What Goes Into A Bare Knuckle? - Magnets
31st March 2023
What does the magnet in a pickup do?
Ultimately, all of our pickups, whether they are Strats, Teles, P90s or humbuckers , generate a signal using the same basic principles: a wound coil is placed inside a magnetic field and, when a steel guitar string vibrates nearby, it disturbs the magnetic field, which, in turn, induces an electrical current in the coil, which then flows through your signal chain. Since this whole process operates within a magnetic field, the strength and orientation of that field is really important to how the whole system behaves.
We use a variety of different magnet grades and sizes to tune a pickup to get the best results and to attain an excellent balance between all of the pickup's elements. Very broadly, we mostly use two main groups of magnets:
Ceramic - a blend of iron and other ceramic materials, usually formed by sintering (pressing the magnet under high pressure from a powdered mixture)
Alnico - an alloy of aluminium, nickel and cobalt, plus some other additives, usually formed by casting the magnet in a mould from a hot, molten mixture. We use several different forms of Alnico, each one having a slightly different blend of core ingredients, which produce differing strengths and properties.
Bare Knuckle founder Tim Mills breaks down the main characteristics of the magnets that we use, in an often-quoted post on our forum:
"Magnets do add to the character of a pickup although it must be understood that a magnet doesn't have a sound on it's own, it contributes by the way it accentuates certain frequencies as current is produced in the coil windings.
Alnico II is the softest and generally has a smooth bass and treble although this is more pronounced the hotter the windings get.
Alnico III is very transparent, low output and clean, sounds great for rounded fat jazz applications-typical of '50s tone.
Alnico IV is probably the best vintage tone IMHO(for humbuckers) and along with II and III was used in the earliest PAFs-this is a fact and not myth as we've had them analysed and a collegue of mine has also seen original Gibson purchase orders that clearly state AIV bar stock being purchased. The tone of AIV is balanced and extremely organic, it produces the most authentic vintage tone and sits better in slightly hotter vintage winds than AII which tends to get very soft in the bass and highs if used incorrectly.
Finally Alnico V is the hottest producing more highs and lows, great for rock applications or where power and cut are important.
Different companies use different grades for personal reasons, we use all of the applicable Alnico grades to suit the correct design, both to be historically correct but more importantly to have the best sound.
Changing magnets in a humbucker can give dramatic results, you soon find the ones that really don't sit right and others that are head and shoulders better. Obviously you can't swap out single coil magnets as they're integral to the coil form.
I've personally spent alot of time voicing all the BKP range with the correct magnets but I do tweak and swap sometimes on consultation with a customer with a specific requirement."
Ceramic magnets are the strongest of all the magnets that we use and will tend to tighten bass response, produce very crisp and clear highs and have a faster pick attack, as well as producing a stronger overall signal. This makes them particularly well suited to fast, concise, heavily distorted styles.
Another important attribute of the magnets that we use is the structure of their magnetic field, with two significant varieties used among our pickup models: Isotropic and Anisotropic
Anisotropic magnets (which make up the majority of the magnets that we use) are very strictly ordered / polarised right down to their inner crystalline structure, so, when magnetised, every bit of them is aligned in a north/ south direction, giving them a very strong and unified magnetic field.
Isotropic magnets have a much more muddled internal structure, so, when magnetised, although they do still have a distinct north and south side to the overall magnet, the internal structure is not aligned nearly as tightly, resulting in a weaker, more "fuzzy" magnetic field.
Some lower grades of alnico such as Alnico III are isotropic by default, but we have also used isotropic variants of stronger Alnico V magnets to great effect in models like the Unity, Polymath and Peacemaker, to create a very natural response with exceptionally rich and balanced harmonic content. It's an excellent option for a "modern-vintage" feel, where it's important to have both clear headroom and an overall full frquency range, driving an amp hard, while not becoming spiky or sterile. The success of those models is certainly testiment to how well the isotropic magnets can work!