audioholic
5,000+ posts
not a moderator
The center pole on the stroker is to allow adjustment of resistance on movement of the cone. This allows you to dial in your suspension to the enclosure used and power provided to maximize cone movement. Ive been told this also allows you to 'tighten' the strokers motion, losing output but gaining some SQ. Ive never played with one of these myself so I dont know.
