Originally posted Aug. 24, 2015
How Wood (And Everything Else) Affects Tone
Guitarists are typically very passionate about the quality of sounds they want to hear from their gear. Of course the single most important aspect is a player’s ability, and there is simply no substitute for talent, combined with a voracious appetite for practice. But beyond the “bone tone” each player brings to one’s individual tonal recipe, there are many other ingredients that contribute to the final output. Today I’m going to write a bit about how the wood an electric guitar is made from, along with other physical aspects, affect its sound.
Recently, there seems to be no shortage of social media and forum debates over tone wood that quickly reach a fever pitch, with strong arguments both for and against the affects of wood on a guitar’s tone. I have no doubt that the folks stating wood has no effect on an electric guitar tone have given this serious thought. I also have no doubt that they are mistaken. Here’s why…
At the risk of unintentionally constructing a straw man, I’ll attempt to summarize the counter argument; that which says wood has little to no effect on an electric guitar’s amplified tone. The argument I see most often states that because the pickup is an electromagnetic transducer it does not “hear” the acoustic properties of the wood. It merely senses the vibration of the string. Therefore, the principal elements responsible for variations in timbre (“tone”) are the strings themselves and the pickups.
If that seems like a reasonable position to you, you are not alone. But let’s think about what is really happening to the energy we impart into the guitar every time we pluck a string. The energy is not simply transferred to the string alone. As kinetic energy (the pick attacking the string) is turned into acoustic energy (the string vibrating and creating sound waves), many things affect that energy over the lifespan of a given note. As soon as the energy wave hits the anchored end of the string, the energy from that wave is transferred into whatever matter it is connected to. Here is where the “tone” happens. The instant the energy wave connects to the mass of the guitar (through the nut/fret/saddle) that full spectrum audio bandwidth waveform is splintered into its component parts, based on the path of least resistance. Every material is going to offer a different acoustic resistance. Acoustic resistance varies according to just about every physical parameter you can imagine and it affects frequency, amplitude and phase differently across each portion of the audio spectrum. High frequencies (treble/harmonics), being more susceptible to acoustic resistance than low frequencies, are affected first. For example, a hard, dense wood is usually less acoustically resonant than a softer wood. Less resonance means that the wood is a good conductor of kinetic energy and so less energy is absorbed. Thus more of the energy is returned to the string, contributing to a longer decay, with less high frequency loss/phase distortion. Conversely, highly resonant wood turns kinetic energy into acoustic energy more easily. This loss of kinetic energy returning to the string results in reduced high frequency content, and a shorter decay time. Other examples of this type of phenomenon happen all over the audio spectrum, in an infinite variety of ways, and it is a major factor in the character of one’s “tone”. If you understand how energy is transferred back and forth from the string, to the mass of the guitar, and back to the string again - thousands of times over the life span of a sustained note - you start to grasp how the wood, hardware, construction methods and quality, frets and even finish can affect a guitar’s tone.
So, it is correct to say that pickups are not hearing the acoustic properties of the wood, as a microphone would. They are indeed only sensing the vibrations of the ferrous material within their magnetic field. Nevertheless it’s a mistake to ignore how the wood, and everything else, affects the strings’ vibrations, and ultimately “tone”. Pickups are certainly a huge factor. But just as the sound of Etta James singing into an SM58 or a U87 is still very much the sound of Etta James’ voice, the tone of a guitar starts at the source - the player, strings and guitar. Those three elements are responsible for how energy gets manipulated by acoustic resistance before the pickup ever has a chance to turn it into the induced current that your pedals and amp can use.
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