Acoustic Guitar Construction

Robert Hosmer wrote:Yeah, Ken, the way thing's can go sometimes my Glenlivet seems to be in short supply.

I consider myself way too new at this to form opinions concerning differing methods in this area.

Just don't want to have to set aside the concept of voicing, taptuning, etc. simply because some of the methods employed may present an obstacle to me personally.

Here's something really out there (for some)- my solution so far is to have my daughter listen while I tap.

When tapping a plate when it is resonating you can feel it. As you thin the plate and tap if it is good tone wood it will come alive in your hand.

Here's an interesting read by Dana Bourgeois, copied from the http://www.pantheonguitars.com/ website - hope that's ok with you Ken? If not please delete it.
This is in reference to Voicing the Steel String Guitar by Dana Bourgeois
American Lutherie #24

Transcribed from Dana's lecture, 1990 Guild of American Luthiers convention.

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That's a good read, with lots to think about.

Somogyi here's part 1 of 2

http://www.youtube.com/watch?v=cRTRhwDprjY


I find Dana and Somogyi both very cryptic in their explanations and methodology. Its my belief you need a model to start, its either in ones head (it does us no good if its in Dana's or Somogyi's head) or an actually physical model -- yes off a successful build -- not far fetched, after all is that not exactly what Martin has done for 175 years? I think we can explore how to try and duplicate a "good/great sound-board". Interesting -- yes?

kencierp wrote:Somogyi here's part 1 of 2

http://www.youtube.com/watch?v=cRTRhwDprjY


I find Dana and Somogyi both very cryptic in their explanations and methodology. Its my belief you need a model to start, its either in ones head (it does us no good if its in Dana's or Somogyi's head) or an actually physical model -- yes off a successful build -- not far fetched, after all is that not exactly what Martin has done for 175 years? I think we can explore how to try and duplicate a "good/great sound-board". Interesting -- yes?

A model (actually three models each of deeper complexity) is exactly what a Contemporary Acoustic Guitar by Gore\Gilet presents in Volume 1 of their two volume set. Their model does not describe necessarily what is good and bad but does help understand the relative effect of changes (top thickness, stiffness, brace height ...) to a the output of a guitar. The do correlate the models they have to a variety of physical models to validate their models. But to Ken's point the models they present are really relative to a physical model which is the starting point of all of the design work they present.

The usefulness of their mathematical model is to allow one to maintain better consistency with a variety of organic components. For example a an individual plate might be thickness thicker or thinner from their spec based on its density and stiffness. The model helps them determine the size of the change off of the nominal design value.

deadedith wrote:I think the daughter idea is cool.

Unless she's tone deaf!

Yes, Ken and John, an actual physical model is what I'm talking about.
If we already have the piece that is, in our subjective opinions, "just right", then we can measure in attempt to duplicate.

johnparchem wrote:

kencierp wrote:Somogyi here's part 1 of 2

http://www.youtube.com/watch?v=cRTRhwDprjY


I find Dana and Somogyi both very cryptic in their explanations and methodology. Its my belief you need a model to start, its either in ones head (it does us no good if its in Dana's or Somogyi's head) or an actually physical model -- yes off a successful build -- not far fetched, after all is that not exactly what Martin has done for 175 years? I think we can explore how to try and duplicate a "good/great sound-board". Interesting -- yes?

A model (actually three models each of deeper complexity) is exactly what a Contemporary Acoustic Guitar by Gore\Gilet presents in Volume 1 of their two volume set. Their model does not describe necessarily what is good and bad but does help understand the relative effect of changes (top thickness, stiffness, brace height ...) to a the output of a guitar. The do correlate the models they have to a variety of physical models to validate their models. But to Ken's point the models they present are really relative to a physical model which is the starting point of all of the design work they present.

The usefulness of their mathematical model is to allow one to maintain better consistency with a variety of organic components. For example a an individual plate might be thickness thicker or thinner from their spec based on its density and stiffness. The model helps them determine the size of the change off of the nominal design value.

I can measure thickness, density, and "level of stiffness" (elasticity?).
Assuming that I want to duplicate the acoustic properties of the model, the question I have is: In what order do I proceed?
1. Attempt to find similar density. I don't like testing for this; to me it's a long, detailed process. I think this is why most people simply weigh the wood.
2. Thickness down to similar stiffness? Easier to do.
But with those physical measurements in mind, could the duplicate still be vastly different when measuring the sound?
Keeping in mind that the idea is to have the duplicate "sound" as similar to the model as possible, is it best to have the acoustic properties take precedence over the physical properties?

By the way, I do not view any of this as a method(s) to "make identical guitars"; rather, I want to be more consistent, knowing in general what to expect before investing time in a build based upon guesswork.

Thanks,
Rob