Equinox / Vanquish Iron Bias " Bug "

[Steve Herschbach]

I read with wide eyed wonder a thread on another forum where it is stated that with the high Vanquish iron bias setting, or higher Equinox iron bias settings, that a dime stacked on a nickel returns a ferrous result. This has been called a bug, and some rather strident demands are being made that Minelab do something about it “or suffer the consequences.”

Iron bias is a variable filter, and the using it is a direct trade off. On an Equinox the F2 setting of 0 is as close to “off” as you can get. You will get nearly all non-ferrous and lots of ferrous will identify as non-ferrous. As you increase the control to maximum, less ferrous items will identify as non-ferrous, but more non-ferrous items will identify as ferrous.

It is a direct trade, one for the other. There is no free lunch. If you run iron bias at max, you will miss good items. Period. End of story. There is no fix. It’s not a bug. It is the way the filter works. Either leave it at its lowest setting, or accept that when you run it higher you will miss many non-ferrous items. Including nickels and dimes stacked together. Or get another detector.

Metal detectors do not know ferrous from non-ferrous. They know phase and eddy current decay. You can also filter on things like target consistency, etc. Iron bias is not a magic ferrous filter. It is looking at something, I’m not sure what exactly. However, ferrous items often give off multiple target id numbers in rapid succession, and this might be a consistency filter of some sort. It is not a ferrous/non-ferrous filter. Again, a detector does not see ferrous or non-ferrous.

Apparently a dime stacked on a nickel triggers this filter at a higher setting. I can understand how that might happen if it is a consistency filter. What I can’t understand is why that is a major freak out event. The manual says there is a cost to running high iron bias (see below). Anyone that knows anything at all about metal detector filters should know there are no free lunches. That’s why I always run all my filters as low as possible on all detectors I use. Did I know specifically about dimes stacked on nickels? No. Could I really care less? Not really. I do not think there are thousands, hundreds, or even dozens of dimes stacked on nickels that I am missing, even if I ran iron bias at max. But I do not. I always run it at 0 unless I use a default mode where there is some cranked in and forget to set it to zero. I run 50 tones and between the tones and high 39 spikes do not get fooled by ferrous enough to think I need employ the iron bias in any situation except perhaps a field full of flat tin steel.

I hunt gold nuggets a lot, and one thing that does is teach a person a lot about filters. All ferrous / non-ferrous filtering, no matter the type, with misidentify some gold as ferrous, especially in high mineral ground. I will never forget a gold nugget that I saw the Gold Bug 2 disc mode call ferrous in an air test. Or the .22 shell casing my F75 and Gold Bug Pro called ferrous sitting in plain view on top of some particular ground. Real eye openers. This also applies to any coins at depth, right at the point where they almost disappear. In most ground the signal will flip from non-ferrous to ferrous at extreme range. It’s how detectors work, and calling it all bugs just means a person does not know how a detector works. Or that all detectors have bugs, take your pick. I’ve actually written entire articles about it.

Some people have a high tolerance for digging trash to get good items others miss. Others really hate digging trash, and employ high filtering i.e. discrimination and other filters. They should know, or need to know, that if they are digging no trash, they are leaving good items in the ground. Every filter comes at a cost in this regard, some more, some less, but the only thing that insures missing no good targets is to use all metal and dig everything. Even then, the ground balance filter will leave good items in the ground.

Anyway, good luck to those expecting Minelab to publicly address the dime on nickel “bug” and good luck seeing it get fixed. In my opinion it is inherent in the filter and the way it works, and the way to avoid it is to run the filter at the lower settings. Or get another detector if you are a person that specifically hunts dimes stacked on nickels.

Equinox Manual, page 52 (emphasis added):

All ferrous targets produce a combination of a ferrous and nonferrous response. Large ferrous targets can even present a stronger non-ferrous response. Also, a ferrous target adjacent to a nonferrous target can produce a similar response.

The Iron Bias Setting provides some control over the Target ID response. A lower Iron Bias setting will allow the natural response to dominate which means that the target is more likely to be classified as a non-ferrous target. A higher setting will increase the likelihood that the target is classified as iron.

In environments with dense iron trash, a higher Iron Bias is recommended in order to mask them. In areas where you do not want to miss any non-ferrous targets amongst iron trash, a lower setting is recommended. This will cause more ferrous targets to be detected and identified as desirable non-ferrous targets.

[Chase Goldman]

Can I give this more than one like. Steve?  You hit the iron biased nail on the head.  This is the kind of thing that drives me bonkers when I read about it on the web.  NO FREE LUNCHES - exactly!  Foks need to realize that, especially when it comes to filter settings like iron bias, notch, and discrimination, even ground balance that NO FILTER is perfect, no filter has perfectly vertical break points (they all slope), and use of a filter merely enables you to tip the scales one way or the other to balance competing effects to best suit your brain, ears, environment, and desired target objectives.  In fact, metal detecting in general is all about balancing trade offs between competing elements - dig it all vs. cherry pick; coverage vs. depth vs.weight; discriminate or all metal; power vs. ergonomics;  visual vs. audio target ID; and so on. 

[GB_Amateur]

28 minutes ago, Steve Herschbach said:

I read with wide eyed wonder a thread on another forum where it is stated that with the high Vanquish iron bias setting, or higher Equinox iron bias settings, that a dime stacked on a nickel returns a ferrous result. This has been called a bug, and some rather strident demands are being made that Minelab do something about it “or suffer the consequences.”

I'm not a violent person but I wish there were a way to virtually slap some sense into someone who would threaten a detector company if they didn't meet their selfish, petty, non-sensical demand.  I know -- invite that person over to detectorprospector.com and see what kind of response his/her 'demand' will receive here.

I don't make it a point of searching for modern coins, but they come along for the ride when I look for old coins.  My recordkeeping (begun at the beginning of 2017) shows I have found a modest (by many detectorists' standards) 3351 modern (post silver, post Wheat penny, post Buffalo nickel) coins.  Although I don't keep track of this kind of detail, my recollection is that I could count on two hands the number of times I've dug coins in intimate contact (and that's not because I had iron bias set too high and was missing them).  And if I have missed a few, imagine the number of good (deep, old!) targets I would otherwise have missed with a super high bias setting.

This reminds me of that person who joined here (apparently) just to point out (repeatedly and with great fanfare) that the Equinox would give an iron signal for a stack of silver coins.  He was trying to get us to praise and honor him as a hero for 'saving us'.

It seems some people think a detector should be perfect at everything, without realizing the tradeoffs they are requesting.  Next they'll be wanting the detector to dig the target for them.

[Steve Herschbach]

I see a detector as a device that picks up everything, including the ground. Then we add filters. We do not like ground signal, so we employ a filter to eliminate that signal. Gold nuggets in particular overlap with the ground signal and simply filtering out one particular hot rock signal takes some gold nuggets with it.

People hate digging aluminum, so they employ a discrimination filter to eliminate the aluminum. For every target id number that can be created, at any scale level, there are "good" and "bad" targets. Eliminating any bad target comes at the cost of some good target.

It's all a choice. I run my detector with minimal filtering which tends to result in noisy detectors, and use my hearing to sort through the resulting signals to decide what to dig. I have a high tolerance for digging trash and so often dig iffy signals I really think are bad just to see. I'm usually right but every once in  a while I get a pleasant surprise. Other people can't stand all that noise, or hate digging any trash, so lean hard the other way. Most are probably somewhere in the middle.

I noted long ago the F75 tone break defaults will call non-ferrous items ferrous. Is that also a bug? In my opinion it reflects FT recognizing that most people hate digging ferrous, so they have dialed in a high iron bias. It literally is the same thing we are talking about here. You can set the tone break to get nearly all non-ferrous, but now you dig lots of good sounding ferrous. or you set to dig almost no ferrous, but now you miss some non-ferrous items. All discriminating metal detectors have some degree of iron bias dialed in, some adjustable, some not, but it is there is all of them. If you have a metal detector that eliminates 100% of the ferrous, you are missing non-ferrous items. That is a fact.

The Vanquish is aimed at beginners, and beginners typically want to dig little or no trash, and just find "good" stuff. It is important when starting out that this be the case, or people get frustrated and quit. As an entry level detector, the Vanquish has a higher level of iron bias built in, with only the 540 offering an adjustment between high (default) and low. The modes may also have different default levels built in which only testing would reveal. This dime on nickel test might help reveal that.

[Steve Herschbach]

2 hours ago, GB_Amateur said:

I'm not a violent person but I wish there were a way to virtually slap some sense into someone who would threaten a detector company if they didn't meet their selfish, petty, non-sensical demand.  I know -- invite that person over to detectorprospector.com and see what kind of response his/her 'demand' will receive here.

My response is simple. By a different detector model by Minelab, or buy another brand. Boycott Minelab for eternity. I sure don't care. The only thing of consequence anyone of us can do is vote with our wallet, and only large numbers of people doing that will get Minelabs attention. These are just toys, not grandmas life support equipment. Discretionary spending at its finest. Tearing of hair and beating of chests just comes off looking silly at best. I know this for a fact.... all detectors miss stuff, and people would be shocked if they knew the reality of what they are walking over. You do not know what you are missing. Ultimately, switching brands is not going to solve this particular problem. The only way to gauge detectors is by what they are finding, and as long as a detector does a good job at the finding, most people are going to be happy with them. But if you think you have a detector that is somehow getting all the goodies and leaving just trash behind, I suggest you get a Minelab GPX 5000 and pick a 20 foot square you are sure you've hunted out, and go ahead and dig everything you left behind. The results might be shocking.

[Skull diver]

1 hour ago, Steve Herschbach said:

I do not think there are thousands, hundreds, or even dozens of dimes stacked on nickels that I am missing

🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣

[GB_Amateur]

29 minutes ago, Steve Herschbach said:

I suggest you get a Minelab GPX 5000 and pick a 20 foot square you are sure you've hunted out, and go ahead and dig everything you left behind. The results might be shocking.

I'm really glad you posted that article since I hadn't seen it.  I've multiple times read the one he linked to (where he searched and dug all metal targets of a baseball infield using a Minelab PI) and found something like 5 times as many coins as previously recovered using an IB/VLF.  Also, those who want to read more about his good finds at this historic site (shown at the end of the linked article and including his conclusions on when and who dropped the gold coin), see page 23-27 of this Fisher publication.

I have a perfect spot to perform a similar experiment but unfotunately it's in a city park where that much excavation would be frowned upon.  I need to find a private (permission) with similar conditions and 19th Century habitation history.

In my years reading magazines, webpages, books and (fewer) the years I've detected myself, these are the most eye-opening revelations I've ever come across, and it's not close.  Dankowski is my kind of detecting investigator.  Thanks for linking, Steve.

[Steve Herschbach]

The X-Terra Iron Mask function illustrates the principle very well. Iron Bias works in a very similar fashion.

Minelab X-Terra 705 User Manual:

In Prospecting Mode, the objective is to find targets in mineralised, ‘difficult’ ground where target signals overlap each other. The Discrimination Scale becomes an expanded Ferrous Discrimination Scale (Iron Mask Discrimination Scale). If the Iron Mask setting is adjusted towards 0 most gold nuggets will be accepted, but some ferrous junk may also be accepted. If the Iron Mask setting is adjusted towards 20, more ferrous junk will be rejected but some gold nuggets may also be rejected.

[Jeff McClendon]

The 540 should not even be included in the conversation. The solution is simple if a person wants the best possible performance on closely spaced or overlapping relatively shallow non-ferrous targets. Put the iron bias on low and hunt with as little discrimination as possible. Then of course, the same people who are complaining about deep iron on that other forum referred to would complain about shallow nails, bolts, nuts, screws, bottle caps, bobby pins, you name it.

There is a problem (I did not call it a bug BTW) with the unchangeable high iron bias setting on the 340 and 440. Walking over near surface closely spaced US non-ferrous coins in a coin spill which can sound like iron is just not okay in my book no matter what level of experience a person has or not. I have repeatedly experienced this with the Vanquish 340 and 440. A coin spill will have broken audio, jumpy numbers, with negative numbers and iron tones included if hunting with all targets accepted. A multi coin spill near the surface can even sound like one big target with really bad audio and numbers=large iron, tin, several foil covered bottle caps together, a set of keys, a corroded battery...........Most American (we don't have steel core clad that sounds really awful anyway like most countries do) beginners would say "yuck, more junk" and just walk on. Maybe that was the intention of Minelab but I doubt it.

Jeff

[Joe D.]

Thank's guys!! I guess I'm on the right track! It's all good!😂👍👍