Maple v Walnut and soundboard pairing

Construction and repair of Classical Guitar and related instruments
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lucho
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Maple v Walnut and soundboard pairing

Post by lucho » Fri Dec 07, 2018 6:14 pm

A two-part question:

1) Does anyone have experience with both maple and walnut? How would you describe the differences? I read through the threads here on both woods and the consensus seems to be that they are very similar but walnut is a tad bit darker/bassier. However, in the Breedlove tonewood chart (see link below)---which, I acknowledge, employs major generalization---the two woods are in opposite quadrants. Specifically, I'm interested in Black Walnut versus Big Leaf and/or European maple.

2) What soundboard pairs well with these woods? I anticipate the forthcoming "depends more on the luthier, bracing, etc. than species of tonewood" and I acknowledge that. But a few comments in the threads I've read suggest that cedar is a good "theoretical" match because of its low damping offsets the high damping of those hardwoods. And yet, while walnut/cedar classicals seems common enough there are few maple/cedar. Is that entirely due to the unpleasant aesthetic of light B/S and dark top?


Tonewood chart posted here:

https://www.classicalguitardelcamp.com/ ... p?t=121995

simonm
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Re: Maple v Walnut and soundboard pairing

Post by simonm » Fri Dec 07, 2018 9:01 pm

I have built with both. Both with spruce as I don't like working with wrc - the dust doesn't agree with me. I have only got experience of European maple which is quite hard but I have tried a number of different walnuts. I suspect that walnuts are as varied as "maples" - some have eben quite hard and others so soft that you could you bend it into a circle with not heat required.

Euro maple is quite hard and needs very sharp planes or wooly will end up hacking it. Walnut and Cypress are my current two favorite woods. I have a few sets of maple but not planes to use them at the moment.

One guy who has one of each from me, uses the walnut (American walnut) as the general purpose guitar and the maple for older music. I was doing a minor repair on the walnut and lent him the maple as a temporary replacement and to get his opinion - both he and his wife loved the sound, so she bought it for hime for his birthday.

Alan Carruth
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Re: Maple v Walnut and soundboard pairing

Post by Alan Carruth » Sat Dec 08, 2018 10:53 pm

I've used both, and am in the camp that thinks they're similar. I don't find European maple to be particularly 'hard', but that's because the local maple here is 'rock' maple, which certainly is. What's called 'soft' maple around here is quite comparable to Euro. Broadleaf is generally quite a bit softer, although, as usual, there's a lot of variation.

I make violins/fiddles as well as guitars, and so far American black walnut and local soft maple are the best substitutes I've found for European maple on those, too.

Either spruce or cedar will work for the top on a walnut guitar: I'm a bit partial to cedar or redwood there. I'm one of those folks who doesn't like a dark top on a light B&S, so I have not used maple and cedar. Acoustically it should be fine if you like the look.

And, yes, I do think it mostly comes down to who's making the guitar. Although low damping should be advantageous in theory, it's hard to say in practice just what it does for you. It's also at least plausible that low damping in the top has a somewhat different influence than in the B&S. With all the variables it sure is hard to sort them out! My preference for cedar/redwood tops with walnut is probably simply confirmation bias: I feel that it ought to work well, so that's what I hear.

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lucho
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Re: Maple v Walnut and soundboard pairing

Post by lucho » Sun Dec 09, 2018 1:07 am

Thanks @simonm and Alan. That's helpful.

I'm probably overthinking all this, but that's what the internet is for...so with respect to tonewoods: what is the difference between hardness and density, or are the essentially the same? That is, do the hard maple varieties have any meaningful tonal difference from the softer varieties?




And I agree with you Alan, that dark top + light B/S is a bad aesthetic formula and yet the opposite combo is fine, even desirable. I'm curious is anyone has a picture of a cedar/maple out there to see if it's as bad looking as we would imagine.

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Michael.N.
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Re: Maple v Walnut and soundboard pairing

Post by Michael.N. » Sun Dec 09, 2018 9:47 am

It's probably 'bad looking' because we aren't accustomed to seeing instruments done with a dark top and light coloured back/sides. If all guitars were made that way it would look perfectly acceptable but for the last four hundred years it's always been spruce combined with another wood.
As for the differences between maple and walnut, one is light coloured the other is dark. A good 80% of guitars that I make are either walnut or maple and it has been that way for a good number of years. I couldn't tell you of any tonal difference between the two. Of course I could sound all clever and wax lyrical about the precise tonal aspects of each. It would be complete BS though, so I don't think I'll bother.
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printer2
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Re: Maple v Walnut and soundboard pairing

Post by printer2 » Sun Dec 09, 2018 2:43 pm

It is the pore filler in Walnut that makes the difference in sound between the two. :wink:
Fred

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lucho
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Re: Maple v Walnut and soundboard pairing

Post by lucho » Sun Dec 09, 2018 5:26 pm

Did some photoshopping to images of maple/spruce guitars in order to simulate cedar. Doesn't look as bad as I expected, and could even be nice with the right hue of WRC and maple.


Image

Image

Image


Still, my aesthetic preference would be spruce on maple.


(EDIT: found a real life maple/cedar that didn't need photoshop:

https://www.guitarsalon.com/store/p4714 ... n-lee.html

I like it. I'm coming around to the look.)

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Michael.N.
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Re: Maple v Walnut and soundboard pairing

Post by Michael.N. » Sun Dec 09, 2018 7:49 pm

Hardly the typical colour of cedar. Even the one at GSI is much lighter than the norm. May as well get a lightweight spruce. Plus you should be careful of pics at GSI. They tend to bathe their guitars in a certain warm light.
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printer2
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Re: Maple v Walnut and soundboard pairing

Post by printer2 » Sun Dec 09, 2018 8:35 pm

Baked maple (better to do the sides after bent)

Image

and baked spruce top.

Image

I could see them together.
Fred

Alan Carruth
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Re: Maple v Walnut and soundboard pairing

Post by Alan Carruth » Mon Dec 10, 2018 12:14 am

Thanks Micheal: I think about 95% of the talk about the differences in tone woods is simply to generate sales. I have a sneaking suspicion that the other 5% has more to do with density than anything else. Basically, it seems that you want a low density softwood for the top, and a higher density wood for the B&S.

With top woods it's easy to see why you'd want to go that way: it's about stiffness and weight. There is not much horsepower in a plucked string, so you can't drive anything very heavy with one and get any sort of treble response or sound power out. The thing that limits how thin and light you can make the top is stiffness. Any wood top that is stiff enough to resist folding up for a reasonable length of time will be strong enough to hold up under the string tension. Stiffness in a piece of wood is determined by the thickness, and the Young's modulus along the grain. As it happens, all softwoods have very similar structure on a microscopic scale, so the Young's modulus along the grain is primarily determined by the density of the wood. If you measure the Young's modulus along the grain and density of a lot samples of softwood and plot the results out you'll find that about 2/3 of them will fall within 10% of the same line. Thus density is not a totally reliable predictor of Young's modulus in softwoods, but it's pretty good.

For two pieces of material of the size and Young's modulus the stiffness will be a function of the cube of the thickness. We all know this intuitively: a 2x6 up on it's edge deflects a lot less under a given load than a than a 2x4 on it's edge. A 2x8 deflects about 1/8 as much as a 2x4, all else equal.

What this means in terms of making guitar tops is that you'll usually end up with a lighter top if you start with a low density piece with a low Young's modulus, and leave it enough thicker to get the stiffness you want. This is one of the big advantage WRC: it's generally lower in density than most of the spruces on average. Of course, there's a lot of variation within any species, and some pieces of wood are just stiffer than they 'should' be for their density. One key there seems to be the proportion in width of soft early wood lines and the harder late wood. Late wood adds more mass than it does stiffness, so dark heavy late wood lines tend to make a piece that's denser than the Young's modulus would predict.

The back has a different job then the front in general. The top is the part that is driven by the strings, and produces most of the sound, either directly, acting as a loudspeaker, or indirectly by 'pumping' air through the sound hole. The back 'steals' all of the energy it gets to vibrate with from the top. It's also facing the wrong direction for the audience to hear, and it's often up against somebody's pudgy aviordupois, so it doesn't have much of a chance to make usable sound. What is does seem to do is contribute 'tone color', but in doing so it also reduces the overall output in general. There are always exceptions, of course; very light backs, such as on Flamenco guitars, do seem to help in producing a 'punchy' sound, particularly in the low frequency range. In fact, if the back does contribute to overall power it's in that low range. Ther is always a debate among guitar makers about whether the back should be 'reactive' or 'reflective'. I'm squarely in the camp that says "Yes!": they should be reactive in the low range and reflective in the higher range. This argues that the back should be fairly heavy, and 'tuned' in some way to work with the top in the lowest range.

All of this ignores or glosses over a lot of subtle nuance. Many makers (most!) prize wood with low 'damping', particularly for the back. Wood like BRW, with low damping, tends to 'ring' for along time when it's tapped, and have a 'musical' sound because it vibrates within a very narrow frequency range. This may help in limiting the amount of energy the back 'steals' as it vibrates, but it's hard to say. There is so much going on n that range of tone that the number of variables you'd have to control to be able to say anything definite is just too great.

In terms of this conversation, and trying to answer a specific question, what that means is that denser 'rock' maple will tend to sound a bit like soft maple, but with more of a tendency toward the 'rosewood' end of things. In my experience, Black Locust, which tends to have similar stiffness to Indian rosewood, but lower density, tends to sound a bit more 'Flamenco' than a rosewood guitar, but how much of that is due to the fact that the color of locust is similar to that of cypress is hard to say. Lots of things to think about...

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Re: Maple v Walnut and soundboard pairing

Post by Stephen Faulk » Mon Dec 10, 2018 5:29 am

Why is everyone so scared of dark top on light body? Cedar with Cypress back and sides had been a standard for flamenco guitars. What's the problem besides personal taste?

The thing you have to do is warm up the finish on the body. It doesn't take much to get a nuanced balance between the top and the back and side. You don't have to make the sides darker, you have to pull the top and body together with warmth in the color of the top and back.

I finish with blond shellac and after the bodying up is complete I work over it with garnet with a touch of gold stain. The nuance I the color shows on the cedar, the color is subtle. Then the sides and back get warmed up until the top and body have a cohesive color relationship. If the maple is warm color and the chatoyance is vibrant and deep the the top and back/ sides will marry.

The one I just finished has a Cherry wood bridge, which also has been tuned down with red - brown shellac glazes. That also helps to make the whole guitar be complementary between front and back.

The light body with darker top is a beautiful look, but you have to work at making it not jarring, which is actually pretty easy. If you leave the sides chalky white looking in comparison to the top, of course it will be grating on the eyes, but if you moderate the tonal pallette of natural wood color and finish color it can be satisfying to look at.
Here's a link to the one I just finished.

I also brought a liberal amount of maple into the rosette and head stocks, which also serves to integrate the chosen woods. It was all done with design fore thought.

https://www.classicalguitardelcamp.com/ ... 1&t=124180
Patience at the bending iron pays in rounded dividends!

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lucho
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Re: Maple v Walnut and soundboard pairing

Post by lucho » Wed Dec 12, 2018 3:42 pm

Thanks all.

As I browse tonewood dealers online I note that ABW varies quite a bit: with/without sapwood, heavily striated or even textured, curly/flamed or not, dark or light, I have even seen a nicely figured crotch piece. Basically everything from very plain to highly figured and complex. While I love a nicely figured piece, I'm inclined to simpler wood (maybe I'm too enamored with the simple backs of Torres and Hauser). In any case, due to its lack of popularity in the classical world there aren't many examples of ABW online.

Those of you that have built AB walnut classical guitars, would you mind sharing some images?

Martin Woodhouse
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Re: Maple v Walnut and soundboard pairing

Post by Martin Woodhouse » Wed Dec 12, 2018 7:50 pm

A black walnut 8-string that I'm finishing at the moment.
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lucho
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Re: Maple v Walnut and soundboard pairing

Post by lucho » Fri Dec 14, 2018 4:30 am

Martin Woodhouse wrote:
Wed Dec 12, 2018 7:50 pm
A black walnut 8-string that I'm finishing at the moment.
Very nice, Martin. The flame is the right amount (for my tastes, at least).

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