This is part of some investigation I've been doing into how the positioning of a pickup affects tone. Discussions about what lies behind the distinctive tones of classic guitars too often concentrate on things like the electronic charateristics of the pickups or the woods used for necks and bodies. While those factors certainly contribute they are by no means the "be all and end all". They do not, for example, explain the changes in tone when different pickups are selected on multi-pickup guitars. To understand guitar sounds you need to understand the significance of pickup placement.This diagram gives a very simplified picture. For a start, the levels of the different harmonics will vary and they are unlikely to all be equal in magnitude as in the diagram. Also, the diagram deals only with open strings. If you fret a string then you change it's effective length and the positions of the harmonic nodes will shift relative to the positions of the pickups. Nevertheless I think I have made a start towards understanding what really causes the differing tonal characteristics of electric guitars.Note, for example, how the neck pickups of strats and telecasters sit over nodes for the 3rd and 7th harmonics, which presumably means these are mostly absent from the tone of the guitar's open strings when only the neck pickup is selected. Contrast with the neck pickups for Gibson Les Pauls.(NB: The magnitude of vibration is greatly exaggerated in the diagram to better illustrate the positions of nodes and anti-nodes.)
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"...The pickup position response is a comb filter curve and the pickup width response is a 6dB per octave low pass comb filter response.
These equations only apply to the mechanical effects of position and width for sustained fundamental and harmonic vibrations. Certainly there are many more factors that affect the sound, including body resonances, the initial transient, electrical characterists of the pickups, and so forth."
Hey! Everything converges on the bridge! This illustrates that obvious point, in a useful and informative way.
I can see why I'm "bassier" when plucking up towards the peak of the 1st harmonic - the longest frequency wave. I see also why I like my bass pickup here, too.
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Recently discovered that someone with better maths and physics than me has worked on this in much greater depth.
http://www.till.com/articles/PickupResponse/index.html
"...The pickup position response is a comb filter curve and the pickup width response is a 6dB per octave low pass comb filter response.
These equations only apply to the mechanical effects of position and width for sustained fundamental and harmonic vibrations. Certainly there are many more factors that affect the sound, including body resonances, the initial transient, electrical characterists of the pickups, and so forth."
Hey! Everything converges on the bridge! This illustrates that obvious point, in a useful and informative way.
I can see why I'm "bassier" when plucking up towards the peak of the 1st harmonic - the longest frequency wave. I see also why I like my bass pickup here, too.
Thanks!