by scmitche » Thu Jun 16, 2016 12:51 pm
Hi,
I think NM refers to Neodymium magnet material. It's one of the most powerful magnets on Earth and is used in some high power loudspeakers as it is also lower density and hence quite light.
It's worth reading a lot of the old articles by Bill Lawrence on pickup magnets, cores and construction. Then you start to realise that pickups with ceramic magnets can be made to sound good, e.g. Godin pickups. The main reason they all sound different is often down to the inductive properties of the pole pieces particularly in Strat pickups, i.e. large inductance = lower resonant frequency and vice-versa. Bill always said that a magnet is a magnet but that its different properties must be taken into account when designing and winding the pickup.
Hope this helps.
Regards,
Steve