Tuning a double top?

[ckmurf]

I bought the Somogyi 2 vol book set and can’t tell you how much I am enjoying them. It shows me that there is more than one way to skin a cat and wind up with a world class instrument. I am particular to Santa Cruz guitars, and appreciate their methods for tap tuning and fine tuning the woods. Then I compare that to the Somogyi method of thicknessing tops by measuring deflection under controlled weight. When purchasing at the same price point (~$20k) the outcomes of the two approaches are both stunning. Which brings me to double tops, aka sandwich tops, and my actual question after the long introduction. It seems to me that there is so little wood on the outside layers of a double top that there is no thickness left for thinning and tuning. So… does that meant that you take what you get, or does that mean that the Kevlar sandwich is so predictable that thickness tuning is obsolete?
I am just curious, about this and many things. Thanks in advance.

[redir]

I only ever built one double top and I am of the opinion that you get what you get. An experienced DT builder might say otherwise and I have heard of some using cedar for example on the inside layer with spruce on the outside to color and shape the tone too. And then there are the braces. Of course you could make the skins thicker too. So I'm sure there is some degree of control but not like a solid wood guitar.

[Alan Carruth]

I make every effort to get the top 'right' before I assemble the box, and change it as little as possible afterward. If you have learned to work that way a sandwich top would be no problem in that respect. If you like to start out thick and voice afterward then you're stuck.

You can, of course, make the sandwich thinner or thicker from one place to another by varying the height of the honeycomb, but once it's skinned that's it for the top. You can do some fine tuning from there on the bracing, but that's more limited than you might suppose.

[printer2]

Almost a blank canvas if you make the skins as thin as you care to and then add weight on the inside rather than removing material.

[ckmurf]

Very insightful replies, thanks everybody.

[redir]

The DT I made felt like a braced top before I even braced it. I braced it as normal because this is what I was told to do, so I did. Years later I reached in and thinned out the braces and it made the guitar a bit more responsive. Definitely made a difference. This is a Spanish guitar BTW.

It's an ok guitar, not great. The one thing it does have is responsive touch and loudness but what it lacks is hard to describe. The words I use are, it lacks that romantic Spanish guitar tone. That soft warmth. But it does jump when you hit the strings.

I might try and build another one some day but for the most part I get what I want from traditional designs and find them easier to control. I always try to get the top right too before closing the box and I think that the neck angle is probably more important in terms of tuning the top after the fact but bracing does seem to do something too.