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Hello All,

Been following the threads over on the Prospecting OZ Forum about Doug and several others claiming the GPX-4000 is missing nuggets in the "Sensitive/Smooth" mode. I can't honestly comment on this, since I haven't tested the Smooth mode at all.

I do know for a fact the GPX-4000 in the "Normal/Deep" mode was able to outshoot my GP3500 hands down with the settings cranked up past the Factory Default Settings. The GPX-4000 heard a very small nugget, a nugget right at 7 Dwt's and another at 1 ounce deeper than the GP3500. This is the only test I have concluded with the GPX-4000 vs. the GP3500.

I'm going to do some testing this weekend on deep nuggets in the "Sensitive/Smooth" mode to see if there is actually a lose in depth. Kind of makes me wonder if there is a "dead zone" in this mode or it just has to do with the soil conditions in Australia.

I promise to keep you posted on my findings. This is the main reason I held onto the GP3500. The GPX-4000 seems amazing, but I want to make sure there are no bugs before I let the GP3500 go.

Here is a post I copied from the other Australian forum -

4000 and large nuggets in sensitive and smooth"

Not sure why those guys are having trouble hearing a larger nugget at

depth? I am guessing they are having problems with setup and or combos

of functions. I have no problem hearing large (planted) targets at

depth equal to my 3500, but struggled a bit at first learning to set

the 4000 up. This detector is not the same as an earlier GP series and

one must learn to use the settings properly to avoid such problems

since they can under most conditions be adjusted to suit most ground I

have encountered (in the US)"

Dear Bill Southern

The guys that did the testing are NOT having problems with the setup

of the 4000.They are extremely experience prospectors and users of all

ML machines and in fact have taught hundreds of others how to use ML

detectors over many years. Their testing over a number of days CLEARLY

shows that in sensitive and smooth that certain nuggets at certain

depths are NOT detectable with ANY size mono coil in sensitive/smooth

with the 4000. This has now been observed also on some VIRGIN nuggets

in VIRGIN ground ie nuggets that gave NO response in sensitive/smooth

were EASILY detectable in sensitive/extra/ deep. Bill you should accept

the findings and not question the ability of the testers or the

testing methods. The 4000 when used in sensitive/smooth has an

"ELECTRONIC HOLE" through which some nuggets including some very BIG

ones will fall. Unlike many forums including yours my forum is not ML

dealer run or controlled and is truly independent and I am sorry if

the testing results irk some ML dealers and promoters which is not

surprising as ML and the dealers are pushing the sensitive/smooth mode

on the 4000 very intensely. If people in the US want to get the best

results when the ground is suitable then they should try the settings

of mono lover as described on my forum with the gain adjusted

according to prevailing ground conditions and EM noise. At least then

they can be confident that they will not leave behind a good nugget

as they may if they use sensitive/smooth.

Best regards


Take care,

Rob Allison

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Guest southerndesert

Hi All,

I never meant to insult anyone regarding their experience at detecting and was only trying to point out some of my own observances regarding the GPX400 and depth.

I should add that I am speaking about the front control Panel "sensitive" setting.

Sensitive smooth is designed to hear only a small range of targets in the top layer of soil and will if used dimish depth on target large and small targets if the operator is hunting deep gold. This setting is mainly for hunting shallow areas with allot of hotrocks etc. and will dramitically improve stability and target response within it's range. This is not a mode designed for deep hunting....

The sensitive mode previously called "sensitive" is now "extra" on the 4000 and I was thinking this is causing some confusion is all.

In extra with a standard hunting setup (per soil conditions ie: N etc.) I see no depth loss when compared to other GP units here in the USA.

Good hunting, Bill

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Doug, Bill, Rob . The sensitive/ smooth settings are definately not for every day detecting . You will definately miss some nuggets. On the other hand, in certain extremely nasty ground you will hear some nuggets that you can't hear in any other mode, including some very small ones, but probably not at extraordinary depths. In moderate to mild ground it should not be used as primary settings. I realized belatedly that I was ,at times using it on ground where it was putting me at a big disadvantage. It will take some folks a little while to figure out the right settings for the ground being detected, but once the detector is learned, in my opinion it is by far the biggest advance in PIs since the SD2100. I'm surprised that Minelab didn't string out the improvements in little increments over 2 or 3 models like they have done in the past. In my opinion this one is a big jump. I think it can handle just about any situation here in the States, except the big slabs of ironstone. Maybe the next one?? I was blown away today when I got 9 nuggets for a total of .5 grams. one was by far the smallest I've ever found with a PI. I had it tweeked almost to the max and almost no interference. Just that reduction in interference alone here in the U.S. was a quantum leap. I know some people would wonder why I was excited that I found such small gold. Well to me this means that I can make short morning trip just outside of town and find a few nuggets on one of the local dink patches. I also think that more sensitivity to smaller nuggets might mean more sensitivity to some deeper larger ones. Time will tell. In the meantime I'm finding nuggets at a faster rate than I have for years.----Bob

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