Hi there, I'm building a speaker for my intro to EE class. We were given ten small washer magnets, some washers, a nut and a bolt. Enameled wire is also provided. My group prototyped a speaker with the following configuration: Voice coil wrapped around a paper tube which fits around the bolt (but does not touch it). The bolt is fixed. Two stacks of five magnets each are on either side of the bolt, magnetizing the bolt so there is (in theory) a magnetic field being produced from inside the voice coil as well as outside. Our prototype sounds pretty good, but I'm apprehensive because it seems like the magnets are being wasted because there's only a small part of the actual magnets that are close to the voice coil. I am considering changing the design to the following: All ten magnets stacked up, with a larger paper tube around them and the voice coil around that. My thinking is that it could be better because the voice coil is constantly very close to the actual magnets (not a magnetized bolt). It would also allow for a larger voice coil. The downside I guess is that the voice coil would be heavier, and would only have a magnetic field generated from the inside. Are there any other factors I should consider? Does one voice coil arrangement work better than the other based on intuition or experience?