I have come to the conclusion that 'soils ain't soils', That soils can be classified as noisy or quiet. Recently I went to some very quiet soil in a gold field and the difference from salty beach sand was amazing. I was able to get a very pure, quiet threshold at the gold field. At the beach, luckily I have a TDI which 'speaks to me' and with some tweaking I manage the noisy beach sand. Wow! Was the gold field a dream ( except for the lead bullets and casings everywhere ) My TDI can pick up a single metal buck shot 30 cm ( 1 Ft ) down, unbelievable. Those Chinese miners really new how to extract gold, clean as a whistle.