Hello fellow TH.I recently used this detector at a site that had a map and marble signs(sorry no pictures) and it's giving me readings that i never had before{tested on different metals with different size and shapes}One in particular is that it's giving a static sound and for some reason the coil is vibrating.I tried to contact the guy who modified it who is from oz, but haven't got any feedback from him.The diameter of the center is about a foot and a half wide.Any inputs would be greatly appreciated cheers.