I am new to forum but have been THing for twenty years with garrett freedom aceplus and then ace 150. Both have been great machines. After 53 years santa finally came through for me with new at gold and WOW.After my 100th hour my best conclusion is that vdi is usually constant on most us coins but not always. Nichels usually hit at 52 but have found several that bounce 51-54 but with constant repeeting tone (no crackle).Quaters are always 86-88. Dimes usually hit 81-82. Finally dug 1st silver a 6 in. merc that hit 81-84 but very good constant tone. Sorry not set up for pictures yet but will soon. Pennies are from 75-82 depending on the dates. 1985 and older screams but the newer ones usually bounce on vdi and have some sputter with high tone. Most of my hunting with AT gold has been in northeast TX on blackland soil .Autoground balance is from 0 to about 15. This soil is very low mineralizied. Have hunted in East Texas on sandy loam and machine ground balances in the 60"s. Have found 1 gold class ring 11grms hit 70. Found and returned to owner after 31 years of being lost. All of my finds including the ring have been in old parks highly trashed and have been hunted and hunted for years. I tell you this is all new playing field with 5x8 DD. I am amazed with all the nichels I have pulled out of the ground including 1 shield 2 buffaloes and 3 Vs all in hunted out parks. I use gray ghost orginals and they work great for me. Looking forward to the next 100 hrs. I think the sky is the limit with this machine. HH