Posted Jul 20, 2012 07:28 PM
WARNING: This article uses the word 'tone' 52 times. May induce vomiting.
The electric guitar is one of the most versatile, articulate, and expressive instruments man has at his disposal, and exertion of control over these aspects of the guitar is inherent to the musicianship of the guitarist. Within mastering this control lies the endless pursuit of tone. 'Tonal nirvana' is something guitarists strive for and progress toward. Everyone's tonal nirvana is unique, and ever-changing. The relationship with one's instrument and its tone is essential, but knowing how to get the tone you want out of your guitar isn't easy when there's so much to be learned and so much misinformation about tone. In this article I'll be discussing a few aspects of tone that I have discovered to be somewhat misunderstood: sustain, resonance, and 'color'.
Here is something you may not have considered before. Guitar pickups are electromagnets. They only respond to electromagnetism, and nothing else. The oscillation of the guitar's strings is the only thing they 'pick up'. Due to this physical phenomenon, the woods and other materials used in the guitar which are extraneous to the pickup and strings make only subtle differences. This is contrary to the prevailing thoughts on how a guitar's construction affects its tonal output. For acoustic guitars, resonance is paramount to all other qualities in regards to tone, and all materials used in the guitar's build contribute to that resonance. The other side of this coin is that an electric guitar can be extremely resonant when unplugged, but once a guitar utilizes a pickup to amplify its sound and is plugged in, the acoustic resonance is not of such great importance because the pickup doesn't care about overall resonance - it only cares about the vibration conductors in a magnetic field (i.e. the strings). The overwhelming majority of the tone as it goes from the guitar to the lead is coming from the pickup's interaction with the strings, because the pickups are electromagnets and their interpretation of the guitar's sound is what gets amplified; they are the basis of your signal chain. Hollowbodies utilize feedback and are far more prone to harmonic overtones being amplified, so they are a bit of an exception. But a demonstration of this physics application is that having a maple top won't make an electric guitar 'brighter' to the pronounced degree it is purported to - keep this in mind. You can put this concept to the test for yourself by plugging in an electric guitar to an amplifier, strapping it on, standing up, dialing in a clean tone, and bending a note at one of your guitar's 'sweet spots'. See how long the guitar sustains and what the note sounds like without the use of vibrato. When you do this, the guitar's body is against your own fleshy body (which would minutely dampen its resonance, according to the incorrect and ubiquitous thinking that a guitar resonating as a whole is the most important factor). Try the same exact thing with the exact same amp settings and attack, but hold the guitar away from your body. Then do it with the guitar's body touching a wall, or something large and hollow (this would make a guitar much more resonant according to the aforementioned thinking). As long as your pickups aren't microphonic, you will find that the note's overall tone and sustain will be almost precisely the same each time. Debunked!
The sound coming from the strings, on the other hand, is affected quite a lot by the mechanical resonances of the guitar, in particular by the neck and its connection to the body as well as the places the strings touch the guitar. This is because on a frequency which the guitar easily resonates at, the guitar's harmonics strengthen themselves when all the components of the guitar resonate at similar frequencies, ergo the strings are able to release much more energy into the environment than for a 'dead' frequency. All guitars have many, many of these so-called 'resonant frequencies'. The transference of these frequencies to the guitar's strings are first and foremost affected by the three points at which the strings make contact with the guitar: the nut, the frets, and the bridge. The way in which these three parts interact with the rest of the guitar has a massive influence on the guitar's sound. They are the guitar's receptors for vibrations from the strings, which receive the vast majority of the instrument's initial percussion from being struck. They are also the parts which ultimately transfer vibration from the rest of the guitar to the strings, resulting in the sound which gets amplified. Remember this fact as I discuss materials. In addition to this, the pickup itself is vibrated by the resonance of the guitar's body (to a minute degree), and this vibration of the pickup changes its orientation to the string, which results in minor changes in tone during, say, a chord. This is tangential to why the location of a pickup along a string's length has a colossal influence on the guitar's tone. Where a pickup is located in relation to the strings has a profound effect on tone because that changes which harmonics/frequencies of the strings' vibrations are more readily picked up. Even a pickup in the same position along a string's length but slanted toward the treble side, or raised in closer proximity to the strings, will sound drastically different than one set evenly or far away.
Now here are some general rules about materials. The denser a material, the more efficiently it transfers vibrations from one place to another. This results in better sustain, because the vibrations which are propagated into a string take longer to die out. This is similar to but distinct from resonance. To illustrate this concept, if a nut was constructed with a very dense material like, say, iridium, it would theoretically allow for very good transference of vibration to and from the strings, and the limiting factor in the guitar sustaining a note would be the stiffness of the strings. A very dense material also minimizes dampening of string movement. I could explain the physics behind why both of these things occur, but I'll spare you the really dry stuff. This is different from resonance, which is when a system (in this case the guitar) amplifies the oscillation of frequencies (resonant frequencies) unique to the properties of the system's components (guitar materials). Pickups are designed to capture these frequencies in a musical manner. (This is a criminal oversimplification of resonance, pickups, and the complexities of human hearing, but this is all leading to a point.) One example of unwanted frequencies being picked up is mains hum (a.k.a. 60-cycle hum), which is just the pickup picking up the 60 Hz alternating current from your power lines (usually). Now that the distinction between sustain and resonance is clear, which materials make for the best resonance? The thinner, tenser, lighter, and stabler a material is, the better it will resonate. This has interesting applications. In any experimental, quantitative assay of amplitude vs. Frequency in tonewoods, the level of acoustic attenuation exhibited by the wood is proportional to its density and the above characteristics. Extrapolation from the results in one study I read (which wasn't peer-reviewed) would indicate that resonance from best to worst is as follows: Redwood, Mahogany, Cocobolo, and African Blackwood. The significant inference to be made from this is that acoustic guitars are most resonant when constructed with lighter, less dense woods for the top and denser, less flexible woods for the back and sides.
What's also of utmost importance is the construction. If a guitar is poorly constructed, it won't matter what materials are used, it's not going to sound or play any good. Quality of construction - the glues used, how dry the wood is, what sort of shapes and types of joints are utilized, etc. - does make a difference. For instance, a bolt-on neck joint affords a different transference of vibration from the body to the neck than a glue-in neck joint does (neither is typically tonally 'better' than the other, by the way - it's entirely preference).
Now I'll return the focus to the nut, frets, and the bridge. These are three of the four major players in an electric guitar's tone, and their design and materials are the most expeditious way to alter the tone of an electric guitar. I will again contradict popular opinion on guitar components regarding two of these parts.
Stainless steel frets are widely used on guitar fretboards, and for good reason. They sound good and are nearly impervious to the demands of a guitar being played often. When you fret a note and play it, it will sound noticeably different (to the trained ear) than an open string ringing. This is because of the nut, which acts as the 0th fret (I won't be talking about actual constructed 0th frets here). This does make a difference in tone. If you wanted your open notes to sound just like your fretted notes, than an ideal nut material would be stainless steel, wouldn't it? The guitar industry currently has the notion that PVC, Corian, Graphite, Bone, and Tusq (synthetic bone) are the best nut materials to use. Most guitarists, if asked, would prefer bone. Why? Because it's traditionally thought to be the best. Tradition needs to be questioned. Those nut materials are all much easier for the manufacturer to cut than a brass or stainless steel nut, but the truth is that they are inferior to a metal alloy nut when it comes to sustain and resonance.
While I'm on the topic, the material used for the fingerboard makes an imperceptible difference in an electric guitar's tone (oscilloscopes cannot even detect it). That's because the string does not come in contact with the fretboard, unless you are pushing down too hard; only your fingers come in contact with the fingerboard. What do you think a scalloped fretboard does? So you may as well get the best-looking, most durable fingerboard. Rosewood is a very porous wood and also wears down very quickly, and will just get mired in all the sweat and dirt of being played on. Maple is a little bit better, but it's lighter in color so it gets dirty-looking even quicker. The best option here is ebony, if your fretboard will not be finished. It's the hardest of the tonewoods and so responds the best to being played, and won't become digusting as quickly. However, you could just as easily coat a fingerboard with a thin polyurethane finish and it will last indefinitely, without noticeably affecting the tone of the electric guitar. Maple fretboards are often finished, so I wonder why rosewood fretboards are never finished? Again, it's solely tradition.
The third and most important component is the bridge. Most bridges are made of the same materials just with a different appearance (e.g. That horrid gold finish that wears off instantly from the acidity in sweat), so that's not something that can easily be changed. However, guitarists often change the way the strings contact the bridge. A reverse wrap bridge, a wrap over bridge, a stoptail bridge, a string-through body, a tremolo block - all these are terms referring to the different way the strings contact the bridge or body. Why does this matter? They all offer different modalities of transferring vibration throughout the body, bridge, and strings. It's not at all uncommon to lower the bridge or tailpiece as far as possible to maximize their contact with the body and to optimize the break angle of the strings over the bridge. This may lead to more string breakage, but it results in a different resonance quality to the guitar's tone. The issue I have with most bridges is that they neglect the simple fact that after the strings have passed the saddles, they make just about zero difference in the guitar's tone. Because of this, contact should be maximized between the saddles and the strings, right? That would provide the most transference of vibration, one would think. Very popular proprietary bridge designs such as the Tune-O-Matic bridge have these ridiculous knife-edge saddles that not only wear down the strings during bends, but also allow for very little vibration to pass to the bridge. A roller bridge is much better for tone and sustain. That's one reason why it's often found that high-end Epiphone models have better sustain (and even resonance) than Gibson guitars: because the Epiphone TonePros bridge has deeper-cut saddles which allow more contact between the string and saddle - even though they have very similar overall designs! These subtle changes make a difference on an instrument of nuances.
So would a guitar carved from a single piece of wood have the greatest resonance of any guitar? Not necessarily. Maybe you have realized by now that it's not that simple, but it would certainly be an enormous improvement over the average five-piece neck, quartersawn, bookmatched, jigsaw style guitar. That's not to say guitars with several pieces have terrible resonance. They can resonate very well, as long as the woods are carefully chosen and the construction is of of high quality. Yet guys like Steve Vai can even hear when a guitar's parts resonate at frequencies which are an atonal interval apart. And what about guitars with chambered bodies? Do they really resonate better? According to the physics of sound, well... Yeah. They do. But when it comes down to an electric guitar's final tone which the pickups will be sending out that cable, it's only a blip on the tonal radar. Most of people's complaints about the newer Gibson Les Paul Standards sounding bad simply because of their being chambered are unfounded, meaning it's what they want to hear in their heads as the reason they don't like their tone. So... If pickups are designed to pick up the vibrations of strings, which are metal, wouldn't a guitar made of something like aluminum be very harmonically rich? Yes, but I don't know enough about that topic to speak authoritatively on it. Hopefully someone who has empirical evidence (not just hearsay) of how good non-wood electric guitars sound can let me know. I do know that several guitarists have used exotic guitars with 'no' body and such, and how do they sound? Great. Steinbergers have no headstocks and they can sound superb as well. Further proof that tonewoods in the electric guitar don't make a great deal of difference.
Now I'd like to talk about a fourth dramatically influential element of tone that I mentioned earlier but have yet to elaborate on: pickups. Pickups do NOT produce a guitar's tone. They only convey it to the amplifier. A great pickup should be very transparent and also very receptive to all the harmonic nuances produced by the guitar. And yet, swapping out pickups will make a great deal of difference in your tone. This is because each pickup has a different design, whether it be in the magnets, the pins, the winding, etc. They all have different outputs and color the tone of your guitar differently. Believe it or not, low-impedance, high-output pickups decrease sustain (think active pickups like EMGs). They pull on the strings and cause a drag on their vibration, resulting in reduced sustain. They also have preamps designed to buffer their signals to high impedance and to boost their extremely low output to an aggressive sound; these preamps contribute an artificial sound to your guitar's tone. Continuing with that thought, single coils have a very distinct, snappy tone, but they are noisy. So instead of going with the stock pickups which might give you that 'vintage' sound, how about purchasing some noiseless Lace Sensors, or N3s, which give you that same Stratocaster sound, but without the nasty buzziness? Here is an illustration of the versatility of just one pickup coil: if you have a humbucking bridge pickup, remove the pins from the coil closest to the bridge. Viola, you now have a legitimate single coil pickup! Yes, this really works. The point is, if your tone is suffering, purchase some pickups which suit the tone you are seeking and replace them. Have someone do it for you or learn how to do it yourself because it's not that difficult. It's not worth struggling with a tone you aren't satisfied with just because you are afraid of change or a little work. There are some amazing pickup options out there; granted, some of the are expensive as hell and don't justify their prices. With that said, I'm of the opinion that a great guitar should come with pickups which are conducive to that tone in your head, not underwhelming pickups which are designed with no attention to detail and are to be swapped out because they are expected to be lackluster and replaced anyway. In the same vein, the wiring of your guitar's pickup system is also a substantial benefactor to a good tone. Bad circuitry will be the difference between a guitar that shines through the mix and one that always seems to need another lead boost. Don't just accept the wiring that your guitar comes with; take a look and experiment to determine what you like or don't like and what could be changed. Most electronics have options which, if rewired, result in a refreshing amount of difference in your tone with minimal tweaking.
So if you equip a Gibson Les Paul and a Fender Telecaster with exactly the same pickups and circuitry, they will still have notably different sounds. Why is that? Firstly, the Les Paul and the Telecaster use wildly different nut and bridge designs and materials, which greatly contributes to their different iconic tones. They also have a 3/4" difference in scale length, which lends the Gibson a hoopier, robust sound whereas the Fender will have a more salient, nasal sound. Again, the difference in string tension and length is making up a big chunk of tone (are you noticing that maybe you should invest in good strings?) But that's not where the origins of tonal differences end. Sustain and resonance are the two most quantitative and measurable qualities to a guitar's tone, but that doesn't mean the materials which make for the most sustain or resonance are the best for overall tone. What matters is entirely qualitative: how good it sounds to the ear of the listener. Going back to the example of having an iridium nut, that would be not only hugely impractical, but wouldn't even sound good! It would be cold, hard, and totally unmusical, albeit with impossibly good sustain. The 'colors' that an instrument's materials lend to its sound are to be carefully considered in conjunction with practicality. The colors in the tonal palette lent by a guitar's materials are obviously especially crucial in acoustic guitars. But the same colors are even somewhat important in electric guitars despite my downplaying of their importance (they're just much less important than the electric guitar industry would have you believe). Guitarists often describe wood species by the type of tone that they are thought to produce. Several examples: Cedar is supposed to be smooth and vocal; Spruce is supposed to be punchy and articulate; Mahogany is supposed to be dark and earthy; Maple is supposed to be bright and singing; Rosewood is supposed to be rich and bell-like; Ebony is supposed to be deep and orchestral. Wood is organic and therefore highly variable, so these qualities don't always hold true, but they are very often recognizable. So despite my diatribe about tonewoods and resonance being overrated on electric guitars, I don't mean to say that attention to the quality of materials should be entirely neglected, because they do make a difference. I just mean don't go buy a bird's-eye maple neck thinking that it is going to be that extra something which makes your tone heavenly.
For those of you who hate reading, I'll summarize what useful information the article contains for you: in the realm of electric guitar, four things have the greatest effect on your pre-amplifier tone, and they also happen to be the four easiest things to customize and modify. Those four things are the nut, the bridge, the strings, and the pickup. Because pickups are electromagnetic, they only detect changes in the electromagnetic field caused by the oscillation of your guitar strings. That means they don't care about what wood your guitar is sporting - they only care about the strings. With that in mind, the harmonic richness, sustain, and just general vibration of the strings is greatly affected by the other components of the guitar, specifically their mechanical resonance. The guitar strings should ideally be in immobilized contact with the guitar at all times in two places: the nut and the bridge. The way to increase your guitar's resonance and sustain in the least amount of time is to purchase good strings (coated strings are not tonally inferior), a low-output, high impedance pickup (a consummate passive pickup like Seymour Duncan makes), a well-cut nut made of a metal alloy (such as brass), and a bridge which allows for maximum contact between the strings and the saddles (such as a roller bridge). A lot of this may seem obvious, but I hope you learned a few things and have a clearer understanding of what really has an effect on your tone. These are things that everyone looks to modify on their guitar, but I think I gave some good insight on what makes them important aspects of guitar tone. After all, who wants to take a saw to their keepsake when a few tweaks can make all the difference? Happy tone hunting!
DISCLAIMER: Yes, I know most of your tone comes from your fingers, from your playing... That's not what I intended to discuss here.