Why no iron bias control in single frequency?

Personally, I think the name does more to confuse users than anything else. I have read a lot about iron bias and have yet to find a definition that really differs from just being a fine tune for the iron range discrimination.

They keep calling it "a filter" that can be used to adjust the "favor/likelihood" of ferrous targets. A lot of fancy words to describe using an expanded ferrous range to adjust the iron discrimination as close as possible to an accept/reject of the user's choice. We've known for many years the key to unmasking conductive targets among ferrous is to adjust the lower discrimination right at the point to reject ONLY likely ferrous targets. In doing so, naturally, any conductive targets with the ferrous will be detected as a possible conductive targets.

No VooDoo, Nothing magical, just an old technique rebranded as a feature.

Not restricted to just SMF or MF. Single frequency detectors have iron bias ability as well.

Detector,

My main hunting sites are vacant lots that date back to about the mid 1800's and have had the dwelling(s) demolished and removed. Fortunately, these sites have little trash such as foil, bottle caps, and pull tabs (well, at least compared to a site like a park). Unfortunately, these sites are filled with rusted nails and all sorts of other "what the hell is this"?, ferrous trash

When I first started hunting these sites with the Legend, the Legend had it's non adjustable preset iron bias. Since going back to these sites after the Legend received its adjustable iron bias control, I would estimate that I unmasked approximately 30% more coins by running the iron bias at it's lowest setting of 1. Even better news, is that even with the iron bias set at 1, I got very little iron falsing.

If I didn't have an adjustable iron bias control, then yes, I could lower my ferrous discrimination range. However, since discrimination applies to all targets, and iron bias only applies to mixed ferrous / nonferrous targets, then the discrimination method means I'll be having to dig up a lot of nails to get those coins. More specifically, using the discrimination method means that I'm allowing the nails to sound like good repeatable signals. That problem doesn't happen with proper use of the iron bias control.



With all that said, the sites I mentioned are in the old downtown area, and EMI is a problem for SMF in those areas. Enough so, that I get better performance using a single frequency, and would prefer to hunt these sites using a single frequency. In addition, I find that in general, SF unmasks and separates better than SMF. But alas! I want to use a single frequency for these sites, but I also need to be able to adjust the iron bias. So there in lies the dilemma, and the reason for my question of, "Why doesn't the manual iron bias control work in SF on the Nox and Legend"?

Is the so-called iron bias on EQx just that. Bias for iron?
I did a video not long ago.
Did folks catch?
Video was not done specifically to show iron bias.
Iron bias did just adjusted though.
Let me find the video.

That's all well and good TNS, but will that video answer my question?

Digalicious said:

That's all well and good TNS, but will that video answer my question?

Click to expand...

Digalicious said:

Both the Nox and Legend have an iron bias control, but it can only be used in SMF and not SF. Yet, it's my understanding that the D2's iron bias control is adjustable in SF modes, although I could be wrong about that.

So, does anyone know why the iron bias can't be adjusted in SF modes on the Nox and Legend?

Click to expand...

To answer your question as you posted it here.
There is no adjustment provided. That’s why you can’t adjust it.

Your question didn’t ask why does Nox using single freq and Legend using single freq have no iron bias option.

tnsharpshooter said:

To answer your question as you posted it here.
There is no adjustment provided. That’s why you can’t adjust it.

Click to expand...

Sheesh TNS, that's the kind of joke a 12 year old would say. I'm sure you can do better than that.

discrimination applies to all targets, and iron bias only applies to mixed ferrous / nonferrous targets

Click to expand...

Think about that statement Digalicious. All metal targets are either ferrous or conductive. So, in fact, iron bias works by trying to best guess if a conductive target exists in with a ferrous. How is this done, By the rebound response telling the detector it isn't just a ferrous target.

I use this all the time with my Simplex+. I know that a solid VDI of 04 from all directions is going to be a piece of iron. Where I hunt it will be a bobby pin, tack, or paperclip, but it will be a piece of iron. All I have to do is see a VDI once of something above 04 to know there is something else, or a conductive target in with the piece of iron. IF my Simplex+ had an expanded iron range, I could asjust it to ignore the iron, yet tell me when a likely conductive target also exists. Iron bias.

Do you notice all these test videos use a standard rusted nail? Do you know why? Because iron bias does nothing if you had, say a slab of iron, with a dime near it. IF it could truly use some special circuitry to tell ferrous from conductive, the size of the ferrous would not matter, right?

Digalicious said:

Sheesh TNS, that's the kind of joke a 12 year old would say. I'm sure you can do better than that.

Click to expand...

Yeah I’m 12 years old. lol
You need to ask Minelab or Nokta Makro.
If I did answer it would only be speculation.
We know it’s possible - due to Xp doing.

Detector said:

Think about that statement Digalicious ///SNIP///

Click to expand...

I completely understand what you're saying Detector. In fact, I use the same procedure, and have even written about it. More specifically, in ferrous infested sites, slow right down and listen carefully for even a "smidgen" or "hint" of a high tone amongst the onslaught of ferrous audio. Using that method alone, and even with a high iron preset, I can sniff out coins that are literally surrounded by rusted nails. I know, because I've done it countless times. However (I always have a however lol), as good as that procedure is, it's not nearly as effective as utilizing an iron bias control. Reason being, in nail infested sites, there are many instances in which a coin amongst the nails won't even produce even a hint of audio or ID, because the preset iron bias is preventing that from happening, and no amount of lowering the discrimination and/or first tone break will allow that coins audio and/or ID from coming through. That of course, is where the manual iron bias control steps up to the plate to solve that issue.

tnsharpshooter said:

Yeah I’m 12 years old. lol
You need to ask Minelab or Nokta Makro.
If I did answer it would only be speculation.
We know it’s possible - due to Xp doing.

Click to expand...

So you can confirm that the D2's iron bias setting is adjustable in SF modes? If so, then as I suspected, it is indeed possible, yet Minelab and Nokta chose not to for some unknown reason. That is really a huge negative for my (and many others) type of hunting grounds

Detector: said:

Think about that statement Digalicious. All metal targets are either ferrous or conductive. So, in fact, iron bias works by trying to best guess if a conductive target exists in with a ferrous. How is this done, By the rebound response telling the detector it isn't just a ferrous target.

I use this all the time with my Simplex+. I know that a solid VDI of 04 from all directions is going to be a piece of iron. Where I hunt it will be a bobby pin, tack, or paperclip, but it will be a piece of iron. All I have to do is see a VDI once of something above 04 to know there is something else, or a conductive target in with the piece of iron. IF my Simplex+ had an expanded iron range, I could asjust it to ignore the iron, yet tell me when a likely conductive target also exists. Iron bias.

Do you notice all these test videos use a standard rusted nail? Do you know why? Because iron bias does nothing if you had, say a slab of iron, with a dime near it. IF it could truly use some special circuitry to tell ferrous from conductive, the size of the ferrous would not matter, right?

Click to expand...

I know this is a bit off topic, but a slight correction is needed. Iron or ferrous IS capable of conducting an EMI, just not as well as a non-ferrous target might. In the quote, we should clarify ferrous and non-ferrous, and not confuse non-ferrous as being the only conductor.

In trying to unmask a coin, for example, a coin might be laying close to a piece of foil or a pull tab or a nail or an iron washer. ALL targets are 'conductive' and we are trying to unmask the more favorable or more conductive target.

The 'blended signal' from the nearby target might likely result in pulling to a proper, higher VDI or higher conductive reading of the coin simply because the offending targets are less conductive and the mix results in a lower-reading. It isn't only the coin read-out but the blended response of more than one target too close together, and in all cases the blend is from the individual target's conductivity. It n be a ferrous target or a non-ferrous target, but they have their own influence on conducting the EMF.

Okay, pardon the interruption. Many folks think there are conductive targets and ferrous targets, but don't think the ferrous objects have any 'conductivity' and errantly use that term of 'conducive' instead of non-ferrous which correctly describes the desired target.

Monte

Thank you for that Monte.

Sooooo, while you're here, are you able to answer my question?

Digalicious said:

Both the Nox and Legend have an iron bias control, but it can only be used in SMF and not SF. Yet, it's my understanding that the D2's iron bias control is adjustable in SF modes, although I could be wrong about that.

So, does anyone know why the iron bias can't be adjusted in SF modes on the Nox and Legend?

Click to expand...

Let me start by saying I don’t have any direct experience with the Deus 2 or Legend, I only use an Equinox 800.

My understanding with the Equinox is that the Iron Bias (both FE and F2 modes) is specifically designed to use the MultiIQ multifrequency mode to get several simultaneous ferrous/non-ferrous data points to more precisely differentiate how “iffy” a target is in terms of ferrous/non-ferrous content before routing that signal through the iron bias filter to determine what kind of tones ultimately reach your ears. In other words, the iron bias feature needs multifrequency to operate…and if you understand what iron bias really does (which I think you do - we’ve discussed IB in a previous thread), you can begin to see that single frequency cannot provide the data necessary to do the job.

Although my familiarity with the Deus 2 goes only so far as having read the manual, it’s probably worth pointing out that technically the Deus 2 doesn’t have “iron bias”, it has a “silencer” mode. Yes, I’m aware that many people seem to be equating the two for comparison purposes, but the reality is that the differences between the two proprietary features probably extend beyond just semantics. Just reading the very short blurb in the Deus 2 manual about the silencer feature leaves me with the impression that the feature may be quite different in how it actually works, which very well could explain why it can be applied in both single and multifrequency modes.

So to answer your original question, I believe Iron Bias is only available in multi on the Equinox while Silencer is available in all modes on the Deus 2 because the two features are apples and oranges. Again, I’m not familiar enough with the Legend, but I’ll guess that their user controlled iron bias more closely mimics Minelab’s feature, and therefore has the same multifrequency limitation.

Equinox “iron bias” not like Deus 1 or 2 iron bias I don’t think.
Why?
Can nonferrous be rejected with Eqx “iron bias”. Meaning nonferrous be rejected in a totally nonferrous target(s) scenario?
I won’t answer.

Thank you for that AT.

My initial suspicion was that true iron bias requires information from at least 2 frequencies to provide an accurate response. More specifically, information from a low frequency, and information from a high frequency. That would coincide with the typical iron bias scenario of a low conductor, and a high conductor. However (I always have a "however"), I dismissed that notion when I was made aware of the D2 having an iron bias control for SF. Given your explanation, it seems likely that my suspicion of at least 2 frequencies was correct, and you are correct that the D2's Silencer is not an iron bias control.

TNS,

Other than your first sentence, I have no idea what you said

Many folks think there are conductive targets and ferrous targets, but don't think the ferrous objects have any 'conductivity' and errantly use that term of 'conducive' instead of non-ferrous which correctly describes the desired target.

Click to expand...

I use it in a general way. A lot of old timers look at the difference between ferrous & conductive as the breakpoint of 0 on the VDI, or a grunt as opposed to a tone on the audio end. Also many think of it as ferrous being magnetic & conductive nonmagnetic. Of course, this concept has flaws, but then again, we're talking in a general sense.

Kind of like how I simplify iron bias as little more than the fine-tuning adjustment for targets compared to the ground balance number that read in the ferrous range on a given detector. Discrimination.

Digalicious: said:

Thank you for that Monte.

Sooooo, while you're here, are you able to answer my question?

Click to expand...

You are welcome ....

I figured you would ask. So, , I can try ... but I am not up on a D2, or a Legend, and haven't had a clear understanding of what it is or how it works.

What is Iron Bias or whatever term a manufacturer uses? Like most others I haven't seen a really good explanation that describes what it is, why we have it, and why some offer that adjustment in SMF and not SF.

It isn't Discrimination because that basically establishes an accept or reject point. The inference to the word 'Bias' might help describe the amount of receive signal from Iron to be accepted and processed.

Why might it only be a function on a SMF model and not a SF? How about a little reverse thinking?

If we really knew what it is and how it works, then we might ask it this way: IF we had it on a SF model that has been in use and we were familiar with it, and IF we could see any benefit in it, would we want that adjustment on a SMF device?

And to further question what it is or how it works, we should select a few current or recent SF models that we use that seem to work great in Iron for unmasking a good non-ferrous target, and locate some naturally-lost targets in the wild and compare performance, side-by-side, with a SMF model using comparable coils and settings.

I have done just that, and even started out yesterday checking a small renovation site to show a fellow and used the Equinox 800 in the four MF Disc. modes. The most observed debris was Iron Nails, but there was other ferrous and non-ferrous trash on or just under the ground surface. I wanted to find an OK non-ferrous signal and then check out the modes using all of the IB settings, low-to-high. Then I could grab one of a few SF units I have and use in Iron and compare performance on that naturally-located target.

I could hear the low-tone Iron responses but did sweep over a high-tone target. It was a partially-exposed Wheat-back Cent. I encountered it when facing west and swept over that coin in 4 directions, from the left and from the right. A potential of 8 good hits IF the target wasn't masked by the very close debris. The good and bad metal targets were so close it made it difficult to get a dig-worthy non-ferrous response, and using the four Disc. modes in 2-Tone and 5-Tone and all of the IB settings in each mode, the conclusion was obvious.

The best performance with the abundant, closely-oriented Nails and other debris was an IB of '1'. A setting of '2' or '3' were usable, but you could start to hear some impaired performance, and very noticeable with a setting of '4', '5' and '6. Higher settings resulted in only one or two clear hits on the coin. The best performance with the lowest Iron Bias setting in any of those modes was 4 or 5 hits and maybe 1 or 2 iffy-signals that were not interesting enough to check out.

I then checked out several SF models. A 10 kHz Bandido II µMAX w/6" Concentric, a 13 kHz F-75+ w/5" DD and 3½X6½ Concentric, a 14 kHz Racer 2 w/'OOR' DD, a 19 kHz FORS Relic w/5" DD and 19 kHz Time Ranger Pro w/5" DD. None of these Single-Frequency models feature any sort of "Iron Bias" adjustment.

The results? ALL of the SF models, using the same sweep routes on the undisturbed coin, produced at least 6 solid hits and both of the 'iffy' responses were good enough to investigate. The Racer 2, FORS Relic and TRP all gave a possible 7th worthy hit.

One last thing to 'test'. i grabbed the Equinox 800 w/6" DD coil and in Field 1 MF w/Iron Bias at '1' for best response, I then selected the Single Frequencies and re-swept the coin, also using all four Disc. modes of Park 1 and Park 2, Field 1 and Field 2.

At 4 kHz there was, at best, only 2 good hits. At 5 kHz it was slightly better as one bad iffy almost sounded good. At 10 kHz the responses were almost the same as when in SMF. The better EQ-800 performance was at 15 kHz and 20 kHz with audible hits that were almost as good as my SF units.

The good thing for me is that I did not acquire the EQ-800 for use in my Iron contaminated Relic Hunting sites but more for the urban Coin Hunting I'll do in low to moderate trashy places. I already have a very good set of detectors and coils to deal with ferrous challenges.

Monte

Monte said:

The results? ALL of the SF models, using the same sweep routes on the undisturbed coin, produced at least 6 solid hits and both of the 'iffy' responses were good enough to investigate. The Racer 2, FORS Relic and TRP all gave a possible 7th worthy hit.

Click to expand...

Thank you for your thorough testing Monte.

I selected that particular paragraph, because that is what I found most interesting.

When I first started using the Legend in nail infested sites, it was with the very high preset iron bias. Yet, by slowing down and listening for even a "hint" or "smidgen" of a high tone, I could pick out coins that were surrounded by nails and other trash. Basically, no matter how poor or intermittent the high tone hit was, I dug it, and with very good success. I'm talking situations in which the high tone was so fleeting, that most would have swung right over it without even hearing it. Even if they did hear it, there's a good chance they were the type of detectorist that only digs "strong repeatable signals", and walked away from it.

You've given me something to think about (as has Detector). I'm looking forward to doing some testing on the matter.

BTW- I've had conversations with a few experienced detectorists that own both the Nox and the Legend. I fully suspected that the iron bias on both worked exactly the same, and they all confirmed it. Anyway, here is a very short video from Iffy Signals sweeping over a nail and coin at the same, while changing the iron bias in real time. If you don't want to watch the video, then what happens, is at the highest setting of 8 on the IB, the coin isn't detected at all. As he continually sweeps over the coin and nail, he lowers the IB in steps, and in real time. As he lowers the IB, the coin signal begins to come through with a high tone, until eventually, the coin is detected with a solid high tone.

https://www.youtube.com/watch?v=BPsDF1yjovQ&t=3s

Thanks for the video and it is similar to some I watched two years ago in other videos when I had an EQ-800 for a short while.

I never use a larger coil in any dense Iron Nail site, only smaller-size coils.

I also prefer to rely on testing a coin and one or more Iron Nails in a natural, 'as-discovered' layout and not in the hand-arranged orientation we see in almost all videos folks make.

Also, and especially when more than one Nail is in close relationship to a coin, it is important to sweep slowly and methodically. As you related, listen closely for any high-tone and investigate. In the past seven+ years I have enjoyed the best unmasking with a Nokta FORS CoRe and FORS Relic, closely followed by a Makro Racer and Racer 2, and the next very close rival are the FTP 'trio': (F19, G2+ and Time Ranger Pro) that share the same 19 kHz circuitry. All of these using their smallest coil.

Monte

PS: If anyone is close enough they are welcome to join a bunch of us Relic Hunting out of Wells Nevada on our 15th Welcome-to-Hunt Outing Sept. 3rd thru 11th. Guaranteed the ghost towns we search have ample Iron Nails and other challenging debris. E-Mail me if interested.

I don't have my NOX 800 anymore to test this, but can someone take a small gold chain and a piece of wire for a test? I want to see "iron bias" used to ignore the piece of iron and sound off on the small gold chain. That would be not just discriminating.