THE SOUND OF THE ELECTRIC GUITAR WOOD
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WHY DO SOME GUITARS SEEM TO PLAY MUCH BETTER THAN OTHERS? WHAT CONTRIBUTES TO MAKE A GUITAR PLAY FANTASTIC WITH RESPECT TO ONE OF A SIMILAR CONSTRUCTION?
I have surfed the web a lot and in we are now in 2010. I am really impressed as to how most of the simplest questions on setup and guitar making still remain unanswered despite the number of professional luthiers writing out there.==============================================================================
Hardwoods sounds brighter... OK. Softer woods sound warmer.. Ok. But WHY? And how can I take advantage of this?
The purpose of this article is to explain matter in simple terms for everyone.
At the end of this article you will have a complete and deep knowledge of how your instruments work and how to select, mix and use the materials your guitars and basses are made of to achieve the goals you have in mind.
I will try to explain in the most simple terms possible. Experts should forgive me for some simplifications I am obliged to use for this subject for it to be understandable by everyone.
The content of this site is copyright © 2010 by Galeazzo Frudua and it is the result of 30 years of guitar making and about 400 instruments. The contents of these pages is far more specific than everything you have heard about or read until now.
If you found the contents of this site useful please help me to spread the word and if you intend to post them in forums, blogs, Wikipedia etc could I please ask you to put link to this site and/or pages. THANK YOU! . .
The electric guitar and bass tone is influenced by a number of factors amongst which are wood, hardware, type of pickups and their placement along the scale.
The role of wood is to resonate and send back to the strings that energy intact to be translated into sound.
This is very important for the luthier and for the pro musician as it's up to wood to make the difference between a superior instrument and an ordinary one.
There are two main factors that influence an instrument's tone:
1) The strings vibration (sustain) purity.
2) The sound each wood produces.
When designing an instrument we have to use woods that will support the strings vibration without interfarence and, at the same time, selecting them, matching them and crafting them in order to get the tone we are looking for.
This is why making an incredible instrument ain't easy.
THE STRING VIBRATION
To simplify, let's think of the "tone" in terms of resonance. A neck resonates at a certain frequency, the one of the wood (or sum of the woods) is made of.
Each neck, cut from the same tree or even from the same blank will produce a different tone. Manufacturers of drum sticks know this very well as they use different means to tune both sticks to produce the same note (in fact with my amp's company we recently designed and produced a device for an Italian company which allows them to do this automatically).
Strings also have a pitch resonance.
Similar frequencies cancel each other out.
If the resonance of the material the instrument is made of interferes with the resonance of the strings, some harmonics
may be cancelled or added and this will cause problems like loss of sustain, "wolf notes", "dead notes", etc.
If the resonance of the wood does not interfere with the resonance of the strings we will get a pure vibration.
If the resonance peak of the instrument is too far from that of the strings, then we will have a material (wood) which does not meaningfully contribute to the overall instrument's tone.
Consequently, you have to choose wood for the body and the neck which will resonate near to the strings peak but not OVER it.
Like a football player who dribbles and dodges past the opponent, the resonant peak of the wood will have to be "near" to the string's peak resonance but never crossing it.
Our first goal is to achieve the most perfect string resonance and then to build a great tone around it.
Talking about the material, the principle which rules how it will influence the instrument's tone is as follows: the higher the mass, the less the material will absorb the string's vibration which will be almost entirely returned to the strings.
When we are sure that the strings vibrate freely, then it's time to build up our tone taking advantage of the different woods tonal characteristics.
The physical properties of the wood we are more interested in and upon which we must focus are:
1) Stiffness (elasticity coefficient along the grain). This is more important for acoustic guitar and violin top construction,
2) Wood density (i.e. coefficient of propagation of sound inside wood),
3) Internal friction friction (attitude of a material to dampen the energy which we apply to wood here).
Commonly softer and less dense woods will produce more volume, less attack and less sustain while heavier and denser woods will produce more sustain and a sharper attack with less volume.
Imagine that till now we have built up the skeleton of the tone. We take care that the wood we chose (later on we will see how to actually do this with "tapping") allows the strings to vibrate freely and does not interfere with the frequencies that the strings mounted on this particular instrument (guitar or bass or mandolin or whatever) may replicate.
Wood seasoning and selection play a crucial role in the
electric guitar and bass construction.
Now this "skeleton" has to be "clothed" with the tone we have in mind. To do this we have tons of different pickups, woods and hardware available.
On an electric guitar the type and model of pickups used have a big impact on overall tone.
What pickups actually do is transform into sound the energy they receive from the strings. But we saw how the string's vibration depends on the material under them.
This is why it's down to wood to make the different between an ordinary instrument and a superb one.
And this is why some guitars sound better than apparently identical ones.
Now we will learn HOW WE CAN RULE these differences.
The most important wooden part of an instrument, no matter if it is electric or acoustic, is the neck. To understand why please read here.
To understand the influence the wood has on the tone and how we can use it to recreate the sound we have in mind, we need to compare the woods into at least 5 different categories:
Soft and less dense woods
Woods that belong to this category are Birch and Poplar, woods you should not use in guitar construction due to their low quality features in terms of stiffness, density and tone.
Their tapping tone is average medium volume and slightly deaf tone with a pretty slow decay.
ATTENTION LUTHIERS!: some external and lower cuts of softer woods like basswood and Swamp ash also belong in this category. External and lower tree cuts are less dense and softer than internal and upper cuts.
Average soft and dense woods
Woods in this category are fine woods for bodies like Alder, Ash, some species of Mahogany, Basswood basswood and other woods excluded with no apparent reason from guitar making like Cherry wood and Chestnut. Tapping them delivers a good sustain and volume and a wide frequency range tone. I call these "neutral sounding" woods, meaning they are a fine starting platform from which to build up our tone using other various essences.
A fretless Frudua Slave Pentabass. Mahogany neutral tone supports the neck through
maple/purple heart design with mids and bass definition. Tuya rot rounds and
softens the maple upper treble a bit. A thin ebony fretboard preserves the
maple tone and features a smooth feel under your fingers.
Average dense and hard woods
This group includes highly resonant woods, ones like Maple, the finest wood for electrical instrument necks and tops, and also some cuts of heavier woods like Mahogany, Ash and also Walnut which is sometimes used for through-neck laminations. Tapping these woods produces a sound with a fine sustain, great volume and a wide frequency response.
Custom Frudua Octabass. The wide use of maple for the body follows the customer
wish for definition and brightness for a sort of "harp" effect on chords and arpeggios.
The Tuya rot contributes to soften the treble a little.
An instrument specificly good for solos.
Hard, heavy and slightly oily woods.
Part of this family of mainly exotic woods are Ebony, Wenge, Purple Heart and Paduak, they mainly used for fretboards and bubinga is also used for the basses. Tapping wise they offer a bright sound with a long sustain but at quite reduced volume. The use of these woods is recommended for neck laminations as they increase neck stiffness, and for top plates and on the neck of through body bass "wings". Used in a reduced thickness in combination with more "neutral" woods like Mahogany, Alder, or Ash, these hard woods help to refine and reinforce the sustain and the fundamental note and also provide a sharper attack.
Bubinga top plate on mahogany body on a Frudua Slave Pentabass. In combination with the
Maple/Purple Heart neck and the Ebony fretboard they deliver a defined tone
on all frequencies. A versatile instrument.
Hard dense and oily woods.
These are woods in which oil and resin content may vary, from a minimum as in Rosewood, Purple Heart, to a maximum as in Teak, Goncalo Alves, Cocobolo, Bocote, Ziricote, Zebrawood). These woods feature a tapping tone which ranges from a good sustain and a reduced volume (minimum oil content) to a generally deaf tone (more oily ) and would have to be used with care and in much reduced thickness for fretboard or thin top plates.
For example rosewood is an oily wood which subtracts sounds from the Maple resonance of the neck and should be used in minimal thickness (*) or to intentionally darken the tone of an instrument that is too bright. These woods help us to understand how oil finish treatment must be handled with care and by skilled guitar repairmen and luthiers to avoid tone dampening.
Water is rejected by the oil particles contained in a Cocobolo piece of wood.
THE IMPORTANCE OF THE NECK'S WOOD
When "designing our tone" we should first concentrate on the heart of an instrument: the neck.
There are many factors which have a big impact on the neck's resonance:
Water contained in the vessels and inside the cell walls influence the way the wood resonates meaning that a dried wood will resonate better than a piece of wood full of water.
The neck's thickness also has an influence in the general tone of the instrument due to the main role the neck has in it. The more resonant the neck is, the better your instrument will play. NB: A thin resonant neck will always play better than a neck that sounds "deaf" when tapped. (This is why tapping is so important).
A thin finish will sound better that a think one. Generally an oil finish will end up in dampening the wood tone if not performed by a skilled luthier.
An internal cut will result in a harder and denser piece of wood (more sustain, less volume, more brightness, more stability), while an external cut will produce a lighter less dense wood i.e. more volume, less sustain, more "body" and harmonics, less stability.
The material the truss rod is made of, the way it is installed into the guitar and the truss rod position when strings are under tension all have an impact on tone (please read related article). Generally the more wood which has to be removed due to the truss rod installation the more the neck becomes flexible and consequently the more it will waeken and lose resonance.
When designing the instrument we must have it clear in our mind what kind of tone and quality we are striving for. The neck is the heart of the instrument.
Concentrate on woods. Cut them in identical blanks for the neck and for the bodies allowing for a little extra thickness in case wood shrinks and swells.
Now let's apply the Frudua tapping technique.
Below you will find some graphical examples showing the relationship between wood hardness, its density and tone.
(*) Leo Fender understood this and continued to reduce the Rosewood thickness of the Strat fretboard until is was a small layer of about 3mm, this was to avoid the negative effects of Rosewood on tone and necks.
© 2010 Galeazzo Frudua. All rights reserved
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