I can say this with certainty.
Anyone for example who is hunting in heavy nails or iron-- if you are not running 18 kHz freq, you are leaving nonferrous finds in the ground.
This doesn't mean you can't hunt these types of sites and make finds--but it would be very possible for a $1 gold coin to actually be detectable using 18 kHz and not with any of the lower freqs.
Anyone for example who is hunting in heavy nails or iron-- if you are not running 18 kHz freq, you are leaving nonferrous finds in the ground.
This doesn't mean you can't hunt these types of sites and make finds--but it would be very possible for a $1 gold coin to actually be detectable using 18 kHz and not with any of the lower freqs.