Pre- finish weight?

[Brad Hall]

I see admonitions like "Build light and tight".Have any of you actually weighed your guitar prior to applying the finish? I'm getting close to that point and am curious to see if I am in the ballpark for a rosewood dreadnaught. Depending on what finish, perhaps the difference is negligible. I'll be using Tru-oil.

[John Link]

Brad.

"Tight" means well fit and well glued joints, which is pretty straight forward.

"Light" is about a whole different set of perceptions. Total weight is, of course, one way to look at it. Less total weight tends to make the instrument's vibrations easier to feel for the player, which translates into a feeling that it is loud and responsive. Brian Burns, on the other hand (somewhat), has found that when he builds the rims heavier (by laminating, I think I remember), the player senses the sound as less loud and less responsive, but when evaluated out front some distance away, the opposite is true. The "lighter" instrument does not project as well. So, when he builds for someone who will play in intimate spaces, like the living room, he uses lighter sides. When it is a professional playing in large venues, he uses the more rigid and heavier sides.

So a case can be made for asking: Which parts should be "light"? And "Should some be heavier?" The soundboard, obviously, is a key part. After that opinions begin to vary. Some say (and I tend to agree) that a heavier, stiffer neck "forces" string energy to release itself more at the bridge end. I don't know that this has ever been documented in an objective way, however. Backs probably work best if they are not too heavy, but if the guitar is held tightly against the stomach, that might not be so important. And it may be important to get the back at a stiffness that interacts with the top to reinforce, rather than cancel, what the top is doing. Such a stiffness is not necessarily associated with the lightest possible weight for the back.

My feeling is to start with the top. Make it light enough to be responsive to what is obviously not that much energy coming from the strings (think solid body guitar string energy, without benefit of an amplifier, and you get a hint of what the various parts of an acoustic instrument must amplify). But not so weak that it breaks. When you look at factory designs, remember that their bias is to ensure no instrument ever breaks, even if they are mistreated. John Arnold has commented that the history of Martin design changes has been driven by warranty problems, not sonic ones. Ervin Somogyi has commented that a maximally responsive instrument deserves to be and must be treated very carefully or it will break. Myself, I've never seen a piece of wood that I can't imagine at least a tiny bit thinner. I call it my "inner beaver". The first guitar I ever made had sections of the back .0625" thick and it is still going strong, 40 years later.

[ken cierp]

My recommendation of "tight and light" is in reference to a well structured guitar design that is built with perfectly fitted joints and seams. The design should be centered around a "lightly" braced responsive sound board.

Within reason, I believe this comment by Chris Martin to be true:

“Every time you brace a top thinner, you’re going to get better sound, as long as you don’t compromise the structure”