Gold depends on a lot of factors, including depth, mass, shape, content, soil makeup, etc..... It can and does come in anywhere from 2 to 40 typically.
Silver and copper most often will register 38+, but also come with the same caveat as gold relative to size if other than a coin.
Smaller HF coils are more sensitive to small low conductors, however they are not as accurate on high conductors. Inversely, LF coils are more likely to miss small gold and other low conductors, but hit hard and are more accurate on high conductors. In part, the reason for this is due to target bin segment width assignments, which are part of the programming. It is also why the MF coils are the most "honest", because they have the most uniform bin segment widths.
If you haven't already, you should go to the Minelab website and download Randy Horton's FREE e-book "Understanding Your X-Terra", and read it...twice at least. And while you're on Minelab's site, you might be well advised to check out Randy's articles "Which X-Terra Coil Is Best For Me?"
Which X-TERRA coil is best for me? part 1
Which X-TERRA coil is best for me | Treasure Talk
Which X-TERRA coil is best for me? part 2
Which X-TERRA coil is best for me? | Treasure Talk
Which X-TERRA coil is best for me? part 3
Which X-TERRA coil is best for me? - Part 3 | Treasure Talk
Which X-TERRA coil is best for me? part 4
Which X-TERRA coil is best for me? - Part 4 | Treasure Talk
