Top carves

[John Bertotti]

Curious if there is a general consensus on some questions.

I have been listening to many shoot outs and I noticed some sound a bit more metallic in the uppers while others are much more bell-like and various tones in between, some are clear all the way up the neck, some have strong mids, some have nice lows that don't get muddy some just don't sound as low.

I can not quantify the whys but some builders more consistently hit the same tone so I can only assume it has a lot to do with the carving process.

Is there any consistent thought on how you carve to achieve a voice you want? Is more or less flexibility on the treble side going to get you more tin or bell? is it the stiffness across the plate or along the plate neck to heel? What makes the bass muddy?

I am sure these are things everyone asks but I have seen no consistent reply. I have Dave Cohens papers in a book but I have not gotten more than a few pages into it yet. Feel free to disregard this post if it is too redundant but I think as more experienced builders build more they gain more insight so I was hoping someone might have some new comments. John Garrity was in the process of explaining to me via emails how his reflection tuning worked when he dropped off the face of the heart. Later I learned he passed so I never fully got the explanation but wonder if anyone else uses this measured approach to top plates? It could p[possibly benefit a new/less experienced builder for the simple fact that no two pieces of wood will flex the same. Thanks all! Once again I apologize if this is too redundant!

[sunburst]

If you get farther into Dave's writings you will learn that there is no "treble side" in terms of how the top (or back) behaves to make sound, so that is an avenue that you can disregard and save yourself the time.

One of the things that I have learned from studying the info that science has produced about mandolins is this: I have learned much more about what not to do and what is not likely to be of any consequence than I have learned what to do.
To me, that is a good thing because it helps keep me from wasting as much time thinking about and experimenting with things that do not improve my building.

From my first mandolin onward I've achieved clear, ringing, bell-like treble, and frankly I don't fully know why. During my early building years I did things trying to improve response in the lower register and each small change was cause for concern that I might loose the clear trebles in the process. Fortunately, that has not happened, but I still don't fully understand what produces those trebles so I just keep doing what I'm doing because it seems to work.

In very general terms, trebles are produced more from the outside of the mandolin body with relatively little involvement of air modes and coupling. Lower notes are produced more from coupling between plate modes and air modes.
In simplest terms I ask myself: "how will this affect the modes?" whenever any consideration comes up about what to do when building, because modes of motion, plate modes and air modes, are by far the most important things we have to work with when attempting to control sound.

[John Bertotti]

If you get farther into Dave's writings you will learn that there is no "treble side" in terms of how the top (or back) behaves to make sound, so that is an avenue that you can disregard and save yourself the time.

One of the things that I have learned from studying the info that science has produced about mandolins is this: I have learned much more about what not to do and what is not likely to be of any consequence than I have learned what to do.
To me, that is a good thing because it helps keep me from wasting as much time thinking about and experimenting with things that do not improve my building.

From my first mandolin onward I've achieved clear, ringing, bell-like treble, and frankly I don't fully know why. During my early building years I did things trying to improve response in the lower register and each small change was cause for concern that I might loose the clear trebles in the process. Fortunately, that has not happened, but I still don't fully understand what produces those trebles so I just keep doing what I'm doing because it seems to work.

In very general terms, trebles are produced more from the outside of the mandolin body with relatively little involvement of air modes and coupling. Lower notes are produced more from coupling between plate modes and air modes.
In simplest terms I ask myself: "how will this affect the modes?" whenever any consideration comes up about what to do when building, because modes of motion, plate modes and air modes, are by far the most important things we have to work with when attempting to control sound.

Thanks! Exactly the info I needed. I will digging I got he book until it’s finished and then probably start it again!

[Jim Hilburn]

I'm a broken record about plate shape, but how the recurve is shaped and how steep the climb to the apex is has a huge amount to do with tone, as much or more than thicknesses. I learned this the hard way too often.

[John Bertotti]

What about the arching changes the tone more bass steeper recurve to crown or other? Etc.

[Jim Hilburn]

If you have a recurve that drops steeply from the side and then steeply up toward the apex, making a trench so to speak, there is no chance for that to be flexible like a very slight drop and then an easy climb up the other side, like a gentle valley and not a canyon.

[John Bertotti]

If you have a recurve that drops steeply from the side and then steeply up toward the apex, making a trench so to speak, there is no chance for that to be flexible like a very slight drop and then an easy climb up the other side, like a gentle valley and not a canyon.

A dish not a bowl. Check! Thanks!

[sunburst]

Higher arch = stiffer plate. That means a lower, more gentle arch has less stiffness for it's weight and a higher, steeper arch has more stiffness for it's weight. Since weight vs. stiffness affects the frequencies of plate modes it is no wander that arch shape has an effect on mandolin sound.

[John Bertotti]

I am using the shape of Hogo's plans but the arching of my A style and adding a scroll. Probably won't try to elevate the fretboard just leave it like my A, would that be an F4 style? Which is why I am asking.

[Jim Hilburn]

Here's a Loar photo that somewhat shows what I mean.