keith -> RE: ports (Sep. 23 2014 11:35:06)
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estebanana--i copied and pasted this post by alan carruth from delcamp by Alan Carruth » Sunday 31 March 2013, 00:39 am Larry Schultz wrote: "Having built a flamenco with an incorrect neck angle that required lowering both the bridge and saddle, and winding up with a shallow break angle, I found a significant lowering of volume. I believe a steeper angle puts more downward pressure on the saddle and results in better transfer of string energy to the top." I have done an extensive and careful series of experiments on this. As usual, it's more complicated than you might like it to be, but the short answer is that string height off the top can have a major affect on the sound, where break angle, by itself, does not. Remember, you changed both. This was established on a guitar that was set up to allow for changing the two independently through some carefully done listening tests using 'standard' plucks recorded in a 'semi-anechoic' closet, as well as extensive analysis of the plucks themselves for level, duration, attack, and overtone content. Listeners could easily pick out a change in string height off the top, but could not hear a change in break angle, reliably. Altering the string height off the top also changed the overtone content of the sound in ways that one would expect to be audible, while altering the break angle gave no significant change in the recorded sound. A higher break angle does increase the download on the saddle, and, more importantly in some ways, the tipping force. This does not translate into more sound being passed to the top of the guitar, though. Basically, the 'vertical' component of the transverse string motion, which is the main driver of the top, produces a known force on the bridge top that must be smaller than the downbearing force of the string on the saddle. If the downbearing is too small then the string will hop of the saddle top at some point in it's vibration cycle, and you'll know it by the buzz. So long as the break angle is sufficient to keep the string in contact at all times (and that only requires about 6 degrees of break angle) all of the string signal will be transmitted to the top. I could go on: as I say, this gets sort of complicated when you look at all the details. The important take away is, though, that break angle is not as important as string height off the top. The devil is in the details, of course, and it's possible that the details in some particular case could cause a change in break angle for a particular guitar to have an effect on the sound by itself. I'm not saying 'never', but 'pretty darn seldom' would not be too strong if what I've seen is correct.
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