Re: can someone explain all of the alnicos to me?
PICKUP MAGNET TYPES
Three types are used: Alnico, ceramic and neodymium magnets, the latter being a fairly new addition.
Alnico Magnets
Alnico is an alloy of (mainly) Aluminum, Nickel, Cobalt and iron, in various measures. Alloy variations make for a range of Alnico magnets that each have their own tonal characteristics when put to use in a guitar pickup.
A2 - Warm, very midrange sounding with smooth treble, great dynamics, loose low-end, low output.
Very useable vintage tone, sweet and dynamic. Great sustain (the weakness of the magnet has very little damping effect on the strings).
A3 - Similar to an A2 but a little brighter, more open sounding, and has a low mid frequency bump. Good note definition. A beautiful, delicate sound.
A4 – A very balanced voicing, medium output. Sounds neither warm nor cool. Superb note definition. String attack has a particular kind of stiffness to it (or directness if you will).
Some feel the A4’s even frequency response sounds a bit flat or lacking character, but this seems to depend, as always, a lot on the kind of pickup/guitar combination it’s in. Some pickups designed around A4’s are simply excellent.
Replacing an A5 bar magnet with an A4 may work wonders if you have a neck pickup that sounds too boomy.
A5 - The hi-fi type of the Alnico family; lots of bass and treble, scooped mids. Treble is of the bright, chimey kind; bass is plenty, fat and round and has somewhat of a spongy attack. High output. Very good note definition. With its clear, scooped, modern sound, it is currently the most commonly-used alnico.
When an A5 loaded pickup’s high end sounds too fizzy, swapping in a “roughcast” A5 will reduce, or even resolve the fizziness.* For neck pickups, roughcast A5’s are a smidge less boomy than A5, but also don’t sparkle as much as a polished A5.
While roughcast A5’s preserve the typical A5 tonality, “Unoriented” A5’s** are different altogether, with more midrange, less bass and treble. Frequency-wise UOA5’s are situated halfway between A2 and A5, like a more midrange sounding A5 or a more modern sounding A2.
A8 – Sounds like an A2 on steroids; lots of punchy, beefy mids. Low-end is tight and well defined, but never dominant. Compared to A2 the A8 magnet has a wee bit more high end, better note definition, and much higher output. In high gain situations the A8 sounds warmer and rounder than the harsher sounding ceramic magnets.
Because of its midrange heavy output, A8 may not be the ideal choice for sparkling cleans, but for overdriven sounds these are great.
A8 is the priciest and strongest magnet of the Alnico family: a Duncan ’59 pickup with an A8 magnet gives about as much output, volume wise, as a Duncan JB–while retaining the pickup’s original PAF dynamics.
There are some other alnico types but not all of them are easy to find, or useable. A6 is said to sound very much like an A8 but a little darker (they are used in some lipstick pickups). A7 is said to be harsh in the worst possible way, and was only ever used once in a production guitar that nobody bought.
*Usually, magnets are cut and polished to a smooth surface to create an even magnetic field. The vintage magnets or yore came unpolished with a gritty surface, like cast iron, so the magnetic field isn’t super-smooth, and this has an effect on the tone. The effect depends on how rough the magnet’s surface is, of course, and this varies from one manufacturer to another, from one batch to another.
**A2, A3, A4 are always unoriented. After smelting, liquid A5 and A8 alloy is placed in an electric field so that all the magnetic particles align in the same direction as the magnets solidify. This allows for a stronger magnet, but it also affects tonal characteristics.
Ceramic Magnets
Strong (A8 is comparable in strength) and cheap magnet. There are varieties but it seems nearly all pickups that use ceramic magnets use “ceramic 8” types. Though cheaper than alnicos, ceramics are found in plenty of quality high-output humbuckers usually designed for metal.
They have a real directness in string attack. The sound spectrum is fairly balanced (with ample bass) and there is an abrasive grit to the tone which is much appreciated by metal players.
Maybe not everyone’s favorite for clean sounds because of its relatively “hard” character, although this is subjective and much depends on the overall pickup design.
Ceramic magnets are rather brittle and snap quicker than you'd prefer.
Neodymium Magnets
These magnets, sometimes also called “rare earth magnets” or “earth magnets”, exist in a class of their own. A handful of manufacturers have produced pickups with them, but these are specifically engineered designs built to accommodate the magnet’s extremely powerful magnetic field.
The sound they produce is very defined from top to bottom across a wide frequency range; smooth, slick, metallic (though never in a harsh way) and very clear.
When swapping them into an existing pickup one needs to take into account that the excessive pull of the magnet will seriously dampen string vibration to the point of killing both tone and sustain, if the pickup is set close to the strings.
