OLD GP and NEW GPX, SIDE BY SIDE TEST


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Hi Guys,

After reading all the feedback & testing on the new GPX 4000, I decided to replace my GP Extreme a couple of months ago and a friend with a GP 3000 did the same.

Hype on the Forums indicated sensitivity on the new GPX was far better than the older GP's and said to handle mineralization much better.

We both watched the forums closely and downloaded all the new operating tips for the GPX. We were anxious to see how much better the new machine was over our earlier GP's.

I had a couple of small 'pickers' that my GP Extreme produced a strong signal on with the stock 11' D/D coil and decided to see how the new GPX 4000 responded with the same coil.

No matter what settings I tried, no signal, my friend had similar results with his new machine. His would produce a very weak response, but only if he made direct contact.

However it was not a strong enough signal that either one of us would have dug.

I finally called the techs at Minelab, to see if we had made any errors in our settings. The techs made a couple of sugestions, but they did not improve response on the 4000.

The Tech felt performance my new machine should at least be equal to my Extreme and recomended I send it in for repair, I sent it in the same day.

About three weeks later I got a call from Minelab, stating nothing was wrong with my machine, that it was working perfect.

When I explained the performance comparison test we had run on small gold again, I was told it was unfair to compare performance of an older GP with the new GPX 4000.

This answer was not acceptable.

A little later in the day I received another very courteous call from Kevin Hoagland at Minelab, Kevin does field testing on their new machines.

After explaining the testing we did, Kevin stated the new GPX should be sold with an 8" Mono coil, not the 11' D/D coil that previous GP's have been sold with.

I took the 8" Mono coil of my old M/L 2100 and put it on the GPX 4000 and ran the test again.

Only by using a smaller 8" Mono coil, would the new machine duplicate the sensitivity of the GP Extreme on small gold.

If the GPX will truely handle mineralization better with a Mono coil, than the previous GP's I'll keep it. Otherwise I'll be using an older GP.

Out of fairness I feel Minelab should supply the new GPX's with 8" Mono coils and ship those of us who already have the new machines free 8" mono coils.

This solution will at least place owners of the new new machines, on a more level playing field and not be missing gold their earlier machines picked up.

Maybe it's time we beepers demand 'unbiased' performance demonstrations on 'new' machines, before we get our wallets out.

Good luck,

Chuck T.

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Chuck > I see you haven't gotten any replies . All I can figure is that the readers are dumbstruck. I can't imagine that your GPX4000 isn't giving at least as good a response as your extreme and it should be better. I haven't heard of anyone having the problem you are having. There are infinite ways to set the GPX4000 and the factory presets aren't anywhere near the best. All of us were confused for at least a week with the GPX4000 but once learned, there is no way the GPextreme will outperform it . And yes the real advantages come with the use of mono coils where a DD was needed before. The nastier the ground or interference the more the GP4000 has the advantage. Stick with it for a few trips and your doubts will fade away.---Bob

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Bob,

For some reason this subject has been causing turmoil on another website and the guys here refuse to respond to these allegations. No scientific data presented and sounds to me like they have not done their homework on setting the machine for the conditions.

Maybe they would like to swap their 4000s for the old Extreme. :blink:

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Hi George,

I guess we'd better ditch our GPX-4000s! Yeah, like that is going to happen!!

I've not seen a detector yet that can touch my Fisher Gold Bug 2 with 6" coil for small gold so I think I'll leave the battle of which Minelab hits the tiny bits better to these guys.

I'm gearing up to head for the mine tomorrow. Hope the weather improves. I'll see you and Gary on the 14th and we will go find some nuggets that are large enough to set our poor little GPX units off. I guess I am well and truly spoiled these days but I do not get enough detecting time to chase tiny bits. In fact I'm going to mess with the unit on some deep, large nuggets while we are at the mine and see what settings will give me the best signal on a larger nugget while best ignoring smaller surface targets. I'd like to pass up those small steel slivers!

Steve Herschbach

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Chuck > I see you haven't gotten any replies . All I can figure is that the readers are dumbstruck. I can't imagine that your GPX4000 isn't giving at least as good a response as your extreme and it should be better. I haven't heard of anyone having the problem you are having. There are infinite ways to set the GPX4000 and the factory presets aren't anywhere near the best. All of us were confused for at least a week with the GPX4000 but once learned, there is no way the GP Extreme will outperform it . And yes the real advantages come with the use of mono coils where a DD was needed before. The nastier the ground or interference the more the GP4000 has the advantage. Stick with it for a few trips and your doubts will fade away.---Bob

Hi Montana,

I must have stated GPX sensitivity 'issues' much more clearly on the Arizona Forum, whole different set of responses there.

I'm not out to ding Minelab, I and others who are having the same sensitivity problems simply want answers.

Some have posted their problems on the AZ Forum in response to my posting.

Before sending my machine into Minelab for repair, we tried settings posted on the forums and spoke with several Minelab techs & R&D staff, nothing improved performance on the two small pickers with the stock 11" factory D/d coil.

My Extreme with the same coil produced a strong signal.

The two pickers were placed together, flat-side up, in a tiny plastic display box and placed on the same ground. One picker weighed 0.25 dwt., the other 0.10 dwt.

The comparative testing I and a friend conducted with our GPX's were very fair and balanced.

Hope i cleared up any missunderstandings.

Best to you all,

Chuck T.

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Chuck . I have no problem finding nuggets of less than a grain with my GPX 4000. That is a fraction of the smallest nugget you were testing with and I never found nuggets that small with my extreme. I can't imagine what is going on with your GPX4000. Do you live in Arizona? I'd be glad to try to help you out. We could compare your GPX4000 to mine and see if there is a difference. If you're not close by then try these settings. On the top part of the menu leave everything on factory preset except the sensitive setting . Put that in extra. Bottom switch on the box set on deep (search mode). Soil / timings switch on sensitive. Ground balance on fixed, Coil switch on mono. In the mode edit section of the menu set audio on normal , gain on 10 . motion on slow. Signal on normal . Ground balance carefully . Since the motion setting is on slow , slowly swing the coil over the target. If it now doesn't scream at you then there is something wrong either with your detector or headphones. If you want to try it with the coil switch in DD , make sure that your swing speed is matched to the motion setting. If you swing too fast with the DD coil while in DD setting on the box then you will get a serious decrease in signal strength. It gets a little tricky because we didn't have the motion option on the Extreme. This is all assuming that you have your 11" factory coil on. The 11" DD coil is very sensitive in mono mode to small gold, much less so in DD mode. I believe the 8" mono is more sensitive though than either mode on the 11" DD. There are several mistakes you can make with the settings on the GPX 4000 that will cause a serious loss of sensitivity on very small gold . You have lots of possible combinations with the 4000 that you didn't have with the turn on and go GPextreme. If you read back through the AZO forum and the Nuggethunting forum you will see that most GPX4000 owners agree they are finding small gold that was missed by previous detectors. Quite the opposite of what you are stating. Don't get discouraged with your new detector. It had us all scratching our heads at first. You'll learn to love it.---Bob

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Hello All,

I pretty much think "Montana" Bob and I use setting on the GPX-4000 that are really similar. We both hunt the same general areas and have done well with all the Minelab PI's. When I first seen Chuck's post I couldn't believe it. I'm finding smaller gold not only deeper, but in areas where prior GP's struggled for me. I had to resort to a DD coil to hunt many of the spots. I'm now able to hunt those same spots with a small mono for better sensitivity and depth.

ATTENTION: Keep in mind, not all gold responds the same. I've personally found nuggets under a grain that gave a decent response with a small mono near the surface. The flip side, I've tried nuggets up to 3-4 grains that will not respond!

The rule of thumb for the Minelab PI's is - More Solid or Flatter the Better!! Gold nuggets that are dense like slugs or very flat solid pieces respond the best on the Minelab PI's.

Hope this helps a bit,

Rob Allison

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Rob . True story that some nuggets don't respond as well as others. I have some patches where sub grainers scream and others where it takes a 3 or 4 grain nugget to get a response. Case in point: I get much smaller nuggets on the east side of the Bradshaws than I do on the west side of them and I suppose you've experienced that also since you hunt both like I do. I don't use the settings I posted above all the time but when I know the gold will be mostly small , that's usually where I'm at . I've also noticed that much of the gold I'm taking off old patches with the GPX are what I call cheesy nuggets. Porous, rough , irregular shape ones. The GPX seems to be able to pick these up better than previous PIs.----Bob

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Hello Montana,

Yep, can find really dinky nuggets on the East side of the Bradshaw's, but hate all the electrical interference some times.

I also noticed the GP3500 and now GPX-4000 seem to find more of the small porous nuggets like you mentioned. I believe this is because we have more control over the timing on the GPX-4000, but I could be wrong.

I have a couple of settings I think will work out well for deep gold. Just haven't been brave enough to battle the Summer heat in those spots.

Take care,

Rob Allison

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