I have an AT Max and, while I'm by no means the most experienced MDer around here, I have composed a "cheat sheet" for several environments that are commonly encountered when MDing. I have gleaned these settings from both the Garrett Users Manual and from my understanding of the settings of users from this forum
To whit:
When in highly mineralized soils
-First Auto Ground Balance
-Lower Iron Discrimination
-Reduce sensitivity if noisy
-Use Iron Audio
-Manually Ground Balance slightly negative (-)
When in trashy areas
-First Auto Ground Balance
-use Discrimination Modes
-Use Notch Discrimination
-Use Proportional Audio Characteristics (audio tones? - Garrett Manual geek speak?)
-Reduce Sensitivity
-Use Iron Discrimination (+or-)
Marine Beaches
-First Auto Ground Balance
-Reduce Sensitivity for stability
-Make flat passes parallel to strandline water
-Manually Ground Balance 3 to 4 steps negatively
-Try to operate either entirely wet or entirely dry
-If aluminum rich, Notch out first notch under "Foil" (fine jewelry resolution may be lost)
My current major onshore search area is highly mineralized (hi 80s when Auto Ground Balancing) and trashy (but not super-trashy). I generally run Zero Mode @ 38 Iron Disc, All Metal Mode at 20. Custom and Coin Modes are currently mid to high 30s.
My current marine beach search area is fine quartz sand with frequent fine dark mineral concentrate seams (probably magnetic). It Auto Ground Balances in the high teens. I have been running the sensitivity at six or seven bars with the subsurface water above the strand line ("dry") 12 to 20 inches below the beach surface. Iron Discrimination as above for trashy areas. I haven't worked a fresh water beach or bank yet, except trying to "nugget shoot" one Rocky Mountain stream bank that contained "hot" (seam of red ferruginous) sediments between the gravel and cobbles and I was totally "green" and bamboozled by the environment and did nothing but get discouraged. I'm going to try that one again with some experience under my belt.
All this is at my current sophomoric level of competence at MDing. I welcome any and all corrections, amendments, criticisms and additions to any of the above from any of the old experts at MDing and with particular reference to those operating Garrett devices and, most specifically, the AT Max. I would have loved to have detailed settings info when I was first trying to learn the game.
