tonewoods tapped and explained by Luthier Kim Walker

[mandotool]

Not only a great builder but a real gift for explaining his craft...
http://www.youtube.com/profile?user=.../6/y3JhauyBQ8Y

[Martian]

Wow! cool stuff, I would, however, like to see the other parts. ( In video, this is referred to part 3)

[mandotool]

try this link for the entire catalog...
http://www.youtube.com/profile?user=guitargourmet#g/u
there are 5 segments to the Kim Walker Pc. and quite a lot of other luthier content and interviews.
Monteleone,Romanillios,Paul Reed Smith,Somogyi,Pagelli,Michael Lewis,Teuffel, Gruhn,Stan Jay,...........
I've only been through a fraction of it...
The production style is a bit annoying at times and i find FFWD comes in handy but the content is overall extremely good..
mangia!

[Tim W]

I don't recall him saying otherwise but I bet there isn't two boards that he banged on that are the same dimensions in thickness or overall mass. So since they are of different thicknesses, this doesn't seem to me a fair comparison and defeats the whole purpose of that video.

Give me a foot square piece of each species and all of them .100" thick and then the comparison would be more accurate as far as how they each resonate or don't.

Also you'd have to hold them all in the same spot and tap in the same spot to get the real gist of it. Although some are more obvious than others, like that hunk of Brazilian.

[JoeProtist]

It seems like he specifically acknowledged the fact that the boards were of varying thicknesses, and I kind of think the varying thicknesses of the wood help to crystallize his point. It isn’t the pitch that he is concerned with, but rather the character of the wood. Furthermore, I have never been so turned on by planks of wood. I mean I would tap that European spruce straight through the night, yeah.

[Rick Turner]

You can learn a lot by tapping and scratching, and it doesn't matter that the pieces are of different dimensions. It is literally the quality of the feedback you're getting that is important here; you're basically sensing the "Q" of the wood, not a specific pitch, and the "Q" is the inverse of the damping characteristics. Low damping, which you can learn to sense, is good.

It's when you're trying to do something like comparative deflection testing that you need to start with a bunch of pieces of wood that are all the same thickness. Still, once you've handled hundreds or thousands of tops, you get a feel for it all no matter the thickness of the wood.

[Spruce]

You can learn a lot by tapping and scratching....

Scratching more than tapping for me...

Combined with a good 'ol digging-in-the-fingernail test (away from the pattern, of course)...

The two little tests will tell you a lot, all within a few seconds.....

[Dave Cohen]

Or, you could download something like Audacity or Wavesurfer, bonk your plates with your knuckles about 0.5 meters away from your computer mic, a few mouse clicks to the spectrum function, and have a record of each plate at any or all stages of carving. That will give you everything you hear, resolve what your ear is not capable of resolving, and be educational as well.

What do I mean by 'resolve what your ear is not capable of resolving'? If you do what I suggest, you will find that there is not just one peak frequency; instead there are many spectral peaks, each representing a different resonance of the free plate. Just as with a string vibration, your ear hears one "note" along with some individual "character" (for lack of a better word) to the note. Your ear hears the sum of all the resonances, and you classify the overall sound as "bright", "muddy", "nasal", etc., etc., based on the sum of what you hear. The spectral peaks represent each of the resonances, give you their relative amplitudes, and the widths of the peaks can give you some idea of the Q factor which Rick alluded to. Why is that worthwhile? Human audial memory is notoriously short. Unless you tap or scratch all of those hundreds of thousands of plates as fast as you can within, say, a minute, you will have (or at least should have) doubts about how each tap relates to all of the others. Is it the same? Or how is it different? Is that what I heard? If you only tap or scratch, you will eventually develope some intuitive generalizations, but they will all be anecdotes. That is, you won't be able to repeat the individual observations. If you record spectra, you will still have your audial impression, but you will also have a record of what you heard plus some details. In other words, you will have captured the event, as oppposed to having to rely entirely on your memory.

http://www.Cohenmando.com