The Effect of Guitar Pickup Pole Pieces
It’s surprising how little pole pieces are discussed, given how important they are in determining the sound of a pickup. Pole pieces are the component that provides magnetism to the guitar’s strings. They can come in many varieties, including magnets themselves. In most humbuckers, the pole pieces are either screws or cylindrical metal rods (called a “slug”) that go through the coils and connect with a bar magnet underneath. This magnetizes the pole pieces, extending the magnetic field to the guitar’s strings.
Pole pieces come in several variations – screws, slugs, magnetic rods, and bars/blades. Even within each category, there are differences in alloy, length, and volume, that all have an additional impact. Different pole pieces have different magnetic properties and affect the pickup’s inductance values, altering the overall tone.
The most common configuration of humbucker pole pieces is called Single Screw (or “6 Screw”), which combines one bobbin with 6 slugs and another with 6 fillister screws. This is what’s found on the earliest humbuckers made by Seth Lover at Gibson, though his original patent images actually show a pickup with 12 slugs (Double Slug).
Double Screw (or “12 Screw”) has become very popular in modern pickups over the past few decades. This configuration removes the row of slugs, and replaces them with the same screws used for the other bobbin. Generally, these are either Filister Screws or Socket Head Screws, both of which behave much the same. Bare Knuckle pickups even allows you to choose between them in their configurator for all pickups that use screws.
There is a category within Double Screw that is different – Set Screw. From the top, these look identical to Socket Head Screws, but they have a uniform thickness throughout. This increases the amount of material, and any difference in ferromagnetic material inside the coils will change the sound. DiMarzio specifically sells many models with set screws, such as the Super Distortion and many of Steve Vai’s models. Unfortunately, these pole pieces are rarely ever specified. As we find them, we’ll continue to call out which is which.
We have 3 great example pickups to show the differences between these different pole pieces – the DiMarzio Titan, Fusion Edge, and Transition. Each of these pickups is roughly 11K, the same wire gauge (43 AWG), and use the same magnet. There is one difference – the Titan uses a brass baseplate, while the others use nickel silver. This shouldn’t impact the overall story of the curves on the next page.
|DiMarzio Titan||DiMarzio Fusion Edge||DiMarzio Transition|
|Inductance||6.68 H||6.77 H||6.36 H|
|Magnet||Large Ceramic||Large Ceramic||Large Ceramic|
|Resonant Peak||2.3 kHz||2.4 kHz||2.4 kHz|
When you notice that Double Screw pickups are generally paired with ceramic magnets, their utilization makes more sense. Ceramic magnets tend to create a steep resonant peak, which can be good or bad based on the context. By using screws, that steep peak can be tamed, adding back more balance to the pickup. This doesn’t mean that a sharp peak is always bad, it just depends on what the player prefers. Suhr Guitars has a great line when comparing their single screw to double screw pickups, saying that “[Double Screw is] warmer and fatter with a smoother response to your picking attack.”