for hunting older coins at old farmstead sites? I have always had multi-tone, manual ground balance machines of another brand, but have always been curious about Tesoros and since I am now having elbow problems, I've decided now is the time for a lighter detector. These sites have quite a bit of iron around them as most farm sites do, but few tabs. The soil in this area on units with a 0-10 GB scale usually runs about 4 3/4 to 5 3/4, which I think would be considered mild by most people's standards. Do I really need manual GB, or do you think I would do OK with a preset unit? I notice that most Tesoros are single tone. How much variation is there in the tone? --- that is, how much info can you gather from it vs. a multi-tone unit? Thanks in advance for your input.