Yeah, they should be different. How much difference could be one of those subjective issues, though.
Although I've used both woods, I haven't used either wood for guitars (yet).
But I've handled a Classical with the WRC. My hearing has been discussed in another thread, so there's your answer as to how I think it sounded versus a spruce top. LOL
Unless you can listen (in person) to something built with each, and are able to consult with individuals who have successfully (again a subjective word) built with each, it may be beneficial to do a comparison of physical properties and go from there. Get the mechanical data on each of your wood options, choose a known wood as your reference point (standard), and you should be able to draw
approximate conclusions about how to proceed with the others.
I'm still new to guitars, but I've spent plenty of time using wood as a structural material for everything from decks to cabinets to furniture. On the shop wall is a chart detailing the properties of the various woods used over the years.
Below, I'll post some details of commonly used "soundboard woods" to illustrate. I'll exclude data that is of no particular concern to making guitars. (e.g., data such as modulus of rupture would be important to a bowyer, and crushing strength would be important to a deck builder, but both properties have very little, if any, to do with guitars.)
Keep in mind that every single piece of wood is different, and data represents an average (often from hundreds of samples). It is easily possible, and quite common, to work with an inferior piece of what is normally considered the "superior" wood for the qualities you seek. Likewise, people often work with an exceptionally superb piece of what is normally considered an "inferior" species.
If you go searching for hard data, sometimes you're gonna find minor differences in figures amongst various sources. That's OK, because you're not really wanting to pinpoint hard numbers; you're wanting to find overall similarities or differences between the species.
Weight- Most sources will measure this as pounds/cubic foot, and the assumed standard is to have the wood at 12%MC.
Weight is important to us because we want a responsive guitar. Lighter means quicker response.
SG (specific gravity)- This is the density of the wood. Since dried weights are nearly always determined at 12% moisture content, most people (including me) don't like to deal with SG. But if yer fussy.....
MOE (modulus of elasticity)- This is a measurement of the stiffness of the wood. Given our geographical location, I'm gonna use
million pounds-force/square inch. Bigger number means "stiffer" wood. If you're new to this, don't get all wrapped up in the huge numbers; remember, you're comparing woods, not testing in a lab.
Stiffness is important to a guitar top. It provides direction on how thick to make the top, and can also guide us concerning special considerations in bracing. Just as important, it can also tell us if the wood is suitable for a particular type of guitar or playing style.
Hardness- These numbers are derived from a test called the Janka(sp?) hardness test. Bigger number means harder wood. Harder wood resists dents easier. So, since our soundboards are made of relatively soft woods, take it easy during the weekend beer bashes when you have your guitar out. Jus' kiddin'.
Hardness is important to the builder. It tells him if he is gonna have to order more sandpaper just to get through the project. It tells him how fast his cutting tools are gonna dull.
More of an issue with back/side woods, it's not really a big deal for typical soundboards, with one exception- very soft woods (such as Western redcedar) require scrupulously clean work environments. Lay it on a dirty bench, and people are gonna have to give you tissues out of charity. Or, if you're the other type, they'll get you a dictionary to find the proper words to replace the new slang you just invented.
Shrinkage- All wood moves with changes in humidity, but it's nice to have a general idea of the extent of that movement.
Different sources express this in different ways, but the most useful to me is expressed as a percentage.
T is tangential shrinkage (along the grain).
R is radial shrinkage (across the grain). Radial shrinkage is almost always the smaller amount of shrinkage, and is
one of the reasons quartersawn wood is preferred.
Some sources also give you the
T/R ratio, even though it's easy enough to divide that yourself. This indicates the overall stability of the wood. A small ratio means the wood will not distort as much during movement; in other words, the tangential shrinkage and radial shrinkage are closer to each other, so the wood expands/contracts more equally in both directions. This is an important quality to prevention of warped wood. Note that a wood can have a high amount of overall movement in volume (total shrinkage), yet have a low T/R so as to be considered "stable".
As a general rule, I like to use the USDA's center for wood anatomy research (Forest Products Laboratory) to get data. But the uninitiated can sometimes have a difficult time making sense of it.
http://www.fpl.fs.fed.us/research/cente ... /index.php
A more straightforward source is Eric Meier's Wood Database. Perhaps not as comprehensive overall, but he lists pretty accurate figures for a lot of the woods we're likely to use. Plus, he does a good job explaining the terminology to newcomers.
http://www.wood-database.com/
Since I'm too computer illiterate (or too lazy) to transfer a spreadsheet here, I'll just type in the figures I'm looking at on the wall, which were taken from the Wood Database.
The order of the data is weight---MOE---hardness---T%---R%---T/R.
Adirondack spruce------29---1.61---490---7.8---3.8---2.1
Sitka spruce-------------28---1.60---510---7.5---4.3---1.7
European spruce -------25---1.41---377---8.2---3.9---2.1
Engelmann spruce------26---1.30---390---7.1---3.8---1.9
Yellow Cedar------------31---1.42---580---6.0---2.8---2.1
Port Orford Cedar ------29---1.65---590---6.9---4.6---1.5
Western Red Cedar-----23---1.11---350---5.0---2.4---2.1
Honduran mahogany---41---1.39---900---4.1---3.0---1.4
Koa-----------------------42---1.57--1,110--6.2---5.5---1.1
You and I are in the same boat- we don't have enough different builds under our belt to form conclusions based upon actual experience, and we both know how things can go if you "ask the internet".
Raw data most certainly doesn't tell the whole story, but
maybe it can provide insight as to why those more experienced than ourselves make the claims they do concerning the use of different woods. Or perhaps it gives us enough reassurance to "take the plunge" when considering use of a new/different wood.
Looking at your WRC, it is often described as "responsive, warm, sweet, less prone to cracking than spruce", etc.
Take a look at the data, and it has the least density of woods commonly used for soundboards. With such a light top to move, would it respond well to a light touch and produce that warm, sweet sound of which the fans of WRC speak?
About stability, although we may interpret the spruces to be "just as stable" as the Western Red Cedar (since they have equivalent T/R ratios), the WRC enjoys a
lower amount of movement in both directions.
BUT, you also hear some people saying that they "hit a ceiling" with WRC, whereas the spruces deliver no matter how hard they play. Take a look at the stiffness (MOE) of the two woods, and you'll see that Sitka spruce is roughly 45% stiffer than the WRC. I don't know if this is the cause of the "ceiling", but I do know that this is the reason you have to go thicker on a WRC top. It is also why some people shy away from using WRC under the high tension of a steelstring.
What about your Yellow Cypress?
About 25% stiffer than the WRC, but still not up there with the stiffer spruces, although its heavier than those spruces.
Stability over the spruces is a big advantage with this wood, so let's raise a toast to your next traveling/camping/backpacking/workhorse guitar.
Speaking of stability, something to consider is that both Yellow cedar and Port Orford cedar
seem to have a unique characteristic about them that makes them more resistant to splitting than any "data" would suggest.
I don't know what it is, maybe some unique grain structure or something. Actually, it's gotta be magic powder inserted into the tree roots a few hundred years ago. LOL (Seriously, though, I've built decks and outdoor furniture with the stuff.)
Hope it helps a little.
Had an hour to kill before gettin' the daughter up for school, and the coffee still hasn't kicked in!