"FIRST IMPRESSION OF THE GPX-4000"


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Hello All,

I will elaborate more on my first GPX-4000 field test later, but to sum it up to only a few words, I'M VERY IMPRESSED!" I can see this detector being a real winner with all the functions/settings you can edit. I ran a monoloop coil across the nasty Rich Hill clay and the machine just purred like a kitten! ;)

Will post more in the morning.

Rob Allison

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Guest goldstudmuffin

Hi Rob,

A couple of questions. How do you think the factory default pre-set program settings will work on our ground in Arizona vs Aussie ground, plus the fact that we have extreme mineralization in one area to another that has very little mineralization? And how would saving a custom program work when the ground rapidly changes every 10 feet in some areas?

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Hello Everyone,

Sorry I didn't post much information last night, but it was a long day yesterday at the Rich Hill pushes. Had to delivery a lot of products to customers and stayed up late Friday trying to get everything organized to take Saturday morning.

For the people that are still considering the 24K Gold Hunters Club, more than 25 nuggets were found on push 2 Saturday. I heard a few more were found after I left, so the count might be as high as 30 gold nuggets found Saturday. I can only count one nugget that was found with a VLF (Kitty! :D ), all other nuggets were found with Minelab PI's (SD and GP series). :o

Ok, onto what I know now about the new Minelab GPX-4000.

(1) The very first thing I noticed when I turned the new detector on was how "Quiet" the detector was! My first thought was something was wrong or the coil was not connected. The detector was super quiet even when I pointed the coil outwards or up in the air. With the prior SD/GP models the minute you brought the coil off the ground the detector would go nuts. This made it very difficult to hunt hills, banks and other spots where you might need to lift your coil off the ground. The GPX-4000 is much more immune to EM interference.

(2) The ability of the GPX-4000 to hunt across very mineralized ground with a mono coil. Using the GP3500 the first part of the day there was several zones where I had to re-balance the detector & coil to hunt the red clay patches and even some of the metamorphic bedrock zones. I actually kept a mental note on these spots and later returned with the GPX-4000 and the stock coil. I ran across them all with just the "factory presets" and then later with my own "tweaked settings" and I couldn't even get the detector to make a sound over those zones the GP3500 talked on! :huh: There is no doubt I can now hunt places with a mono coil where with prior detectors it gave me a problem.

(3) Liquid Crystal Display (LCD) Screen is awesome! The ability to go in and "tweak or edit" the factory presets is great. It's amazing on how many features you can change, from the ground balance setting, volume, signal, gain, sensitivity, tune and a bunch more. You can now tweak the settings up or down to get the best adjustment for certain ground conditions. The use of the LCD and the two knobs is very simple to understand, but can sound confusing when someone tries to explain it on the net.

(4) Manual Tune to adjust other detectors out. Saturday at the Rich Hill pushes I waited until later in the day to hunt with the GPX-4000. However, even later in the day there was at least 5-6 PI's still working the push, but with the GPX-4000 I was able to "manual tune" them right out. I was so impressed with this feature that I even had to show my hunting partner how it worked. There was a guy using a GP3500 really close to me and the machine was getting very noise. All I did was turn the manual tune adjustment to clicks (from 8 to 6) and the other detector was completely eliminated. I actually had to do this a couple of times, but it was slick, just a couple of clicks and the other guys were gone! ;)

(5) The fact you can use all aftermarket searchcoils with this detector. All the previous searchcoils (aftermarket and Minelab) should work with no problem. However, at this time you can't use any aftermarket battery system with the GPX-4000. You must use the stock Li-Ion battery and power cord.

Overall, I was very impressed with the new GPX-4000. Just the detector being quieter than previous machines will equal better performance. I'm hoping to get more time with the new GPX here soon and report back more of my findings. Heck, within just an hour I found several nuggets with the new GPX-4000! :P

If you would like more information on this new detector, feel free to contact me at - (623) 362-1459 (business line) or (602) 909-9008 (cellular), email - auplacers@yahoo.com or Private Message through the forums.

Take care,

Rob Allison

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Hello Goldstudmuffin,

Hi Rob,

A couple of questions. How do you think the factory default pre-set program settings will work on our ground in Arizona vs. Aussie ground, plus the fact that we have extreme mineralization in one area to another that has very little mineralization? And how would saving a custom program work when the ground rapidly changes every 10 feet in some areas?

Well first off, I doubt anyone would want to run just factory default settings in my honest opinion. The default settings might be ok for Aussie ground, but here to get the optimal performance you're going to want to experiment around and find what you can fine tune.

In area with very low to moderate mineralization you're going to be able to tweak the settings more to get greater gains in performance. In areas where the ground is very nasty (extreme mineralization) you're going to be able to lower the settings to adjust. Unlike the previous GP series detectors, you pretty much have to use what Minelab gave you. On the new GPX-4000 you can actually use a mono coil over nasty ground and adjust the settings to get a smooth balance. On prior GP's you might not be able to work with a mono and would have to resort to a DD coil and then with the stock settings. Now you have the ability to choose the coil (preferably mono) and adjust all the settings to match the ground you're working.

If the ground is constantly changing you can adjust the tracking speeds or change the ground balance modes. There are a couple of modes on the new GPX-4000 that work very well on extremely iron mineralization and over volcanics such as basalts. However, I have yet to test those modes, but will in the near future.

Hope this helps a bit,

Rob Allison

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Guest goldstudmuffin

Hi Rob,

Thanks for the reply! After you have ran a mono coil on a manual ground balance detector for many years and in many different areas, it makes you very aware of extreme mineralization, so it makes you ask dumb questions. :blink: I'm looking forward to seeing the GPX 4000 run in some of those black sand washes with a mono coil. Maybe I'll let you try my sooped up 2100 if you'll let me try your 4000. :rolleyes:

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Hello Russ,

There really are no dumb questions in my book. I try to do my best to explain the best I can over the forums and Internet. I'm a very visual/spacial person, so I love to explain things hands-on. It's much easier to show someone in person in my book.

There's no doubt that a monoloop coils gets better overall performance than a conventional DD coil. I love monoloops and will use them whenever possible. Since the GPX-4000 is configured better for the use of mono coils, I'm going to really like it. Like I mentioned, the GPX-4000 with a mono coil just purred across the nasty red clay at Rich Hill without a single peep! Earlier in the day with the GP3500 I had to ground balance about a half dozen times to keep the ground balance smooth.

I'm really impressed with what I seen so far on the GPX. After I get a few more hours on it I will hit a few old patches and see what I can turn up. I'm pretty confident what I seen so far my old patches will produce some more gold, hopefully some larger chunks. :blink:

I'll head over to "18" and see how it runs and report back to you! :o

P.S. I'm down to just a couple more GPX-4000's in stock. I have another batch on the way, but uncertain when it will arrive.

Take care,

Rob Allison

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Guest goldstudmuffin

Hi Rob,

Since the GPX-4000 is configured better for the use of mono coils, I'm going to really like it. Like I mentioned, the GPX-4000 with a mono coil just purred across the nasty red clay at Rich Hill without a single peep! Earlier in the day with the GP3500 I had to ground balance about a half dozen times to keep the ground balance smooth.

I've got at least three holes I dug Saturday at "18 ounce" with the NF 14 E mono that were mineralization, I'd love to see what the 4000 will do using the same NF mono coil on those dig holes!

I'll head over to "18" and see how it runs and report back to you! :o

Why don't we bury 3 nuggets at "18", a 1/2 ouncer, a 1 ouncer, and a 2 ouncer in that wash and will do some testing using mono coils on the GPX 4000 vs an old 2100 on steroids. If the new 4000 can detector any deeper than the 21's Scott and I will each buy one and dinner at Screamers! :rolleyes:

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Hey Russ...If the 4K works as I think it will, I'll buy dinner at Screamers for the next five years for all three of you since it's just down the road from my house, and you buy three 4k's from Rob, who will discount steeply, give me one 'cause I have a pretty smile, and am deeply deserving.... :D:D:D What more can I offer??????? :rolleyes::rolleyes:B) ... Cheers, Ron

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Guest goldstudmuffin

Hi Ron,

That sounds good, do they still have the 1 pound Screamer with green chiles? I have no doubt that the 4k will out do all previous Minelabs on small nuggets. I do have my doubts about large nuggets at depth in severe mineralization! I doubt Rob really wants to know the answer to that, or he already does! ;)

PS. kool pic of Screamers!

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Hello Uncle Ron and Nephew Russ, :P

There will always be debate if the GP series can keep up with the "Super Duper SD Mod" in hot ground. I havent' done enough testing to see what the GPX-4000 can really do. Right now I'm confident enough from what I seen so far that I will find more nuggets in old patches. Will it just be smaller nuggets at depth, or maybe some larger ones is still the questions? :mellow:

I know for a fact, cause I've looked my my own personal collection, that at least 200, if not more, gold nuggets were found behind the SD. Yes, most of them were smaller, but I'm not talking 2-3 grainers. Many of them were 1-3 Dwt's at depth. Heck, if you take 200 nuggets at just a 1 Dwt average weight, that is 200 Dwts or 10 ounces of gold. Heck, that alone paid for just about all my GP detectors if you think about it.

Russ, I'm sure we both would agree there are a lot more smaller nuggets (pieces under 2-3 Dwt's) vs. multi-ounce pieces. Out of all the nuggets I have found with the SD/GP series, only 0.5 - 1.0% of them have been big boys. Logically, the "beans and bacon" of electronic prospecting is really the smaller nuggets and smaller nuggets at depth.

Not to razz you, but what about all the nuggets you left in those side gullies and even the 3-4 Dwter in the red spot near 18 ounce wash? I think I have close to 2 ounces that you guys left behind? You mentioned both you and Scott hunted them hard during the original discovery. :o Just curious if you give the GP3500 credit for those finds or its it just my amazing touch with a detector? LOL :P

Always fun to talk with you Russ. You're really a special friend even though you're swinging a "Dino-Detector!" ;)

Rob Allison

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Guest goldstudmuffin

:wub: Hi Rob,

Wow, Rob that really hurts... I feel like I just get kicked below the belt! nutkick.gif

No mention of the 70+ ounces found with SD 2100's or the new meteorite discovery made with a SD 2100, only that we left a few nuggets behind in a 3/4 square mile nugget patch in some very nasty ground in Az and the terrain is very rough for a couple of 50+ year old farts! B) Nope we didn't get every nugget, We didn't get over every inch of the area it's too big! Rob you are one of the best with a Minelab so I won't razz you either, I won't tell about the penny dwt'er I found with a 2100 following you up a small side wash! B) The Gp's find smaller gold at depth, that's one of the GP's strengths, one of the strengths of the SD 2100's is large nuggets at depth in ground to hot for the GP's with a mono, maybe that explains why we have found 10 nuggets over an ounce with SD 2100's.

Your Nephew Russ :wub:

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Hello Russ,

It's always fun having a debate with you. First off I trust you like a Brother, or even a Nephew! :D Working at "that area" it's not uncommon to miss nuggets due to the extreme mineralization. Yep, you did find some nuggets behind me, I know I can't even get them all if I really tried. I'm just razzing you when I said you left nuggets, you guys didn't leave anything of size to talk about.

I would agree that the GP's find smaller gold at depth over the SD's. I would also agree that the SD2100 does really well with big gold at depth in mineralized ground. How the GPX-4000 will fit in this mix is still up in the air. Would be interesting to see how it performs at the patch.

P.S. I know both you and your Brother are deadly hunters with the modded SD's. I know you have shown me nuggets that never were posted or displayed on the Internet. :o Have you ever thought about going back to LHC?

Talk with you later,

Rob Allison

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Guest goldstudmuffin
I know both you and your Brother are deadly hunters with the modded SD's.

Especially if we've been eatin chile beans! :D:blink:

The last time I was at LHC was about 3 years ago and I saw foot prints in every wash in the area, we had a 5 year membership and enjoyed every trip up there! General Patten shot 50 cal and 30 cal bullets everywhere, the bullet to nugget ratio was about 15 to 1. That dosen't sound too bad unless your hunting deep washes, how many 2 foot 50 cal bullets can you dig? Yes I'd like to go back, we did very well up there!

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Rob. I found the factory presets to be a little noisy but I came up with some dead quiet custom programs that blew me away . I picked some spots in the Rich Hill area that always gave me problems before because of ground noises , hotrocks , and horrible interference. These problems were gone but I was suspicious that a P.I. could run this smooth and still be sensitive. It didn't take long to build my confidence as I picked nuggets from less than .1 gram to 12.1 grams in ground that drove me nuts before. It may not go as deep or be quite as sensitive in these settings but the flat line threshold and GB lets every metallic target jump right out and catch your attention. No more listening around the warbling or double checking ground noises and very seldom a hotrock. That ironstone hillside at the Ranch would have been finished off in a couple of days with this detector instead of the years of kicking hotrocks that it took to do it . This weekends gold from the Hill.----Bob

post-100-1162267109_thumb.jpg

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Hello Montana Bob,

Well, that's one hell of a run of gold you found there with the new GPX-4000! :huh: It took me about one minute to realize after I turned it on the machine it was much quieter than the GP3500. I was running across one of the pushes at Rich Hill that contained that fresh, nasty red clay. When the red clay is damp or freshy cut it's nasty on a detector, but after some time when it dries out and hardens it's not as bad.

I ran the GP3500 across this same ground for a few hours and found a couple nuggets. However, I had to balance the detector often.

The GPX-4000 was much quieter on this ground than the GP3500. I was running the GPX-4000 in Fixed, Sensitive, Mono, Volume Maxed, Gain 13 ... Will have to check what esle I was running.

I'm really impressed with what I seen so far on the GPX.

Take care,

Rob Allison

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Rob. With a little experimenting , I found that I could get the GPX4K as sensitive as the GP3500 or maybe even more so , but then the hotrocks , interference, and ground noise were back. My gut feeling was that I would be better off to run in the dead quiet modes I found and probably lose a little depth and sensitivity. Here's my reasoning on that. As I think back over all the nuggets that I've found , there were probably 500 at less than a foot to every one over a foot deep and most of my biggest ones were very shallow. If I can tune out the majority of the hotrocks and ground noise , then I have cut out wasted time it took to check these signals out. Add to that the fact that my threshold now is a dead smooth flat line, and the fact that I can now do this with a more sensitive mono coil, I feel that there is a net gain. Also figure that most desert placers are richer on the surface as many have found out after bulldozing off the top foot and finding that the deeper ground is often poorer than the surface. Gullies and washes are the exception . There will be times when I'll amp the new beeper up to gain some depth and deal with the noise but for doing hillsides and most flats I'll choose the quiet settings . We can have it both ways now if we choose.-----Bob

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Now that I have learned to navigate through all the settings, I have found that saving some programs is no big deal. It is so quick and easy to change things to suit the ground conditions it is actually redundant. Those who already understand detector language will have no problem telling when an adjustment is needed. For instance if you start picking up ground noises, just reduce the gain one notch or change to a quieter setting on the audio. There are several ways to tame ground noise and hotrocks and these soon become apparent. It looks scary at first but it is in reality dead simple. Too bad the manual is so confusing. From the new battery system to way the control box is set up , it is an engineering piece of art. It feels a lot lighter too.-----Bob

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Hello Bob,

Well the GPX-4000's are selling well, but still a bit slower than normal due to the lack of field reports. I still get a lot of calls and emails about them, but people seem to be waiting for more reports to surface. I've sold a couple more this week, so I'm hoping these guys will get back on the forums with their findings. I will be out this weekend playing around with it again. I would like to test the "Quiet" and "Smooth" modes over Basalts and even an Iron Stone patch I know about.

So far I've been very impressed with the unit. Talk with Steve Herschbach last night and he's also stated he was impressed with the GPX-4000 so far also.

Thanks for posting your findings so far. Wishing you the best of success with the new GPX! ;)

Rob Allison

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