18 is a 3.5" //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif2.5"....the Solo X is a 3 inch coil.
Yeah, I see were you are coming from. I just figured some of the things listed like glue and cooling should be close in most reputable speakers now. I thought the coill diameter would play a larger part.Material, surface area to height ratio, glues used, any additional cooling machined in, etc. Coil diameter is a very small part of power handling.
Neil