Walnut top characteristics?

[printer2]

Originally Posted by Wade Hampton

Hmmmmmm.....yes and no. Obviously the design of the guitar or dulcimer has a great deal to do with the sonic results you can get, and the same is true of how well the design is executed. But you're still dealing with some basic issues here, and it's hardly accidental that the vast majority of acoustic instruments have tops made from softwood conifers like spruce, cedar, redwood or larch. To get optimal tone, volume and projection, you need a top that combines light weight with great strength and cross grain stiffness. Which is what spruce, cedar, redwood and larch deliver.

Hardwood tops, whether walnut, koa, mahogany, sapele or others, usually have the strength and the cross grain stiffness, but they're denser than softwood tops. This has an impact on how loud the guitar is, how well it projects, and how many tone colors can be coaxed out of the finished instruments.

One of the main reasons guitar builders can even get ANY tonal results from hardwood tops is the amazing amount of energy that steel strings can impart to the instrument. Steel strings generate about three times as much tension and thus three times as much energy as nylon or gut strings are capable of generating.

Which is why steel string acoustic guitar designs can be so wildly and widely variable in the first place. The energy that steel strings transmit to the top makes all sorts of acoustic guitar designs and top materials possible in the first place.

Have you ever wondered why there are about a zillion different steel string acoustic guitar designs but only one commonly used body shape and size for nylon string guitars? It's because what we think of as the classical guitar shape (and its close cousin, the flamenco guitar) will only really WORK with the typical size and shape of the classical and flamenco guitar bodies. That's basically what you have to use with these relatively low energy nylon strings.

In startling contrast, you can make all SORTS of guitar body shapes and sizes when you use steel strings, because when compared to nylon strings they have energy to BURN...

Which is really the only thing that actually makes hardwood-topped acoustic guitars even possible: the energy that steel strings can transmit.

Which is why you won't find any classical guitars with walnut or mahogany tops. Nylon strings will not and really cannot drive those tops efficiently, it's that simple.

So the woods actually have a great deal to do with the sort of sounds you can get from a guitar.

Hope that makes sense.


Wade Hampton Miller

Well it was bound to happen. The first time I disagree with your post. My post on the way it is made is meant to take into account strait bracing, scalloped, the scalloped would have more bass than the same straight braced guitar. No, a hardwood top is not equivalent a softwood top. Mind you I have some dense spruce and light weight poplar, I doubt they would be too different in volume.

I agree with TBR in that it is tradition that drives the classical guitar. While the size is about as large as it can reasonably go to utilize the energy of the strings smaller guitars are made for nylon stings. What most everybody wants in a classical guitar is a Torres derived instrument. Most classicals are a standard size but then again you can go into a music store and most of the steel string instruments are dreadnoughts. I am building a 00 for a family member and he is surprised by the narrow waist being only familiar with dreads.

I am on my third Martin size 5 nylon string, have also built two other smaller guitars but of a different shape. They are not concert instruments and were not intended to be. In the following video there is a collection of instruments at the side of the stage showing a range of sized classical instruments. The guitarist is playing a smaller Torres.



Different sized instruments will give you a different sound. If you were interested in playing concerts then the standard size does work best. But that does not mean a nylon instrument has to be that size. There are 3/4 and 1/2 sized instruments that would be perfectly adequate in a home situation just as an 0 sized steel string would be fine at home rather than the concert sized dreadnought.

[tadol]

If the builder accounts for the differences between a hardwood top and a spruce top, thru the finished thickness as well as changes in bracing size/thickness, it can make an outstanding instrument. The only generality I would offer is that most hardwood topped guitars are a bit more fundamental (fewer overtones) and slightly less loud, but that may be because builders tend to keep the top a hair thicker and brace it a hair heavier than is needed. But thats where the problem comes up - when you take a hardwood down that thin, you run a very serious risk of it becoming more susceptible to cracking, either from impact or humidity swings. So you can’t blame them at all for keeping a little extra thickness to minimize repair issues.

The other problem with hardwood top guitars is the market seems to be more wary of them, maybe because of their appearance, so builders just don’t build as many, which means many people have a really limited opportunity to try them. And if they end up trying one of the many overbuilt ones, they’ll probably not give others much of a chance, so builders won’t build very many, so there aren’t many to try, etc, etc, etc -

Some of the small shops, as well as some of the solo builders, make hardwood top guitars that are really fantasic. An all walnut guitar that Bruce Sexauer built a couple years ago still haunts my memory - add that to my list of shouldof’s -

[Alan Carruth]

Listen to Wade: I usually do.

It's stiffness along the grain that determines how thin, and therefore light, you can make a guitar top. Cross grain stiffness may be important acoustically, to the quality of the sound, but structurally it's not as helpful. Guitar tops don't usually break from static string loads; they fold up slowly and swallow themselves through the sound hole.

Stiffness is determined by the thickness of the top and the Young's modulus of the material, for the most part. If you measure this on a bunch of different kinds of wood, you'll find that most of them fall within a similar range. Walnut tends to have a Young's modulus that is pretty close to that of spruce. On softwoods the Young's modulus along the grain pretty well tracks the density: denser stock is stiffer. Hardwoods have a different structure that varies more, so that simple rule of thumb doesn't hold. The walnut I've tested has been anywhere from somewhat denser than any spruce I've checked to much denser. Usually the Young's modulus for walnut is in the middle range of values for spruce. For a given stiffness along the grain a walnut top would normally end up weighing about twice as much as spruce.

You can thin the top out a bit, of course. Many spruce tops, particularly on production instruments, are thicker than they need to be. You can also stiffen it up with heavier bracing. Still, it's hard to make a walnut top that's stiff enough to work over the long term and as light as a spruce top without going to some pretty fancy bracing design.

Strings don't have much horsepower. If you've got a small engine and want a car that has acceleration and top speed, you have to keep it light. Treble response in a guitar equates pretty well with acceleration, and sound power with top speed. Guitars with heavier tops tend to have less power and less high end. Often they're perceived as 'bassier'.

I made a walnut topped acoustic-electric bass guitar a couple of years ago. It worked about as expected. The timbre was 'bassy', and because of the added mass of the top it suffered less from feedback at high gain. Walnut has it's uses as a top, but if you want power and treble, I'd go for softwood.

[printer2]

Originally Posted by printer2

I think as any guitar the way it is made can determine the sound as much as the wood. I built an all walnut a few years ago, a buddy did a quick demo for me with a handheld recorder. Nothing planned and a few rough spots. I think this link should work but you have to download it as it does not seem to want to play otherwise. I think he might have overladed the mic a time or two with too much of a dynamic range. Also because it is a single 0 size it will not have the bass response of the dred.

https://tnpgkg.by.files.1drv.com/y4m...ownload&psid=1

Well that didn't work. Click on the link and when the page opens up right click on the All Walnut Guitar icon and select download. The file should play.

https://onedrive.live.com/?cid=443A2...&action=locate

[AZLiberty]

Originally Posted by The Bard Rocks

I have not seen a crossover that looks like a classical; it wouldn't be a crossever if it did.

If you take a Classical body and fit it with a narrower neck with a 16" radius (instead of flat) it's a crossover.

Plenty of those out there.