"strange" behavior of my S.E.F coil vs. Minelab's "Pro" coil...

For those of you who don't know, I used to own a Fisher F70, and I live in Oklahoma where the soil is generally iron-stained red clay. While the soil does not register as being highly mineralized, I found the 10" stock concentric coil on the F70 -- though being very GOOD at hitting targets quite deep -- very POOR in terms of offering a dependable ID on coins deeper than about 6". On a deeper than 6" or deeper penny or dime, this machine/coil combo would consistently want to ID these targets as "13" -- solidly iron (despite the fact that it could "see" these same coins down to a good 10-12" of "absolute" depth.)

I then added a Fisher Gold Bug Pro to my arsenal with 11" DD coil, and quickly found that I achieve MUCH improved ID capability at depth with this machine. While it does not have the absolute depth capability of the F70, it IDs coins more accurately to a substantially deeper depth than the F70 did in my soil, making it "effectively" deeper.

I also now own a Minelab Explorer SE Pro. I have used the 11" DD "Pro" coil almost exclusively, and found that ID numbers are respectable, if not pretty good, down to depths approaching the depth limits of this coil (similar to the Gold Bug, much better than the F70).

Now, having said all this, I recently bought a 6x8 S.E.F. coil for the Explorer, which I understand to have some characteristics of a DD coil and some of a concentric (whatever that means). In any case, I have found this coil to be a nice coil, and accurate in terms of ID down to between 5 and 6 inches. I almost always run "iron mask 22" on my machine which means, for those who don't know Explorers, that I am discriminating out all targets whose FE numbers run from 22 up to the max FE value the machine assigns, which is 31. Normally, any target whose FE number is 22 or higher is decidedly an iron target, no matter what the CO number is.

Well, in running the Explorer/S.E.F. coil combo through my test garden yesterday, I discovered something interesting. This coil (which from experience I had found will only "see" coins consistently to about 6" deep) was, as expected, hitting my 6" pennies and dimes just fine. It would only chirp occasionally, at best, on an 8" coin. So far, so good -- this matched my previous experiences with this coil. But, out of curiousity, I turned off all discrimination (I "opened up" the machine and "accepted" all iron). I was startled to find that, in this mode, the 8" dimes and pennies became quite detectable, hitting very hard -- but with a FE/CO identification as 31/31 -- a solidly IRON ID. So, I went to the 10" dimes, and -- while not as consistent, and clearly approaching the limits of detection, the coins were still clearly seen -- and again, with 31/31 ID. This is the SAME BEHAVIOR I saw with the 10" stock concentric coil on my F70, and at the same time a decidedly DIFFERENT behavior than I observe with the Gold Bug Pro and 11" DD coil, as well as with the Explorer and 11" DD coil.

So, I put on the 11" DD "Pro" coil for some additional testing. Running IM 22, the 6" dimes/pennies ID'd well, the 8" dimes/pennies were less repeatable but still good ID, and the 10" dimes were less repeatable still, but still with semi-ok ID (NOT solidly good, but CERTAINLY not iron). Then, I switched out of IM 22 to the "no disc." mode, and -- unlike the S.E.F. -- saw little if any improvement in ability to acquire that 10" dime. Still only semi-repeatable hits, still semi-OK ID. I wondered if switching out of disc. that the 11" DD coil might ALSO show greater absolute depth, but with solidly IRON ID. NOT SO. In fact, I think the 6x8 S.E.F. coil hit that 10" dime "harder" than the 11" DD -- i.e. more repeatable and consistent, despite the AWFUL ID. So bottom line -- in terms of "effective" depth, I find the 11" DD "Pro" coil to be a good 2-3 inches deeper at least, BUT -- the S.E.F. coil is AS DEEP, if not DEEPER, in terms of absolute depth.

For whatever reason, putting all of this together, it seems that in MY soil, concentric coils (and the S.E.F.) in general may be DEEPER than similar-sized DD coils, BUT, their ID performance is DECIDEDLY worse than a DD coil.

Two questions related to this...

1.) Do these results imply anything unique with respect to my soil, to any of you experienced users, such that I could possibly find some ways to improve my detecting strategies and abilities in my dirt? My soil seems a bit strange, to me, in that it seems there is enough iron present so as to really screw up the ID acquired from a concentric coil, AND YET there does not seem to be much effect on ABSOLUTE depth. It seems I can get the "depth" performance of "mild" soil, and yet ID performance (with concentric coils) that is suggestive of at least moderate mineralization. Seems strange, to me...

2.) Would I likely be better off, in terms of a "small" coil, to trade the 6x8 S.E.F. in for a small DD coil, such as a Sunray X-5 or 6" EXcelerator coil? While maybe not as "absolutely" deep as the S.E.F., would I likely see improved ID capability such that the "effective" depth of the small DD coil would be better? I like the S.E.F. coil otherwise; it separates well in trash and does give good, stable ID to about 6". I just wonder if, without having tested a small DD on the Explorer, if I could get another inch or two of good ID depth out of a small DD.

Steve



Edited 3 time(s). Last edit at 10/03/2011 07:59PM by steveg.

Steve,
Your smaller coil will do better if you have a lot of trash around your targets ...tt wlll not include as many targets because of it's size and it will be easier to determine good targets, as you can cherry pick better with the smaller coil ......When you made your test garden , did you check the ENTIRE area even deeper sections for any iron ? ..... It sounds to me like you have iron in the ground and mixed with the dime or pennies when running in sort of an ' All Metal " mode, the iron is mixing wth your pennies or dimes and giving you a partial iron ID since it's more dominant ..... I haven't used my SE since it's all apart since I got it used , to make a water machine out it so I can't even tell you how it works ......Can you discriminate out the dimes or pennies ONLY on the SE like you can on an E Trac ? ..... If you can , try discriiminating out only the coin and see what your detector reads when you go over the coins ....My guess is that you might have iron in the area that is giving you a different reading when you basically run all metal ....Be aware that certain Minelab machines will penalize you for running discrimination .....The E Trac does NOT penalize you, and I don't think that the Sovereign does either .... .....not sure on the SE .... Jim

BTW , those little SunRay colls go DEEEEEEEP !!!....

Jim --

Yeah, I know the small coils will do better in trash -- and when hunting coins in trash, that aren't likely to be over 6" deep, that's when I like to use the small coil just as you say.

As for asking about the setup of my test garden, I did not "sanitize" it with a rare-earth magnet as NASA-Tom would suggest. However, I did run through it with my F70, before burying the coins. I ran in all-metals mode, and spent alot of time being sure that I got all of the targets out that it could see. Could there be rust particles? Sure -- but I got the larger pieces that the F70 could see in all-metals. My yard is a newly-developed lot within what used to be an old pasture, so there is not an over-abundance of trash/targets around. The ground is about as "clean" as you could expect, without "sanitizing" with the magnet.

Steve

I think on the explorer if you dont accept all target's you leave a lot of the past 7 inch stuff in the ground.....

The explorer is deep but the people who dig the 15 inch coins accept all and dig by sound not by the ID. of the machine...I never had my explorer I.D. anything properly past 7 inches...and I have dig 17 inch deep bullet's that read Iron on the meter..But had a nice whisper flutey tinkerbell type hit...Hard to describe but sounded like it was way off in the distant but had a ring to it....I.D. was iron...all the time...

The S.E.F. coil is an awesome coil and it handles mineral extremely well by the design...Dont worry about the Sunray it's nice too but it's not going to be all of the sudden coins popping out of the ground everywhere you have all ready been..

Learn the excellent 6x8 S.E.F. and get used to it and get out and dig...The S.E.F. is cutting edge design...The sunray is old tech ...There nice and work great because they are built well but the newer coils coming are better design technologically ....


Just me take...

But heck I really like S.E.F. Butterfly's


Keith

Steveg......... No, No. The REAL question is:

Do you see any merit in a proper/well-orchistrated test-garden now?????? :-) :-)
(((Talk about "driving a point home"))).

Well said!.... Well written, Steve.

1. Due to your iron lateritic red-clay mineralized soil...... your resultant is the expected norm. In a nutshell........ a tighter electromagnetic footprint (generated/enveloped by DD coil) will see LESS mineralized dirt; subsequently..... giving better ID's at depth. A concentric coil takes on-board a large 'volume' of dirt to be analyzed..............and...............yep............ is MUCH more 'interfered' with by the large 'volume' of mineralization. Resultant: less accurate ID's....especially at depth. Yes, "depth" vs "effective depth". But............. more specifically...... in this case.......... "overall depth" ... vs ... "overall depth WITH ID" effectiveness. To hear 10,000 deep iron grunts in an afternoon's hunt........ and try to determine which TWO of the 10,000 iron grunts is a deep silver coin........ is futile. Accurate ID is paramount.

2. I believe the small DD coil will surprise you. BUT........... your test-garden will be your ultimate tell-tale.

Keith -- interesting that you say that the people who dig the REALLY deep coins, do so in all-metals mode. Makes sense; that's a "dig it all" (if it's deep) philosophy, which I can see oviously has some merit.

However, what I DON'T understand is the implication that these folks can tell "by sound" which of the deep iron-VDI targets ARE IRON, and which of the deep iron-VDI targets ARE COINS. I am of the belief that the sound really doesn't tell you that -- unless there is a subtlety in that sound that I simply don't hear. To clarify -- I fully agree that the Explorers ABSOLUTELY have alot of information contained in their tones, and since (unless I am mistaken) the numerical I.D. "circuit" and the tones "circuit" are separate -- i.e. they ID targets independently of each other -- they could conceivably arrive at differing determinations of what a particular target might be. So, yes, there IS alot of opportunity to "hear" things that help with target ID within the rich audio language of the Explorer. BUT -- my experience is that the tones and the VDI numbers match up very closely, the vast majority of the time -- i.e. the two circuits arrive at the same "answer." And given that, the problem is then that many 03/29 targets (say, a Mercury dime) sound JUST LIKE a 24/29 target (i.e. a bent, deep rusty nail) when running conductive sounds -- because obviously both targets have the same conductivity. So, since you are effectively hearing the "tonal" representation of a 29 CO number, then both of these targets, if similar in size, sound VERY similar. THAT is the problem -- and so I don't know how someone running all-metals on an Explorer can say that a deep coin which is IDing through the "numerical ID circuit" as iron at 24/29, can actually reveal that it's a coin through the SOUND circuit. See what I'm saying? The sound is cued by the 29 conductivity (assuming you are running "conductive" sounds on the machine). This brings us to what NASA Tom said -- trying to find the deep coins, when running in all-metals mode, would mean digging a boatload of "good sounding" (i.e. high conductivity) iron fragments, to find the two "good sounding" (i.e. high conductivity) coins! If you are in a "target-sparse" environment, that's fine. In a nail-littered site? Fuggedaboudit!

Any thoughts on this Keith?

NASA-Tom -- yes, I do see the merit in a properly laid-out test garden!

You say that my results are what you would expect in my type of soil -- and you explained the "why" being due to the fact that the concentric is taking in more volume of soil. Makes sense. I still don't know why the OVERALL depth is not limited also -- due to the iron, but instead the limitation seems to only be realized when trying to ID the targets...

But, your last point is exactly the dilemma -- sorting out the occasional deep coin from the multitude of deep iron falses. So yes, a coil/machine setup that IDs AS DEEP AS POSSIBLE is key, in trashy locales. Along these lines, you feel that a small DD coil might surprise me...so I think I'll try to get my hands on one, and check it out, in my test garden. Because as you say, if my 6x8 can see a dime at 12", but IDs it solidly as iron beyond 6", then the effective depth is, SIX INCHES in most situations. BUT, if a small DD coil can only see the dime down to 8", but it IDs it properly all the way to 8", then I have "effectively" picked up two inches of depth. I will try to find a small Explorer DD coil to check out in my garden...

Steve



Edited 1 time(s). Last edit at 10/04/2011 12:51AM by steveg.

Oh, I know what Keith is talking about....that slight broken mid-tone, no VID at all...yep...got to know the machine to pull it off......
Done it a bunches of times....

Hey Steve I never used the SE but did use the XS for 5 year's straight...and the Meter and the tone's when I was in -16 iron mask( as low as it would go)

The tone's would be different from the I.D....But I mean real deep target's...past 15 inch's ....it would show up on the I.D. on the upper left hand corner but would be a ringing tinker bell type faint hit?\Again hard to explain....But know I was hunting places that were hunted out ...Not park's or yard's but Civil war campsite's....

And till this day I have never seen a detector dig as deep as the explorer does in the ground....Bad ground or good ground...


The explorer does mask pretty bad in iron if the sweep is not just perfect....

But again I never saw the explorer I.D. correctly past 7 inches in my dirt....

Actually the tone will be heard when the I.D. screen quit's...it may be showing a target on the screen but it's just locked up on it usually...

Deep hunting with the explorer is an learned trait...I probably could not do it now since I have not been serious with it in a few year's now...


But it's like any other detector..it I.D.s better than most on the market maybe the best....but once you get into the deep hunt mode...there's a whole new world of depth to EXPLORE!!And different behavior to to understand and use...

it's all about tone and it is a learned skill....and very easily overlooked till you become accustom to it...

It's like the Sovereign...people will argue with you all day saying that the sovereign is deeper in Disc mode than all metal...well for them it may well be...But untill you have witnessed and done it with your own eye's it's very hard to understand that the all metal mode is way deeper..

But it's just detecting and if they are happy with there way and style of hunting then so be it...but stuff does get left behind for other detectorist who have learned there machine's behavior far better...

There's lot's of nuanced trick's to hunting deep that the majority of the detectorist don't understand or dismiss as hogwash...But it's very very doable...

Keith

Why would you not want your test garden to be the same type of soil you normally hunt in. If you pull out all of the natural iron out of it you may get better depth and ID accuracy, but if thats not the kind of dirt you hunt in, whats the point?

Keith ive never found targets as deep as you, but im sure a lot has to do with where you are hunting. Having field and woods hunted its a lot quieter and you can get more concentration. People say its hard to get a TID beyond 6 inches.... but some targets are predictable based on target jump. The screen is just slow enough i believe it stays in a location on the smartscreen longer than in the digital screen. Part of what you said about the tone being heard long after the TID quiets is like you said a learn trait. Like learning a new style of hunting say raw gold hunting, if you have never done it you dont know what you are listening for or where. Some of the threshold tones can help.... like pitch hold or long which few machines have. The high sensitivity you have to run to get these deep deep targets do tend to swing the targets because of wrap around. To often people run their sensitivity high everywhere they hunt. Thats not always the best.

Ive just started using the Xcal and it seems mine is deeper in disc or at least as deep. BUT..... it may be the mellow tone of PP when turned down and not understanding that some of those tones ARENT minerals. You can learn to hunt with a bad machine and get the best out of it. I never have been as impressed with MLs PP as i was with the Whites just because it was a processed signal in the Explorers.

Dew

Dew.
There are those on other forums who are beach hunters that use Excals as there are not that many targets to have to hassle with ......Some of these beaches are sanded in or have targets that are VERY DEEP ......The method used by many of them is going to a bigger coil , and running an additional audio amplifier .....They will run the sensitivity high as you can afford to do this at the beach in many cases , and they run wide open all metal , and turn the threshold down to where you can hardly hear it and then turn the audio up on the amp ..... Larger close targets will knock your head off , but the VERY DEEP targets will not even give you a tone ......The only thing you will get is a slight change in threshold .....This method is ONLY used with no discrimination ....It works quite well for those who are tuned into it ..... When I say deep , I mean small targets that are down more than 12 inches in the sand !!...... I'd love to get down to Florida to try this method .....You'd probably hear folks talking Chinese !!!!.....LOL !!.......I've owned a few different older Minelab machines , and they have ALL gone deeper when run with no discrimination .....When doing a reverse discrimination ( running in no discrimination and checking in discrimination mode ) which is how I would run on the beach , when I go to check the target in discrimination mode, I can't even hit the target if it's too deep ..... Take a poll and see how folks run the Excal on the beach and see for yourself ..... If you are happy in discriminate mode, by all means continue to run this way , but I have to agree with Keith on this one .....Jim

Nice thread!

Steve.............

A DD coil will acquire the deeper targets with less signal strength....... BUT...... with 'cleaner' and 'higher' ID resolution/accuracy.....due to more 'concentrated EM energy' on the actual target..... via 'seeing' less dirt interference/mineralization.
The same deep target...... but.... this time...using a large concentric coil.............. and the signal strength of the target will be greater/easier to see...with a concentric coil. TO A POINT. Your SPECIFIC dirt mineralization level/status dictates. Even in medium mineralization (vague term)..... a large concentric coil will 'see' (realize) a deep target via a greater angle-of-attack from more directions into (and on) the target. The electromagnetic (EM) energy from the concentric coil is more of a 'broad' coverage ... as the EM energy will wrap completely around the target/object. A DD coil........ on the other hand......... eminates a EM footprint that is very tight/narrow. SOooooo..... the DD coil will only 'see' a finite sliver/slice of the deep target..... from only one angle. A DD coil is monodirectional.... whereas a concentric coil is omnidirectional.
Now............... when dirt mineralization goes from 'medium' mineralization............ to 'high' mineralization....... a redline/threshold/turning-point is ascertained..... whereby..... excessive dirt mineralization feedback will attenuate TOO much EM energy....... and that deep target will NEVER be 'realized'. The signal strength of the dirt mineralization becomes stronger/overpowering; subsequently.... the signal strength of the deep target is sub-baseline (((below the threshold level of detection))).

Robbing Peter to pay Paul. = The less dirt mineralization you 'see'....... the better/more-effective the ID accuracy will be. Yet......... this can only be achieved by narrowing-the-EM-footprint. The smaller the coil......coupled with...... a tighter footprint (via DD). This severely reduces depth capabilities.....but increases ID accuracy. (((Depth vs Effective Depth))). Now........... now...that you have narrowed the footprint and gained ID accuracy via 'seeing' less dirt mineralization........ the intent is to regain the lost depth via boosting the sensitivity gain. And in doing such..... you re-induce some err again. Boosting the sensitivity/gain..... EMI becomes an issue..... and .......... although you are seeing less dirt/mineralization with a tight EM footprint..... by virtue of boosting Sens/gain......... what little dirt mineralization you ARE seeing/realizing...... it TOO becomes 'boosted' .... to..... ......once again..... induce err.

Desperation paradigm shift is in high demand.

NASA-Tom --

I followed everything you were saying there, and it makes complete sense; I enjoyed the additional info on the DD vs. concentric, DD being monodirectional and the concentric omnidirectional, able to "wrap around" a target as it sees it from more directions...thus "hitting harder" on a deep target but also with worse ID capability due to seeing more volume of soil (and mineralization included therein).

The "robbing Peter to pay Paul" idea in the next paragraph also makes sense. Using a DD coil to get better ID (at the expense of depth), but then cranking up sensitivity too high to re-ascertain the depth capability, and you are then bringing the mineralization back into the equation -- and decreasing ID capability. Trade-offs, trade-offs, but one thing I can take from this is what I've been working with recently -- and that is that sensitivity/gain adjustment is critical, and varies based on site (EMI, soil mineralization, soil moisture, amount of trash), and also varies based on coil type being used...great info here, and I thank you. And yes, I continue to see why you keep bringing up "paradigm shift..."

Keith (and Steve(MS)) --

I do know what you mean when you say sometimes the Explorers will report audibly beyond the depth where you can get a VDI number...and yes Steve I have heard, I think, the "slight broken mid-tone" you describe. I usually dismiss it, though...

Keith -- it sounds like I have much to learn, and the fact that I haven't dug coins deeper than about 7" with my machine confirms that. I am working with learning how critical sensitivity adjustment can be right now, and I really want to learn the subtleties that you guys are talking about in terms of deep coin hunting. This statement that you made above...

"Deep hunting with the explorer is an learned trait...I probably could not do it now since I have not been serious with it in a few year's now..."

...is absolutely intriguing. This is a trait I really, really want to learn. But, it sounds like you are talking about less trashy sites; is this a trait that can be learned when your hunting spots are filled with moderately deep nails? Turning down sensitivity from the normally super-hot level I run at (to reduce the falsing) is what I am working with right now, and it is helping. Beyond that, I'm not sure how to learn to pick the really, really deep ones -- as I have no idea what to listen for; until I find a few very deep coins, and can correlate what the machine was telling me at the time, I am finding it difficult to accomplish this goal/learn this trait.

Steve

Well Steveg.....I work area's with lot's of nails that are quite deep.....
I also run sens wide open 32...iron mask on the explorer XS -16...Actually the open iron range helps to your benefit by allowing the iron tone to be heard instead of being nulled....

You can train your ear to the flutey tinkebell hit of deep target's Sort of way off in the distant sounding but a unique sound....

Again it's something you learn after hour's of use...really study the sounds intensely....Forget about everything but the detector....investigate stuff that your brain has caused you to ignore....re-learn the machine if you will..

All machine's are capable of great depth if you learn the nuances to it...Again deep hunting is accomplished by a trained ear....it's not something you can read in a book or even see a video of it being done...It's just like you and the detector are one and it's your 6th sense for lack of better word's...

I believe a few year's back Monte Von on another forum was talking about some bud's of his from out west touring the eastern coast with the explorer's and just cleaning up everywhere they went....(Park's) He would keep people posted on the forum's about what they were pulling out of the hunted out park's...They would hook up with people in different towns along the east coast from invite's and then show the local hunter's what they were missing....

I remember following they're exploit's with great curiosity to what the next hunt would bring...Lot's of people were dismissing them and saying bad thing's about the guy's but the the plain fact's of the matter where that these 2 men where just plain in tune with there machine's .....I remember reading report's from some of the people who invited them in....They said coins like that and in that multitude had not surface in 25 year's....Lot's of seated's and pre civil war coin's where the norm....they would usually end the trip with well over 100 pieces of silver a piece on a 2-3 week run through New-England and down to Virginia...They mostly came from remarkable depth's....

I know this is off subject and lot's of people dismiss the extravagant claim's of deep coin's and relic's made on the forum's and such as fish tale's...But if you have never made such find's your self it is very easy to dismiss as tall tale's....'BUT' get a man in-tune with a detector and great thing's can and do happen ....

My best advice to you on deep digging is really explore the explorer....Study it inside and out and study it some more make adjustment's learn what target's do at different depth's....etc etc..


Hey Dewcon4414

Even machine's that null's rejected target's like the explorer or sovereign or white's 5900...don't dismiss a null as a piece of iron or trash....

Synthnut talks about deep hunting and I believe he is tuned into the sovereign...when using all metal mode and checking the target's in disc mode don't dismiss the target just because when flipped to disc mode the tone's null even on the lowest disc setting...that just mean if the target sounded weak in all metal that in disc mode it could have pulled down to the iron null range...so take that into consideration...now you want an eye opener run the sovereign in all metal barely audible thresh then get just a whisper of a signal but it has a good round sound to it and check it in disc zero and this mode will not hear till some dirt is removed ...then it will start to null the disc thresh but don't give up yet get a little more dirt out of the hole till it either gives a solid consistent null or the tone comes in ....then the true depth of the sovereign can be seen....I promise you wide open sens in disc mode still will not be as deep as a tuned ear hunt in all metal....the difference is I would say on average 3-4 inches deeper in all metal mode on a coin sized object...

Actually a sovereign has a lot of signal nuance in all metal mode..I know a couple of hunter's who are very proficient with just the all metal mode digging desirable deep non-ferrous relic's...Hardly ever using the disc mode on there hunt's..


But to clarify this if you are happy with the daily outcome of your hunt that's all that matter's ...

To be truthful I am not even sure detector manufacturer's are fully aware of the capabilities of there design's...


Keith



Edited 1 time(s). Last edit at 10/04/2011 10:39PM by Keith Southern.

Keith --

Fascinating post, it really is. I'm going to PM you on this, so as to spare everyone else the details -- since my questions will be very Explorer-specific.

Thanks for sharing this most fascinating information...

Steve

Now that we have the technical aspects out of the way speaking from a laymans standpoint which most of us are indeed the dirt your hunting in, humidity, personal settings, swing speed as can influence the behavior of any coil and for that matter the coil or coils in question can be a little or lot out of spec's. Now you know why I smile when a bystander watching you detect says what a simple hobby and I should get one of those finder things...
Probably a rookie with 20 years in the hobby compared to some of the forum members but do know we can never learn enough and always learning which makes this forum so good as members always willing to help or add their input which in turn gets us that good find the other guys missed..

Yep I have a planted garden and use it often as planted for close to 20 years it sometimes provides a wealth of info.

Yeah, Dan -- coin gardens are invaluable, I agree.

And I also agree that we can never learn enough, and that this forum is outstanding in that regard...truly an unparalleled, one-of-a-kind location on the web to learn about detectors and detecting.

Steve

I replied Steve....

now while I have witnessed outstanding depth with the Multi Freq's they are also very prone to masking....and not a first choice for iron laden area's...

I have another story for ya...

I had a buddy who was a dealer and instructor for detector's use....He was hunting a Yard over in Athen's Ga with a Multi freq Sovereign....He was very very proficient with it....

The yard was a antebellum home and he was diggin lot's of thing's and pretty well worked it down in one area pretty clean because of some coin find's in that spot.....well he went back with a simple Tesoro model and hunted the same spot and low and behold dug a Franklin College Button ( Pre University of Georgia)
He thought how did he miss it? Put it back in the hole got the sovereign out...Zero disc ...go across it constant null no target....got to check and the Button was lying inside a coat hanger....So there is a horror story for ya...

By the way a Franklin College Button is real real rare and his was the only one known with the backmark his had ...it was gold plated over silver also...

He turned down $20,000.00 offer 10 year's ago...

so remember the right tool for the right job...

Heres another story which to me proves you don't have to have the newest most expensive unit on the planet to score.
Hunting an old meeting house lawn that is still used from the 1800's and has been scanned many times over the years as the caretaker will let you hunt if you are neat.
Using a Tesoro toltec 100 from years gone by recovered a 5 inch 1839 seated dime that was standing straight up in the bottom of the plug and as the yard is not that large one wonders how many coils went over it comes to mind and some of the best hunters with the most expensive equipment were among the many that hunted this area.

Keith,

I appreciate the PM reply, and really enjoyed your story! Dan, enjoyed your story also! SO much to learn...

Hey HOBO --

No one has answered your question yet, so I'll take a stab...

I can see why you'd want a test garden that mimics the type of ground you hunt, junk, and all. Makes sense in a way, so that you could get used to how targets respond in a more "real-life" hunting situation.

On the other hand, however, the reason for a "sanitized" test garden is because of the scientific experiment-approach of "isolating variables." When doing experiments, as a scientist, and you are trying to measure the influence of a particular variable, say "X", you have to take care to hold all the other variables constant, so that when you measure the response you get by changing "X", you know that response you measure is likely to be due specifically to your change of "X", and not a response to some other, unknown, external change that has occurred and has subsequently influenced the effects of you changing "X".

For instance, say you bury an 8" dime, and a 6" dime in a new "test garden" you are setting up. And say, unbeknownst to you, the 8" dime has a nail sitting just off to the side and just above it. Let's say you are using a Fisher F75 with 5" coil -- and you disc out nails. You run over the 6" dime, and your machine hits it. You run over the 8" dime, and your machine hits it. So far, so good. Now, you want to test to see if the 10" concentric coil works well on your machine. So, you buy one, and run over the 6" dime, and it hits it. You run over that 8" dime though, and it is silent. Well, you may assume "gee, I guess this coil isn't very deep, it doesn't even see an 8" dime." You might then conclude that this particular coil doesn't work well on your machine. So, you send it back, and you buy an 11" DD coil, and run it over that 8" dime, and it hits it fine. You might conclude that the 11" DD coil "works well" on your machine, and also that it is "deeper" than the 10" concentric, since you can hit the 8" dime with the 11" DD and not the 10" coil. Obviously, that's not necessarily true, since INSTEAD, the truth probably was that the nail was masking the dime when you were using the 10" concentric, but not when using the small 5" coil, or the narrower-EMI-footprint 11" DD.

While this may be a silly example, it illustrates the issue. When you want to test different machines, or different coils, or different sensitivities, or whatever, and compare them to each other (or to some other "known" standard), it's best to see how these alterations perform in a CONTROLLED environment -- so that you are comparing apples to apples. An un-sanitized test garden is an UNCONTROLLED environment, and thus your results may misleadingly drive incorrect conclusions.

Now, if you want to set up a KNOWN dime-next-to-nail target, to test how well a given machine can separate a good target from a nearby trash target, that's fine -- as you are then testing a "controlled" difficult target. In other words, YOU PURPOSELY have set up the scenario of the coin-next-to-nail, and thus you know exactly what you are dealing with. But again, if that dime-next-to-nail, was an UNKNOWN situation, in an un-sanitized test garden, how would you ascertain what was happening when one coil, or machine, might hit the target and the other would not? Do you see how it would be easy to draw incorrect conclusions in this case?

Hope this helps answer your question...

Steve



Edited 2 time(s). Last edit at 10/06/2011 02:57PM by steveg.

THANK YOU Steveg! (I've been short on time).

Well said steveg.

What an excellent thread, thanks to all who have contributed. I to have an unstanitized test garden where I know there are many nails, foil, and siding slivers. I now see the need for a sanitized one. Thanks for all the good info. -- Randy

REMEMBER = JUST because your detector does NOT hear a unwanted/interference target in your test-garden..... does NOT mean that "nothing is there"......... NOR does it mean that it will not interfere with your detectors performance.

I love science!!!

"Happy hunting" - Schultzie

NASA-Tom -- you are referring to potential "silent masking" from rust flakes, for example? That's why my method of "sanitizing" (using a deep machine, in all-metals mode, and digging all the targets I COULD hear) is not a "perfect" solution, as I obviously left all the targets I COULDN'T hear, targets which might be causing masking issues that I'm not even aware of. Obviously, your "rare-earth magnet" sanitization of all the soil in the test garden, after clearing all "audible" targets with your detector, is the ideal...

Steve

Steve............ correct. SILENT masking in a 'controlled' environment is NOT a good (wanted) condition.

"now while I have witnessed outstanding depth with the Multi Freq's they are also very prone to masking....and not a first choice for iron laden area's... "

Keith ,
One day I was going to prove to my buddy that I could get targets just as well with my Sovereign as he did with his E Trac .....NYC parks are very well known for all the trash that exists there ......SO much iron to deal with .....I totally agree with you that the Multi Freq machines are NOT the best when it comes to masking , but out of all of them , the E Trac has a very wide discrimination range, along with pin pointing what targets you want discriminated out via the matrix system, and I have witnessed going over a Silver Barber Dime in the park that my Sovereign went over and did not even give an inkling that there was Silver in the hole ....... I called my buddy over with his E Trac and it hit this dime like it was 2" down !!......We stood there for a good 1/2 an hour setting and re setting my Sovereign to try to hit that dime ....No cigar !!!........That dime had a lot of trash around it , and it was a good 6-7 inchdes deep ..... My buddy turned me onto that article that Tom wrote about Silent Masking and it was THEN that I started reading more of what Tom had to say .... I learned so much from that one day , that I ened up getting an E Trac and use it exclusively on dry land .......I sitll love my Sovereign and Excal on the beach .... Not as much of a chance of masking , and I hunt more by tone than meter on the beach ...... I went back to a lot of area's in some of the parks with my new E Trac where my buddy found more Silver , and I was finding far less when hunting with my Soveriegn ..... It was a real EAR openner to say to the least !!..... Understand that these were all very much hunted out parks in NYC ....Other guys in the area laughed when we told them we were hunting Silver in these parks ..... A couple of older hunters had already pulled BAGS of Silver out of these parks over the years and said there was nothing left ..... Beieve 1/2 of what you see , and none of what you hear !!.....Jim

Even the so called great unmaskers...one has to learn the nuances and what to do.
For instance, get a 2 way 90 degree signal, that is a no brainer on most any model.
Then one has to find out the falses any model produces and see how it fits in to "when to go for it".
Then ground is different from one area to another, what might be great in one region may not do in another.
For instance here where I live, some of those unmaskers have a real problem with locking on to broke nails, say about an inch long
calling them good on one angle hits....these are usually mid depth to deep.....
Of course using pinpoint mode as well as other techniques will help one to dismiss some of those.
Sooo which to err? On the side of calling nails good or having a clean reject of most of them?
It seems these great unmaskers only do well with very low disc settings, once one tweaks it to knock out the troublesome trash or nails, they
may only be run of the mill unmasking.
These are rhetorical question as I don't need a response.
Most every model has its quirks, some are general knowledge while some info can only be found out by buying the model for oneself.
(This is one area where I would like to see more honesty.)
The point being be careful what you ask for, you just might get it along with other non-desirable traits that won't line up with your final objectives..

Keith - INCREDIBLE story with those old timers finding those deep coins - it should be made into a metal detecting stories book! I wonder if they had their machine set up in a special way to aid them or (and?) was it just their connection to their machines? What machines did they use? All meta? Would love to hear more or have a link if you know of one.
Oh, when you say multi freqs are prone to masking, I haven't found that when running in 3 freq on the V3i, but need to cross check with single frequencies more often. I've actually been able to hit coins in iron in 3 freq that my Omega 8000 won't. I do need to use it more in single frequency though. The one exception I have found in testing is a small hammered in my yard that I can only hit in 22.5 and not 3 freq.

Regarding coils - I got out yesterday and used my first concentric in years (White's 950). The area had a fair amount of iron, but not trash and the coil was really interesting for me to use compared to the DD's I have been using exclusively for 5 years or so. I felt I could really "probe" the target due to that cone shaped detection field. Of course pinpointing was a Godsend compared to a DD. I had to overlap my swings much much more than usual as I could tell from when I found a target how small the target window sometimes was. Nothing like a DD's big window. The ID's were a bit harder for me with the concentric when iron was around, but I felt like a surgeon moving around the target with that coil. Not the same with a DD coil. Hard to describe, but it was fun in a different way, but that said, in iron I don't think I want to use the concentric that often. Still have to play more with it. I would love to try an SEF coil in iron now.

Steve(MS) - I run my V3i with no discrimination BUT set the iron tone to 0. I find this really helps in unmasking targets as I don't get any masking from the normal iron grunt sound nor audio fatique and can focus on the targets only. After using the T2 and Omega for years I can say it really is an improvement imo. I couple the iron tone 0 with running a threshold and the machine "nulls out" over iron - but this does not mask as the "null" is actually a tone of 0 (no sound) and the discrimination circuits are not occupied. This is an interesting way of setting up a machine as from what I have read it is similar to the older TR (is that right?) detectors that ran similar to this by default and did excellent in iron by their nature. Also, I run correlate (similar to what the DFX had by default) in iron and this really seems to help quiet the iron falsing down.

I wish a few more people had the V3i as it seems to do very well in iron, even at slow recovery speeds and sweep speeds. It is so adjustable that I'm sure a few of you guys would discover some interesting and powerful ways of using it.

Thanks for the great thread,
EMS