"every piece of wood has a pitch"

[Black Napkins]

As i reading the last steve vai interview, i was stunned by his words on how he have chosen EVO among several jem7vwh.
He say:"every piece of wood has a pitch "

and

"if you have a neck and a body that resonate a perfect fifth, or an octave or even in unison from each other, you're going to have a more solid, resonant feel"

I found that very funny, and immediately " tap" to pitch my 7dbk.....and his neck seemed to be an E, and his body the octave above.

I want to know if someone here have already 'tapped" his wood, and what are the resulting notes?

[bammbamm]

I was polishing my wood and ...oohh.. wait... wrong concept I think...

Bamm

[Black Napkins]

hihi

I only knock on the dbk cause i can't bear doing that on my " hardly -polished-mint" finished guitars .

And yes , it's probably a stupid concept for poor human being like us.

[GreasyKid]

how do you even do that?

[caprile]

EVERY object has a natural frecuency, that depends on material, geometry and support condition, that is, a neck by itself has a different frecuency compared to a bolt on neck.

[Kevan]

..and no two snoflakes are shaped the same.
:-)

[dcord]

Isn't it "snowflakes"?

[Lonely Raven]

Satriani said something about the natural resonance of his instruments
many years ago.

Now, everyone will tell me otherwise, but I was told that my JS-3 Donnie
was one of the first 7 made. Joe has several sent to him, and plays them
for a while, and picks one, or maybe two that just SOUND better. He's
always said that his "Black Dog" guitar resonated the best and
sounded the best. At least until the chroming started doing cool stuff to
the tone and not chipping off and cracking between screw holes.

Now, I hate to be a stick in the mud about natural pitch of your guitar,
but honestly......

Do you think your guitar, or ANY guitar for that matter, just happens to
be in perfect tune? I mean, do you think your guitar or any guitar is a
perfect 440 A? I think not.

I understand Steve's theory, and in some way I agree with it, but it's
more of a harmonic thing then an actual pitch thing. IMHO

[eviltwin]

not too long ago I stumbled upon some research into this phenomenon. I found it somewhere on the 'net, done at a university which I can't remember [duh]

The basics of this research:

Analyzing natural frequencies by Finite Element Method [simulations] as well as full scale testing [shaker test] and comparison of these results. The subjects of these tests and simulations were a number of musical instruments including a Spanish style acoustic guitar and an Epiphone Flying V

All I can remember is that the V demonstrated some amazing resonance low A, IIRC.

bottom line: This is not BS this is Science

Now; if anyone is interested; with a proper 3D model [Pro/E, Ideas, step, IGS, vda etc.] I may be able to run some simulations on a Jem or UV. I am too busy to do the 3D-modelling myself, although I have an old 3ds4 model of a Jem somewhere on my harddrive. Just for the record I studied aerospace engineering at DUT, Specializing in computerized structural analysis and aeroelasticity.

[caprile]

i love tech talk! i'm a structural engineer (well, 1 semester away!) and have pretty extensive experience in finite element methods. i would love to see that study (please if you find a link tell me!). the result are useless if the mesh used is not adecuate, so a convergence study is mandatory. wood is not an isotropic nor homogeneus material (that is, it doesn't have the same mechanical properties is any direction, and has parts of uneven density/stiffness) so a model isn't necesarily too representative.

[eviltwin]

That's very true in theory, caprile. However, the biggest problem is not in details, or in convergence. Eigenfrequency problems can actually be approximated with very crude models. The challenges and solutions I see are [Note! contains Tech Talk]:

1. Material; non isotropic behavioiur can most likely be approximated by isotropic or use orthotropic: parallel to grain/perpendicular to grain say 1:2 or 1:1.5

2. Boundary conditions; hanging the guitar from a strap is similar to a free-free BC on both points. Note that when measuring the lowest EV on an aeroplane, one simply puts the plane on its wheels with low pressure in the tyres, and excites the plane at the wing tip.

3. Neck-body connection; a glued in neck is not as stiff as the wood in all directions, and may not transmit high frequencies as well as a bolt on. All of this will influence the overtones but will not affect the low eigenfrequencies or resonance much.

4. Strings; since were still in the linear part of the wood stress-strain curve, I doubt pre-tension will have any effect.

[caprile]

wow! this is great. do you have any links on aerospace aplications of FEM? that's very interesting. my experience is exclusively in structures, and yes, crude models are very accurate, for instance you can model walls as bars and get precise EV's!
free vibration tests are a little more difficult in my field i guess, i once participated in a test in where the excitation was a truck speeding and hitting the brakes real quick!

back to guitars....one of these days i'll model a jem in sap2000 starting from the autocad file posted here. let's see what i get

[smorg007]

.....or you could just rap the muther with a mallet, see what note it makes....hopefully not *crack*

[eviltwin]

caprile, I checked google [images] for "natural frequencies" and a bunch of links came up pertaining to aerospace FEA, such as this one:
http://www.coe.montana.edu/me/facult...t_analysis.htm

the same when entered "aerospace FEA",
including a complete lecture:
http://www.engr.ukans.edu/~rhale/ae5...re1/sld001.htm

finally I checked "finite element", and this came up:
http://www.wrightflyer.org/WindTunnel/testing4.html
no results in that one...

http://www.physics.cornell.edu/sethn...tions/FEM.html
includes a great picture of a ruptured KC135

http://caswww.colorado.edu/~charbel/aesim.html
aeroelasticity is fun

there's loads-a-stuff, you just need to look for it.

[caprile]

thanks! aeroelasticity.......cool word....maybe my next band's name!