Steve Herschbach

I think this chart was lost due to websites going offline, etc. It is by Reg Sniff, and attempts to illustrate the White's TDI tone shift on some targets, at different ground balance settings. Where the colored lines cross the “minimal audio change” line the object has fallen into the hole and is eliminated. At proper ground balance settings of around 8 on common ground the TDI exhibits a huge loss or inability to detect nuggets in the 1/4 ounce range, but due to nugget variability the actual loss is extremely hard to predict. See my photo chart below as to why that is. Gold nugget target id numbers Source

All ground balance systems tune out and miss gold nuggets. Gold responses and ground responses overlap. Tuning out any particular ground range or hot rock tunes out the gold that reads the same. Simply put ground balance really is just another type of discrimination system with similar issues with masking as you see with standard discrimination. Try to notch out aluminum, you will also notch out gold. Dual channel systems reduce this ground balance “hole” issue significantly but do not eliminate it, as in the GPX 6000 example given. If you are tuning out ground, you can lose gold. That’s why applying the minimal amount of ground balance needed and digging a few hot rocks is not a bad thing. Running multiple machines over ground will almost always reveal a few nuggets missed by other machines, or taking a detector like a GPX 5000 and running multiple times with multiple settings tends to find a few missed nuggets. The GPZ 7000 probably gets more gold in a single pass than anything else due to ZVT technology, but rest assured it still misses gold that reads just like the ground it is tuning out. If you don’t tune out the ground, you can’t find the gold either since now the ground also sounds off. Another example is tuning out saltwater. Gold and salt signal overlap. If you do not tune out the salt, wet salt ground signals continuously. Tune out the salt, now the gold that reads like salt goes away also. It actually is an issue that cannot be fixed using conductivity or signal constants as your basis of operation. Such blind spots are inherent in the technology. Steve’s Guide to Why Detecting Thin Gold Chains Is Difficult Steve's Guide to Detecting Tiny Gold Jewelry In Saltwater Steve's Guide to Testing Weak Gold Targets & Ground or Salt Settings All this was a long winded way of saying that the PI hole is severe with single channel machines like the TDI, where adjusting the ground balance can actually eliminate good targets just like a disc control, and people have used it was such. Dual channels lessen the problem but do not eliminate it. So while an Axiom would be far better than the TDI in that regard, it’s not perfect, nor is any detector that rejects anything. In fact, engaging the Axiom “ground balance window” feature engages a ground balance notch with a huge range that can be set to knock out almost anything, just like with the TDI, and needs huge caution when used for the same reason The bottom line is simple with metal detectors. Everything, everything is a trade off of sorts. Eliminating anything via filters has a dark side, one that is rarely mentioned. We focus on what we find, and we almost never know about what we are missing.

The PI “hole” is a characteristic of single channel ground balance systems as used on the TDI and its predecessor's made by Eric Foster, and any other single channel systems out there, like the QED. Minelab pioneered dual channel ground balance as a way to fill the hole. The SD 2000, SD 2100 and SD 2200 actually gave you the ability to independently balance each channel. This went away on later models with automatic ground balancing. Garrett came up with their own version starting with the Infinium, then the ATX, and the latest with Axiom. The best explanation I’ve seen of it online was by Garrett engineer Brent Weaver at the link below. In addition, the Axiom has a proprietary “ground balance window” feature which is basically a hot rock notch setting. I’m sure this is what Chris was referring to, and why a SDC seems better if it’s tuning out rocks the Axiom is not by not using the control. The SDC is very aggressive and so it really knocks out problem rocks, but it’s not without a cost in missed gold.

I agree. But these are not the 600 and 800 - completely new housing, no matter how similar it looks. The fact the issue existed in the 600 and 800 and were specifically addressed in the 700 and 900 should actually give people confidence, not the other way around. Engineer jobs are on the line with this one. Fail once - oops. Fail twice when you know about an issue the second time around, time to look for another job. But as in all things new, only time will tell.

I have the three oldest Equinox in the country, spent plenty of time underwater, and never had a leak. For every Equinox that ever leaked, hundreds did not. It’s a fact that improving the waterproof integrity of the new Manticore/Equinox/Xterra models was a major design goal, reflected in the increased depth rating. This is one concern I think you may be overemphasizing Jeff.

These are your ground balancing pulse induction (GBPI) options new in U.S. dollars when not on sale here. Prices will differ in other countries. Don’t bother with anything else unless shopping used, then older model Minelab GPX detectors like the GPX 4500 might be a bargain possibility. Frequency does not matter with GBPI enough to even get into that. The case can be made the 7000 is not a PI but also not worth dwelling on that. Minelab GPZ 7000 $8499 Minelab GPX 6000 $5999 Minelab GPX 5000 $3999 Garrett Axiom $3995 Minelab SDC 2300 $3399 Garrett ATX $2379

I’ll just say the reason I posted the videos without even looking at them is that, as far as I’m concerned, the 6000 and Axiom are both good detectors. Some will prefer one, some will prefer the other. Some like me would be happy using either, and reality is I don’t feel any need to push one over the other. Just review as many information sources as you can if shopping both, and rest assured whatever you choose, you’ll be fine. But yeah, new Axiom owners, run the default sensitivity or a notch higher or lower, no more, until used to the machine. Axiom Sensitivity - A Must Read For All New Owners!

Well with my lack of enthusiasm for wireless coils and grumpiness over Minelabs antics, the Legend may very well be the solution to what ails me. Thanks for the very direct feedback on that Jeff. 👍🏼

PI pinpointers do not go deeper than IB pinpointers in mild ground. They simply lose depth at a far smaller rate as ground mineralization increases. The worse the ground, the better the PI unit will look relative to the IB models.

Gun to head right now, you can only keep one of the three, which is it?

The question was not how physically complicated the models are or how complicated the tuning is, but what the ground handling capabilities are like. I’d rate the 5000 as superior to the 6000 when it comes to handling severe ground and hot rock situations. The 6000 is great in general but in some places with the wrong hot rock it just bangs away every swing or two. There is almost nothing the 5000 can’t handle with the right coil and setting combo.

I’m not a fan of super large coils personally. I really liked my Nugget Finder 18” round mono for the GPX 5000 and can give it a solid recommendation. It’s relatively light for its size. But even larger coils are heavier and unwieldy to the point I’ll pass personally for anything but the rarest of situations.

These are not my videos, but a series being posted by Randy’s Treasure Adventures starting a couple weeks ago, with the last just posted today. I’ll add more if any appear later. I don’t know Randy or anything about him, and frankly I’ve not even watched the videos. I’m sure something can be gleaned from them one way or the other though by those that watch videos so here they are. Mar 12, 2023 I spent a few days in the Arizona gold fields recently and here is the first of several videos comparing the Garrett Axiom to the Minelab GPX6000. They’re not the same, but how different are they from a results standpoint? Mar 18, 2023 Scouring a hillside in the Bradshaw Mountains with the Garrett Axiom, looking for a nugget patch. The Axiom is light, powerful, and well balanced for this task! Also a little view of operations on one of our claims with a fun quad ride. Mar 22, 2023 Another day comparing the Axiom to the GPX 6000. I could not help myself and had to film multiple waterfalls, and in this video, you only get to see a sample of the waterfalls that I stopped and and took video of. The high desert in Arizona is just so picturesque. It’s hard not to lose focus and just take pictures!

If you are happy with your detector then maybe a new coil is a good idea. If you are unhappy with your detector - maybe time for a new detector.

It’s a self fulfilling thing. Any salesperson will tell you the time to sell accessories is right when the customer has made the buying decision. “Would you like an accessory coil sir? It will help you have better success with your new detector. And how about a spare lower rod - just in case? Plus it will make swapping that spare coil out much easier.” And so it goes. By not having accessories available when people are buying the detector, they are missing sales. Once the excitement wears off, or the machine turns out not to be all the new buyer was hoping, the desire for the spare coils wears off also. It’s just Sales 101 and bad business to be leaving dollars on the table by not having all the ducks in a row when they need to be. The fact companies like Coiltek and Nugget Finder exist proves that entire businesses can be supported with the coil sales that Minelab misses with their inability to figure out how to do coils right.

I’ve had both the 11” and 9” on mine, and could get the 13” right now if I wanted one. But I’m not saying I’m a huge Deus fan nor a fan of their limited overpriced proprietary coil selection either. I’ve bitched endlessly about the wireless overkill - give me cheaper wired coils any day. It’s just I’ve already got one, and Minelab seems determined to push me to be satisfied with that. I’d love instead to be a thrilled Minelab cheerleader, but it ain’t happening right now.

Well this is just nuts. This thread started in January, and here it is almost April. Unless I’m missing it there is no sign of either of these coils being available yet. Maybe I’m shooting myself in the foot, but this sort of thing is really just putting me off of Minelab in general. I had a chance to buy a Manticore a few weeks ago. Held the box in my hands. But I kept thinking maybe I’d be better off with an Equinox 900 since I have the 6” coil, 5x10 coil, and 12x15 coils already. As a result I just dithered and did nothing. And the longer this goes on, the more I’m thinking I should just learn to love my Deus 2 and forget Minelab entirely. To the point that I’ve passed on super deals also on the GPZ 7000 and GPX 6000. It just does not feel right for me to support with dollars behavior that really bugs me. I wonder if anyone at Minelab knows how disgruntled both their dealer network and many of us long time supporters are over this never ending coil nonsense with their new models, and the difficulty in being able to get the detectors themselves from our favorite dealers. The silence from Minelab, as always, is deafening. Would a news release telling us what the coils will sell for, along with a firm commitment to a delivery time, be that hard for the worlds largest manufacturer of consumer metal detectors?

Nobody is disputing that. The myth that is raised regularly is that detector designs are impeded in any way for fear that they are exceeding those limits in the U.S., which betrays lack of knowledge about how detectors work. The only issue regarding FCC certification is in relation to included Bluetooth or other wireless methodologies, not the operational characteristics of the detector itself, as such characteristics fall well below any thresholds they need to meet. And FAA and interfering with jets is where this started anyway, and that’s just way outside the realm of being an issue of import.

Hearing airplanes with a detector is not a FAA safety issue. As far as debunking, well, you could read the book referenced above to learn how metal detectors function. They are not radio transmitter devices, but based on alternator theory. Here are some basics though…

It’s like whack-a-mole. But mainly just wanted to agree that Inside The Metal Detector is a real gem.

FAA? Airline communications? No. Absolutely not. It’s actually impossible. As is any talk of metal detectors exceeding some kind of power transmission limits in the U.S. That’s always been a myth. Your “connected source” just lost all credibility and can be safely ignored in the future. And delay? What delay? How can a detector that has never been announced and exists merely as rumors be delayed? I’m not trying to jump down your throat at all. I’m just trying to stop misinformation being spread via these forums. I do agree however that any focus by Minelab with a new gold machine needs to be on depth attained on multi ounce nuggets, not the small bits.

Typical depth responses. Everyone leaves out what should be a mandatory disclaimer “In my ground.” Depth increases depend on the target size. On very small targets you should not expect a depth increase going to a larger coil. The larger the target, the better the increase. On quarters and men’s rings or larger I’d expect a depth increase depending on the ground. The ground being the key. In mild or low mineral ground I’d expect a 10-15% depth gain on larger targets over the 11” round coil. As ground mineral (magnetite and salt) increase, there will be a point where the depth on the 11” and 15” are about the same, so all you get is better ground coverage. In EXTREME ground the 15” coil will see too much ground compared to the target (target to ground ratio) and blowback from the ground will tend to overload the larger coil, calling for a decrease in the gain. In the worst ground, there may therefor be a depth loss going to a larger coil. In summary it’s the target size / orientation and ground that determines whether you will see a depth gain going to the larger coil. In general I consider that a bonus, with increased ground coverage being the primary reason to use the larger coil. Long story short I think the Nox 15 is one of the best large VLF coils I have ever used, and would not hesitate to use it in most situations where huge areas need to be covered. It has a superb combination of depth on larger targets combined with surprising sensitivity to smaller targets. Remember, it’s really a stretched 12” coil, not a 15” coil. The coil nose is an excellent pinpointing tool, so good I got to where I hardly need to use a pinpointer when running the 12” x 15” coil. The exception would be anywhere magnetite or salt or both combine to create extreme mineral conditions, in which case smaller coils will likely be the better choice.

People are always asking for canned settings. Hello - presets. If a metal detector company actually knew what it was doing, then the presets should represent a number of absolute best settings possible for several given situations. All that should normally be required is pick the proper preset (Beach vs Park etc), optionally bump the gain up, ground balance, and EMI scan. Testing the presets reveals which companies know how to best optimize the detectors they make, and tells the majority of normal users which detector would be a best choice for those who don’t wish to become settings wizards. In general, messing with presets too much should degrade performance, not improve it. Unless the presets are really bad, and if that is the case… why were they created in the first place? It’s a general myth in the detecting world that the stock coils suck, and presets suck. Everyone seeks alternatives, when in reality the engineers try very hard to make sure the coil that comes with the detector is an excellent choice for general use, and that the presets are a very wise place to be unless you know exactly what you are doing when you change them. Sure, there are exceptions, but they are just that, and not the norm.

Then you already have the best tools available. There are many companies selling long range locators - the concept itself and the excessive claims are the proof of scam at work. Nobody has to test them any more than you need to test a crystal ball to know that it can't tell the future. Companies prey on wishful thinking by making excessive claims, and the fact people think it is illegal to make such claims, so the claims must be real. Nobody has to prove these devices do not work. If I say I can flap my arms and fly I have to prove it. Nobody has to prove I can't and most people will have sense enough to know that I can't. If you want to ignore what you are being told by everyone here that is fine, but at least you were warned. Good luck.