There are two main types of magnets used in today’s pickups – Alnico and Ceramic. And with these two pickup magnets comes their own set of features, most prominently of which is tone. Of the two, you’re likely to hear that alnico magnets give off a brighter tone. This unfortunately is incorrect; it’s not what the magnets are made of that influences their sound but their strength. But as that old saying goes, where there’s smoke, there’s fire, and in this case, there actually is something to that rumor of alnico being brighter.
Alnico is a lot more expensive than ceramic; so much so that alnico is almost never used in grades of 5 or higher (grades are used to tell a magnet’s strength but only in comparison to magnets made of the same material). In order to keep down costs but still have a magnet with strength high enough for something like a high output pickup, ceramic is used. Interestingly enough ceramic magnets are actually weaker than alnico when they are of the same grade and size – but only after a certain point though. When it comes to magnets the size used in pickups however, ceramic is actually stronger. Which brings me back to that rumor of alnico pickups being brighter; if you had pickups the size of a football, yeah, the alnico will be brighter – but good luck trying to fit that inside your axe!
Magnet Age and Tempering
Another general thought regarding alnico magnets is that they weaken with age. Well, that’s technically true, but as far as tone quality goes, it’s completely irrelevant at best – and a misleading idea at worst. Most manufacturers state that magnets lose their strength at the rate of 0.2-2% every one hundred years. Besides the fact that most of us will probably never see that age (assuming we bought out pickups when born), 2% is nothing to worry about. Not only that – aging can actually be quite beneficial to a pickup. There are a lot of manufacturers out there who artificially “age” their magnets all the time by applying a high degree of heat. Yes, this does make a magnet weaker, but benefits of heating far outweigh any loss of magnet strength (which is so small that it you probably won’t notice any negative effects, at least not nearly as much as you’ll notice the positives). By heating an alnico magnet – also known as tempering – you actually end up evening out the strength of the entire magnet, giving you a balanced output for each of the poles (and in turn, each of your strings).
There are a few different things that can lead to an alnico magnet being uneven in strength. One of the more common causes is a difference in the magnetic strength of the poles which can wear into the pickup after some time. Also, some alnico magnets simply aren’t tested for evenness in strength. Fortunately though, it’s not a common problem with new pickups and even still, tempering is not that tough of a job – as long as you have the right tools and take the necessary precautions. Also, you can just stick with ceramic magnets.
The Little Things
While these may not be a crucial to the overall sound of a pickup, there are a small changes that can affect the tone of their magnets. First off, how they are placed has an effect on the signal that is created by the pickup. If you take a look at a P-90 type pickup, you’ll find that the polarity of the magnets are repelling each other while most others tend to have the polarity attracting each other. As far as tone goes, having magnets facing in opposing polarity tends to sound rounder but “less focused.”
And with that said, don’t even be afraid to experiment with different types of pickups. You never know, a tone that really speaks to you might be just a few mods away!