If that's the case, why do we reduce the sensitivity to reduce ground chatter? There must be some co-relationship between the two. Other wise detector stability and the ability to detect a target would be impossible. Think about it, black sand is a metal (iron) and as such you would need to lower the sensitivity to it or to discriminate it out to not detect it.
Well I have thought about it, extensively. Like I said in in my response above, if the detector does not have adjustable transmit power, your ONLY choice may be to reduce sensitivity in order to gain stability, but in that case you are significantly losing depth from both the mineralization attenuating the transmit signal and your reduced ability to sense the target signal because you have lowered sensitivity. Not ideal. However, by having the ability to lower transmit power to reduce the effect of the reflected mineralization noise "signal" and then being able to independently raise sensitivity to be able to "see" or compensate for the reduced strength target signal (due to the lowered transmit field strength) you at least have a better chance of retaining some depth capability.
That's why some people find that using the Equinox in beach 1 or 2 mode in hot dirt and letting it go into overload with reduced transmit power to be an effective way to deal with mineralized soil conditions. This is also why the Deus is considered a good hot dirt machine, because the X35 coils also give you the ability to manually adjust sensitivity independendent of transmit power and is a technique taught by Andy Sabisch and myself when I assist as an instructor in his Deus bootcamp sessions. Equinox just gives you less control than Deus because it is an automatic process that is only available in the beach modes.
One other, less effective, but available adjustment you have to lower mineralization ground noise on both Equinox and Deus is increasing recovery speed. Again, you sacrifice some depth, but if you can lower the ground noise overall in the process, it may help to reveal some shallower keepers in the mineralized muck.
Here's another way to think about it, BH505Man: If lowering sensitvity alone was the key to dealing with black sand, why did ML bother with having an automatic process that simply lowered sensitivity. Just give the user an indication when to lower sensitivity manually. The answer is obvious when you think about it, it is because the user does not have ready access to a transmit power adjustment on Equinox, so the process has to be automatic in software. ML could have chosen to give the user access to a manual transmit power adjustment similar to Deus but for reasons known only to ML, they chose to do it this way, perhaps for user simplicity because you would only encounter it very rarely. That is also why ML carefully and intentionally used the term "transmit power" and not "sensitivity" when discussing the black sand overload feature in the manual.
None of these techniques and features for dealing with mineralization are foolproof btw. Similar to dealing with EMI (where lowering transmit power really has little to no benefit, but lowering sensitivity and/or recovery speed or transmit frequency can help), they all involve reducing noise at the expense of some depth capability, and finding the sweet spot in the tradeoff or at least some level of improvement in an otherwise bad situation (black sand salt beach, super hot soil of Culpeper VA (where I frequently detect) or near an electric cattle fence) can make the difference between finding something or packing up and leaving empty handed.
HTH.
Hope you got the just released latest edition (Blue cover) that references the latest firmware updates. Ironically, I scanned the book and I can't see that he specifically addresses the Overload feature. If you come across a section where he addresses it, let me know. But the book is top notch regardless and gives you some great tips and explanations. Congrats.
