Mixed Magnet Pickups; 1) Alnico magnets
So why bother with mixed magnet pickups? Well, opinions vary, but personally, I feel 80% of a guitars tone (excluding the amp / speaker set-up) is derived from its pickups, the rest from the mechanical construction, woods etc.
And of that pickup tone, the magnet type is the major tonal contributor. There are many other factors (see Ironstone's own Electric Guitar Pickups Explained), but the magnet type sets the basic 'palette'. So understanding how a mixture could influence tone offers interesting possibilities.
In the first part of this blog I will focus solely on Alnico magnets. I'll follow up with ceramic mixes later.
As you may be aware Alnico magnets are simply magnets made primarily from a mixture of aluminium, nickel and cobalt. The ratio of these main ingredients gives variations, and guitar pickups usually focus on Alnico II, III and V (i.e. 2, 3 and 5). There are many excellent and exhaustive sources of magnet information on the web, so check out some examples;
Alnico types and characteristics;
Based on A. R Duchossoir's Stratocaster and Telecaster histories, Fender originally used Alnico II and V. Alnico III is also now a little more common in mainstream pickups like the Tonerider Hot Classics.
To very briefly summarise the Alnico capabilities;
Alnico V; By far the commonest Alnico pickup magnet variant. The strongest of these 3, its well suited to bridge positions where the string vibration is smallest. Tonally its normally described as hotter, more aggressive and warmer in the mid-range. So a natural match for Bridge pickups and lead guitar work.
Alnico III; The weakest of these 3 and actually has no cobalt in it (so its really an 'Alni' pickup!). With the weakest magnetic strength its ideal for the neck position where the string vibrations are strongest. A softer overall tone than Alnico V, but with great clarity and note separation.
Alnico II; The grandfather of pickup magnets tracing its line back to the Telecasters of the early 1950's. Soft clear tones are the key to Alnico II, without any treble brittleness.
So how can you mix it up?
Using different magnets in different pickups.
From an experimentation perspective (and mindful of budgets!), the easiest things to try are putting pickups based on different magnet types in the same guitar. Ironstone's own Telecaster set does that. An Alnico V is used for the bridge to give the set 'bite' along with an Alnico III neck (as the Toneriders I mentioned before). The Alnico III neck gives a fuller bass and seems a better match to that ideal vintage 60's tone.
The Eric Johnson signature Strat set uses the same neck and bridge combo.
Otherwise its simply a question of scouring around for a second-hand set of different magnet pickups from the style you already have.
Using different magnets in the same pickup pickups.
OK, so this is the one for true guitar tinkerers! Its possible to buy different Alnico rod magnets for guitar pickups from a number of sources such as;
Thinking of Strat pickups, traditional fibre bobbin construction does not allow pole piece changing. But with some care, in most plastic bobbin styles its possible to pop out magnets and place new rods in. There is some risk of damaging the coils, so best practise on a cheap basic pickup!
Simply tap the required poles out from the bottom using a small screwdriver tip and a small hammer, taking care not to touch any exposed coils with the screwdriver. New pole pieces (correctly magnetically orientated) can then be tapped back in, again from the bottom.
So that gives the possibilities of putting (say) Alnico V magnets in the 3 treble slots and Alnico III for the 3 bass string pole pieces. That's a real 'boutique pickup' configuration!
So there is some real fun and experimentation to be had by mixing up those magnets. In fact its a bit surprising that more of the larger manufacturers don't offer mixed magnet pickups as standard!