Guitar Pickup Poles

Guitar pickup poles primarily sense vertical string movement (moving toward and away from the magnet) because this causes the greatest change in magnetic flux. Horizontal or side-to-side movement does not significantly change the string’s distance from the pole, meaning that being slightly “off-center” doesn’t change the core signal as much as changing the vertical distance would. Thinner strings (like the B string) often sound naturally louder, so their pole pieces are sometimes lowered to “tame” them, regardless of their proximity to the center of the pole. A question recently arose regarding the proximity of the two high “E” strings over the middle guitar pickup poles on the above pictured guitar.

I understand that all pickups are not created equal. As a builder I also understand that the pole pieces do not have to be centered-they just have to be close. Understanding the physics of a pick-up means that the string only has to be in the orbit of the magnetic pole piece to operate.in the coil’s sensing range. When the guitar is plugged in and played only then can you tell that being off 1/2 mm has no effect on the volume and tone of those two strings. So, the overall influence on the character of the sound is determined by the nature of the pole piece of a pickup’s magnetic field and how it interacts with the strings.

A pickup does not create six isolated “spikes” of magnetism emanating only from the pole pieces. Instead, the magnetic field is a large, unified “cloud” (often described as shaped like half an apple) that extends well beyond the edges of the pole pieces. Because the strings vibrate within this wider plane, they don’t need to be perfectly centered to produce a full sound.

The permanent magnet in the pickup magnetizes a portion of the string itself. The vibrating string then acts as a small, moving magnet. The copper coil around the pickup “listens” to this moving magnetic flux. As long as a portion of the string is sufficiently magnetized and moving within the coil’s sensing range, the exact horizontal alignment over a pole piece is secondary to the overall height and magnetic strength.

• Magnetic Dampening: Too much pull from the magnet can physically interfere with the string’s vibration, killing sustain and causing “wolf tones” or odd oscillations. Too much pull can also take strings out of tune.
• Non-Linearity: Extreme proximity can cause the pickup to become too aggressive or shrill, as the magnetic response becomes highly non-linear ” (relationships or systems where changes aren’t proportional, causing sudden jumps,  or complex behaviors.) 

One has to remember that guitars are simply “tools” for musicians to get across a musical point. All are created slightly differently which can produce “different” sounds and tones. In some cases these slight changes can define a great instrument. The point is to “look with your ears” and not your eyes when seeking out a great guitar. Try not to select an instrument on the basis of “beauty” or “perfection” but how it feels, plays and ultimately sounds in your hands. Lots of great guitars have been passed up by using the wrong methods to select a great sounding instrument. Not everything in this world that looks perfect-“is perfect”. Never judge a guitar by how it looks.  Judge a guitar by how it feels, sounds and plays.