Magnet Types

Written by Kenneth Prochazka

Sometimes, a vehicle’s engine is visible on the outside, and sometimes it is hidden inside, either front or back. But no matter how it is mounted, the engine is what powers the vehicle.

The same holds true for electric guitar pickups. They are entirely designed and built around one very specific component that you may not even be able to see: the magnet(s).

Because magnets are so integral to guitar pickups, they influence everything from attack to dynamics, from compression to sustain, and ultimately the overall tonal character. Understanding them helps explain why two pickups with similar specifications can sound dramatically different.

In this guide we'll explore:

• Alnico II's warm, vintage response

• Alnico V's stronger attack and presence

• Ceramic magnets' aggressive output

• Rough Cast versus Smooth Cast construction

As always, the goal in this is not determining what is “best”, but understanding what is best for you.

Alnico II Magnets

Alnico magnets were first developed in the early 1930’s in Japan, when Tokushichi Mishima combined iron with nickel and aluminum to create a material with double the magnetic coercivity (resistance to demagnification) of available steel magnets. Adding cobalt improved the durability and magnetism, and thus AlNiCo (Aluminum, Nickel, Cobalt) magnets were born.

In the 1940s, the MMPA (Magnet Materials Producers Association) standardized the grading of Alnico magnets into their current range from Alnico I through Alnico VIII. Before that point, there was simply no standard designation of magnetic power in Alnico magnets.

Alnico II is a low-powered, isotropic magnet, meaning that it does not require a magnetic field during heat treatment and can be magnetized in any direction. It has a moderate amount of cobalt (10-15%) along with the aluminum, nickel and iron, and often includes small amounts (3-5%) of copper.

Compared to higher grades of Alnico, Alnico II has a lower magnetic pull. This means that it tends to produce a relatively warmer, sweeter and smoother tone. Trebles will usually be less harsh, with a rich mid-range and a loose “spongy” low-end. The weaker magnet lets the strings vibrate more freely, allowing notes to “bloom”, and is more sensitive to dynamic pick attacks and rolling off the volume.

Alnico II is famous for being the engine inside of original Gibson P-90s and PAF humbuckers, and is well-loved for blues, jazz and vintage voicing.

We use Alnico magnets as the engine in our '59 Clone pickups.

Alnico V Magnets

Alnico V is a higher-powered anisotropic magnet which is subjected to a magnetic field during heat treatment; this process helps to maximize the magnetic output. It has the highest cobalt content of standard Alnico grades (~24%) along with aluminum, nickel, iron and a small amount (~3%) of copper.

Compared to lower grades of Alnico, Alnico V has a much stronger magnetic pull. This does not allow for as much vibration of the strings, but provides brighter, punchier tone and clearer note separation. Trebles tend to be bright, airy and “bell-like”, with slightly scooped mids and a tight, focused low-end.

Because of its clarity and focus, Alnico V is very versatile and is favored across a spectrum of genres, from blues to rock, and from jazz to metal. It can be found as the engine for Fender Stratocaster and Telecaster pickups since the mid-late 1950s, and as the base for many modern and hot-vintage humbucker pickups because its “snappy” response provides plenty of definition and bite, even in high-gain situations.

Ceramic (Ferrite) Magnets

Ceramic magnets (also known as ferrite) were first commercially available in the 1950s, and are composed of iron oxide mixed with other metallic ingredients like zinc, manganese or nickel.

Because ferrite is less electrically conductive than iron, it performs better than Alnico magnets at higher frequencies. And, with its increased magnetic pull compared to Alnico or iron, it does not need as many coil winds to achieve the same inductance (resistance to electrical change). These two factors combine to give ceramic magnet pickups higher output, sharper attack and more clarity, especially with higher gain.

Compared to Alnico, ceramic magnet pickups will tend to be brighter, more aggressive and more articulate, with a tighter low-end response and an increased ability to cut through a mix. Especially when heavy distortion is employed, ceramic magnets tend to have a sharper, more percussive attack than Alnico magnets. This makes them ideal for hard rock and metal players who need as much clarity as possible during fast, distorted runs.

Ceramic magnet pickups usually have much higher output than Alnico ones, with more cutting highs and compression. They tend to be more consistent because of their composition, but most players give Alnico the edge regarding touch-sensitivity.

(There are some who regard ceramic magnets as “cheap” because they are less expensive to produce than Alnico, and can thus be found in many low-cost pickups. However, the truth is that they are ideal for high-gain purposes and almost a necessity for modern metal and progressive rock.)

Rough Cast vs Smooth Cast Magnets

Rough cast magnets, as the name suggests, have a textured, unpolished and somewhat uneven surface. Smooth cast magnets have uniform surfaces that appear to be lightly polished.

The uneven surface of rough cast magnets slightly scatters the magnetic field, which results in softer highs, more sweetness, and a more vintage nuanced tone. The flatter surface of smooth cast magnets typically results in stronger magnetic pull for a brighter and more defined top-end, as well as tighter bass.

There are no absolutes in guitar tone, but bridge pickups can often benefit from rough cast magnets by reducing some potential “ice pick” harshness, while neck pickups can often benefit from smooth cast magnets by adding clarity and chime.

Which of these is right for me?

The answer to this question will change between guitars, playing styles and musical genres. With this, as with so many components of your own personal tone, your ear is the only true guide - so it should be trusted first and foremost. The only thing left is to get out there, find your sound, and love your tone!