ARE MINELAB PI'S SUPERIOR?


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Hello All,

I know over the years being a dealer people might find me arrogant, or maybe promote Minelab a bit too much. Although, what you might not know is the fact I want to use a detector that is "best for me." This means something that has the best mineral immunity and depth superior to all other detectors in this class.

Don't get me wrong, I was a multi-line dealer and sold other manufactures in the past. I've spent years with the VLF metal detectors and found gold with a bunch of them. I still think the Fisher Goldbug 2 is the best mine dump and specimen detector due to the high 71kHz freq.

If I was only looking for shallow nuggets, or small nuggets near the surface I wouldn't probably invest in a $2,000 - $4,000 metal detector. However, in the Western US the mineralization can range from mild to extreme and the depth of the alluvial gravels can range from a few inches to many feet in depth.

Due to years of erosion and the high specific gravity of gold, many of these nuggets are now at depth. The easy pickens have been picked up from earlier generations of detectorists.

Most of the gold nuggets I'm looking for today are in old areas where I need maximum depth and superior mineral immunity. The Minelab PI's fit right into this spot for me.

Many of my best gold nuggets have been found at the depth of 1.5 - 2.5 feet deep. I found these with the Minelab SD/GP series and larger searchcoils. Most of these nuggets just generated a slight signal or break in the threshold. There is no way, shape or form I would have found these nuggets with anything besides a Minelab Pulse Induction (PI) metal detector.

By any means, this post is not directed to knock any manufacture or brand of detector outside of the Minelab line. All detectors will find gold, just have different limitations.

When I attend these gold outings and see people in the field detecting anymore, I rarely see anything besides a Minelab PI.

Is it hard for some to face the fact that most are now using Minelab PI's to find gold nuggets? When you visit the bulk of the Internet Gold Forums (US and Australia), why don't you hear much about other detectors?

In the last six months working the 24K Gold Hunters Club at Rich Hill I've only seen three detectors that were not Minelab PI's. At the last AZO Outing I didn't see anything but Minelab PI's and there must have been 200+ people. :o

Is it hard to come to reality since Minelab is not an American Manufacture?

I'm going to use what performs the best for me and that is the Minelab PI's. I've personally paid for all the Minelab PI's over the years with gold nuggets. The bulk of them being at depths I wouldn't have achieved with other metal detectors.

I guess there is a difference of arrogance and facts.

Would like to hear what others have to say.

Rob Allison

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Found gold with The Tesoro Lobo ST and the Whites V-sat. up graded to the 2200sd, they all have there place, but I don't know if I could go back to anything but a minelab, for the most gold. Although, I think the Lobo was one heck of a gold getter. On thing, is I don't like a detector with a meter of any kind on it, I depend on my ears, as bad as they are to get the gold. a meter is a waste for me. I dig everything anyway. Grubstake

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grubstake,

I totally agree with you about the meters.

Meters, we don't need no stinkin' meters!

LOL

First nuggets I ever found were with a Garrett Deepseeker at La Paz. Since then I have used a Gold Bug, Goldmaster II, Vsat, GM3, GM4b, GMT, Minelab XT17000, XT18000, SD2000, SD2200d, GP3000. In my arsenal today is a GP3000, SD2000Mod, XT18000, GM3, GMT, and MXT. Each one serves a certain purpose and has a niche that it fills.

RSJ

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Hey Rob, you bring up and interesting question in that,"where's the Beef(nugget)"

The post I saw recently said adding the pocket Rocket to a SD2100 gave new life because of the deeper punch.

Which is more important, deeper deepth or rejecting ground mineralization or... what % of either is better.

I don't have a ML or a GS 5b and here in NC there are not a lot of places that have nugget that would make much of a difference. Reason: private land Forest service, etc. Though I have seen nuggets as big as a thumb nail recovered somewhere near me.

If we were to line up 3 machines ML 3000 or 4000 then Ml sd2100 or 2200 w/pocket rocket then a GS 5b (Eric lastest) over several test areas, say RH or other, Who at the end of the day, has a fatter poke.

From what I've read on this and other forums, Eric's machine might find some nuggets that others don't see But if these are only a small % of the nuggets out there(if that is true) are you better off ignoring these targets and punching deeper.

Since you folks do the miles out there, what do you want from a detector?

Just thought I would see where this goes. Wyndham

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Hi Rob,

Ok, it is time to pick on you a little since I haven't done it for a while, so here goes.

Yep, I agree, you are arrogant in your own way.

Yep, I agree again, you do brag up the ML and clearly indicate that is your choice.

Now, you are also young and big enough that the weight of the ML is not a problem. We will see what you have to say in a few years. Time and age have a strange way of altering one's ideas and priorities. Start having joint problems and you may think differently.

Now, one other thing you fail to realize is not everyone can afford what you call the best. So, for them, the best is going to have be something else. Will they find gold with a different detector? Sure they will if they are happen to get their coil over the right nugget.

Now, you know that far more small nuggets buried at shallow depths will be found than the larger deeper ones. So, if a guy wants to find a nugget, he has better odds targeting those he more likely to find.

During my last trip to AZ, I spent 3 days on the 24K club. While there I talked to a few guys who had been there for a while and hadn't found gold of any size. One guy had been there almost a month. Another guy had been on the claims for over 3 weeks and still hadn't found a nugget. Both were using one of the later versions of the ML.

By the second day, I had found one small nugget with a detector that just happens to be something else than a ML. The nugget was only about 7 grains in size, but it was a nugget. One of the guys happened by and we ran a couple of air tests on his GP trying the various modes to see if he could find the one that worked the best. Well, when it was all said and done, my low powered PI would match his Gp on that particular nugget for depth. Surprisingly, I could detect the nugget just as well as he could and at the same depth.

Is it possible there were nuggets around that he could detect that I couldn't? Of course, but neither of us had run into them. Again, we also have to realize that most of the nuggets found today are small and are shallow. This is obvious by the pics of the nuggets found recently.

Now, one other big difference between my PI and the GP is "poundage". I wasn't carrying a tree stump. Yep, I didn't need a pet gorilla to carry mine around all day for me. At about 3 lbs, battery, coil and all, I could hunt for extended periods of time without feeling like my arm was going to fall off. Instead of using a trash can lid for a coil, I was using a small rectangular coil that only weight a few oz's. Did my choice of coil mean I would have a disadvantage of depth capability? Of course and I knew that.

Now, for me, weight and ease of use are more important since I do not get the opportunity to hunt for nuggets on a daily basis. For me, the two weeks a year I hunt, it is just for fun. If I find something, fine. If I don't find anything, that is fine too. I also know that when I hunt an area that has been pounded hard, I have a much better chance of finding a smaller nugget that has hidden from the trash can lids. So, I target that type of nugget. At least, I do initially in heavily hunted areas and it usually pays off.

I knew the easy nuggets were long gone and I would have to find one that had hidden from all those previous detectors. BTW, the specific spot where I found this nugget had been walked over a lot. That was obvious by all the foot prints.

The bottom line is technique can be about as important as the detector used. If I had been using one of my old VLF's I would have probably found the nugget with it because of the techniques I use. I simply choose to use a PI type detector because it ignores more rocks and the black sand type ground that gives VLF's fits.

Now, here is something that many people will not believe and that is many of the areas pushed on the 24K club have very mild ground. At least, for a PI, it is mild ground. Yep, I have the ability to turn off the ground balance on my detector and I did that in most of the locations and the detector ran quietly if I used a DD type coil. So, the ground isn't as bad as one might think in some of the locations where people assume it is bad.

Just one more note, the more ML's in an area, the more crosstalk there will be. Fortunately, my little PI does a better job of minimizing that problem so I can hunt closer to them without running into problems. In fact, I worry more about causing interference on their detector than I have. I do ask if they are having problems.

One final note, my PI in its basic form is a whole lot cheaper. Unfortunately, mine is modified, but the basic unit doesn't work bad and is quite close to mine for depth. It simply doesn't have ground balance.

One final note, I am hoping that Dave Emery's Pulse Devil works as expected. Competition is a good thing.

Reg

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Then there are those of us that wish we were close enough to a goldfield to even use a VLF. Hi Reg and Rob, I hope all is well for both of you. I can't justify any of the big Minelab PI's even though I'm a dealer for them. Why not try the Infinium, seems no one ever gives it a try. I agree with you Reg if your an occasional nuggethunter then I would be happy with a VLF or the Infinium or the SD2100V2. Now if you are truly a gold prospector that derives an income from the yellow stuff then I would want a 4000. From what I read Eric's GS5 is looking pretty good too. I just wish they were a bit cheaper and not just one dealer. But I'm not in a good position to say much about gold nugget hunting. I do still hope to get out your way Rob and give nugget prospecting a go. I know Reg, I am hoping the Pulse Devil will be what Dave is hoping for! I just hope by the time I get to go to Arizona that there will still be a few nuggets to be had. Ok God Bless fellars and happy hunting!

John Tomlinson,CET

John's Detectors

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Rob your quote

"When you visit the bulk of the Internet Gold Forums (US and Australia), why don't you hear much about other detectors?"

The answer to this question is easy. The above are really Minelab PI forums much more than they are nugget hunting forums. Which finds more gold in this country- VLFs or PIs? The real answer is probably VLFs but you would never know it from the above forums. Newbies who visit these forums and can only afford VLFs are commonly told to move up to a ML to join the club. A lot of them really don't like this viewpoint and never return to these forums.

Minority PI users are less likely to post on ML nugget forums as they really don't want their detectors to be trashed or themselves attacked by Minelab loyalists. There is a reason why Dave Emery posts where he does. The last time I posted information on my GS5 on a ML nugget forum was when I responded to a GS5 thread on another AZ forum. The Minelab moderators on that forum threw an absolute hissy fit when I explained that my GS5 was quite superior to my SD2200d in iron ID. Hey who wants their reputation to be assaulted?

It will be interesting to see the fallout when Dave's Pulse Devil is released. A lot of fur flying for sure.

My 2 cents

George

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Hi John,

You brought up a good point in the fact, it is hard to justify owning an expensive gold machine if you don't get to hunt for gold on a regular basis. Actually, this holds true for any expensive detector that is not used often.

As for the infinium, it would work just fine for gold also. Like other detectors, it has its limitations, but has its advantages also. Being waterproof allows it to be used in places other detectors can't go. From what I understand, the Infinium didn't measure up to the MLs depth wise so it has seen limited use. However, its lower cost does make it look more attractive to the casual hunter.

As for the GS 5, I don't think it was given as fair of a run as it could have been given. No, it didn't go as deep as the ML on some tests, but again, it has advantages also. It will work quietly in places were the ML has a very difficult time working. Also, the iron ID is becoming one of its favorite features. I know, I have a friend using one and he doesn't want to give up that feature. So, the superior ground balance, the ability to ignore hotrocks better, the iron ID, and the ability to use ML compatible coils makes this detector more attractive to some.

As for me, I still use a Goldquest clone. I prefer the light weight and the simplicity. The down side is this unit doesn't have ground balance and that can be a problem when trying to use a mono coil. So, I use a DD or now, a concentric type to minimize the ground signal. The later versions of this detector can use ML coils with the use of an adapter.

Personally, I think Eric should convert to the 5 pin connector on this unit also so an adapter isn't needed. At least, that should be done for sales over here. Also, the addition of ground balance isn't that difficult and should be done. At least, that is my opinion.

Now, one aspect we haven't looked at is a PI you have to build. Yes, there is a decent one for those who want to tackle such a project. It is called the Hammerhead and is designed by Carl Moreland. It is a very decent detector when done. No, it doesn't have the ground balance feature, but like the GQ, the ground response is significantly reduced with the use of a DD coil. Also, if you can build this project, you can build a ground canceling coil. This will somewhat less depth, but is very quiet over most ground. On this project, Carl just sells the pc board. It is up to the builder to gather up all the parts, which isn't that hard to do.

Now, this build your own does let you try a PI for a very low cost and does let you know more about what is involved. So, for those of you who want to know more about the technical aspects or difficulties involved, this project will help answer those questions.

Reg

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Hi George,

You are absolutely correct about the forums today. Most are geared to focus or promote the ML PI. Instead of trying to provide info that will help a new VLF owner find more gold, the first thing they tell him is to buy a ML. The same holds true for other PI brands. You are right, why should a VLF owner or one who owns a different PI come back when he finds little help or deals with smart ass remarks.

BTW, I remember the forum discussion where you were challenged on your knowledge. Questioning your knowledge was very unprofessional, however, your answer was quite professional and to the point.

Now, I also agree that more gold is found with VLF's simply because more are used and more of the gold found is small enough that most PI's have a real hard time finding it. If you look at the nuggets displayed on another thread, The Birth of Nugget #100, it is obvious by the size of most found are quite small. The reason is simple, there are more small nuggets. When it comes to the real small stuff, a good VLF will generally do a better job of detecting them. On some, the ML will have a very difficult time even being able to detect them.

Now, use the same size coil on a PI and a VLF and in most ground, there will not be that dramatic of a depth difference between the two types of detectors. I know, I have done a whole lot of testing along these lines. The PI advantage shows up in the fact it will ignore the type of rock or ground that gives a VLF fits. A second advantage is there a a lot of larger coils available. In black sand laden areas or areas with magnetite hotrocks, the PI clearly has an advantage. In places such as Gold Basin there are large areas where the rocks will wreak havoc on a VLF but cause just a whimper at best on a PI. In such areas, the PI really shines. So, overall, where gold is found, there is a strong possibility the PI will operate much quieter, thus making it easier to adjust and use. This is the true advantage.

Reg

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Nothing wrong with VLF's. Gold Bug 2 is one of my favorites if you want to do a little crum crunchin to get your gold fix but VLF's buy the beer, Minelab PI's pay the bills! As far as weight? I hip mount mine, no problem. Im over 50 and the only problem I have with Minelab is the holes are getting alot DEEPER. ;)

AzNuggetBob

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Oh Rob:

You're just trying to stir up the pot, and it seems like a lot of folks are accepting the bait.

In the last six months working the 24K Gold Hunters Club at Rich Hill I've only seen three detectors that were not Minelab PI's. At the last AZO Outing I didn't see anything but Minelab PI's and there must have been 200+ people.

On the other hand, in California where I hunt more than 90% of the detectors finding gold are VLFs. Most mother lode locations are not nearly so bad for hotrocks as is Arizona generally. Plus I think overall the guys in California have a better track record at finding gold than the folks on the 24K pushes.

These are mostly locations where the gold is small, the bedrock shallow and the trash plentiful. Rob, I'd be happy to do a test with my White's VLF vs your GPX 4000 in a trashy shallow exposed berock locations like that! I have no doubt I'd do better.

Hey Rob How did the guys at Gaines Creek do with the Minelab PIs and big coils? One gets pretty tired of digging deep trash in a trashy location.

So by your own logic, is that proof VLFs are actually better than PIs?

Not hardly.

To me this is not a question like "which is better Fords or Chevys?" A lot of people tend to make it out that way. Its more like which is better a phillips head or flat screwdriver?

The questions does not make sense since if you have a flat headed screw you would stringly prefer a flat headed screwdriver, and if you need to work on a phillips headed screw, you'd strongly prefer a phillips headed screwdriver.

If I was doing trashy shallow bedrock creeks in the Mother lode, I'd prefer a VLF. Trashy Mine dumps with wiry gold, same thing. Ditto for tailings piles like Gaines with deep, deep trash.

On the other hand, I know plenty locations in the desert and in the mother lode where PIs have a distinct advantage.

The important thing is having the right tool for the job at hand.

Now I have to strongly disagree with this statement:

use the same size coil on a PI and a VLF and in most ground, there will not be that dramatic of a depth difference between the two types of detectors

Even according to Whites dealers I know, this is only true assuming very low mineral ground or a bench test through air. Mineral content in the ground has a dramatic effect on depth of detection for VLFs, far more than it effects PIs. I don know all the places you hunt Reg, but I've been a number of places in CA and NV as well as a few now in AZ, and AK, and most gold bearing soils and gravels are more than very mildly mineralized. Many are fairly heavily mineralized. I also assumes the VLF is being run at maximum gain. Normally, when running in typical gold bearing soil with a VLF and a larger coil, you will need to crank the gain way back.

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Hi Reg, By the way I have both the thru-hole and SMT Hammerhead PCB's. I just haven't had time to go to work on this project. I don't really have a big enough workbench either. I will eventually get it done. I am wondering if anyone cares to comment on the Minelab Eureka Gold VLF as to how effective it is in the gold fields compared to the Lobo and Goldbug II?

Reg does Eric still build each of his detectors one at a time or is he now able to produce a steady supply of them? I have seen pics posted of gold nuggets found under the power lines that cause such great interference to the electronics of most detectors. Looks like he has the interference problem taken care of for the most part. For me I like to try different machines and experiment and the same for coils. Ok I have rambled enough.

John Tomlinson,CET

John's Detectors

Best Little Detector Shop in Texas!

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Hello All,

I knew if there was one way to get the forum rolling it would be a Minelab debate! :P

First, I mentioned in the first sentence "best for me." This does not mean best for everyone. The Minelab PI's are the best for me at this time. I'm hoping, just like others that another manufacture will make something similar in performance to the Minelab PI's.

Reno Chris - you wouldn't beat me cause I dig all targets. If that meant working that area for weeks I would do it. If I find a spot that seems to be productive I will dig all likely targets.

Where you hunt in California might only represent 1% of the California nugget hunters. Most of all the nugget hunters that I know in California are using Minelab PI's (probably is also a low percentage of the total).

I do agree, working very trashy areas can be a pain in the butt with Minelab PI's. The SD2000 and SD2100 don't even have a discriminator. :(

Reg Sniff - You mention this, not sure who it's directed at -

You are right, why should a VLF owner or one who owns a different PI come back when he finds little help or deals with smart ass remarks.

I've always been here to help anyone, regardless of what they swing. Why don't you ask Elly how many hours I've spent with club members when I could have been swinging my detector. Also, I've talked many poeple out of purchasing Minelab PI's and referred them to VLF's. I could have pushed a PI on them if I really wanted to.

Do you think I have a problem finding small gold with the Minelab PI? You have seen the stuff I have found, many of them are small and at depth. In all honestly, I don't use a Minelab PI to find nuggets under a couple of grains. I would rather take the depth advantage and find larger nuggets at depth. One nice nugget at depth might equal several hundreds of those sub-grain or grain nuggets.

I do agree that if a person don't have the time, a Minelab PI could be out of they league. However, I strongly believe if they learn the machine and spend enough hours with it, the expensive price will justify out.

Lastly, I respect you very much Reg. You've taught me more about Pulse Induction Metal Detectors than I could ever imagine. I've truely enjoyed all the hunts in Arizona with you and your Father. Hope we are able to get together again.

AZNuggetBob - We found 4 more small nuggets on a Weaver Patch.

George - The first question I ask when a customer calls is, "How much time can you spent, how much experience do you have at this hobby, what are your interests (coin, relic or nuggets) and what are you able to afford?" These four questions allow me to help the customer get into the right detector (VLF or PI).

I won't get too excited until I see the Pulse Devil in action. I think it will take one heck of a detector to convince me to lay down the Minelab GPX at this point. However, I'm always optimistic! :D

wyndham - Some great questions you have there. In my opinion, the GP series and GPX-4000 perform better than a SD2100/2200 with the regulated battery system. The depth on both might be close, but the GP/GPX will find smaller gold and smaller gold at depth.

The Coiltek Pocket Rocket Li-Ion System will add performance and stablity to the SD series. Most notice more depth and stability right away.

The PI's don't do well on very porous type gold, dubbed the "Invisible Nuggets." However, Minelab PI's love the chunky, solid slug or flat gold.

Talk with you all later,

Rob Allison

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Hi Chris,

You are right, Rob did stir the pot and that is a good thing.

Now Chris, I am curious as to where you hunt in AZ that you feel the ground is heavily mineralized? As for me, I have hunted from Gold Basin, to the La Paz area, to Rich Hill, the Vulture area, LSD, around Dewy, Prescott, Tuscon area and in the Bradshaws at different places including Oak Creek, Johnson Flats, and a few others I can't think of right now. Probably the worst area for a PI is around Octave.

Now, that brings up another good point, what do you call mineralized? Is it something that wreaks havoc on your VLF or on your PI? It does make a difference. To define it even more, if it is bad ground to a PI, just which one? This makes difference also. Actually, it makes a difference on different VLFs too, but for little different reasons.

Now, I don't ask these questions to be a smart aleck, but to point out it does make a difference as to what might be considered bad ground.

From a technical standpoint, VLF's are bothered more by magnetite either in rock or soil form (black sand) than they are from the types of soils that give a PI problems. Many PI's ignore magnetite and black sand but do detect basalt and red hot clay type ground. Actually, about any ground with heavy clay concentrates will cause stronger signals on a PI but not necessarily on a VLF. Minimize the clay and the ground signals are also reduced signficantly on a PI. Generally this problem is caused by the maghemite in the soil.

In other words, in my opinion, what is "bad ground to one type of detector isn't necessarily bad ground to the other. The ground "levels" or TID measurements on a VLF don't necessarily reflect much on what will happen on a PI.

As for what I term to be hot or bad ground, well that is simple to define for a PI. If I turn off the ground balance and I get a strong response that is really tough to deal with, I consider that bad ground. If I do not get that strong of a signal, then I know I can hunt this ground with a mono or a DD coil with no ground balance. On this tpe of ground where I don't have to worry much about keeping the coil level when using a mono coil and no ground balance, then that is mild ground. medium ground is somewhere in between. By this I mean, it is difficult to hunt with sloppy techniques with a mono coil but it can be done. When using a DD coil, the ground signal is quite mild and even sloppy techniques will not cause serious problems with false signals.

As an example, when I hunted the La Paz area, I was surprised to find the ground to be almost dead. It could easily be hunted with a PI with no ground balance at all. This would be an ideal place for a VLF also since there was little black sand to deal with. At least, there was little where I hunted.

Again, some of the tougher ground for a PI is around Octave on the Flats. The red clay does generate a strong signal and ground balance is prefered there. Now, toss in the basalt and the ground can get a little noisy. Now, move up the hill and on to the pushes and the surface clay has been removed, thus much of the maghemite has been moved. The result is less of a ground signal to deal with. Granted, there are steaks where it gets stronger, but nothing like down at Octave.

Chris, is your reason for disagreeing with my statement about the depth difference based upon what a White's dealer said or from experience? I think you will find John Blennert will disagree with you also. He has done more testing of his Whites against the ML's and finds it can come quite close to the same depth capabilities in many areas. He has posted this several times on different forums.

As for me, I did a lot of testing when I field tested the SD 2200 and a lot more testing using my dad's 2100. Now, I have not tested the GP series, but I don't expect them to be much different. As for VLF's, well I have actively used and owned most everything Tesoro has built including the Lobo and the LST. As for ML VLF's, I have tried and owned most of their units from the 18000 back. I still own a GB 2 which I prefer for a couple of reasons. The list does go on but that isn't the point. The point is, given reasonably decent ground and I have not found the PI to detect gold much deeper than the VLF when similar sized coils are used. Reduce the size of gold and the VLF begings to shine. As for what I consider decent ground. Well, for a VLF it is ground where the magnetite hotrocks are not that common and the black sand is relatively low. By this I mean, you will still end up with some in a pan if a full gold pan is panned down, but it won't be a thick layer either.

The two areas where the PI will really excel are areas where black sand is dominant such as some washes, and the second is areas loaded with rocks containing magnetite. Hotrocks are killers on VLF's. Under these two conditions, the PI really excels and can detect gold that can easily be missed by a VLF. In such areas, the PI can easily beat the VLF for depth. As a good example, when you hunt Gold Basin, the ground is generally reasonably mild. Now, get out where it is flat and you run into patches or areas where the rocks will drive a VLF nuts but cause little or no problems for the PI user. This could be considered bad ground for a VLF, but not for a PI. A nugget snuggled up under one of the hotrocks will easily be missed by the guy with the VLF, but easily detected by the guy with the PI.

Now, what I hve seen in the past, is people have a much more difficult time adjusting the VLF and end up with a less than desireable setup. Under such conditions the PI will display a clear advantage. Fortunately, the PI is more forgiving in this respect, so the PI can show a depth advantage because of setup.

As for the gain adjustment, most nugget hunting VLF's have way too much gain for most areas and do need to be reduced, regardless. Unfortunately, many people think they are gong to miss things so they are reluctant to do that and just deal with all the odd signals. This causes a lot of problems which again will make the PI appear lile a much better detector.

Now, a couple of final notes that need to be pointed out. First, I have hunted with the ML PI's so I know how they function. Generally, and maybe with the exception of the new 4000, hey are noisier than other PI's and do respond to things other PI's have no problem ignoring. Power lines are a perfect example. I don't need a special coil, or change modes, or do anything else to hunt directly below them with my PI. In the past, I have hunted along side guys using ML's and had them complain about all the interference and wonder what they are talking about since my unit is as quiet as a church mouse. Personally, I have wondered just why ML's have a tendency to have so much problem with external disturbances. What it does tell me is something about the technique used in the design. So, I think I have got that one figured out finally. The reason I mention these items and how they affect the ML is because some people treat such problems as being related to the ground conditions, when in fact, they are not.

Finally, in all fairness, the ML's have clearly shown that in many areas and under the right conditions they can clearly find things deeper than the other PI's out there incluidng mine. So, they clearly do have their advantages.

Reg

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Hi Rob,

Sorry if you took my statement "You are right, why should a VLF owner or one who owns a different PI come back when he finds little help or deals with smart ass remarks." personally. It was not aimed at you. In fact, going back over previous posts, you do a fair job of trying to direct people to what might fit their budget and needs.

The point I think George was trying to make and what I was agreeing to is if a VLF owner or one who can only afford or prefers a VLF asks a question on this forum or most of the other gold prospecting forums, will they get a constructive answer pertaining to the particular detector they have asked about, or will they most likely get responses that tell them to buy a PI rather than focus on trying to point out more about the VLF's in his price range?

Now, over the last few years, I have seen so many of the posts try to steer people to the PI's that I just avoid the posts all together. I think that is what George has seen also, but I can't speak for him.

Again, I apologize if you took the statement personally. It was not meant to be directed at you.

Reg

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Hi All,

I noticed that the ProspectinginOz forum has mentioned this thread and, hopefully, may draw a few responses. So, I am hoping, some of the guys over there can fill in some blanks about a test that occurred over there quite some time back. It was a test run by Finders, I believe.

If I am not mistaken, it was those tests that caused Finders to get into trouble with ML. From what I can remember and I hope anyone from OZ who notices what I say to be wrong will jump in and correct it, I remember something about a comparison of one of the latest models of ML (at that time) and how it compared to the previous model and also how it compared to some VLF's. The targets, were buried lead objects, I believe. Now I don't remember all the details, but I do remember that one of the VLF's actually did better than the latest ML in detecting several of the lead targets. I think, overall, one VLF, a Whites I believe, actually did better and could detect more lead objects deeper than the the latest ML version at that time, and that caused quite a stir.

I believe this test was posted on Fnders for some time. Anybody else remember this test and have more details?

Now, lead or a lead alloy objects have been used for years as a substitute for gold when testing different detectors. A quick test with a lead slug such as a 38 slug and a similar size piece of gold will not show that much difference in depth of detection. There may be more of a difference once we get down to pieces maybe 1/2 the size of a 22 cal bullet or smaller because of the lower conductivity of the lead, but overall, lead does work well to test a detector.

Now, the reason I brought up this particular test is tests have been run in many places around the word and many of those tests do not show a really dramatic difference in depth of detection between a VLF and a PI. What will determine the differences are the actual ground conditions and the type of target being used as a test target.

Reg

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those tests do not show a really dramatic difference in depth of detection between a VLF and a PI

Again this is true only if you do an bench test through air, or bury a target in a location with real mild soil conditions. Just this summer I hunted an area with a friend, he was using a GBII in a location with strongly mineralized soils. Although he has found pounds of gold with his GBII, this site was giving him fits. He missed a 7 dwt nugget at 5 inches which I easly picked up with my GP Extreme walking along behind him when I went through the same area a few minutes later. My coil was slightly larger than his, but not that much. Now there is no question he could have picked up that nugget, which weighs nearly 11 grams, at a lot more than 5 inches through the air with his GBII, but in that hot soil he didnt hear a peep. It screamed so lound on my GP Extreme that I thought it was trash at first, but when I got down through the top couple inches of soil (where 95% of the trash is at that location), I was pretty confident it was going to be a good sized piece of gold. I got a second nugget just under one dwt about a foot from the first. There was even an old shallow VLF dig hold about 5 feet from that nugget, so I assume that operator probably missed the 7 dwt piece too. If PIs and VLFs detect the same with same sized coils in basically all soil conditions, why in the heck was there a gold rush in australia and the US when the SDs first came out? Big VLF coils existed in those days, and operators had pounded the heck out of many well known locations with VLF detectors for many years before the first SDs were sold. Reg, you are free to believe what you want, but the proof is in the results.

Strongly mineralized soils have a definite negative impact on depth of detectection for VLFs, especially those with high frequencies like the GBII and the Gold Masters. Not only does it make the threshold erratic, but the iron also acts basically as a dampener for the magnetic flux by absorping or reacting with the field created by the coil. Because the PI pauses after inducing the magnetic field, it ends up seeing little of the adborbing effect of the iron because it decays away so fast (much faster than the current eddys induced into metal targets).

Chris

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Hi Chris,

It sounds like your friend needs to either get his detector fixed or learn how to use it if he actually passed over the size nugget you say he did and didn't detect it. Personally, I doubt that he even passed his coil over that nugget even though he went through the area.

Now, there is a discussion over on the nuggetshooter forum pertaining to ground balance and detecting small gold with a VLF. In that discussion Don, Gatorguy, stated for the best results, set the ground balance for perfect balance. Several guys jumped in and said, no, set it on the plus side. Who is right?

Better yet, why.

I will give you a hint. They both answers are correct, the difference or when one is better is determined by what conditions? Any idea why, or when one is better than the other? BTW, bad ground is not the answer. The answer to this question also answers why so many nuggets are missed with a VLF and detected by a PI.

BTW, I have given several demonstrations over the years and one fun trick is to show just how easy it is to miss a large nugget with a VLF. It really is easy if you know how to do it. I used to show how a 1/4 oz nugget could easily be ignored.

Now, as for your discussing testing, I rely very little on air testing. My testing is buried nugget testing and then controlling the rest of the environment as much as possible to determine just what happens and why.

Reg

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Heck Reg,

I always enjoy your posts, mate, But I think you are flying a bit low with one engine out here. :D

I know a bit about those tests, mate, fun and games. I hope they come over too.

In the meantime I will say that I have seen many tests between a gmt and a 2000.

In every one of these tests the gmt ended up silent and the 2000 boomed over the target. :D

I had a mate who owned a 17000 with about a 20" dd coil. They were pretty common over in WA before the 2000 came out. We did a few tests on the local goldfields here against my 2000. Now most of the ground where I am, I would call mild. Most of the targets I picked up using a stock 11", he couldn't even hear. <_<

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Strongly mineralized soils have a definite negative impact on depth of detectection for VLFs, especially those with high frequencies like the GBII and the Gold Masters. Not only does it make the threshold erratic, but the iron also acts basically as a dampener for the magnetic flux by absorping or reacting with the field created by the coil.

Because the PI pauses after inducing the magnetic field, it ends up seeing little of the adborbing effect of the iron because it decays away so fast (much faster than the current eddys induced into metal targets).

Chris

This latter statement is only partially correct. How fast the ground decays will depend on the transmit pulse length and it may well be that the ground signal is still present long after the conductive target has decayed away if its TC is very short compared to the transmit pulse length. The ground decays as 1/t or 1/t squared and conductive objects exponentially. For example compare a nugget with a TC of say 10 u secs and a pulse length of 200 u secs. After 50 u secs the =5 TC the nugget signal will have essentially decayed to zero but the ground signal may not be decayed away until 200 u secs . If we sample at say 15 u secs after pulse turn off ( a common situation in Pi) with say a 15 usec sampling window then the integrated voltage will be a "mixture" of ground + target signal. To remove the ground signal component we may sample again much later and integrate and subtract the integrated voltage from the early sampling window. This is why we can get a wee or a whoo signal on ML machines.

One of the main advantages of Pi over VLF is that VLF is continuous sine or frequeny domain EM method and you are always trying to measure a target signal in the recieve coil in the presence of transmit signal .In a Pi you measure in the time domain where the the recieve coil is only "switched on" after the transmit signal has died away and there is little or no induced voltage in the recieve coil) in the absense of a conductive target ). However it is now possible in VLF machines to use coils where in the absense of a conductive target there is never any net voltage(signal or phase shift) in the recieve coil. Such VLF machines can also give target info that no Pi can get. eg the in phase and quadrature response which can dramatically improve discrimination particularly if multiple receive coils are used at 90 deg to the plane of the main recieve coil. I have info on my forum and you can read more by going to:GEM-3 Broadband EMI Sensor at :http://www.geophex.com/GEM%203/GEM-3%20home.htm and for those really interested:http://www.geophex.com/Publications/publications.htm

Doug

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Hi Inhere,

Glad you jumped in. Now, I didn't say the PI couldn't beat the VLF for depth. What I said was the difference normally isn't that dramatic. Now, you also have to remember that most of the nuggets found over here are much smaller than those found in OZ.

One of the posts some time back indicated a ML PI will go 2 to 3 times deeper than a VLF. In fact, at one time I think ML even used such statements. Personally, I have never seen anything near that amount of difference providing both detectors are properly adjusted for the conditions. Yes, a PI will generally go deeper, but the depth difference is generally much less, maybe 10 % or so when using the same size coil. I don't consider 10% to be dramatic. I do consider twice or 3 times deeper to be dramatic.

Are you saying you could detect nuggets 2 to 3 times deeper with your 2000, or are you saying you could detect the same object an inch or two deeper? There is a big difference.

Now, it is much easier to influence the VLF detection depths and just how that happens is the point I am trying to get across. If improperly adjusted, a VLF can display serious depth loss in certain cases and under cerntain conditions.

BTW, on the 2000, the 2100 and maybe on the 2200, certain nuggets in the 1/4 oz range were very difficult to detect at any depth. On these nuggets, a VLF could easily beat the PI for depth.

The reason I wanted to pursue this issue the way I am is because of just how the VLF is influenced. Instead of just blurting it out, I decided to make a game out of it. This gets more people guessing, which, hopefully, will cause more VLF owners to remember it.

Now, the GMT is somewhat like the GB 2 and works on a higher frequency which will suffer more in some aspects, but work better in others. It also has one other drawback that can have a negative impact I won't mention at this time.

The basic rule of thumb is you can gain about an inch in depth on a coin size obect by doubling the current in a coil. To gain the next inch you have to double the current again. As you can see, it doesn't take long before the current needed for an additonal inch of depth is dramatic to say the least. Now, take a relatively flat 1/3 oz nugget which one could most likely detect at somewhere close to a foot in depth with either a VLF or a PI. The difference may be an inch or two difference at the most and even then, there is a good chance something is influencing the test. The key is to know what and why and how to use it to your advantage.

BTW, when the 2000 first hit over here, a friend of mine bought one and we did quite a bit if testing in gold country. We would both scan an area and find targets and then compare the results of the signals we got from both detectors on that target. I was using a VLF at the time. He had the 11" DD coil and I was using an 8" coil on the VLF. Over a period of a few hours, we had checked several targets and there was only one I couldn't hear. There was one I could hear but would dismiss as ground noise. On the 2000, that particular signal was extremely weak but could be determined to be a target.

Reg

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G’day Reg,

Mate, I’m no tech and I know half of nothing about Vlf’s.

I have seen many demo’s and yes they may be flawed.

I just read a test on the Xterra 70, claimed the 3500 only beat it by 20 or 30% in quite ground, when he tried it in warmer ground, that went out to 60%.

I know a very good prospector who does well with a GMT, who has no doubt that he can’t get near the Minelab PI’s for depth. The thing is, you can’t just pick your ground.

I almost bought a GB2 a couple of days ago, just for ore dumps.

I have a liking for all detectors, and yes, I often stick up for Minelab PI’s because I have no doubt that, at this time they are the best gold detectors for the sort of nugget hunting I like to do.

Most of you guy’s that are tech’s, know and talk to one and other, someone brings out a detector and It may have many good points, much better discrimination,unaffected by atmointerference, in fact all the things that Minelab PI’s don’t do well.

But If they miss that last 2†in depth, few people seem to want them. It’s the nature of the beast. To most people who detect as a hobby, deep down, there is a dream component, you hear that faint sound and dig up a football sized nugget. So most would sell their mother in law into white slavery for an extra 2†depth. :lol:

I know that some of these detectors would be better then the Minelab PI in some ground.

Then most people who use these Minelab PI’s sooner or later find that they sometimes detect nuggets at depths they have trouble believing possible with the size coil that they are using.

I’ve had it happen to me a couple of times.

I do know about the coil current thing, I read a nice post somewhere by Candy stating the same thing.

Anyway, lets hope Dave’s Pulse Devil rewrites the rule book, I’ve read a bit about it lately and I get the feeling Its going to be a real good thing. <_<

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Hi John,

Sorry I missed your first post about your purchase of the Hammerhead. I would build the thru the hole unit first. It will take less soldering skill to build. Trying to hand solder SMT devices can be a real challenge. Now, I do recommend you make the mods necessary so you can use DD coils.

Now, in answer to your question about Eric and how he makes his detectors, I am not sure just what all is involved. I suspect he does most of the work and final assembly.

As for the interference problems, Eric's design is clearly superior. Most low frequency noise is canceled so noises such as signals from power lines and even wind generated low frequency noise is canceled. So, his design will run quiet in areas that give the ML's fits.

BTW, the HH you are about to build uses a similar design so you will be able to use it under power lines also.

I would like to help you with your question about the Eureka, the Lobo and the GB 2. I have used and still own the LST (Lobo Supertrac), the original Lobo, the GB 2, but do not own nor have I tried the Eureka. I do still own an 18000 which is the basic unit built before the Eureka. Now, to the best of my knowledge, there really isn't that much difference between the Eureka and the older 18000. As for comparing all three of the VLF's I own, I would hate to say which one is the best. Each has its place.

As for placing one in the hands of an inexperienced person, I would be inclined to give them the 18000 first, then the LST.

BTW, the LST has about the best discrimination of small iron of the three and does so in the all metal mode. The trick is knowing how to set it up and what to do.

Reg

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