String Theories: Guitar Physics

Internationally acclaimed guitarist Enrico Santacatterina duets with NYUAD student Ana Karneza (Photo courtesy of Francesco Arneodo)

How wood affects the sound in an electric guitar is a long debated topic among musicians. When one thinks carefully about it, it is actually quite surprising that there is even a debate. The sound of an electric guitar is not dependent in any significant way on the materials used for the body and neck of the instrument. Contrary to what happen in an acoustic guitar, where the sound is the result of a resonance induced by many components–among which, the quality of the wood is of paramount importance!–there is no material-induced resonance involved in the sound of an electric guitar; hence tonality qualities of the wood of the neck and body of the instrument are irrelevant.

The output of an electric guitar is actually an electric signal; its final sound happens only after some magnets called pickups generate a magnetic field and ‘pick up’ the alterations in it created by vibrations of the metallic strings placed above them. Those changes are transformed into small electric signals; they are significant but still too small to produce sound, so they are channeled through an amplifier and then eventually to a loudspeaker.
Given the electronic nature of the sound, it can be altered ad libitum using effects: delay, chorus, overdrive, fuzz and so on: the list is endless.
In simpler terms: the sound of an electric guitar has nothing to do with the natural sound produced when played as if it was an acoustic instrument. The presence of a TV or a mobile phone in the room will do more to alter the magnetic field of the pick ups than the material of the body of the instrument.
Everyone who has ever witnessed what a pick up switch or a pedal does to sound, instinctively knows this is true: wood is irrelevant in regard to the final output.
Given this elementary truth of science, it is fascinating to see how the milieu of electric guitar players is almost unanimously agreeing on the opposite: wood, they say, is–somehow, in some undetectable, indecipherable but still vivid way–a fundamental component of the sound of the instrument! One can find hundreds and hundreds of books, websites, interviews with famous players and guitar makers where woods are examined as more or less apt for their ‘tonality’ in guitar making. And 99.9% of the guitar players will tell you that it is fundamental to hear the guitar when not amplified, as if there were any meaningful relation between how an electric guitar sounds when amplified and when not. There are some who can tell you that certain guitars have a specific sustain because how much they weigh or how the weight is distributed. Some insist that even varnishes or protective coatings determine noticeable differences.
They are all wrong.

Artists can be excused if they mix the playability of an instrument with the output: a beautifully polished maple neck, or a lovely time-induced patina, or a pristine rosewood fretboard might indeed be of utmost importance for individual players. And they might well have very valid reasons to back up their feelings on playability, but that has nothing to do with sound: in a controlled experiment, with all other things being equal, no musician will ever be able to discern the sound of an electric guitar made with a certain wood instead of any other material. But of course, we can forgive artists: their passionate involvement with the instrument, with its craft, is what make them capable of creating art; every guitarist who swear about their beloved guitar having that specific tone because of its paint, or wood, must indeed be excused. They’re blinded by their love for their art.

People who should, perhaps, be less excused are the writers of technical magazines and the guitar manufacturers themselves. It might be argued that they would do a better service to the community by, say, reviewing the quality of material in cables and amplifiers, giving proper credit to these fundamental components of the final sound, rather than indulging in never-ending, scientifically meaningless, debates on the veneer on the fretboards, or paints on the bodies, in articles where, and I quote “tonality of the combination ash+rosewood is results in more tonal brightness compared to the maple-mahogany combo”. Fact is that there is no such thing of tone wood in electric guitars.

In the Tech Talks page of their website (https://www.fender.com/articles/tech-talk/do-different-woods-affect-your-electric-guitar-tone) the producer of some of the most sought-after electric guitars  in the world answers to the million dollar question « Do different woods affect your electric guitar tone? » –perhaps settling it, albeit unwillingly:
Their answer starts by acknowledging that it is “a debate that has waged on among beginners and advanced players for a ling time”, “a muddy situation, as there are vociferous defender on each side of the issue”. And then they add: “those who do not believe wood affects a guitar’s tone point to the physics of how an electric guitar works(emphasis is mine)
Indeed. Yes. That’s what we all should do. In order to establish the plausibility of a physical fact in the physical world, we should all point to physics of how things work. Nothing else is required. But for some reasons–reasons, alas, that science alone cannot fully explain–so many of us refuse to do so.

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