, so far as I can tell, but some way behind it, depending on the break angle. The actual torque of the bridge is a function of the string height above the top and the total tension, assuming the strings are attached to the bridge and not to some sort of tailpiece. At least, that's what my measurements said.

Torque on the top is mostly detrimental so far as I can tell. It does allow the tension change and longitudinal wave signals in the string to drive the top, but these hardly add any power (none that I could measure) and only change the timbre a bit.

I'll note that Flamenco guitars can be quite loud, even though they generally have the string much lower to the top than Classical guitars. In fact, I'd say that having the strings lower is what allows them to be so loud. The top can be built more lightly, since it doesn't have to resist as much torque load, and that makes it easier to move. This shows that torque doesn't produce sound, but can actually hurt sound production.

At any rate, if the goal is the reduce the peeling stress at the back edge of the bridge why can't you just make the bridge wider? It worked for Martin. If you're making it narrow to keep the weight down, why not use a lower density wood? With lower stress along the front of the slot from moving it back and/or slanting it you don't need the strength of rosewood or ebony to keep it from splitting out or peeling up.
so, a lot of your comments leads me to the thought that using a tailpiece would produce quite a bit of improvement in tone and sound, if what you say is correct in that torque is detrimental. This reminds me of the old Gibson 12 strings that used a tailpiece - most were quite good sounding, until string tension caused them to implode.
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