Low Weighted Multi Vs 5/10 Khz To Avoid Tiny Targets

[Chase Goldman]

3 hours ago, Argyris said:

However, I do have a question regarding iron bias: is there any reason to run iron bias at zero (f2=0) while underwater in salty conditions? Does iron bias could make me miss thin chains/earrings or other difficult or very deep targets if no iron is present to mask them? Iron masking and junk doesn't seem to be an issue underwater in my beache,  so I left it at f2=6 (I prefer F2 over fe) since it was my first underwater hunt and thought that maybe higher iron bias would help to eliminate some chatter from deep salt & underwater minerals...what's your usual Iron Bias setting while underwater in salt? Any pros/cons or tips regarding iron bias while underwater?

Just leave it at the default, if you don't have iron, it is not going to mask anything.  You can give it a try, but F2 = 0 is just very chatty on land for me.  I will not go below F2 = 4 which is equivalent to FE = 0.  Have not had a lot of opportunity to beach hunt with F2 as it just came out at the end of last year's beach season for me and haven't been to the beach since.  Don't over think it and if you have are curious, just set it to the setting you want and see what happens.  If you are finding stuff, avoid the urge to tweak.  If it ain't broke, don't fix it.

Nice ring.

[GB_Amateur]

34 minutes ago, Chase Goldman said:

You can give it a try, but F2 = 0 is just very chatty on land for me.  I will not go below F2 = 4 which is equivalent to FE = 0.

For quite a while (most of my time with the Eqx since the lartest software tweak came out with the new F2 iron bias setting) I just left F2 = 5, per your recommendations, Chase.  I would never blame anyone for my experiences as it's completely up to me to decide what settings I use, and whatever others suggest are merely that -- suggestions -- and in pariticular what works best for them in their soil conditions.

I noticed a few times that deep coins (which I determined were deep coins by digging them 😁) were giving me an iron grunt at the edge of the swing -- say about 3-5 inches from the target sweetspot in all directions (with 11 inch coil which I use 95% of the time) which means getting close to the coil edge crosses the target.  (I'm not saying this has anything to do with the coil edge being over the target -- I have no idea either way why this occurs.)

Last week I got similar iron hints on a 12-13 TID coin at four bar signal strength ("depth indicator" -- another one of those inaccurate terms).  Before digging I decided to go from Iron Bias F2 = 5 to F2 = 0.  Low and behold, the iron grunt/hint disappeared.  I then dug a 5-6 inch deep Buffalo nickel.  I've since been using F2 = 0 setting exclusively, without much evidence either way that it's different from when I ran F2 = 5.

Of all the settings on the Equinox, Iron Bias is the most baffling to me.  I've never had a detector with this kind of setting.  Further, there are some experts here who dislike filtering and thus set Iron Bias to its minimum.  From what I've read it is at least partly included to identify crown caps -- targets that are the least of my concerns.  I've not found that it helps with nails -- easily the most incidious iron target I encounter.  Maybe it does, but so far I haven't seen it in my soil and admittedly in my limited testing.

Chase, I know you do a lot of relic hunting in difficult (magnetite and/or maghemite loaded) soils.  My soil is intermediate (2-3 bars on the ~6 bar Fisher scales of the F75 and Gold Bug Pro).  Maybe that is why my appreciation for Iron Bias is lacking.

[Jeff McClendon]

Awesome ring and hunt Argyris. The Nox seems to like you.  

I would do as Chase says and use Beach 1 or Beach 2 with default iron bias settings until you get more time to experiment. I  use F2=0 only on highly mineralized dry ground which has magnetite, volcanic rock and ash fragments so I don't get so many iron grunt responses on good targets. I get iron responses just waving my coil over the ground with no visible targets even at F2=0 using the horseshoe button. In spite of all the natural iron, I managed to find a nice 1943 Mercury Dime today at 9" deep. Amazing that I could hear enough nice high tones in the midst of the iron grunts and numbers. When I'm gold prospecting I try to keep F2=0 and recovery speed as high as possible so I can really hear all of the tiny targets.

Continued good luck,

Jeff

[Argyris]

Thanks everyone...going underwater seems to verify everyone's insights regarding beach hunting: treasure/junk ratio is the best possible in the water, vs in the dry part where I have to dig 100 aluminum junk targets for every good target. No light trash underwater since waves take care of them and drive them in the shore...only heavy good targets stay in the water...so I guess I'm already hooked to the underwater thing 🙂

Anyway, regarding iron bias and following GB Amateur, Phrunt and Jeff's comments, when I tried in the dry beach part the other days and used high iron bias to help some with melted aluminum nuggets, I experienced the same iron grunts on many good coin targets with no iron nearby, and I also had iron grunts in complex alloy targets such as bimetallic coins or big melted aluminum...but I''try to describe how I understand it after reading some Clive's posts to help some:

High IB settings allow to "brake" and give strong iron grunts in not pure consistent one-metal targets or not good microscopic-level mixed alloys, or targets that are very "grounded" (their metal is very well mixed in the soil such as rusted iron for example because iron especially is more close to the ground characteristics than a non-ferrous), so iron bias reads this inconsistency between ground-metal or between the multiple metals of inconsistent alloy targets and depending of the setting either favors iron buzz or high tone. A shallow gold ring eg. of whatever karats or silver coins (that are well mixed alloys in microscopic level - clean metals- and not multimetal or "grounded-mixed in the soil") always give a pure high tone no matter the Iron Bias setting. However, targets that are macroskopic-mixed alloys or bimetallic compositions, or very rusted-corroded items (eg bimetallic 2€ coins, big melted pieces such as alum nuggets that probably contain other metalls too, rusted corroded coins that behave as multi-metal targets due to rust, bottlecaps offcourse and many other "complex" aloys that contain multiple metalls), with a max iron bias they "brake" and give strong iron grunts because iron bias reads this inconsistency due to multiple metal composition. The same happens with  iron due to the "ground-mixed" effect descibed above. I quote some Clive's info on iron bias from another thread which describes what I'm talking about: “Iron Bias” is a filter. Whereas the ground’s signal represents a large, unstable, response, a good target can be seen as a small, narrow and consistent response. “Iron Bias acts to mediate the “line” where this distinction is made. This doesn’t just include iron—but any object which contains multiple metals. So “Iron Bias” can be used to change responses from bottlecaps, corroded coins—anything that’s not “clean” metal such as silver, copper aluminum or gold.  What a detector does is to assess both the ground and any metal that’s in it and then separate the two—based upon this consistent / inconsistent scale. This is the scale that an “Iron Bias” control operates on." So from my perspective, this could explain the iron grunts in some non ferrous targets but also explain why very deep targets (week signals) could be mixed with the ground response and give iron grunts, due to a high iron bias setting which acts in the "incosistency line" of ground response vs metal.

Regarding underwater, I must play with the iron bias setting to further decide what to use but when unerwater, testing is quite difficult....The way I see it, high iron bias can help to eliminate some underwater-ground & minerals response or black sand incosistent response, but a high setting could also give iron buzz in small good targets or deep ones if ground signal & minerals dominate over them...Iron masking is not an issue when underwater in my beach since there is almost no iron junk, but there are many "ceramic" red rocks and some other black coal type soft ones and also some black sand in some areas that experienced when faning with my hands (one of the reasons I notched out -9 to -7 vdi), so a high iron bias could have a bad effect and give iron grunts in good targets near them.....that's the reason I'm thinking to run with iron bias F2=0 but I must check again if I'll have underwater stability issues due to salt/ground/minerals etc with the lowest IB setting.

Thanks everyone for your comments, this first gold with nox was a good boost to continue hunting this difficult beach.

best,

Argyris

 

[GB_Amateur]

10 hours ago, phrunt said:

I have zero bar mineralisation on my Gold Bug Pro/T2 and I REALLY dislike F2.  The original Iron bias is OK but I find F2 does put iron grunts on small silver coins, in the worst case scenario it makes them completely disappear, especially when they're very deep.  This is in the default F2 setting.  I've never experimented with lowering or raising it... I'd rather just not use it, I see no benefit to it for me in my relatively iron junk free hunting environments.  The odd thing about this is people have been saying the Vanquish is using F2 iron bias, I don't know how verified this is but I do find the Vanquish hits the small deep silvers with no issues and no iron grunts.

Simon, are you referring to default Iron Bias settings in Park 1?

 

[GB_Amateur]

When in doubt, read the manual. 🤔

(Ignoring the bad grammar) I don't understand what it means to mask iron.  Mask it from what?  I thought 'masking' in metal detecting terms refers to bad targets negatively affecting the response of good targets.  The second sentence "In areas where you do not want to miss any non-ferrous targets..."  (yes!  I don't want iron to mask good targets) "...a lower setting is recommended."

So I see the advantage of low Iron Bias, but not the advantage of high Iron Bias.  (Specifically, I'm referring to the manual's explanation.)

While I'm at it, I'm going to get something off my chest which has been bothering me since the Equinox came out -- mis-use of the word 'alloy'.  Further, other than in reference to Iron Bias, I can't find any use of the terms 'macroscopic alloy' or 'macro-alloy' or 'microscopic alloy' or micro-alloy'.  The word 'bimetallic' (and relatedly 'trimetallic', 'tetrametallic',...) are used elsewhere, but apparently not in the same way as has been used when discussing metal detectors.  (Note, there is a word used in econimcs -- bimetallism -- which has a different meaning.)

Alloys are a type of mixture of elemental metals where that mixture occurs/exists at the atomic scale.  In this way, 'micro-metallic' is redundant and 'macro-metallic' is an oxymoron.  But even bimetals (such as USA clad coins) don't necessarily give separate Target ID's.  USA (cupro-) nickel coins -- composed of an alloy of 25% nickel and 75% copper -- show up around 12-13 on the Equinox TID scale and pure copper (depending upon size) typically in the high 20's and up.  A USA (bimetallic) clad coin has outer layers of the same alloy as USA nickels and an inner layer of pure copper.  But it doesn't give mixed TID's.  At least I've never seen that.  Has any of you?  Rather the more conductive component -- inner pure copper layer -- dominates in setting up the eddy currents and the TID is reflective of that part only.

However, I do see effects of different metals in intimate contact with one another.  A machine nut of one metal composition (e.g. brass) screwed onto a machine screw or bolt of another (e.g. steel) will show two TID's representing the two components, at least sometimes -- I won't go so far as to say it always happens.

[Chase Goldman]

 

I'm a detector geek's geek, but I really can't get into this level of analysis on a feature we don't know much about on a tool that is inherently a crude instrument that is just measuring phase change and reactance vs. resistance based on induction balance for some metallic target that is obscured by the properties of the matrix of everything that is between the target and the coil.  The best you can do is "infer" what the target is and let the programmers decide how they are going to process and interpret the target which is always going to be subject to human error because it is based on imperfect modelling of very complex, multi-variable physical parameters and principles.  So, Chuck, I have no answers for you on why mixed metal coins ring up the way they do.  I guess I would have to understand the models that formed the basis for the signal processing algorithms in Equinox and examine the source code.  You think that is going to happen?    We can't even get a straight forward layman's explanation of what Equinox is doing.

When it comes down to it, metal detecting is more about feel than anything else.  A metal detector, despite the technology (electronics, microprocessors, digital signal processing, etc.) is an inherently crude instrument.  I detect mainly by feel, informed by a fundamental level of knowledge about what the settings roughly do in an ideal sense and then stick with what works for me. 

When I do get the chance to actually detect, which is not as frequently as I would like as I am still working and trying to put kids through college, I am really going for it and swinging the coil continuously for the few hours of bliss that I do have and that leaves little room for experimentation and rolling the dice on settings.  I don't really have an ideal, tweaked machine philosophy. 

What I like to do is go with a nice, wide field general search program, detect a target and then quickly interrogate it using the versatility inherent in the machine I am using.  That is why I prefer selectable multiple single frequency machines or multi-mode multi frequency machines like Deus and Equinox.  Punch a button and illuminate the target with a completely different mode/frequency and see how the target responds and make a dig decision. Move around the target and try to lock in on the sweet signal if possible.  Listen for tonal stability and distortion, iron buzz, determine the target footprint.  I can do all that within about 10 to 30 seconds.  I dig or move on at that point.  

As far as Iron Bias is concerned.  I like F2 at the default.  I know it might give me an edge off iron buzz, so I switch frequencies/mode to see what else happens to the target signal.  All iron bias is there to do is to process what it interprets as a mixed ferrous/non-ferrous signal based on Multi F interpolation and cheat the tone over to ferrous.  The degree to which it does that is determined by the IB setting.  FE is limited to the middle of the range so it has a more subtle change in response over it's range.  Whereas F2 has a wider dynamic range and is therefore more pronounced with each step change.   In multi, I think there is always going to be some level of iron bias processing applied to the target even at the "0" settings.  FE probably more so than F2.  Bottom line, I prefer F2 but keep it near the default  (4 to 6) and can't go much lower in my hot dirt and get any useful information when running in horseshoe mode.  This is similar to Jeff's experience.  Yes I am primarily a relic hunter but my best silver has come out of relic sites including several seated coins and a Mexican 1/2 reale.  The silver targets were unmistakable.  To be fair, however, I have not had as much F2 run time and most of my latest silver finds were with Deus/Orx.  I probably have not found a silver (though plenty of clad) since the version 2.0 SW has come out.

If you have multiple targets under the coil detection field including ferrous/non-ferrous, it can mask the non-ferrous which can work opposite to the recovery speed setting.  Coil control and interrogation with multiple modes can help you make the decision or avoid a masked target.  Simple as that.  I can't describe coil control and feel because it has become second nature to me.  I don't like to talk settings because, other than setting up a newbie, I basically dial in based on the site conditions and what is working and not working and go from there.

If someone wants to nerd out in their test garden (Chuck I am talking to you and your 3-4-5 right triangle tubes), I think we have an opportunity to determine something a lot of us have just taken as gospel but have not actually tested for ourselves.  Is F2 = 4 actually equivalent to FE = 0 as we have been preaching since last summer/fall or whenever Equinox 2.X software was released.  Chuck you mentioned that at F2 = 6 you got an edge of iron buzz and decided to dial F2 all the way down to 0.  If F2 = 4 is equivalent to FE=0 then you must have been getting an edge of iron buzz in FE =0  off deep coins for the entire time until Version 2 came out.  But I can't believe that was really the case.  Perhaps you can test FE vs. F2 settings on some deep silver in your test bed and see what the "false iron buzz" response on non-ferrous actually turns out to be.  I know that at the beach deep quarters will give me an iron buzz but the ID is fairly stable and that is how I can tell them apart quite easily from high ringing but unstable bottle caps.  Anyway, give it a shot.  Meanwhile, I will hopefully get a chance to do some detecting this week and I plan on just going with the F2 defaults for now.

HH everybody.

[GB_Amateur]

Thanks for the detailed reply, Chase.  As typical, what you say makes sense to me.  (Well, most of the time, although it might take multiple readings which is normal for me when learning complicated topics.)  I'm minutes away from heading out for a coin hunting session (I also prefer that to testing 😁) but I will elaborate a bit later for those who aren't already bored by our digging deeper into this (Iron Bias) subject.  I also first need to review this thread (plus probably Bruce Candy's white paper and Carl's and George's book).   Another thing to look at (although not specifically addressing Iron Bias) is the Minelab marketing (filtered) explanation of how the Equinox works.

 

[Argyris]

2 hours ago, GB_Amateur said:

While I'm at it, I'm going to get something off my chest which has been bothering me since the Equinox came out -- mis-use of the word 'alloy'.  Further, other than in reference to Iron Bias, I can't find any use of the terms 'macroscopic alloy' or 'macro-alloy' or 'microscopic alloy' or micro-alloy'.  The word 'bimetallic' (and relatedly 'trimetallic', 'tetrametallic',...) are used elsewhere, but apparently not in the same way as has been used when discussing metal detectors.  (Note, there is a word used in econimcs -- bimetallism -- which has a different meaning.)

Alloys are a type of mixture of elemental metals where that mixture occurs/exists at the atomic scale.  In this way, 'micro-metallic' is redundant and 'macro-metallic' is an oxymoron.  But even bimetals (such as USA clad coins) don't necessarily give separate Target ID's.  USA (cupro-) nickel coins -- composed of an alloy of 25% nickel and 75% copper -- show up around 12-13 on the Equinox TID scale and pure copper (depending upon size) typically in the high 20's and up.  A USA (bimetallic) clad coin has outer layers of the same alloy as USA nickels and an inner layer of pure copper.  But it doesn't give mixed TID's.  At least I've never seen that.  Has any of you?  Rather the more conductive component -- inner pure copper layer -- dominates in setting up the eddy currents and the TID is reflective of that part only.

However, I do see effects of different metals in intimate contact with one another.  A machine nut of one metal composition (e.g. brass) screwed onto a machine screw or bolt of another (e.g. steel) will show two TID's representing the two components, at least sometimes -- I won't go so far as to say it always happens.

JB Amateur described very good which targets I was trying to refer, but just to make myself more clear (since English are not my mother tongue but i'm trying to do my best), by the term "bimetalic" or "macroscopic mixed" alloys I indeed do refer to targets that are composed of two (or more) separate metals joined together or mixed inconsistently (not in atomic scale), instead of being a mixture of two or more metals that are well mixed together like real alloys (in atomic scale, hence I used the term "microscopic" for the latest)....

There, regarding Iron Bias setting, the answer is yes by me....it has a major effect as can be witnessed when set F2@max, and swing over a "complex multi-metal mixture" 2€ coin (Outer segment: copper-nickel. Inner segment: three layers: nickel-brass, nickel, nickel-brass.) vs a 10k gold ring (alloy mixture in atomic scale)....none of those targets contain any iron, but still, the 2€ coin is giving strong iron buzz with F2@max and you miss it, when the gold ring gives pure high tone. Same thing witnessed to some large inconsistently melted aluminum nuggets at the beach as others have adviced me to try...max iron bias eliminates them to! When lowering the iron bias, 2€ coin returns to a pure high tone.....so, based on this 2€ coin or inconsistent melted aluminum experience, I trully believe that a high iron bias F2 setting may give iron buzz (as many witnessed) in some good targets that not contain any iron neither have any iron junk nearby (eg a jewelry composed of different metalls...not alloy, same as the 2€ coin example), hence my comments about it regarding using high IB underwater when jewelry hunting when you probably don't need to due to absence of iron issues. Just an observation anyway, maybe I'm wrong, but Iron Bias seems to not only affect iron containing targets but iron free targets too... so maybe it needs some extra attention when using it.

Apologies if I wasn't clear, hope it makes sence now since I was reffering to iron bias properties and how could affect good unmasked and iron free targets

Thanks for the usefull comments everyone 🙂

 

[GB_Amateur]

5 hours ago, Argyris said:

2€ coin (Outer segment: copper-nickel. Inner segment: three layers: nickel-brass, nickel, nickel-brass.) vs a 10k gold ring (alloy mixture in atomic scale)....none of those targets contain any iron, but still, the 2€ coin is giving strong iron buzz with F2@max and you miss it...

Interesting.  Pure nickel is ferromagnetic at about 1/3 the 'strength' ('absolute permeability' being the scientific term) of low carbon steel -- highest permeability for commonly used steels.  (AFIAK only iron alloys made specifically to be used for their magnetic properties have higher permeability among steels than low carbon steel.  Low carbon steel is sometimes called 'mild steel' but I don't know if that is an exclusive term.  Further, I seem to recall that "low carbon" isn't an exact formulation either.  My reference book gives permeabilities of "mild steel" with 0.1% carbon.  But I don't take that to mean that all mild steel or that all carbon steels have the same carbon composition.)

Having noted all that, I don't know if there is enough pure nickel in the 2 Euro coin for it to be attracted to a magnet.  Anyone tried that?  (I may have one in my safety deposit box so next time I go to the the bank to secure my upcoming gold nugget finds 😁 I'll check.)