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Sustain: Maple Vs Mahogany


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Let me frame an age-old question in a slightly different way: suppose you have two (electric solidbody) guitars that are built exactly the same except for woods: one is all hard-maple, the other all mahogany (even the fretboard for this example).

Now we know the maple one will have more "brightness" and the mahogany will have more "midrange".

But which one will have more sustain? The hard-maple is a slam dunk, right?

Not so fast... what are the reasons that the mahogany might be better? Anything to do with sympathetic resonance?

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the harder and stiffer the wood the longer it will sustain. the specifics of the wood dictate which frequencies sustain the most (as well as the design an many other things).

I've always understood that you need mass to get good sustain. Pick the heaviest block of wood you can find and that will sustain the longest.

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All of the above is partly true, but nowhere near the whole story. You need low damping (= 'absorbing' vibrations) to get the best sustain. Mass can contribute, but doesn't have to; ebony (high mass) is one of the least 'sustaining' woods I've worked with. Stiffness is part of it as well, but again, it can be stiff and still dampen certain frequencies.

'Long sustain' is, IMO, a pointless thing to be chasing. You want good tone. Most woods we use have good enough sustain (just tap the unprocessed blanks, listen to what they do), it's the manner in which the vibrate that's interesting. Do they absorb the high end? The low end? Which part of the tonal spectrum is emphasized? Things like scale length, construction (set neck, bolt on, neck-through, chambering), bridge type, string type, pickups all affect the perceived sustain.

I mean, Les Pauls are sort of considered a 'gold standard' for long sustain (rightly or wrongly), and they're all mahogany. Just because a wood's brighter and heavier in no way means it'll 'sustain' the frequencies we want best.

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matia made me want to elaborate a bit

i agree that sustain is pointless in chasing using wood types, i believe its something to look for when buying a guitar as it shows that things are correctly adjusted and the neck is firmly fixed as well as the bridge being well attached and high quality.

things that i didnt mention, and mattia didnt completely go into is the way some woods dampen some vibrations due to the oiliness of the wood. think a cardboard guitar. theres a big difference in its sustain when its wet compared to dry. thats what oils in wood do, but not quite so severe. it would effect the harmonics more so than the fundamental note, but still effecting the fundamental to a small extent. also consider that a wet cardboard guitar/oily wood guitar will be heavier than a dry cardboard/oilfree wood guitar.

id say that the stiffness of the wood effects the fundamental note's sustain, where the internal resonance and dampening effects the harmonics alot.

i dont think weight has a big part of sustain, but people always say that ebony doesnt sustain well, and it has more of a percussive sound. id say this is a result of too much stiffness and too little internal dampening, making it resist the strings vibrations by not vibrating itself. keep in mind that too much isnt nessisarily a bad thing, just a different result.

basically ive described what creates different wood tones. warm sounding woods basically have a higher internal dampening to stiffness ratio.

speaking of les pauls, they have a maple top, increasing the stiffness and reducing the internal dampening of that section of the stucture (maple is stiff and bright sounding, suggesting low internal dampening). they have mahogany necks, which isnt particularly stiff, but les pauls have fairly thick necks, and the mahogany is quarter sawn increasing the stiffness. being mahogany, it has a higher internal dampening than maple, so it is not so bright, but has a fairly stiff neck, allowing the fundamental frequency to resonate for a while, which supports the idea that a les paul has alot of sustain, and is quite warm sounding.

the electronics have alot to do with the tone coming through, and even the magnets on single coils effect the sustain by pulling at the strings more than humbuckers (the pull from alnico poles is stronger than the pull of slugs/poles magnetised by a alnico or ceramic magnet.

i think i got well and truly off topic here, but atleast it has preoccupied me with something other than an uni assignment i left too late.

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Thanks mattia and black labb. If I understand correctly... Ebony, which has a lot of mass (density), has little sustain because of high dampening or too much stiffness? (is ebony considered "oily"? I dont think so)

An consider Oak which has a very similar mass/density as hard-Maple... yet Oak is regarded as a terrible "tone wood". Is that a case of too much or too little dampening? (again, is Oak considered "oily"?)

Edited by Cherryburst
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Hmmm...

Black_labb Some of what you are saying has merit, but you are making a few assumptions that don't quite add up from what I have found. You are mixing how a wood will create sound(as it vibrates), with dampening and relating it to electric instruments. I am not disagreeing with much of what you are saying, but don't agree with all the corrilations.

things that i didnt mention, and mattia didnt completely go into is the way some woods dampen some vibrations due to the oiliness of the wood. think a cardboard guitar. theres a big difference in its sustain when its wet compared to dry. thats what oils in wood do, but not quite so severe. it would effect the harmonics more so than the fundamental note, but still effecting the fundamental to a small extent. also consider that a wet cardboard guitar/oily wood guitar will be heavier than a dry cardboard/oilfree wood guitar.
The water analogy is a little deceptive, but has merit at the same time. Wet wood will act differently. One it is not as stiff, two it is has a higher density than dry wood. So you have lower stiffness and higher weight(water fills cells and softens the fibers as well as breaks down the bonding components of wood). Oils and resins will not have have the same properties as water, nor will they interact with the lignin, Cellulose,Hemicellulose in the same way. So you are talking apples and oranges.

the harder and stiffer the wood the longer it will sustain. the specifics of the wood dictate which frequencies sustain the most (as well as the design an many other things).
If you look at an example of a wood that has the ability to sustain(or keep vibrating very well)-Redwood vs a wood that tends to be very low dampening hard Maple. Maple will not sustain for nearly as long as Redwood. Redwood will not produce high frequencies as well as Maple. This is all being related to the way these woods sound when they are vibrating(producing sound). Now if you want to talk about what these woods used as the support system for a string on an electric guitar. The string will not vibrate and produce sound exactly as the wood does.

Your observations are good, but the conclusions you are drawing are jumping from what the wood itself sounds like to how it effects a strings vibration. Many of your statements ring true to me though. A stiff anchor will allow a string to have a stronger fundemental(this seems solid to me). Stiffness to density ratio will certainly dictate how the neck and body accept string energy(and how much energy). Stiffness, Density, shape and thickness, internal dampning will shape the resonance of the body and neck as well as amplitude and duration. How the energy is shaped will color the energy that is reflected back to the strings as the body and neck vibrate.

You are covering a lot of ground in a few statements, so I am probably over analizing.

Cherryburst- If you start by looking at how a string vibrates and how that vibration can be altered (directly) and then after you are totally clear on that subject. Then use that understanding to look at what you may be able to do to alter the string vibration indirectly. You are talking about direct and indirect and it is making it hard to get to basics. Keep in mind (and learn to live with this), even the sharpest luthiers and masters have different opinions on what happens on the "indirect" side of altering a strings vibration, and we build with a variable material(wood) so you will have different results from piece to piece. Look at acoustic guitars made by Taylor. Same species wood, same body design and specifications(very accurately made), and yet the sound varies from guitar to guitar. Things like humidity, strings(condition), player technique, and so forth all effect output.

Look at all the guitars that use mahogany necks and bodies(and think about the pickups, hardware,size and shape and such). Then look at guitars that use Hard Maple necks and bodies(well maybe Alder to get a bigger sampling) and again consider all the components. Look at all these factors when you evaluate what a guitar made with a certain wood sounds like(maybe you will find there is a lot more than just the wood that is making them sound a little more bright or whatever). Sometimes we overthink a small point.

"Tone wood" is used a lot today to describe woods used on guitars. There was a time when it was used to describe the wood primarily used to produce sound(such as a soundboard or plate). Some woods, such as a fretboard on a double bass would be considered more of a structural wood. Certainly some of the woods we use are effectively more structural than a producer(or significant contributor) to the sound of a guitar. I think Siminoff describes some woods as "reflectors"(I believe he was describing an acoustic function though). Since a guitars design is not a simple stick made of one material with similar volume across its length, mass will vary a lot with design as will structure(or stiffness). You want to modify the properties of a body, make it thicker, thinner or hollow it to some degree. If you want to alter the properties of a neck, make the headstock bigger/smaller or add reinforcing rods, use a thicker fretboard. All these things will vary the overall properties just as different woods will. If we only built one design things might be different, but we don't.

If you don't really want to think about any of that. May as well go look at Warmoths "Tone-O-Meter". It is probably as reliable as anything else.

Peace,Rich

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Look at all the guitars that use mahogany necks and bodies(and think about the pickups, hardware,size and shape and such). Then look at guitars that use Hard Maple necks and bodies(well maybe Alder to get a bigger sampling) and again consider all the components.

Yep, LP = mahogany = complex glued construction vs Strat = maple/alder = simple bolt on contruction.

But I'm still curious as to why ebony, which has such a high mass, is not considered to have good "sustain" in guitar construction?

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Go tap an ebony fingerboard blank, then go tap, say, a cocobolo, honduran rosewood, brazilian rosewood, even indian rosewood fingerboard. The ebony's 'thuddy', short sustain (fundamental decays relatively quickly, few overtones), while the rosewoods are 'glassier' and ring out more.

(conincidentally, rosewoods really mess with the 'oil=damping' theory. Oily woods, but fantastic tone and resonance. There's a reason they're used as marimba keys.)

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Off-topic-- I don't know that I'd call a set neck construction style particularly "complex" in comparison to bolt-on; nor is creating a tight bolt-on pocket and installing the neck properly a "simple" operation, necessarily.

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Whilst we're off-topic Greg - it seems music might be turning back towards those single-finger two-minute sustained note solos again because everyone is talking about that damn sustain again! Music must be slowing down again.

+1 on the tone.

The thread waits anxiously at the red light....and they're off!!

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Yea, its all Gary Moores fault! :D

Considering the example of ebony vs rosewood marimba keys, while the rosewood may be better for that application, bringing it back to having a guitar string thats strung over a piece of ebony vs another over a piece of rosewood.... I guess the ebony will impart less internal dampening and the plucked string will have more upper harmonics sounding out, while the rosewood with more dampening will cancel some of those upper harmonics?

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One question: Does a wood's tendency to damp or resonate certain frequencies contribute to what I would call "perceived" sustain? In other words, is it possible that what people are looking for is the increased perception of sustain, even though two different woods might vibrate for the same amount of time? Is 'resonance' the word we should be using instead of 'sustain'? That's more than one question, isn't it?

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One question: Does a wood's tendency to damp or resonate certain frequencies contribute to what I would call "perceived" sustain? In other words, is it possible that what people are looking for is the increased perception of sustain, even though two different woods might vibrate for the same amount of time? Is 'resonance' the word we should be using instead of 'sustain'? That's more than one question, isn't it?

I think that is right. Often "great sustain" means "this really sounds good." The tone of a wood is largely which frequencies get damped fastest. Take two equal size blcks of wood, say maple and sapele (not really a mahogony). Both are bright, which means they are stiff and so resonate at a higher frequency than other woods. But they sound very diferent. The maple is sort of brittle, while the sapale is clean. Different frequencies last longer. Someday I want to quantify this with some measurements.

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One question: Does a wood's tendency to damp or resonate certain frequencies contribute to what I would call "perceived" sustain? In other words, is it possible that what people are looking for is the increased perception of sustain, even though two different woods might vibrate for the same amount of time? Is 'resonance' the word we should be using instead of 'sustain'? That's more than one question, isn't it?

I guess its possible that you could have a guitar that would sustain for ages, but with the majority of the energy being 'released' at frequencies inaudible to the human ear, which would actually make it appear to have little "perceived sustain". And resonance would indeed have something to do with that 'perceived sustain'.

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According to this website, "Quality factor” Q = sqrt(C × Cc) / d where C and Cc are the speed of sound longitudinally and across the grain, and d is the density of the wood. "

The 'Quality factor' is basically what determines somethings 'sustain' (be that pleasing, audible sustain or otherwise), so If anyone were ever to try to actually quantify the sustain of woods, this may be a starting point. I couldnt find a table of typical Q values (or typical speeds of sound propagation) for different woods in a quick google search, but there may be one out there.

Of course theres a lot more too it than just the Q of the wood you choose, but as I said, it is perhaps a start.

Someday I want to quantify this with some measurements.

Someone fund me and maybe I'll do this as my PhD thesis :D

Seriously though, it would be cool if you did.

And also, if anyone were to try to measure the speed of sound in woods, there are some ideas here of how it could be approached experimentally, and by the look of it, not too expensively.

Edited by Ben
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Look at all the guitars that use mahogany necks and bodies(and think about the pickups, hardware,size and shape and such). Then look at guitars that use Hard Maple necks and bodies(well maybe Alder to get a bigger sampling) and again consider all the components.

Yep, LP = mahogany = complex glued construction vs Strat = maple/alder = simple bolt on contruction.

But I'm still curious as to why ebony, which has such a high mass, is not considered to have good "sustain" in guitar construction?

LP v Strat. Pickups, bridge, neck angle, headstock angle, body shape and mass, neck shape and mass, tuner configuration the list could go on. Apples and oranges.

You are still curious about Ebony not being a wood that sustains well because mass (density) is NOT the only factor to consider. The way a wood sustains is a combination of factors. The earlier mentioned density to stiffness ratio is probably a closer measure, but you also have crossgrain to longtitudinal stiffness ratio that is a big factor as well as composition. Again as mentioned earlier environmental factors such as moisture level will also play a role. Ebony is a very stiff, strong stuctural wood. In the typical volume or dimensions that a fretboard requires, it will add a lot of stiffness to a neck as well as weight(when compaired to other hardwoods). Again a stiffer foundation will lead to a stronger fundamental(what I believe most people are thinking of as percussive). Again, I would point out Redwood as an example. Redwood sustains or is able to keep moving for a very long time. It does not have a high density, it has a density to stiffness ratio that allows it to continue to vibrate very well. Same could be said of Sitka Spruce to a lesser extent. I would also point out that this is all still talking about how the wood will vibrate, with a little direct effect on strings mentioned when we talk about the strength of the fundemental.

A string has a limited amount of energy. When it is set in motion it will try to move whatever is holding it in place, and that will cost it some energy(like a shock absorber). If the neck and body were set in motion the guitar will try to move the string. Try this... tap the back of your guitar while it is amped up. The strings move, there is no doubt their is an interaction. However you have a lot of energy to impart on the guitar, strings do not. Tap the back of your guitar near the bridge area. See how much energy it takes to even start to approach a fraction of what a plucked strings movement will be(just don't damage the body). Point being it takes a lot of energy and a string will not have that much available, but there will certainly be a little trading going on. A lighter and less stiff guitar will require less energy to set it in motion. A rigid are very heavy object is not as easy to move or bend. When you set a heavy object in motion it is harder to stop, but also requires more energy to get it moving. If that heavy object also resists being moved due to its stiffness it will be both hard to set in motion and it(its own properties) will want to stop it from continuing to move. You can start to see why strings with a limited amount of energy will be able to move one guitar easier than another, and why one may want to keep moving longer than another. You have to now go back to the string itself, and figure out what will happen to the string if the guitar allows the string to transfer a lot of its energy easily. When you transfer energy to set the body in motion you use energy(you will not get back everything you put into moving that guitar). The string will want to move the guitar in a similar fasion to how it is vibrating. The body will not move just as the string want to move it. How the body wants to move will be reflected in the way it moves the string as it transfers energy back to the string(what did it sound like when you tapped the guitar, that is how the body wanted to move the strings). I keep mentioning "transfer energy", this only means trying to make something move or applying force.

Keep the concepts simple, if you try to predict phase relationships, specific resonances, consonance or disonance of harmonics. You are going to be grasping at straws, and real world results will be more reliable indicators anyway(because the variables are simply overwelming).

Peace,Rich

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Yea, its all Gary Moores fault! :D

Considering the example of ebony vs rosewood marimba keys, while the rosewood may be better for that application, bringing it back to having a guitar string thats strung over a piece of ebony vs another over a piece of rosewood.... I guess the ebony will impart less internal dampening and the plucked string will have more upper harmonics sounding out, while the rosewood with more dampening will cancel some of those upper harmonics?

No, the ebony will damp the vibration more (eat the upper frequencies, in part because of mass), while the rosewood will them ring out. Mind, I'm iffier on how this works in necks, but acoustic bridges are a great place to look at this; overall, ebony (heavier, higher damping) will be less 'shimmering' and resonant than a rosewood bridge, which is lighter AND has lower damping.

Mind, this is all tiny details we're talking about; I use ebony fingerboards quite a bit (because it's hard, stiff, wears very well, and is forigiving to inlay into), millions of guitars have been built with ebony bridges (almost all Taylors, for instance, although practically no classical guitars every have ebony bridges. Fingerboards, yes), and they all sound...like guitars. Many of them good, many of them crap, all built with the same woods. There's more to it than merely selecting the right species.

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Prostheta-- I hear ya. I can't remember for the life of me the last time I played a note and just listened to it trail off. Even Neil Young's famous "one-note" solo featured much pick-attack action, anyhow!

Sustain for sustain's sake is so wonky. But if that's what people are after, they're better off looking at psw's thread, OR investigating compressors OR looking into the natural compression characteristics of a tube amp. The actual "sustainer" sustain and the perceived compressor/distortion sustain are going to be more impactful than actual vibration of the guitar anyhow. All else failing, find the right spot in the room and stand there. Sympathetic vibration is pretty great for sustain. :D

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That's it exactly. I suppose we can bang out all the physics we want, but sustain from an instrument is most probably going to make for a less characterful TONE which is what a seasoned player desires more. Acoustic instruments may be a different kettle of fish, but hey.

As a system, an instrument is passive and all frequencies will be dampened as opposed to reinforced. Adding amps and a method of this amp inducing sound to the instrument introduces a loop to the system. Feedback, reinforcement, call it what you will.

When it comes down to it, an instrument which sustains indefinitely or as best it can will by definition not dampen frequencies. That would mean the tone is flat. Characterless. Unless you have singing fingers, voiced picks or timbre-laden strings. Doubtful.

I think what makes instruments sound INTERESTING is down to the selective dampening of wood (filtering and interference if you will) which is in effect going to reduce sustain.

The whole topic has been done down to a tee by better people than us, and it was probably still a bucket of yap.

So yeah, what Greg said! All due respect to the physics heads (which I dabble in when relevant) but I think it's the wrong avenue to pursue! Wrong question, whether there is an answer or not (in my opinion)! :-D

Edited by Prostheta
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