GPX Coil Opinion Request

[toby]

Did you look at the Elite coils by chance? See some good talk about them on the Oz forums, but thats all I know about them.

[Roughwater]

4 hours ago, toby said:

Did you look at the Elite coils by chance? See some good talk about them on the Oz forums, but thats all I know about them.

Yes I did and I was impressed by the reviews. Over on Gerry's website there is a good review about the 14" mono and how sensitive it is to small gold with the GPX. The 18" Elite is also available now as well.  At the point in time where I became aware of those coils I already had a 16" NF round mono but no elliptical's and a couple of folks mentioned the NF evolution 17X13 and I happened on one at a good discount so I went with that.  There is a thought that there is a bit of extra "Hype" around these newer coils and to some degree there probably is.  These newer higher tech coils do seem to be enhanced but maybe some of that is in part due to the GPX machines they are attached to. The downside of some of these newer coils, they are more expensive and can be heavier.  The Detech 15" ultra DD is a heavy coil. I was away from detecting for a few years and I see some improvement in the build quality over all of coils.  There is nothing wrong with the commander coils either that I can see. They seem to be a tough and reliable coil. 

I put my used NF 16" advantage coil on my GPX yesterday just to get an ideal of how it felt and to verify it worked OK, it did and it was surprisingly light for such a big coil. the downside of it is that with it being spoked, I could see it hanging up on things. I also checked out a 8" beat up commander mono coil I had bought a while back and I put a new skid plate on it. It worked fine as well.

I feel I saved a lot by buying used and so far every thing I bought appears to work as new.    

Terry

[PhaseTech]

14x9" evo is awesome. For really hot ground I prefer the 12" round, but in milder ground the 14x9" is dynamite. It pretty much matches what an 8" mono will do but with greater depth and ground coverage. 

In some recent coil tests I carried out, I used an 0.125g nugget my customer brought along, which in his words "is always a hard target to find in tests". It was initially buried at max depth that an 8" mono could find, using pretty revved 5000 settings. The best coil was the 14x9" Evo and the 11" Detech ultra. The 6" Detech mono could also get it quite clearly but you had to be over the sweet spot of the target. 

Interesting observation was that the GPZ couldn't get that piece. In Normal, HY and the Sensitivity right up the threshold was doing something over the target area, but only because you knew it was there. I wouldn't have believed it myself if I didn't see it.  

[Roughwater]

11 minutes ago, PhaseTech said:

14x9" evo is awesome. For really hot ground I prefer the 12" round, but in milder ground the 14x9" is dynamite. It pretty much matches what an 8" mono will do but with greater depth and ground coverage. 

I really want to get the 14X9 Evo.  I could see it as a coil I would use a lot being smaller and lighter than larger coils but better ground coverage than the 8" mono.  I would like to see a side by side test of this coil and the 14X9 Coiltech "Blitz" for comparison. 

Terry

[jasong]

6 hours ago, PhaseTech said:

Interesting observation was that the GPZ couldn't get that piece. In Normal, HY and the Sensitivity right up the threshold was doing something over the target area, but only because you knew it was there. I wouldn't have believed it myself if I didn't see it.  

I had the same results with 3 large nuggets. The first was a 3/4 oz chunk and I was hitting it about 3-4 inches deeper with my GPX + 17x13 Evo no matter what setting combo I used on my GPZ. And I run with a ton of stabilization on my GPX too so it was like running in High smoothing. So it's not just small nuggets.

I didn't feel like incurring the wrath of the public by mentioning it though (I remember a few guys in Oz being almost run off forums early on for saying things like this) so I reported it directly to Minelab instead and gave an open invitation for them to come test it themselves (this was like 4 or 5 months ago now), which they can verify. In the following weeks I found 2 more nuggets, both over 1/2 oz, that peformed similarly - about 10-15% less depth on the GPZ no matter what I tried. I'm thinking I probably missed more last winter too for the same reason.

Some people want to murder me for saying it (ok, overexageration, but still, it feels like it), but there are definitely holes in what the GPZ will hit deeper than a GPX with the right coils. Just like there are definitely some types of gold the GPX misses that the GPZ sings on no matter what coil. I'm just hoping it'll go less noticed in a thread about GPX's haha, because it should be said. 

Anyways, a good reason to always be testing things.

That 17x13 hit on those nuggets noticeably and repeatably harder than the the 17x11 did which is another reason its become my favorite coil. Harder than would account for just the slight increase in size. I'm sure the Elites are great too, but I don't like rounds for general use hunting, just my personal preference though because I hunt a lot of places I need to get into tighter spaces and the ellipticals are easier to pinpoint with IMO especially for in situ nuggets in deep holes.

[Au4Gold2]

Now you have done it..........but in all seriousness we should thank you for your honest opinion. Although I do  not yet own a new tech coil, I have been using the older ones, the one that surprised me was the Wallaby coil..... less than quarter gram .19 piece found with it..how much smaller do you want to fiddle with anyways. I think a GPX with a few new tech coils and you are covered for most nuggets in the ground.

[fredmason]

Jasong, truth is truth...

I am curious if you were hunting, finding a target and then cross checking? carrying two elephant guns could be tiresome.

I know from your other posts you do quite a lot of testing.

We all know no one machine, coil or setting gets everything...but still it hurts to thinck twice the detector could be 40% less-haha-oh the pain.

fred

[PhaseTech]

When it comes to the Zed I've seen two extremes. I found a piece that was seemingly a solid bit of gold, at respectable depth. When I checked in on the GPX, I could only see it at about 40% of where the Zed was seeing it. Tried all timings and a bunch of different coils. The new spiral coils definitely saw that bit a lot better, but the Zed was on another level. 

Then, during some coil testing on the GPX, out of interest I pulled out the Zed to see what it would do. It was as good if not slightly better across a range of nugget sizes, with the biggest improvement on ironstone encrusted pieces. But one piece, a 0.5g I was getting very poor results on. This was comparing Fine Gold on the 5000 with HY/Difficult on the 7000. 5000 with a range of coils was clearly outperforming it. However, when switching the Zed out of Difficult into Normal, the depth nearly doubled! 

This experience really hit home why there was so much variation in opinion when the Zed came out. The type of ground and type of gold being used in the tests would have a massive bearing on the results. 

[jasong]

Fred, I wasn't using both detectors on the same ground in-situ, I was just doing lots of experiments re-burying nuggets. The only place I've crosschecked in-situ is in Nevada but these nuggets all came from Arizona. I test like crazy anytime I use a new detector or go to new ground so I don't waste weeks of time missing gold while I learn the area and my 4500 is the closest thing to a trustworthy baseline that I have since I've run it basically in every type of US ground. Just a bit of background.

The first nugget always struck me as an oddball because it was such a weak signal in the ground and thus I thought it should have been deeper, and I was also convinced it was trash when I dug it so I wanted to experiment with it. IIRC it was only about 14-15" down and kinda weak when I found it, way too shallow for a 3/4 oz'er. My 4500 was hitting it at 18" no prob reburied and no combo of settings could get the GPZ to squeek over it at that depth. I actually got it down to about 19-20" with the 4500 by cranking the gain and taking away most of the stabilization. That test caused me to test all my finds weekly thereafter to see how common it was and I found the other two. I'll go back and recover the same ground with the GPX someday just out of curiosity but its going to be a while before I get out of Wyoming again as I'm changing gears and have left the full time prospecting thing for now.

All three nuggets gave warbly wire-type signals. One was like a wad of chewing gum with a couple thicker wire type protrusions but otherwise a real dense and pure chunk of gold, the others were spongy-ish/irregular with solid "stealth-fighter" type edges which were pyrite casts and lots of goethite or hematite inclusions. It's been a while so I'm not sure I'm remembering all the numbers correctly, but I gave a pretty thorough report to Minelab back when I found the first one.

Just to be clear though, all the other nuggets I tested were at least equal or better on the GPZ (I didn't test anything under 1/4oz though, so it's interesting for me to read PhaseTech's posts too). I'd still use one over my GPX if it didn't cost so much and have such an unstable resale value. But I'm pretty happy and comfortable with the 4500 w/17x13 too.

[FishBamboo]

Roughwater,

I have been using a 12" Evo on my 5000 as it out performs the 8x6 Saddie, and the 14x9 NF on both very small and large gold. The 12" is now my go to coil. However if I am look deep for larger gold then I move to a larger coil. In most cases I will jump to a 20" NF.  I do sometime use a 25" NF  but it is rare. Also I agree with Jasong on the 14x9 over the stock 11". I am a NF dealer and hear it might be awhile before we get the 14x9 Evo's. I have been told it is an            extremely sensitive coil from someone who has tested one of the prototype.  Hope this helps.