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nuggethunting

MINELAB GPX-4000 PUNCHES DEEPER!

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Hello All,

Leaverite and I spent a few hours testing the GPX-4000 against the GP3500. The first test was to see how both machines sounded on a 1-ounce solid gold nugget at depth. We dug a hole and placed the nugget to where the Minelab GP3500 could just hear a faint whisper type signal. We then buried the nugget back up and leveled out the ground and re-check the response. The signal was so faint on the GP3500, if you didn't know a nugget was there you probably would never even hear it.

The next step was to test the GPX-4000 using the same coil and headphones. Since the battery system was different on the both detectors, we couldn't use the same battery. We check the factory pre-set settings on the GPX-4000 over the buried gold nugget. It was kind of discouraging knowing the factory pre-set modes could not even hear the nugget. The "Deep" mode was just able to hear a peep, but for the most part the factory pre-set settings are less than what the GP3500 stock has to offer.

Well, we were not really interested in the pre-set modes, but more interested in seeing how you can "tweak" the GPX-4000. We pretty much tweaked the GPX to the point where we could easily hear the buried nugget, and even to the point where it was a very good target. If I had to make a guess how much more depth the tweaked settings were getting, I would say somewhere in the range of 1-3 inches.

We pretty much conducted this same test on a smaller nugget at depth. I set up the GPX-4000 in the "Sensitive/Normal" mode and then tweaked the settings for the best results for small gold nuggets at depth. The results were pretty much the same, getting an easy 1-2 inches more depth over the GP3500.

Overall, Leaverite and I were very impressed with the results. From reading all the Aussie reports I was getting worried, but now I'm confident enough to know the GPX-4000 is outperforming the GP3500 without any questions.

Later in the day I found a nice 2.7 Dwt nugget that I missed with the GP Extreme, GP3000 and even the GP3500. I was just at this location about 3 months ago with the Coiltek 14-inch round and GP3500 and flat out missed this nugget at depth.

For all the people that currently own a GPX-4000, start playing around with the settings. I'm not going to just give you the settings, I want you to play around and learn the machine. Everywhere will be different; my best settings could be the worst settings for your ground conditions. You're going to be very impressed with this detector once you get some hours behind it! ;)

Check out the pictures below -

Rob Allison

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Rob,

My 3000 now going by what you have reported here will be way behind in depth compared to the 4000.

Previous reports between the 3500 and 3000 here show the 3500 was ahead of the 3000 in depth so adding those inches onto the extra depth of the 4000 over the 3500 I had better not head anywhere near ground down over by the 4000.

I will be looking forward to what the guy( Doug) down in Australia has to post on his site regarding depth differences between the 3000,3500 and 4000. So far in his test results the 4000 is behind the 3000 and 3500 but is yet to post results with settings I hope that are similar to yours to see what the Aussies have found compared to yours. The tests in Australia are in undisturbed ground and not reburied as you have done.

Anyway will wait to see the comparison from down under!

Thanks for your results.

Brian.

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Rob:

What kind of soil conditions would you say you were testing in as far as mineralization?

Mild, moderate, heavy, extreme?

Chris

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Hmmmmm...... interesting results, to say the least, that has now been posted on the ProspectinginOz forum down under in Australia. Maybe my 3000 is not behind the rest as I have been led to believe.

Regards,

Brian

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Thanks Rob, :)

I too have the new 4000 and will be starting to use it this very morning. I have already played in the back yard with little learned, for obvious reasons. But I will say this......

There are features that I am really excited about on the 4000 that were simple givens on prior models.

First to mind is the ability to adjust the gain, where before you have been subject to whatever the factory setting was and just lived with it.

In my opinion the 4000 will be an asset to those who can grasp the concept of total control verses limited control as with prior models. Control over thing like timing, gain, ect., will in my mind, give some advantage where used properly.

If your going to turn on the 4000 and run in factory pre-sets then you may as well use what you have, because there will be no advantage. Only time will tell what this new controlability will show. I for one am excited to get started..........and that begins right now............ :)

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Hi,

The Oz testing seems focused on the Smooth setting. It seems they are missing the point of what that setting does. The owners manual says smooth sacrifices depth to help eliminate signals from hot rocks and ground noise. So tests that point this out should not be surprising.

The GPX-4000 has four Soil/Timings settings, where the GP 3500 had three. Both units have SALT, both units have NORMAL, and both have SENSITIVE. But on the GPX-4000 you get two SENSITIVE settings, EXTRA SENSITIVE and SMOOTH SENSITIVE.

Sensitive is optimized for improved response on smaller, shallow nuggets. There is a loss of depth on larger nuggets, so you should not use sensitive when seeking out large deep nuggets. This is verbatim from the owners manual. EXTRA SENSITIVE is the same as SENSITIVE on the GP 3500. SMOOTH SENSITIVE is for areas where you are looking for small, shallow targets, but where you are constantly getting signals from hot rocks or very hot ground. SMOOTH SENSITIVE sacrifices additional depth compared to EXTRA SENSITIVE while still hitting smaller gold. If you want to use a small mono coil in very hot ground to chase tiny gold bits, this is the mode for you.

So for the Oz forum to go on about how this mode has poor depth on larger gold in highly mineralized ground is not only unsurprising, it is to be expected. Their test only proves what the manual says.

If they want larger nuggets in mineralized ground they need to be experimenting with NORMAL or even the SALT mode and higher GAIN settings.

The biggest question for most of us should be about how the GPX-4000 does here in the United States. I'm convinced the unit will excel in our ground conditions. Information out of Australia is interesting but frankly does not have much bearing on our situation. I'll put more weight on what Rob and theother guys here in the US say by far. I know the Minelab units pretty well, and I feel comfortable that the GPX-4000 is the best Minelab yet for conditions in the United States, and Alaska in particular. This is not to say everyone with an older model need sell it and get a GPX-4000. What everyone always forgets is not everybody already owns a Minelab! If you are looking for one now, and want the best, then get a GPX-4000. If you wait a year to let us all prove that without a doubt, then you simply will end up being one of those that complains when the next new Minelab comes out. Right now that will probably be in a couple years, so buying now means you get to have the best for a couple years. I've already sold my GP 3500 and will be using the GPX-4000 going forward.

Thanks for the great report Rob!!

Steve Herschbach

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Well guys, The info is starting to trickle in and with 75 nuggets that I have found with it so far I would say that it is definately a good detector. As I have stated before, the ability to make it run with a dead smooth threshold is its greatest advantage. I have learned to trust it to the point that the slightest variation of the threshold brings my pick out if it is a repeatable variation. The number of false targets has been reduced to a fraction of what it was. I have even found that a slight null of the threshold is often a small target at depth. With previous detectors I would never have picked these out because of the wobbly threshold even though it was probably there. JP mentioned this in one of his videoes , that a slight null could be a good target at depth. With the lack of interference in the W.A. outback he would have picked this up. We would rarely be able to with our conditions.

Rob , you are right on about not posting any detailed settings. They definately change for each location and for each coil size . There are no "best settings" . The guys who really experiment and learn the detector will kick butt. The turn on and go guys will not see any advantage at all over their current detector. I was getting bored with detecting with the same old factory presets. I can now tune to each spot quickly and easily knowing that if I do it right that I will have an advantage over those who have gone before. It may not be huge but we have learned from the past that new technology comes in small increments in the detector industry. This small but definate advantage has already put me well on my way to having the new detector paid for in just a few short weeks. Here's a photo of last weeks finds with the new beeper from very pounded patches that were loaded with nasty volcanic hotrocks, every hilltop with a radar site on it, and F-16s like a swarm of bees overhead and surrounded by military bases. Barely a peep of interference and no hotrock headache for a change.-----Bob

post-100-1163301860_thumb.jpg

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Hello Guys,

Good to hear everyone is doing well with the new GPX-4000. The Australian results show no merit to me or what I do here in the US with the GPX-4000. People put too much faith in what the Aussie's are saying, but don't understand the ground conditions over there are 180% from what we have in most locations here in the US. I'm impressed with the results and I've only have found seven nuggets with the new machine for about 5-6 hours of total use.

The Minelab GPX-4000 gives the user many more options than any gold detector on the market today. The user can now pretty much "tweak" all the settings. This will allow you to open up the detector on low to moderate mineralization and turn down some of the settings on the worst mineralization. With the GP3500 and prior detectors you have to work with what is given, you can't "tweak" or "fine tune" the settings to each location like you can do now with the GPX.

Today I picked up a 4-5 grain nugget at 4-5 inches at Rich Hill. The GPX-4000 is most impressive to say the least. ;)

Montana Bob - Congrats on the 75 nugget run. Are those all from one location or patch, or multiple spots since you've had the GPX?

Steve H. - I don't care much for the "Smooth" mode from what I seen so far. You do loose a lot of depth and sensitivity. I don't think the mineralization is bad enough for me to use it, but if I have to that is just another options I have. I like the "Normal/Deep" mode, Volume 40, Fixed Balance, Signal 15, Extra Sensitivity, General Balance, Gain 12-13 and Normal Signal. I picked up a 2.7 Dwt nugget at nearly a foot yesterday with the above settings. The target was just one of those faint whispers though.

Roger - You're going to love the GPX. The more I use it the more excited I get. The machine has so many options it's going to open up a lot of spots where you might have been limited or only able to run a certain coil or settings. Now you can really experiment with different coils and all the settings to find the best overall settings for different patches and goldfields. Thanks for returning my PM; I will be in touch with you. Thanks a million for the offer! ;)

Take care,

Rob Allison

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As far as tests of the 4000 in Oz goes, I would have to go with Rob and Steve.

I have read everything on the forums here (Aust) and I would take no notice of any of these tests to date.

I haven't even seen much put out by JP.

As far as being better for your conditions, well maybe. Your a big market for Minelab. But I think that It will work just as well here. Oz is a huge place, in my state, the ground is mostly mild to moderate. Down in parts of VIC and WA the ground can be extreme, but if the controls on the 4000 work, as they should, I believe that we will also get a small increase in depth even in extreme conditions. I still reckon that this thing will get a 512 k memory stick added in about 18 months. <_<

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Rob, Bob, Steve and all :)

Was that the 14" round or Wallaby you were using with those settings Rob?

Because of the tiny size of the iron meteorites I've been hunting, many of which won't even weigh on a scale, the only coil I have any time on is the Joey mono. And that's a red hot little coil anyway. And I just ran normal, slow and 12-15 on the gain, and smoothe. Most of these are very near or on the surface.

I normally run if fixed, but did try tracking occasionally during the day to see how well it would keep the treshold smoothe and I personally thought it did a tremendous job. But, I don't think I could ever change over to using tracking, and the ground I'm hunting doesn't warrant it's use.

I did find the the sound of the 400 to be somewhat diffrent but easy to get used to almost immediately. Lots of basalt but it has a very distinct uneasy and gurgling sound that leaves no doubt as to what it is. The tiny irons laying near the basalt rang out loud so there was never a doubt.

All in all my first day was most successfull as I intentionally stayed within an area I know has been pounded. :)

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Rob. The 53 nuggets in the picture were from one general area and actually a series of five more or less seperate patches, All pounded for years and all completely covered with basalt boulders. I was able to completely tune out all the basalt that gave a nugget like sound and the few that did give a signal only gave a gurgle as Roger says. The good targets came through loud and clear and .1 gram nuggets were no problem at all even with the detector de-tuned in smooth settings and quiet audio. This was one of those spots where the big problem has always been the hotrocks and interference, not shear overall depth. Customizing for the local problems is where this detector will shine. The basalt hotrock problem is solved but on another spot where extremely high iron content "ironstones" were the norm I couldn't do much with them. They were after all basicly solid metal. I still have some experimenting to do on these pesky things .

The other nuggets I have found with it so far were from the Black Canyon and Rich Hill,----Bob

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Hello Bob,

Congrats on all the nuggets found. I sure wish I had the time to get out like you. I know I'm always waiting for your field reports to come in. I wish I had more free time, but just have too much going on at the moment. I'm hoping after Christmas I will have a bunch of time to really get out and hammer some spots.

I haven't hunted anywhere with Basalts or Ironstones of any quantity lately. Most of the places I'm hunting have just moderate mineralization, but I'm able to really crank the GPX to the max with very little if any background or EM Interference noise.

Have you played around with the "Specific" Ground Balance mode much? I haven't experimented much with it, pretty much just using the "General" mode.

I haven't noticed a huge difference running the "Signal" from 15 thru 20. Just curious what you might be running? I pretty much leave mine on 15 when I'm hunting for deep gold.

Also nice to have the "Inverted" response mode for deep, faint targets. I haven't gotten used to the response, so I'm still using the "Normal" mode. However, a couple of new GPX owners at Rich Hill this weekend really liked it.

"Some Advice to a Friend" - Get your butt out to Stanton. A bunch of customers are clueless how to run their GPX-4000's. Unfortunately we didn't get the sales, but these people need a lot of help. Funny how customers are willing to buy the best detector, but are clueless how to run it. I spent several hours trying to get a few guys back on track since they got no instructions whatsoever. Oh, let me take that back, the person that does the instructions for them is pretty much clueless!!! :lol: I should be nice.

Talk with you soon,

Rob Allison

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Dear Rob;

Congratulations on your recent find my friend! I knew you'd find something the first time out with the GPX-4000, shoot you could prolly snipe nugs here in Bolivia without any detector and make a fortune at it! I did notice that you failed to mention what coil you were using with the GPX4K. Was this an intentional omission or an oversight? I am very curious to know how the GPX4K handles hot ground with mono coils, especially the 14" to 18" range of mono coils.

Your friend;

LAMAR

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Hello Lamar,

The first time out with the Minelab GPX-4000 I used just the stock 11-inch round. I found (2) nuggets within the first hour with it. The second and third time out I was using the Coiltek 14-inch round mono. This is my favorite searchcoil for deep gold. The GPX is able to run a mono coil in places where I couldn't with a GP3500 without a lot of ground noise.

I have yet to try a DD coil on the GPX since it run smooth with a mono in all the places I tried so far. I'm hoping I won't have to ever use a DD again. :lol:

On another note, when do you want the items you purchased shipped? Is your shipper still around? Hate to keep all this stuff here knowing you paid for it a long time ago.

Talk with you soon,

Rob Allison

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Rob. The factory presets on the signal and volume are just fine as far as I can tell. I did crank the volume to Max for most of my detecting so far, but don't know if it does any good.----Bob

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Dear Rob;

I will let my shipper know to be expecting my stuff next week, my friend. I was hoping that someone would be returning to the USA soon and they could bring my stuff back with them in their whole baggage but that doesn't look like it's going to happen.

I am very pleased to hear the GPX4K can handle hot ground with a mono coil. I've felt the DD coils weren't actually the best coils for any particular job, I've always looked at them as 'compromise' coils. From the field reports I am starting to get the impression that the GPX4K is more of an all around detector than any previously offered ML PI detector and this is a very good thing. This could help eliminate a person having to purchase multiple detectors in order to cover all of the soil types in any particular country. Again, this is right in line with predictions which were made about 6 to 9 months ago. Also, do you feel the GPX4K is bridging the gap between the VLF and the PI detectors in regards to sensitivity on small shallow targets? This was another one of my predictions, that eventually the ML PI detector would be able to have the same sensitivity to small shallow targets as the current VLF offerings.

Your friend;

LAMAR

Dear Rob;;

BTW, what did I purchase from you anyway? Shoot, it was so long ago that I can't even remember what everything was...

Your friend;

LAMAR

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Hello Lamar,

Small gold? :blink: One of the biggest advantages of the GP series detectors (GP Extreme, GP300, GP3500 and now the GPX-4000) is the fact they find much small gold, and smaller gold at depth. I know you know this, but I just have to say it again.

I found this small 3 grain nugget yesterday with the Minelab GPX-4000 with the Coiltek 14-inch round mono. The nugget was 3-4 inches in depth, but just a faint target. Uncle Ron and several others were right in the area to verify the find and the depth.

gpxgold.jpg

I hear from time to time that guys are just hunting for big gold nuggets. I think it kind of silly knowing 90%, if not more, is smaller gold nuggets. The larger the nugget the more scarce they become. Hey, I love the big gold to, but I like the fact I'm finding all the smaller stuff, smaller stuff at depth and getting the bigger ones if they are there to be found.

You ordered the following products:

  • Minelab GPX-4000 :P:lol::D
  • Complete Otto Fiberglass Shaft
  • Two Hipsticks
  • Minelab SD/GP Handle
  • Minelab Bow Knuckle
  • Four DVD Videos

Hello Bob,

Are you using a Signal Enhancer with the GPX-4000? Reason asking, the volume seems low when it was set at the factory Preset of 25. Seemed when I cranked it up to the max (40) it helped out. I'm not any Signal Enhancing devices on the GPX.

Rob Allison

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Hey Rob, that was impressive beeping up that dink right at the spot on Push 5 that has really been pounded for a few weeks because it's where Jim found the largest nugget of all the pushes and where you and a couple other guys have found several...I scared up more than 20 targets yesterday within 10 feet of where you found this last one, but none of mine were gold...Just old rusty crap smashed down into the rotten bedrock....Cheers, Ron

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Hello Uncle Ron,

I know if I had time to work push 2 or 5 with the GPX very methodically I can find some more. They might not be big nuggets, but I'm certain there are some more 1/4 - 1/2 Dwters at depth there.

Take care,

Rob Allison

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Rob. My amp and external speakers won't work on the new beeper. I hate going back to headphones after using my dual external speakers with an amp. Waiting on word from amp suppliers as to when adaptors or new amps will be available that are compatible with the new beeper. I can get one that runs on its own battery but would rather have one that runs off the dettector power supply. Power drain will be no problem with the new battery on the GP4K. Man does it have have a huge capacity.----Bob

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Hello Bob,

I was going to suggest the DeTacc that runs off a separate battery. However, I would also prefer to have it run off the main power supply then it's own separate battery.

I also agree with your statement about turning the settings & gain down in highly mineralized ground conditions. People always talk about more depth, but more depth can be achieved in nasty ground if you can get a detector to run dead quiet! This is just another reason I love the GPX-4000. :P

Save a few of those old ironstone patches for me! :o

Rob Allison

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Dear Rob;

That was a VERY interesting statement which you've made my friend. Please explain this in a bit greater detail. When you stated that you can run the GPX-4K "dead quiet" do you mean that you can actually run the detector with a completely nullified threshold, in other words without any audio threshold whatsoever, or one which is stable and yet barely audible? And if this is the way that I read it, would this not sacrafice some valuable depth? If you can actually run the GPX-4000 with a quiet threshold WITH a mono coil in heavily mineralized patches, then in all reality you will have achieved greater depth because the audio return of the previous Minelab PI detectors effectively masked those nuggets on the fringes of it's depth, then a detectorist will truly have a very potent detector in his hands with the GPX4K. They will effectively be able to *see* right to the very outermost limits of the coils' depth and this is a big advantage, IMHO.

Your friend;

LAMAR

Dear group;

Perhaps I should explain my prior statement a bit more fully. For example, the Coiltek 14" mono coil is a deadly mid sized coil BUT it is a rare occurance to be able to cleanly discern a 1/2 gram nugget at 14" in highly mineralized conditions. The best depth that I have been able to achieve is about 9" and if there were some way to quiet down the threshold without sacraficing depth, then the 14" mono should be able to cleanly pick up a 1/2 grammer at very close to 14". In effect, this will gain about 5" in depth penetration.

Your friend;

LAMAR

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Hello Lamar,

The Minelab GPX-4000 is amazingly quiet to start with. One feature you have on the GPX is the "Smooth" mode, which works extremely well in high iron enriched areas and volcanics. I pesonally haven't tried the "Smooth" mode as of yet, but have some spots I would love to test at.

I believe Bob "Montana" Dansie has tried the GPX-4000 on some ground in S. California that is capped with Basalts. Sounded like the GPX in the "Smooth" mode worked well there, much better than prior GP series. Sounds like you might sacrifce a bit of depth, but you might make it back up not hearing other false targets such as the Basalts. Maybe Bob will elaborate more on this.

Talk with you later,

Rob Allison

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Lamaar , You can get the 4000 threshold so rock solid smooth that it can be turned to a much lower level than with previous PIs which had to have a fairly high threshold hum to smooth it out. This high threshold hid so many targets just because it drowned them out. You may not have the interference problems we have up here , so you may see less of a difference. I run the 4000 with the threshold barely audible. With no interference spikes I hear things that I passed up before without knowing it. The nuggets are rolling in again . Got 40 yesterday.----Bob

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Hello Montana Bob,

I have a couple of virgin patches I never shown anyone that are laced with ironstones. Most of the ground is shallow, but contained handfuls of small nuggets. I pretty much had to just kick the ironstones and then recheck the signals. From time to time I would kick an ironstone and a nugget would be right below or next to the ironstone. Any suggestions for an area like this? You mentioned the "Smooth" mode work well on Basalts, but does it do much on actually Bradshaw Ironstones? I'm interested in taking the GPX-4000 to a couple of these spots to see what it will turn up.

Talk with you soon,

Rob Allison

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