GPX4000 - Sensitive or Normal; Deep or General???????

I have a dilema which I hope you can help me solve.
I have a 4000 with the standard 11'' DD and I have recently purchased a Coiltek 470 x 300 mono.
I have been at it for about 18 mths and usually manage to get out once a week to Talbot Dunolly etc.(am now well and truly infected with the bug)
To date I have had about 30 finds ranging from 0.09g to 5.77g, most have been on inside bends of gullies in clay.All have ranged in depth from 1'' to 6''.I have tried venturing over the hills around the gullies but to date have had no luck. Because all my finds have been in shallow ground I suspect that I am not getting the maximum depth out of my gear.
With the mono I find that I can only operate in sensive mode(gain between 8-10). I have tried switching to normal but end up reducing the gain to 6 and wonder if this is so low I will pick up nothing.
The other thing that puzzles me is deep mode , I operate almost exclusively in general. My understading of deep mode is that it will enhance the deeper signal and weaken the shallower signal . And that sensitive does the reverse. So deep and sensitive would tend to cancel each other out?

Hope you guys can help solve the mysteries of my universe before I go totally nuts!
Michael

Hello Michael, the GPX-4000 was different in a number of ways compared to the previous Minelab offerings, firstly was the new digital interface which allows Minelab to include a lot more user controls by making changes in a menu structure rather than a dedicated switch on a panel somewhere. The second thing new to the GPX was a brand new timing that allows an operator to detect in extremely high mineralisation with minimal ground noise being generated.

To access the new timings the operator of a GPX-4000 has to select a switch (Sensitive mode on the Soil/Timings switch) on the front end cap (the panel where the coil lead attaches) then the operator has to scroll down through the menu using the Function select dial till they see the Sensitive menu, then with the Setting dial select Smooth from the two options (Smooth and Extra). The Smooth timings should only be used in combination with a Monoloop coil with the detectors Ground Balance set in FIXED.

Because the detector will run very quiet you can as the conditions allow increase the Gain from a Factory Preset of 8 up a little higher to increase signal brightness but be careful because more noise can cancel out the advantages of using a higher Gain level.

When using a DD coil I would recommend you detect in Tracking mode with a menu selected speed of Medium, on the front end cap select DD mode on the Coil/Rx switch, Tracking on the GB switch, N or Normal on the Soil/Timings switch, and General on the search mode switch. If the gold tends to be shallow and small then selecting Sensitive and opting to use Extra in the Sensitive Soil/Timings menu will bring the smaller targets response in much stronger. When using the Normal timings I recommend you revert back to a Gain of 8 and increase from there, I rarely have to go below 8 which is the factory preset of all other other previous Minelab PI's.

Now to explain the Search mode switch positions, Minelab have named them Patch, General and Deep. Each one of these search modes can be personally optimised to suit your particular detecting style but as set from factory are recommendations only so if you liked you could make them all exactly the same. Where it gets confusing is the detector has two Deep modes, one is the Deep search Mode option and the other is an audio filter option which confuses a lot of people.

I use my GPX in Deep mode all the time (thats the Deep mode audio option found in the Mode edit menu under Audio). It is perfectly fine to use Deep audio and Sensitive extra together contrary to the logical thought of the two counteracting each other. Sensitive Extra is a timing change where the receive circuit is turned on at an earlier stage which means the eddy currents of small targets are still present compared to Normal timings. The Deep audio filter is just that a filter that slightly broadens and strengthens the audio response so that deep targets stand out from background noises, generally the filter has minimal impact on targets closer to the coil but does have a huge impact on deep nuggets especially ones right on the maximum detection range.

Hope this helps answer some of your questions,

Jonathan Porter

Hi Staples and JP,

I am not lucky enough to have a 4000 or 4500. Only got a 3500.

I think every 1 who is a member of this forum are lucky, why, lucky to have some 1 like JP offer his time and advise to newbies.

I am not sucking up by any means here.
Just think its great JP is willing to lend a hand.

So to all the Individuals who bag a certain person " stuff you all"

just my 2 cents worth.
sorry for hijacking the topic

madmax800

Jonathan,
Thanks very much for those tips. I have made a copy so that next time I am out and totally confused - I can get them out, dial them in and feel confident again.
Jigalong

Jonathan,

Many thanks for the advice which has cleared the confusion in my mind,appreciate yourself helping a newbie

Thanks again

Michael

Glad I could help Michael.

JP

Madmax800:
I think Jonathan Porter has a wealth of advice for both experienced and novice Prospectors alike and his advice stems from personal experience and a genuine interest in his Detecting pursuits. He drops by a number of forums online, answering questions from time to time, and it just goes to show how enthusiastic his passion for Detecting runs. He takes time to respond to a lot of simple questions that many others don't seem to have the time to answer. And he's always happy to share what he has learned.

I was detecting a property this morning and wondered how JP would handle the soil their (ie. what sort of coils and setting he would use). In the end, I just had to figure it out for myself but it was a case of mysterious Ground Noise that had me quite baffled and hampered my detecting for a while. I don't mind saying that JP's tips have been very helpful to many people - including myself.

3500:
There's so many detectorists who prefer the 3500 to any subsequent release (including the GPX) - so hang onto that detector. You'll probably see more people here asking questions that have previously owned a GP/SD and are trying to get their heads around the new GPX's. The 3500s are considered by some to be their preferred Detector.