Exposed pole pieces, does it matter?

[Kwesi]

Does having exposed pole pieces on pickups noticeably alter the tone compared to having them covered?

[joeyl]

hard to say because usually pickups with polepieces are geared towards vintage sound and closed cover pickups are geared toward a more modern smooth sound. Should make too much of a difference for the exact same pickup since the covers are transparent to magnetic fields, except you won't get the "clank" sound of the strings hitting the polepieces

[Ach]

No, polepieces won't alter the tone if covered. Plastic does not affect on electro-magnetic flux.

However pickups with covered magnetsd are usually has a rails instead of polepieces