The main difference between the two styles of guitar pickups is the magnetic field.
Mini Humbuckers use a single bar magnet that sits between and below the coils. The magnet physically touches each set of posts and creates an opposite magnetic field in each set.
A Firebird pickup uses two “rail” style bar magnets, one or which is placed in the center of each of the bobbins that the coils are wound around. This design does not use steel posts because, the rail magnets are able to pick up the string vibrations. The main difference between the two styles of guitar pickups is the magnetic field.
Mini Humbuckers use a single bar magnet that sits between and below the coils. The magnet physically touches each set of posts and creates an opposite magnetic field in each set.
A Firebird pickup uses two “rail” style bar magnets, one or which is placed in the center of each of the bobbins that the coils are wound around. This design does not use steel posts because, the rail magnets are able to pick up the string vibrations.