Hardwood Guitar Top Considerations

[Keith7940236]

I was curious about how to approach using a hardwood like mahogany or walnut for a guitar top. I had a chance to hear a 1944 all mahogany J-45 and was surprised at how much I liked the sound. I've played a Santa Cruz 00 that was all mahogany that was very nice as well.

Now I'm considering building my own J-45 all mahogany, walnut, Sapele or some other all hardwood instrument.

Is it important to use straight vertical grain like with softwoods?
Does the wood need to be thinned down more than a softwood top?
I would think that the bracing may be lighter as the soundboard would be stiffer, but perhaps that depends on the grain orientation, species, etc?

Thanks in advance for advice.

[Codfather]

To my surpriseI have seen both wenge and paduck topped accustics this past year that looked great!I can't comment on the sound but they sure looked incredible

[Alan Carruth]

The problem with using hardwood for guitar tops is that the Young's modulus along the grain for most hardwoods is not all that much different from that of softwoods. For a guitar top the important thing is to get enough stiffness along the grain. Stiffness along the grain is a function of Young's modulus and thickness; two pieces of material with the same Young's modulus will have the same stiffness at a given thickness.

The problem is that hardwoods tend to be much denser than softwoods, even though they are not generally much stiffer along the grain. There is not much horsepower in a plucked string, and if you're going to get good trebles and a lot of sound, you need to keep the top light.

Hardwood tops tend to have a 'sweet' sound, without as much high frequency in it, and are usually not as loud as softwood tops. A lot depends on the wood, of course. A hardwood top can work very well on an electro-acoustic; the added mass reduces feedback issues to some extent.

Some folks do make hardwood tops thinner than softwood ones. In theory this could be a problem in the long run. I have not seen very many older hardwood topped guitars that didn't have issues related to strength/stiffness in the top, such as the bridge lifting due to top distortion.

[joe white]

Two of my (long gone) favorite instruments from mass production guitar makers were an all claro walnut jumbo 12 string from Taylor and an all mahogany dreadnought also from Taylor. The 12 string had a dry sweetness to it that worked very well for the 12 string and the dread had a warm mid range that was well balanced with the bass and high end of the guitar. I wish I still had both of them.

[printer2]

I made a walnut bodied guitar although only a 0 size. When I made my walnut guitar and wondered how thick the top should be. Ended up in the 0.080-0.085" range from my foggy recollection. It turned out sounding terrific.

[Kenneth Casper]

A number of years ago I built a walnut guitar with a butternut top. I think it was the 5th or 6th guitar I ever built. I still have that guitar around and play it regularly as it does have a sweet tone. However, I have found that it cannot be driven as hard as spruce. The sound gets muddied and if pushed too hard seems to flat line. I don't play it if I am digging in deep with a pick and doing heaving strumming. It sounds best with a light pick or fingerstyle, very engaging and sweet.

Ken

[Halcyon/Tinker]

This is where experience with data from deflection and resonance testing comes in handy.

No matter what it's made of, the top has to be stiff enough to take the string load without undo deformation over time.

If you had that data for spruce tops, you could translate into any other wood.

I've built with primavera, walnut, Sapele, and mahogany for tops, and have used deflection testing to get them to the initial target stiffness appropriate to the model, and it's worked well.

Unfortunately I can't recall off the top of my head if they were thicker or thinner or what.

But 5 or 10 thou can make a big difference in the stiffness of a piece down around average top thickness...

[Keith7940236]

Thank you for the input, I appreciate it!