Help me understand something about FBS technology

Minelab tells us that FBS detectors run at frequencies from 1.5 kHz to 100 kHz. This should make them the most gold sensitive detectors on the planet. And while they have a great reputation on silver and copper, when it comes to gold the reputation falls off. At 100 kHz, that machine should smoke machines like the GMP and the Gold Bug 2 for sensitivity. They don't.

So why not?

I think you will find this answer elsewhere on this website. But, basically the FBS uses only two frequencies, with the main power in the lowest freq, though there are many harmonics, they are not sampled. The net effect is a low freq detector with some higher freq characteristics (due to the second higher freq), that makes it sensitive to high conductors (silver) but less reactive to low conductors (iron). The FBS is not sensitive to small gold (low conductor) to include thin or small rings or jewelry. You can put a thin ring on the coil and get no response. But it has other qualities such as handling mineralized ground without losing depth which make it suitable for many things, but not gold nugget hunting.

This topic has indeed been covered in some detail before, on here, and on other forums (eg,Geotech1, Minelabowners). Here's one link:
[www.dankowskidetectors.com]