What factors affect a guitar's ability to sustain a note?

Question

There are effects and gadgets that can create a long sustained note, but what about the guitar itself?

I have a squier standard strat which I can't help but feel could be letting notes ring longer, but I am a complete beginner and wouldn't know how long is long enough. I looked around about it and got many, many answers.

I've heard that these can affect how long a guitar will hold a note for:

• the kind of tremolo system if any
• the material used for the tremolo block
• whether the tremolo is balanced or rests against the guitar body
• the type of strings used
• the tremolo tension springs
• the quality of the pickups and which are being used
• the quality of the nut
• the quality of the tuning pegs
• the presence or absence of string trees
• the body - whether it is solid or hollow, quality of wood etc.

Which of these are true and to what extent?

Answer 1

Dr Mayhem gives a good answer, but I think it's worth adding something about the physics.

When you pull a string out of its resting position, you are giving it potential energy by stretching the string. When you release it, it converts that potential energy into kinetic energy (that is, movement). As it passes the centre position, all the energy is kinetic, and as it slows down to reach the other side of the vibration, it becomes potential energy again. At the moment it changes direction, it is all potential energy.

So the string goes back and forth, converting the energy from potential to kinetic and back. This is called harmonic motion. In theory this could go on forever - infinite sustain. The second law of thermodynamics says that in converting from one form of energy to another, you always lose some as heat, so the vibration would decay eventually -- but you could hypothesise systems where that loss is tiny.

But, a string vibrating in a vacuum is of no use to a musician. We need some of the energy in that vibrating string to get transferred into moving air -- because that is how sound gets to the listener's ear.

On an acoustic guitar, the primary route for turning a vibrating string into vibrating air is for the bridge to carry movement into the soundboard.

On an electric guitar, the primary route is by inducing a current in a pickup, producing the signal that the amplifier handles.

Either way, what affects sustain is:

• The rate at which the sound-producing component takes energy away from the string.
• What other components take energy away from the string.

A powerful pickup, for example, would get a really strong signal from a given string vibration, but the cost would be that it would take lots of energy from the string. By producing a weaker signal and taking less energy, the pickup could allow the string to sustain for longer. The acoustic equivalent of this is a relatively inflexible soundboard, for less volume but more sustain.

An "ideal" electric guitar would be completely rigid so that only the pickup takes energy from the string. However, as well as being a physical impossibility, it's also probably not entirely desirable, since most people like the body's acoustic characteristics to add tone to the sound.

Likewise an "ideal" acoustic guitar would be completely rigid, apart from the assembly of bridge and soundboard; the only loss of energy from the string goes into vibrating the soundboard. But even if this were possible, it may not give the tone people really want.

Also in the electric world, you have a few extra ways of getting sustain.

You can make the most of the quiet tail end of the note -- with lots of amplification. You get this if you crank up the gain -- if you don't mind tons of distortion at the louder beginning of the note -- or you can achieve it using a compressor.

You can coax some more vibration out of the string by applying vibrato and scraping the string against a fret.

You can add energy to the string by striking, shaking or flexing the guitar.

You can make use of feedback, by cranking an amp up loud and finding the sweet spot where your instrument resonates.

You can use a gadget such as the Fernandez Sustainer, which is a kind of in-instrument feedback loop, using the output of your pickup to induce vibration back into the string.

Answer 2

Taking your list, I have added a quick note to each:

the kind of tremolo system if any

• Yes - any tremelo will dissipate some of the energy in a vibrating string, so your best sustain should come from a fixed bridge. There are varying types though, so some perform better than others.

the material used for the tremolo block

• More appropriately - the mass of the tremelo. The less it vibrates, the less energy gets transferred to and dissipated in the springs.

whether the tremolo is balanced or rests against the guitar body

• Yes - resting against the body will deliver greater sustain. See the first point.

the type of strings used

• Yes - thicker strings should give longer sustain as they have greater mass, and therefore greater energy.

• Also, flatwound strings will tend to have more sustain than roundwound because they produce fewer non-harmonic overtones, concentrating the energy into the fundamental and lower partials. [droog]

the tremolo tension springs

• Sort of - but not as much as the effect the mass of the tremelo will have

the quality of the pickups and which are being used

• Yes - along with what type of preamp you are using. Better pickup and better amp can give better sustain

the quality of the nut

• A locking nut should give the best sustain, as it reduces the amount of energy dissipated beyond the nut.

the quality of the tuning pegs

• Not really, although if they vibrate, they will dissipate energy

the presence or absence of string trees

• Sort of - they can help hold the strings tight in the nut, which takes you some way towards a locking nut equivalent.

the body - whether it is solid or hollow, quality of wood etc

• Yes - hollow, resonant bodies should have the best sustain. For solid bodies, hardwoods tend to have the best sustain.

Answer 3

The bottom line is that if you want the most natural acoustic sustain, don't play a guitar designed along the lines of a Fender Stratocaster. Get a guitar designed along the lines of a Gibson Les Paul. This is why many guitarists own one of each; they are suited to producing different kinds of tones.

In particular, a guitar with a fixed bridge (hardtail) will have more sustain than a guitar with a tremolo bridge. Tremolos are great for vibrato and dive-bombs and other expressive effects, but this all comes at the expense of long sustain. You can't have both. So when you want more sustain, get a second guitar that does not have a tremolo bridge.

The easiest way to examine differences that contribute to sustain are to look at the differences between classic Fender construction and classic Gibson Les Paul construction.

Fenders and Gibsons

To begin with, a guitar that does not have a tremolo bridge will have much more sustain than a guitar that has a tremolo bridge. But there are other aspects, too.

Every component of a guitar contributes to its acoustic sound. All things being equal, however, most guitar builders have associated more sustain with more mass and density, in the body woods, in the weight of the bridge, the type of metal used, and how it is anchored to the body, and even in the weight of the headstock and the metals used in the tuners and fitments.

Fenders have their own very appealing sound, but many aspects of the Fender design were created not for acoustic properties but to design a guitar that was the easiest to mass-produce. Fenders involve the simplest wood carving procedures. The body design, the way the neck is connected to the body, and the design of the headstock (read below) on a Fender Stratocaster are all designed to require as little wood-carving skill as possible, and to make it easy to interchange parts after the guitar is built. Second, there is the floating tremolo bridge with springs, which reduces sustain. Also, Fenders, classically, have bodies made of inexpensive alder or ash, which have appealing acoustic properties but are not known for producing great sustain.

However, Fenders certainly have their own sound that is very popular--sustain isn't everything.

The classic Gibson Les Paul design was created to provide the most sustain. Its body is carved from a slab of solid Honduran mahogany (rare and expensive, and now endangered) with a slab of hard maple glued to the top. These woods are dense and selected because of their mass and sustaining qualities. The guitar is carved with an arched top to provide the most thickness, mass and density directly under the bridge, and this is said to increase sustain. The mahogany neck is carved using techniques that require a lot more woodworking and skill than the easier-to-mass-produce Fender necks. Significantly, the Gibson neck has a more complicated carved angled headstock, and the neck heel is glued into the body, rather than bolted on. Finally, the classic Les Paul design uses a fixed bridge system (or "hardtail"), not a tremolo bridge.

How the neck is attached to the body

A neck can be:

• bolted to the body ("bolt-on")
• glued in ("set neck")
• the neck runs the entire length of the body ("neck-thru")

The conventional wisdom is that the bolt-on design has less sustain than the set-neck construction. However, various guitar manufacturers dispute this and say that a properly constructed bolt-on neck construction can have just as much sustain as a set-neck design. Everyone agrees that the most sustain comes from the neck-thru design, but this is not common in guitars because it is a much more expensive method of construction.

Bolt-on neck

Set-neck. Gibson's latest design, showing how the neck block, or tenon, fits into the body. The neck is glued to the body.

Neck-thru design in a bass guitar. Notice that the neck is constructed of pieces of wood that run the entire length of the guitar, headstock, neck and body. The "body" is merely two pieces of wood glued to either side of the neck block.

Headstock angle

Another factor you have not mentioned can be the angle of the headstock. Fender-style guitars have a headstock whose surface is parallel to the fingerboard. Gibson-style guitars have a headstock that tilts back several degrees, and this is generally regarded as to contributing more sustain. Luthiers talk about the "break angle" of the string over the nut and also over the bridge saddle as contributing to sustain.

The Gibson-style headstock tilts backwards and is regarded as contributing to greater sustain. [Carving a neck in this fashion out of a single block of expensive and rare mahogany requires a lot of labor, and most of the wood is carved away and lost. Today many copies of the Gibson design, including their own Epiphone Les Pauls, utilize two pieces of wood glued together at an angle in a scarf joint to reduce the amount of woodcarving and the amount of wood required, and to improve durability.]

Fender-style headstocks are flat and the string break angle is quite shallow. This is thought to create less sustain. [However, it requires much less wood, and simpler woodworking procedures, to carve a neck in this design compared to the Gibson design. Furthermore Fender necks are made of hard maple, which is not increasingly endangered like mahogany is.]

Answer 4

There is a lot if myth and hear say about the topic. Here is a study that attempts to debunk the whole "how the neck is attached" angle. http://liutaiomottola.com/research/sustain.htm

It's also not true that the pick up sucks mechanical energy out of the string. The physical mechanism required to do this is called "Back electro magnetic force" or back EMF for short. It's proportional to the current through the coil. For guitars pick ups these are a few micro Amps at best, so it's completely negligible.

There are actually have been scientific studies done, although the ones that I know off are commercial and not public. It seems to mainly boil down to bridge and body wood which are the two primary mechanical loss mechanism for string energy.

Answer 5

I would also question the assertion that heavier strings --in and of themselves-- increase sustain. Indeed they have more mass --which implies more inertia to keep the string moving. But this ignores or discounts the opposing tensile force of the string material itself which resists stretching from resting to extended position as the string vibrates. So, increasing the mass must also increase the opposing tensile force, although the proportional strengths of these forces is certainly a subject for further investigation.

Answer 6

This whole topic is fraught with anecdotal evidence and received wisdom. As far as I can tell, there have been no side by side laboratory tests of different construction methods, testing one factor against another with all other things being equal.

It is widely believed that Gibson Les Pauls have longer sustain than Fender Strats. But, Les Pauls are often equipped with heavier gauge strings due to the shorter scale length and paired up with higher gain amps. Strats tend to be favoured for lower gain sounds.

On the surface it would seem logical to think a set neck would pass more vibration through to the body than a bolt on neck. However, I have heard it agrued that the set neck is joined by spongy, non resonant, dampening glue whereas in spite of their smaller surface area bolts transfer more vibration. There's yet another school of thought that says the wood has no real affect on the amplified sound anyway, so set, through or bolt-on is of no real consequence. I'm not claiming any of this to be true, just saying that there are compelling arguments for different methods of construction.

Headstock angle. When a note is fretted, it is either fretted adequately to give a clean note or it will choke. Is it not the case that this is a threshold to cross and once crossed you can't get the note cleaner? Well does the same thing not apply to the nut. I've certainly heard it argued that the material the nut is made of is a lot more important than the break angle. Is the break angle only supposed to affect open notes? Presumably it's fretted notes that you add vibrato too that you care about sustaining? Again, I'm claiming nothing, just showing that there are counter arguments.