A spa speaker system is disclosed having a housing with a speaker mounted within it. Relatively small ports are drilled at the grout line every 4-6 courses along the vertical plain of one hollow core and this and every second core is then filled with a high density expanding resin thus filling the core there by providing sufficient strength and rigidity, yet flexibility to the wall structure to withstand significant seismic activity. The metal layer is then removed at a first removal rate wherein a dishing is induced on a top surface of the metal layer until the sacrificial layer is exposed, and simultaneously removing the metal layer and the sacrificial layer at a second removal rate without substantially removing the hard mask. Another embodiment provides that the force magnitude is greater than a magnitude of the sensed user-applied force. The coil bobbin is preferably supported by the leg portions of the first outer flange part and the leg portion of the second outer flange part.