Today I was looking for Gold rings, but ended up with 8 nickles, some dimes & quarters, my settings on my ORX using the 9" HF coil where . Coin Deep -72 gain , 2 sweep speed- disc set to 5.5 Now I have done some testing on 6 gold Items from 10k-- to 14 K in yellow and white gold I wanted to find which frequincey Hit the Gold the best . and after going threw 13.3- to 58KHz i found i got all objects better and deeper using 15.6 khz so if i run across gold i have probably the best chance of finding it
Anything higher than 20khz is more for tiny gold nuggets not gold with alloys like jewelry. I assume you are hunting gold jewelry?
Alot of the older vlf, single frequency detectors that were great at finding small gold jewelry ran around 14khz to 17khz so your 15khz is right there in between. Big thick gold rings can be found easily as low as 4khz.
Alot of the beach detectors will run very low frequencies to deal better with the mineralization found on the beach in salt water.
Frequency should be better selected by what you are hunting for and where. the the two things that really make a difference are type of metal/alloys and size. And then there is depth.
Low frequency better on high conductors and bigger targets, better depth
High frequency better on low conductors smaller targets, less depth
This is where multi frequency gives the best chances on a wider range of targets and depth.
The 15 khz might hit a smaller ring but maybe only up to 6”in your soil and miss that ring at 7”.
The beach is the best place to look for gold rings and some can be very deep.
Air tests and actual in ground results can also be very different