Technical discussion: "The guitar's natural tone"

[Cuthbert]

How much affect would fretboard wood make? It is part of a guitar but a very small piece. The strings don't even touch the board just the frets.

The strings run on the board for 3/4 of their vibrating length, if you have a 24 frets guitars...the wood of the fretboard is more important than the body, I've a Strat with two neck, one rosewood,one maple, and the difference is HUGE.

All the other parameters (nut, pickups, body etc..) are equivalent.

[Newc]

The strings run on the board for 3/4 of their vibrating length, if you have a 24 frets guitars...the wood of the fretboard is more important than the body, I've a Strat with two neck, one rosewood,one maple, and the difference is HUGE.

All the other parameters (nut, pickups, body etc..) are equivalent.

A double-neck Strat or one you swapped necks on?

[javert]

Regarding the resonance of the guitar body, I found a webpage some time ago documenting some experiments with different shaped guitars and solid and hollow bodies:

http://www.kettering.edu/~drussell/guitars/index.html

It's quite interesting (and they have some nice animations). The experiments show that the shape of the guitar actually affects the modes. From some of the slides, it appears that one thing they would like to investigate is the correlation between lack of sustain and the body shape.

On top of the obvious effects, there are all sorts of weird effects that cause the sound to change. For example, usually the stiffness of the strings will cause the harmonics to be stretched, i.e., higher than integer multiples of the fundamental frequency, but due to interaction effects between the bridge of a guitar and the body, they may actually be lower for low tones.

[Sunbane]

Regarding the resonance of the guitar body, I found a webpage some time ago documenting some experiments with different shaped guitars and solid and hollow bodies:

http://www.kettering.edu/~drussell/guitars/index.html

Wow, that was really interesting!

"The asymmetric shape and the "wings" of the Explorer contribute to more motion of this guitar body. ... This is bad, because if the body vibrates the strings cannot sustain as long as they should."

The general notion in the guitar community has been that body/neck vibration is a good thing, while these guys seem to be saying the exact opposite. In the past, I've also seen a luthier state something along the line of: "The body wood is there to dampen all the vibrations."

[m2pmd70]

I still wanna see/hear EMGs on a 2x4. lol

[phill_up]

well.. Not sure if this fits into this subject but it's kind of interesting.. I actually didn't notice the guitar had no guts until he said it..

http://www.youtube.com/watch?v=UiV56mn7OMo

wow that led me to this. http://www.youtube.com/watch?v=0CsjPomb_0E&NR=1
very interesting

[Cuthbert]

A double-neck Strat or one you swapped necks on?

Same guitar, swapping necks.

Same nut, same machine heads etc...the difference is huge and even non-guitarists can notice that.

[phill_up]

I still wanna see/hear EMGs on a 2x4. lol

You just made me think of the steinberger.

[Newc]

Same guitar, swapping necks.

Same nut, same machine heads etc...the difference is huge and even non-guitarists can notice that.

Do you have recordings of the two? It'd be interesting to hear the differences that way.

Then again, you have to take into consideration that any change to a guitar will alter the sound.

Record the maple-boarded neck, then put the other one on and record it, playing the same song/riff/whatever.

Next, remove the neck and put it right back on, then record the same thing again.

The strings run on the board for 3/4 of their vibrating length...

But what he's saying is the strings do not actually touch the board.

Composite materials such as carbon-fiber are basically plastic, yet many professional players have sworn allegiance to replacement necks produced by Modulus. As I understand it, Philip Kubicki basses are/were also built with composite-material fretboards.

Then you have the Parker guitars.



WARNING: Have an aspirin handy for this next part:


Let's review the technical background info:

An open/unfretted vibrating string will oscillate a given number of times for a given period of time.
This oscillation cycle is influenced by string length, diameter, material, material quality (new vs "used" strings), force at which the oscillation was initiated (pick attack), method of initiation (finger, plectrum, material composition and material density of plectrum, etc), anchors (bridge/nut including material and material density), material in which the anchor points are themselves anchored (wood, metal, material density, etc), atmospheric conditions (ambient temperature (heat causes metal to expand, cold causes it to contract), humidity (heavy moisture will weigh down a wound string because of its mass. Though these are both very slight, it is measurable with the right equipment).

Now, any shortening of the string (i.e. fretting) will increase the oscillation frequency but shorten the duration.

Now you add more factors into the pile of things that affect the string's oscillation cycle:
Fret material
Fretting pressure
Material used to shorten the string (i.e. finger vs slide vs capo)
Fretboard material

Vibrational force follows a wave pattern like water. A ripple in a lake caused by a pebble will expand exponentially from the center until it reaches a point that resistance to the ripple is greater than the wave's motion force.

The same is true for a vibrating string.

While the vibratory force's primary characteristic is audible, the inaudible vibratory force is also present. This wave can be affected by forces other than itself just like the sound wave.

These forces add the body, neck, and fretboard (including material, shape, and density of each) to the stack of other factors mentioned previously.

While these physical forces also affect the audible waveform, their effect on the physical waveform is no less, and is no less detectable.

Just as soundwaves reflect, so do physical waves. Material density affects soundwaves in the same way it affects physical waves; glass reflects more than cloth.

You may have made a telephone when you were a kid using 2 paper cups and a length of string.

The principle there relies on the cup to act as a magnifier since it is a smooth, dense material (dense enough to reflect soundwaves back onto themselves so they increase in volume) and the string to act as the conductor, which transfers the vibration to the cup on the other end as long as the string has enough tension on it. As the physical waves reach the other cup, they are amplified by bouncing off the smooth walls of that cup just as they were in the transmitting cup.

It's interesting to note that there is absolutely no electronic or magnetic force in that situation, yet somehow vibrational waves are restored to their original shape.


Now, the unfretted string's vibration transfers to the anchor points at either end and is reflected back into the string (as the sound in the paper cup was reflected onto itself) AND, because of the intensity of the vibration being greater than the resistance of the anchor material, is passed through to whatever that anchor point is touching - the body, neck, whatever.

The bridge transfers vibrational force to the inside of the body just as air transfers the soundwaves to the outer surface of the body.

In turn, the density of the inside of the body/neck determines how much of the incoming vibrational force is kicked back to the bridge/nut and thus to the string and how much is passed through the body/neck itself.
Whatever is not reflected back into the string dissipates.

Because the surface is smooth, it reflects more soundwaves out into the room than it absorbs. Acoustic guitars work on the same principle as the paper cup telephone - sound goes into the hole, bounces around in a pattern that does not cause the waves to crash into each other and therefore cancel each other out, and then is passed back through the hole since it is the path of least resistance. Additionally, the surface of the body reflects soundwaves which adds to the volume.

For the neck, the fretted string's physical vibrational force passes into and through the fretwire and into the fretboard and neck. Because the fretwire is dense, it reflects some of the physical force back into the string in the same measure it is received, which causes the wave to regenerate.

Likewise, a softer, more porous fretboard wood like rosewood cannot grip the fretwire as tightly, thus reflecting less of the physical vibration back into the fretwire and therefore the string.

To go back to our paper cup telephone, if you use a length of yarn instead of thread, most of the signal is absorbed by the line rather than passed through to the other cup.

However, because the act of fretting the string shortens it, it also reduces the oscillation frequency. In turn, this means the fret has less to work with than the bridge.

A fretboard and neck material equal in density to the fretwire will reflect the majority of the physical vibration into the string, as well as add mass to the instrument as a whole, which will result in an increase in sustain. See the old 70's/80's metal Kramer necks.


With all that out of the way, we go back to the original question:

What is the "natural tone" of an electric guitar? Is it the acoustic sound? Is it the sound heard when strummed/plucked while resting on the building table, or leaning against a wall, or pressed to your ear?

How can an electromagnetic pickup be expected to "pick up" either of these tones?


I suppose to answer this we'd have to go back to the first electric guitar, which was undoubtedly a hollow or semihollow that was fitted with a pickup (note the issue of who actually invented the first solidbody electric guitar - Les Paul or Leo Fender - is still open for debate. I'm referring to the very first guitar that ever got a pickup put into it).

Since Les Paul is credited as the inventor of the electromagnetic guitar pickup, I'd say the first "electrified" guitar was his Epiphone that later became the Log, though Charlie Christian is also credited as being the first one to use an electric guitar (guitar with a pickup) in the 1940s.
Then there's the Rickenbacker electric Lap Steel from the 1930s.


Let's assume it was Les, and that he wanted to amplify his guitar yet have the freedom to move around but not have to deal with a 3 lb steel-encased mic. We could also surmise that the only tone he knew at the time was the acoustic tone, and therefore wanted that tone to be amplified.

If that's the case, then the question becomes "is that still the goal of today's pickup and or guitar manufacturer?"

[javert]

Newc, you make some good point and ask some good questions. I made no attempt to answer your question earlier simply because I believe that we are way beyond the point where it's a matter of 'reproducing the original sound'. What most people associate with the tone, I suspect, is a combination of all these effects and they cannot be separated.

You could ask the same question about a poweramp. In electrical engineering a good amp is one that is linear and does not introduce any nonlinearities, i.e. distortion. Its purpose is simply to amplify the sound and not change anything but the power, but that is hardly the case for guitar amps. In a similar way, you might suspect that the original pickups were designed as a transducer that aimed at nothing other than converting the wave from a mechanical one to an electrical one. And to answer your last question, it is certainly no longer the objective of pickups to simply just reproduce the original wave, just as a guitar amp does not aim at linearity.

[Cuthbert]

1)Do you have recordings of the two? It'd be interesting to hear the differences that way.

Then again, you have to take into consideration that any change to a guitar will alter the sound.

Record the maple-boarded neck, then put the other one on and record it, playing the same song/riff/whatever.

Next, remove the neck and put it right back on, then record the same thing again.

2) But what he's saying is the strings do not actually touch the board.

3) Composite materials such as carbon-fiber are basically plastic, yet many professional players have sworn allegiance to replacement necks produced by Modulus. As I understand it, Philip Kubicki basses are/were also built with composite-material fretboards.

Then you have the Parker guitars.

1) At the moment I can't record, but if you have a strat, you can make the experiment by yourself. It surely works, and as said before if you use the same nut and keys all the other parameters of the experiment are under control and any difference MUST come from the neck.

I hate to show my credentials in a discussion on a internet board, but I'm a mechanical engineer, and I work in R & D. I also worked as a experimental researcher in a pair of universities for my PhD and I think I know how to make these experiences work properly.

2)This doesn't have anything to deal with the experience: we are talking about mechanics of vibrations, and how a material can have a influence on the free vibration of a string. The problem has been studied ad nauseam by scientists since, I think, D'alembert. The nut and the bridge to have a influence because they are the boundary condition of the equation of vibration of the string, for instance, if you're using a locking nut, the constraint you have to give is "clamping" like it is called in science of construction, that is different from "position", aka the one you use for a normal nut . Same for the Floyd Rose bridge, who doesn't have anything to deal with "bringing the vibration to the body"....if the bridge didnt' touch the body, I would have worked the same way.

The fretboard doesn't touch the strings but it reflects the vibration waves from the strings, it reflects 95% of the total vibrating energy it receives, but THE WAY it brings back the vibration makes the difference, in our university we had a interesting seminary with professors of mechanics of vibration and classical luthiers who make violins, and the results of their experiments were EXTREMELY interesting and confirm what I'm saying.

Not to mention that according to this principle since in a acoustic guitar the wood never touches the strings it shouldn't paly any role in the tone. This is, of course, absurd and scientifically impossible.

3) NO. Composite materials and carbon fiber are NOT plastic, at all. Carbon fibers are, like the names states, more similar to texture cloth than plastic, they consists in short of long thin fibers of carbon with very high tensile strength that are crossed in different directions in order to be isotropic and they're mold in a resin cast in order to be cohesive...

Anyway, from a acoustic point of view, the density of the material is what makes the difference, therefore very dense plastic would be indicated, and for instance, I know a pair of plastics by dupont that would work well for the nuts.

4)Ok I took the aspirin and read through that document. What I can say is that the author doesn't clearly have any kind of scientific background and he doesn't clearly know what he's talking about.

[Newc]

Interesting.

How do you figure #4, though?

[Newc]

As an aside - I was playing the Purple Sullycaster through a Roland MicroCube about halfway through this thread, and I had it on the JC Clean setting. I backed the Volume knob of the guitar down to 0 and strummed a C Maj, then rolled the volume knob up.

The sound coming out of the amp was identical to the acoustic tone, only louder.

[Cuthbert]

Interesting.

How do you figure #4, though?

Sorry, I'm at work, I reread the article and it wasn't that bad, at least the first part.

Since here:

Now, the unfretted string's vibration transfers to the anchor points at either end and is reflected back into the string (as the sound in the paper cup was reflected onto itself) AND, because of the intensity of the vibration being greater than the resistance of the anchor material, is passed through to whatever that anchor point is touching - the body, neck, whatever.

The bridge transfers vibrational force to the inside of the body just as air transfers the soundwaves to the outer surface of the body.

The downfall.

In a acoustic instrument it is true that the bridge brings the vibration to the top and the bracing system, that it should resonate IF it's properly made (too thick tops don't resonate well because there is too much material to put in vibration, too thin can lose elasticy after a while, like the violin luthiers know well) but in a electric guitar there is not this effect, and a Floyd Rose could also be "floating" on the body, it doesn't matter. The most important thing is that the strings are close to the body so it would not dissipate the energy through the air.

Besides that, as Leo Fender said, the bridge of a electric guitar should be "as solid as the rock of Gibiltair" or you lose sustain....his first design for the Strat bridge didn't work because it vibrated and therefore it dissipated the mechanical energy of vibration of the string.

Same thing for the nut. If it wasn't like that, Floyd Rosed guitars would have no sustain.

[Newc]

I wasn't speaking of the audible portion of the vibratory waveform, I was referring to the actual physical portion.

If vibrational force hits an object that is resistant to sympathetic vibration (i.e. you pluck the string but cannot feel it in the bridge as strongly as in the string itself), then the wave is reflected back into the string. It has to go somewhere, and it will follow the path of least resistance, and like a shock absorber, the string is the path of least resistance. Therefore, the bridge and nut (anchor points) reflect incoming vibrational force back to the source.

The physical wave passing through the minor space of air between the string and fretboard is reflected back to the string by bouncing off the fretboard, however, it is not reflected with the same intensity as the audible portion of the waveform, and therefore does not perpetuate (sustain) the oscillation as much as the harder material the string is in direct contact with.