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| Anyone built a maple topped acoustic? http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=56945 |
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| Author: | Mark Mc [ Wed Jan 08, 2025 5:30 am ] |
| Post subject: | Anyone built a maple topped acoustic? |
Softwoods are traditional for soundboards because of their weight to strength/stiffness ratio. But hardwood tops of mahogany, koa or walnut are also seen fairly frequently. A couple of years ago Taylor released a solid maple topped model, which is the only example of a maple soundboard that I am aware of (apart from some maple veneer ply-top guitars). Have any of you tried a solid maple top? Any thoughts about how thin you would go and how you would brace it? I am asking because I have a dreadnought that needs retopping and have some spare maple sets that I could devote to an experiment. If nothing else it could look pretty with a burst finish. |
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| Author: | Colin North [ Wed Jan 08, 2025 8:44 am ] |
| Post subject: | Re: Anyone built a maple topped acoustic? |
Never built one, but would thickness it by testing the maple for stiffness and then thickness it to be the same stiffness as my normal tops (I test all my tops for stiffness) Then brace as normal (I would still use spruce for bracing) |
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| Author: | Mark Mc [ Wed Jan 08, 2025 1:52 pm ] |
| Post subject: | Re: Anyone built a maple topped acoustic? |
Thanks Colin. I was thinking along the same lines. I test my tops also, so it would make sense to aim for a similar stiffness as for any other soundboard material. I suspect maple would therefore end up rather thinner than a spruce top. |
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| Author: | Colin North [ Wed Jan 08, 2025 3:13 pm ] |
| Post subject: | Re: Anyone built a maple topped acoustic? |
Mark Mc wrote: Thanks Colin. ...... I suspect maple would therefore end up rather thinner than a spruce top. I would think so too. |
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| Author: | Trevor Gore [ Wed Jan 08, 2025 4:24 pm ] |
| Post subject: | Re: Anyone built a maple topped acoustic? |
I would follow the approach of aiming for the same mass of soundboard as for a spruce top on the same guitar and then stiffen up the bracing to suit. I outline the approach here, where I used a Koa top. Nick Royle was discussing using maple/sycamore as a top wood, so follow the first link in the linked post also. |
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| Author: | GregHolmberg [ Wed Jan 08, 2025 6:45 pm ] |
| Post subject: | Re: Anyone built a maple topped acoustic? |
There are many species of Maple, with a large range of densities. I see that Taylor used Bigleaf Maple, one of the lighter-weight Maples. https://www.wood-database.com/bigleaf-maple/ Based on the average properties reported there, I calculate that it has a sound radiation coefficient of 7.9. This is a measure of how efficient the wood is at creating sound. R = SQRT(E/ρ³), where E is the flexural modulus and ρ is the density. Sitka Spruce is 12.0. So what a 7.9 is telling you is that Bigleaf Maple is way too heavy for a sound board. The other species of Maple are the same or worse. I calculated a thickness using Trevor Gore's formula and averages for the species, and got 3.20 mm for a 390x490 mm top to hit the target frequency he gives in his book. This would make the top 252 g, while a sitka top at 2.86 mm would be 175 g. So the Bigleaf Maple would be 44% heavier. Given that the panel makes up about 80% of the mass of the top, that's a lot to give up, in my opinion. It would make a pretty good active back though. For comparison: Honduran Mahogany R=7.0, thickness=3.31 mm, mass=282 g Koa R=6.8, thickness=3.29 mm, mass=289 g Black Walnut R=7.1, thickness=3.17, mass=278 g So, I guess Bigleaf Maple is better than any of those! This is all assuming using the same bracing as with Sitka. You could go thinner and then compensate with stiffer (probably taller) braces to hit the same frequency target. I think the top will still be heavier though. Here's a spreadsheet I made with all these calculations for 225 species commonly used for guitars. Hope this helps. Greg |
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| Author: | Mark Mc [ Thu Jan 09, 2025 5:32 am ] |
| Post subject: | Re: Anyone built a maple topped acoustic? |
GregHolmberg wrote: Hope this helps. Greg Thanks Greg – that is a sensational data set. Thanks for compiling and sharing it. A great resource. The message in the numbers is clear when you compare hardwoods like mahogany, koa, walnut or maple – with sitka. Higher density but no more, or less stiffness - meaning a significantly heavier plate if you are going to achieve the same stiffness. It explains the sonic character of hardwood soundboards – mostly fundamental, less overtones and lower volume. All makes sense. Taylor essentially admit it themselves in their ad when they describe their maple guitar’s sound with adjectives that include “fat, woody, chunky, earthy, rustic” – not exactly the most elegant or beautiful descriptors of guitar sound! However, many people do like all mahogany or all koa guitars, for that sort of sound as well as the distinctive looks. You are telling me that big-leaf maple might perform similarly – if built in a way that gets the right stiffness without being outrageously heavy. OK, a lot for me to think about and calculate. Thanks too Trevor for the great koa example and the link to Nick’s old thread. You guys are such a font of knowledge. I will need to spend some time getting into Section 4.4 |
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