Almost exclusively use disc 1, iron audio on and 28 iron disc here for land hunting where there is trash/nails.... Listen for a cleaner tones from any direction, you can trust the iron audio to a darn high degree, I have yet to have it lie to me (but I still dig most of the bad sounding targets....). Found a couple smaller gold rings this summer on land, if I remember correctly, one read 32 and the other either 28 or 41/42 (can't remember). In all metal, for hunting cleaner sites, around here, depth is increased by 2 or 3 inches. Used mine for this past season and love it, never imagined it would be such a performer!