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speal

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  1. As a violinist, I have a had experience with unfretted instruments. I've dabbled on upright bass and cello as well. The biggest differences between fretted and unfretted instruments will be: 1. The required skill level for the player. There's not much room for error without frets. 2. The warmth of the tone. Your notes will lose some brightness because the string isn't vibrating over a metal fret, it's vibrating on a hard piece of wood and your finger. Probably a nice sound for jazz guitar. I wouldn't see chording as a problem, since I play right up behind the frets. One thing you gain is the ability to adjust intonation. If one string is going flat, you can simply play it higher. This is pretty common practice with orchestra string instruments, and is a much easier adjustment to make than bending a string to make it play in tune. It's an interesting idea, and I say go for it. It'll take some getting used to, but I bet you'll find the intonation comes with practice. Also, I'd have to say leave the fingerboard all black. Bassists and cellists can play their instruments without markers, and so can you. It'll make the instrument more striking, as the lack of frets seems to be the main point of interest for this guitar.
  2. That's probably because of damping. A stiff neck will absorb less of the sound energy, and you'll sustain better. It's important to distinguish between resonance and sustain. Sustain is the length of time your guitar will continue to produce one particular note above a certain threshold of volume. Resonance has to do with your guitar's natural resonant frequency. This can determine the complexity of the overtones generated, and depends on design, materials, and environment. Good analysis of resonance takes a LOT of data, and a lot of complex math...so it's tricky to get it just right. Oddly enough, resonance also affects sustain. If your guitar's natural resonant frequency (or one of them; it will have many) is near that of a note you play, this particular note will be louder, and sustain longer. It's not hard to observe this in an acoustic, where some notes will really ring out above the others. Feedback in semi-acoustic electric guitars is generally at the body cavity's resonant frequency as well. The chart I looked at showed that sound travels across the grain at a speed around 1/3rd that of the speed along the grain. So yes, this would make a big difference. Your open strings still have wavelengths beyond the scale of your guitar, but the first and 2nd octave harmonics will have wavelengths very near that of your scale length. At this point, a difference of an inch for pickup or neck-join placement could have a big effect on overtones, and thus the "warmth" of your guitar. ------------ Thanks for all the good feedback on this. The key to what I've been doing is to simplify the problem so it can be understood using very simple physics. Unfortunately, resonance and interference in any musical instrument is very complex, so a thorough treatment is a very involved process. I may end up writing a java simulation that combines some of the effects we've talked about. Unfortunately, this will have to wait until at least a few days after the holidays. I'm also going to be fitting in a through-neck guitar project. As a side note, would anyone see a problem with a 1/2" strip of cherry down the middle of a laminate maple neck? I haven't worked much with cherry, so I'm not familiar with it's strength or application to necks. Merry Christmas!
  3. The frequency I used, 329.63Hz, is the high e string frequency. I used this because the formula I derived only accounts for open strings. The thing I overlooked is that harmonics also vibrate along the full length of the string, and can be used, and these harmonics are the overtones you hear when you pluck an open string. Octave harmonics are the most audible, and occur at frequencies that are powers of 2 * the open string frequency. This corresponds to a length that is one over that power of two. So, the first octave harmonic occurs at 1/2 the string length, and is twice the frequency of the open string. On the maple/mahogany laminated neck mentioned above, an amplitude reduction of 10% occurs at a frequency of 4185Hz (scale length of 25.5"). This is around 16 * the frequency of the open B string. 16 = 2^4, so this is four octaves above the open B string. Not all harmonics occur as natural overtones, but it's safe to assume that an octave harmonic would occur as an overtone. As you increase the distance between the fundamental pitch of the string and an overtone, the amplitude decreases. 16 * the fundamental frequency is going to be MUCH quieter, so this reduction, although significant, may not be audible because this overtone is so far from the fundamental frequency. I'm going to do some more in-depth work on this problem, since you end up with some interesting interference between waves originating at the nut and the bridge. That, and resonance could have some interesting effects. One thing I'm particularly interested in investigating: Waves moving in opposite directions interfere and form standing waves, not unlike the vibration of a string. There are particular positions along the wave that will always be the peak amplitude, and others that will always have zero amplitude. I'd be interested to know if placing a pickup at a zero amplitude spot would sound different from a pickup at a higher amplitude location. Keep in mind this amplitude is for the body's vibration, not the string. ------------------------------- As far as speed of propagation for sound through wood, there are many factors that could affect this speed. 1. Each piece of wood is unique. There are no concrete rules, since imperfections (including desirable ones, like figuring) can affect transmission speed, as well as natural variations in density/water content. 2. Sound propagates at a different speed for each frequency, as well. In a medium like air, the variation is so small for the audible range, we stick with a single value. In wood, the speed is significantly higher (by more than a factor of 10). The variation due to frequency may actually be worth looking into. I'll get some concrete numbers for this. 3. Tension on the wood will, with absolute certainty, affect the speed of propagation. Speed along the grain is much faster than across it, so the fastest propagating sound waves may follow the curved path of the wood grain if the neck is bent. When you're talking about small percentages in interference, this difference can be significant. 4. The width of a piece of wood will affect its resonance. At some frequencies, propagation along the width of the wood can lead to interference in the length propagation, effectively reducing the transmission speed. 5. Environmental factors like temperature, humidity, air pressure, etc... will play a role in sound transmission and resonance, so these may be worth looking at as well. So, in the end, the problem becomes MUCH more complicated. Developing a good model will be difficult. Luckily, the wavelength of your low E string is around 10 meters when traveling through maple. This leaves a lot of room for error. My intuition tells me that laminated necks aren't going to have any real effect on the sound of the guitar. More important will be the relationships between bulk masses in the guitar, and their resonant frequencies. The contact area of the neck joint could really affect the resonance of the instrument as a whole. I'll have to brush up on some acoustics and look into this to give you a real answer though. ---------------------- This could be only due to the mass change. The relative volume is the same, but mass is greater, so density is higher. Water is also a terrible conductor of sound, so the sound waves may take jagged paths through the wood. Since the simplest look at resonance depends on the length of the longest and shortest possible "paths" for the sound, the change in humidity could easily change the character of the wood. You're not just imagining the tone difference either. Again, the water is probably the culprit. A slow sound transmittor decreases wavelengths, lowering the minimum frequency for interference. You'll lose more overtones as you introduce more water into the wood.
  4. Boy, I bet it's hard to do barre chords on that many strings. Will my fingers even be long enough? I imagine the appeal of an 8-string is the same as that of a 19 piece drum kit. More stuff = better music, right?
  5. Okay, so here's what I've got for the density issue in laminated necks: Assumptions: --------------- 1. String vibrations are transferred to two pieces of laminate at exactly the same moment (ie, the string slot in the nut is right above the join between the laminates). 2. The rule I derive applies only to open strings, as the contact point for vibration is at the nut. 3. Wave interference is said to be "completely destructive" when one wave is half-way through its period, while the other is just starting it. Adding these two waves together yields a straight line. What I'm doing: ------------------ In a set-neck or bolt-on guitar, the neck resonance will be transfered through a "point" (the joint). If a neck is made from at least two types of wood, can the different densities of the wood lead to destructive interference at this joint, and thus hurt the sustain of the guitar? Okay, here it is: ------------------- Two strips of wood (our laminates) run parallel, and are length L. This length is the distance from the nut to the neck joint at the body. The speed of sound transmission for our laminates is known (it can be looked up in a table). Our frequency will be the same at all places (we'd hope: this determines the pitch of the string). Wavelength, however, depends on the density of the material that the wave is propagating through. For destructive interference, L should equal n * l1 (l1 is the wavelength of our wave in the first piece of laminate. L should also be equal to (n + 1/2) * l2, where l2 is the wavelength in the second piece. One fundamental law of waves is that wavelength * frequency is equal to the speed of propagation(c1 or c2), so we can substitute this in: n * c1 = (n + 1/2) * c2 a few steps bring us to this result: n = 1 / (2 * (c1/c2 - 1) ) since n is some number of wavelengths in laminate 1, we can reuse the equation L = n * l1. By multiplying both sides of the equation by l1, we get this: L = n * l1 = l1 / (2 * (c1/c2 - 1) ) And because wavelength * frequency = c, we get this: L = c1 / (2f * (c1/c2 - 1) ) ----------------------- Okay, lets plug in some numbers: Frequencies: -------------- E = 82.41Hz A = 110.00Hz D = 146.83Hz G = 196.00Hz B = 246.94Hz e = 329.63Hz The highest frequency is going to give us the smallest wavelength, so we'll use high e to find minimum neck lengths for interference. Speeds of Propagation: -------------------------- Rock Maple: 4200m/s Honduras Mahogany: 4970m/s Honduras Rosewood: 5217m/s Beefwood (for comparison): 3364m/s Let's try a neck with laminated magohany and maple: L = 4970m/s / (2 * 329.63Hz * (4970 / 4200 - 1) ) L = 41.12m Yes, 41 meters. So, clearly this isn't going to be much of a problem unless you're building a super-jumbo guitar. Let's try a bigger difference in woods (the biggest I could find). Rosewood laminated with beefwood: L = 5217m/s / (2 * 329.63Hz * (5217/3364 - 1) ) L = 14.37m Oh, much better. This guitar only has to be 14 meters long.... So, clearly, this particular possibility for interference has no effect at the frequencies of regular guitar strings. I'll explore the possibility of interference between waves originating at the bridge and waves originating at the nut soon. EDIT: I thought I should add this bit of information. At a 25.5" scale, the reduction in amplitude due to interference with a mahogany and maple neck is around 1.5%. I can't say how much, but the neck's vibration doesn't account for much of the actual output of your guitar, so this 1.5% doesn't lead to a noticible reduction in guitar volume. Thank god, since this would be one more thing that could lead to dead spots along the neck, assuming the same rule applies to fretted notes (it's probably close).
  6. I'll have to tackle this one with a pencil and paper in a few minutes. There could be some interesting consequences of using similar density woods in a laminated neck... it may end up being nothing though.
  7. I couldn't help but post, having seen all the bad physics going on here. Let me start by stating my position: The tension on your string, assuming a frictionless nut and bridge, will be exactly the same at all places along the string. Your spring is anchored at both ends, and somewhere in the middle, there is a pulley (frictionless, of course) that raises the height of the string. The angle between the two sections of string is the break angle of your neck. While the string exerts a downward force on this pulley, the pulley is not accelerating. F = ma, so if there is a net force on the pulley, it would HAVE to accelerate down through your neck and away from the string. The reason it's not accelerating downward is because the neck provides the necessary normal force to counteract the string pushing down. If the string tension and/or breaking angle is too great, the neck will snap. Otherwise, it'll just flex forward at the location of the nut until the force of the neck resisting the flexing is equal to the downard force on the nut. So, tension is the same everywhere. Now, if you take friction into account, you will STILL find equal tension, except when bending. The force due to friction is defined as F = f * N, where N is the normal force between the string and the nut, and f is some constant of friction dependent on the nut and string surfaces. The friction force, when starting a bend, will point from the nut toward the tuners. The string will not move across the nut until the difference in tension between the lower (between nut and brudge) and upper (between tuners and nut) sections of the string is greater than the frictional force exerted by the nut. Once this force has been exceded, the string will all have the same tension everywhere. This happens because the friction constant of two surfaces once already moving is almost always less than that of the static frictional constant (before they're moving). When you release the bend, the opposite will happen. The upper string tension will be greater than that of the lower string tension as you release, but the tensions will equilibrate as soon as the difference in tensions is greater than the frictional force in the opposite direction (toward the bridge). One thing you'll notice is that the frictional force depends on the normal force. The normal force is directly related to the breaking angle. A breaking angle of 0 degrees will have no downard force on the nut, and thus no friction. A breaking angle of 180 degrees will exert twice the tension on the nut. So, increasing your breaking angle increases the friction between the string and nut, and makes it more likely that your guitar will go out of tune after you bend. I haven't plugged in the numbers just yet, but I imagine the difference between a breaking angle of 11 degrees and 18 degrees would have almost no effect on your guitar's intonation after bending, since the friction constant for most nut materials is intentionally very low. You're going to make a much bigger difference (or, a noticible one) in intonation if you use a high quality bridge and tuners, and adjust your guitar's intonation properly. If anyone reads this old thread and wants to see a diagram, I'd be happy to make one.
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