For gold rings, what machine...

Since a (unsuspecting) large percentage of gold jewelry ID's as 'foil'....... (about 97%)............ and I may add: substantially below 'nickel' readings............... the 'foil' region of conductivity is VERY important.

That being said................. the CZ-3D has a 'specifically assigned individual tone' for exclusively/only the 'foil' range of conductivity. This alone...... constitutes an advantage for finding gold jewelry. In addition............ the CZ's audio responses are well buffed (heavily preprocessed, filtered, artificial intelligence); yet, there are subtile differences between a wad of chewing gum foil........ and a ring. The audio differential between the two items is very minute' .... yet..... human ear discernable (should you choose to learn the electronic sub-culture language).
---The Minelab Sov audio sub-culture language is a bit more discernable (subsequently, easier to learn).

The F75/F70/T2 are more sensitive (resonant) to the low-conductor 'foil' range.............. and do have a audio language of their own; yet, there is not a specifically designated tone for the 'foil' range. Your eyes must ride the moving VDI faceplate as you sweep the coil.... in order to 'see' (not hear) the detected 'foil' conductivity range targets.

The Explorers also can increase these small targets buy using FERR over Cond. You pick up EVERY tiny gum wrapper out there. On a beach ive found it great.... just kick the sand a little to see if its a surface target. Not certain this wouldnt drive ya nuts in a park. Risk and reward..... you might as well do a pattern like the jewelry mode with pennies and above knocked out.

Dew

Foil on the Sovereign has a good bit lower tone than the nickle range of numbers, so it's rather easy to note and avoid or dig if you want. What I've found is that odd shaped blobs of foil (thus being most foil found at a site) will give a rather sick warbly sound to it. Not only because the foil is oddly shaped, but also because the foil has surface "hills and valleys" or fine ripples running through it. Thus, gold rings that read well down into the foil range *usually* have a nice smooth, warm, round, "quality" sound to them, while most foil won't. The rings will tend to lock onto one or two VDI #s no matter which way you sweep, while the foil, especially odd shaped for and other odd shaped junk as well, will tend to roam by 3 digits or more depending on which way you sweep. Rings, like coins, being round, should most lock onto one or at the most two VDI #s no matter which way you sweep. Out of over 100 gold rings we tested there was only a handful that sounded sick or warbly and also would roam by 3 digits or more in VDI. These were rings with fine webbing or many holes in them. Even a super thin gold ring won't do this warbly/sick/roaming thing. It's due to the nature of the ring structure that'll make them sound like odd shaped trash.

Can you post pictures on here in threads? If so let me know how as I've got some charts we compiled that will blow your mind. For instance, while the original thread's intent was to chart VDI numbers on rings and tabs for the Sovereign...All found via random samplings, meaning by not digging only certain zones or only digging good sounding targets...All these rings were found by an Excal water hunting over several years digging every signal above iron. I've seen gold ring test pools used in the fact to attempt to chart where they tend to fall. The problem is usually those rings were found by selective hunting, so that distorts the true nature of the test pool and biases it. Same with the tabs we graphed. All dug at numerous sites digging every signal we came across.

Anyway, the first page or two of this thread shows actual Sovereign VDI numbers. On page 3 of the thread you can see that I broke that VDI range down into more understandable (generic) numbers in terms of where the foil range, the nickle range, the tab range, the coin range, and so on falls on the Sovereign...And thus what percentage of rings read "in the foil range", and what percentage reads "in the nickle range", and so on for application to other brands and models of metal detectors. Shockingly, for example, 47.1% of all gold rings fall in the foil range. Even more shocking, only 9.1% fall in the nickle range. And for further jaw dropping statistics, only 31.4% fall into the round and square tab range. Many people would have suspected that most gold rings fell in the tab range or perhaps the nickle range. So, even if you combine both the nickle and the tab range, that still is not as high of a percentage of rings as there are in the foil range. That alone should blow a few people's minds.

Obviously, keying in on the "nickle zone" is a rather poor choice in terms of percentages, but it's still fun to do when only coin hunting and so perhaps you might pop an old nickle or a ring, if not at least a modern nickle. But, keep in mind that these "zones" depend largely on how high the resolution is on your detectors. Most, if not all, detectors do not have as high of resolution as the Sovereign in terms of from tiny foil all the way up to copper penny. All coins above copper penny are compressed into the 180 VDI #.

Zinc pennies read around 173 or 176 on the 180 meter. From 170, so just a hair below zinc penny, all the way up to 180, there are only 12.4% of gold rings that read that high. I bet many would be shocked that as low as that is, it still is a higher percentage of rings than what read in the nickle zone. More details at this link. The third page has this data on it in a chart, but the prior pages as well as ones after page 3 also have various charts displaying that data in various ways. Later in that thread I started showing various target ranges via bar graphs, which gives a very visual representation of these numbers on the spectrum of the conductivity scale.

[www.findmall.com]

Hi Critterhunter,

Your information appears solid and confirms with Bob Brockett's testing and my own results. Gold is down there in the aluminum range. And digging the right signals at the right locations will increase your odds that one of those trash targets recovered will be gold.

I want to add, this is valuable information to gold jewelry hunters and should be in your notes for periodic review!

HH
Mike



Edited 1 time(s). Last edit at 06/12/2012 05:58PM by Mike Hillis.

Hey critterhunter, what a WEALTH of information you are sharing. I, for one, MUCH appreciate this. It gets my mind working, which is just what I need...

GREAT stuff here...

Thanks so much for your time and input into this thread...

Steve

Critterhunter -- I read your Findmall post, and I'm thinking through the logic...very, very solid approach that you had in doing all this, in my opinion. There's some very good logic being used on your part...I'd like to chat with you some more on this...sending PM momentarily...

Thanks so much!

Steve

Sure, PM away. I might not get to it until the next time I'm on. My female long haired (wooly) husky Sky just passed away unexpectedly a few nights ago, so I'm about burned out with the typing for one day. I've kept myself occupied for a good part of yesterday and today by surfing the net, when I wasn't downing beers and getting drunk crying with my neighbor about long lost pets we now share the experience of losing. Keeping busy on the net has helped me forget it for a few minutes at a time, but I'm about typed out for one day and ready to try to occupy my time with some Wheel of Fortune and Jeopardy. :') If I don't get back to you tonight I'll try tomorrow. Glad you enjoyed the links and compilation.

Yes, I know splitting hairs on rings is a controversial subject with the "dig it all" approach being the only true way to be sure you don't miss something, but the key here is selective digging criteria by way of certain conductivity ranges (to avoid the most common trash at a site), or by sound (to avoid as much trash in the ranges you are digging), and so try to improve the ring to trash ratio at least at certain sites where you can see a viable strategy to use there. The trick is that the strategy can't be static. You have to adjust to it. Flooded with pull tabs? Avoid those. The site is loaded with foil? Then avoid that range and dig everything else, or at least avoid any foil range targets that sound like junk. But, both the VDI resolution as well as the audio detail ability of your machine can play big factors in this, and so you might have to further adjust your VDI or audio "tools" to compensate. Of course much of what I wrote was based on the Sovereign's strength in VDI resolution and awesome audio abilities, but the information can still be applied to many other machines in various ways. Again, glad you enjoyed it...

OK, one more thing to thing about and then I'm off...Part of that strategy also involves the "sex" of the rings you expect to find at a site. More than likely a female lost a ring there (say behind a baby swing in a park)? Then dig the foil range. More than likely a "male" ring in that it's being found at a horsehoe pit, then dig say from nickle on up. Then again, both male and female rings of various sizes can and do read low or high for any number of reasons, including being "white gold" or having certain levels of copper or other alloys affecting both the K value as well as the general conductivity of the target.



Edited 1 time(s). Last edit at 06/12/2012 11:04PM by critterhunter.

Thanks for all the info and the kind reply Tom.

I do know there is a member of the forums that does EXCEPTIONALLY well on rings with a White's M-6.
I did read up on it...I believe it has 7 different audio tones assigned to the VDI scale.
I believe it is considered a DIGITAL unit.

What are your thoughts on that one? How does it compare OR not compare to a CZ-3D?



Edited 1 time(s). Last edit at 06/13/2012 03:04AM by Coilfishing.

An update...

I dug a couple of rectangular tabs that ID exactly like my wedding band. So tonight, I set my wedding band (14K large men's band) on the ground, next to the rectangular tab -- both IDing at 08-19 on the Explorer. I swung over both targets for quite awhile, over to the tab, back to the ring, etc. I could tell ZERO difference between the two tones, on my machine. I listened as closely as I could, and they were identical. If I rotated around the targets, I did notice that the pull tab was less consistent, tonally -- i.e., more changes in tone, than the ring. The ring was very consistent. This is the same tonal "clue" I use, when digging nickels. I think this is the "roundness" thing some folks speak of -- in that a round ring will give a consistent tone from any direction, whereas a rectangular tab will give a very slightly different tone as you hit it from different angles. BUT -- without rotating, and just doing a few east-west passes across the tab, and then a few east-west passes across the ring, there was ZERO difference in the tone that my ears could hear, on my Explorer.

One other note, and this SHOCKED me...on noise cancel channel 11, my ring consistently ID'd at 09-13. Every pass. On noise channel 1, it's 08-22 -- every pass. That is INCREDIBLE. On the middle channels, it's 08-19. This is an INSANE amount of difference, just by changing the noise cancel channel. And for what it's worth, the rectangular tab that ID's the same way as my ring, changes exactly the same way, ID-wise, when changing the noise cancel channel. In other words, it ID's the same as the ring no matter the channel chosen. Anyway, there appears to me to be a VERY SIGNIFICANT amount of things going on by simply changing noise cancel channel, and this is something Minelab does NOT discuss openly, for some reason. On a related note, I was reading my manual tonight (trying to remember how to save a user-defined discrimination pattern), and it is funny to me how Minelab really touts their "learn" function, where you can take a particular target, sweep the coil over it, and then choose to "learn accept" or "learn reject" that target. They say that this is perhaps one of the most important features on the unit, i.e. the ability to "learn" and then "reject" a particular type of trash item that is prevalent at your site (say, a particular type of rectangular tab). However, it appears that the noise cancel channel being used could render the "learn" function COMPLETELY useless! If I wanted to reject a tab, and so I employed the "learn" function (when my machine happened to be using noise channel 11), and the machine thus "cancels" the 09-13 ID that's all fine -- UNTIL I NOISE CANCEL MY MACHINE! If my machine chose noise channel 1, let's say, that 09-13 tab is now IDing as 08-22 -- ENTIRELY different than my discriminated 09-13 target, and thus my machine would NOT discriminate that tab! While I don't use the learn function as I don't depend on ID or discrimination given the complexity that all of us on this site understand, I still find this whole issue of differing ID based on noise cancel channel to be very intriguing.

Perhaps I should make a phone call to Minelab to discuss this...

Steve

Steve, you are right, changing noise channels can affect tones and assigned numbers on Explorer, especially the low conductors.
I have been knowing that for many years.
If you want to try using the Explorer and go for gold rings, you could use audio 1, it is sort of similar ( so I have been told) to the Sov. long drawn out sounds.
Then if you scan slowly your gold ring and then the pulltab with same ID number, you may pick up on a subtle difference in the warbles.....for instance nickels
tend to start low tone and then high and end up low again with its warble. Then pulltab mimic to the nickel will usually end on a higher tone....it is subtle....
Rings should respond sort of like nickels......except the ones that are wide on top and thin and bottom.
Probably similar to what the others on this thread are relating differences between foil, tabs and gold on other machines.
But the problem I found with those subtle differences are they tend to not be as easy to "hear" when tested with in the ground real world objects....
especially when the ground is fairly mineralized.
Perhaps some other model(s) would be better at shooting for gold rings rather than the Explorer, if you have the time and resources, let us know in a few years....
There are the "dig it alls" and then there are those that play the odds....
I never could find a system that I could discipline myself to follow IRT going after gold rings....and I never really considered myself a ring hunter.

steveg...... it's about time! You are the first person to capture this.......... and articulate your findings into words on this forum. This is one area that I have been waiting for years to see if someone else would identify this condition/phenomenon with the noise channels in concert with learn/edit function on the Minelab. There remains other areas of 'discovery' .... still yet to be identified. Let me give one clue:

Start testing with a woman's small white gold 10K ring........ or........ especially a pendent. Test several different channels on the Minelab......... with minor attention to ID readings......... and primary focus on depth capabilities.
-------------------

As time progresses......... folks are starting to learn more and more............ that gold jewelry reads/ID's as 'foil'. The fact is........... over 97% of the gold jewelry in the world ID's as 'foil'.

critterhunter............. Your findings about audio tonal signatures are correct. I may add.... the less audio pre-processing/filtering that is employed......... the greater the differential in 'audio signature' will be presented.

Steve..... do the same test in Ferr and see if you can get the tone differences better. Did you check those depths per channal? That consistancy is the ROUND tone most talk about it tends to size the target. This is another reason people say .... im not getting the same reading on say a penny as you are. Their noise cancel may vary from yours which changes not only the digital reading but depth of the target. Looks like to me Tom that foil reading also depends on Karet and mixture. Some rings ive tested tend to move way up the dital scale because thay may have copper mixed. Great observation about about the LEARN. I use the learn occassionally i have a vary narrow penny disc. It breaks up the tone of a NEW copper penny but most of the larger copper rings ive tested are just outside of that reading. NOW.... i know i have to be aware of the channel.

Dew

critterhunter Wrote:
-------------------------------------------------------

>...Yes, I know splitting hairs on rings is a
> controversial subject with the "dig it all"
> approach being the only true way to be sure you
> don't miss something, but the key here is
> selective digging criteria by way of certain
> conductivity ranges (to avoid the most common
> trash at a site), or by sound (to avoid as much
> trash in the ranges you are digging), and so try
> to improve the ring to trash ratio at least at
> certain sites where you can see a viable strategy
> to use there. The trick is that the strategy can't
> be static. You have to adjust to it. Flooded with
> pull tabs? Avoid those. The site is loaded with
> foil? Then avoid that range and dig everything
> else, or at least avoid any foil range targets
> that sound like junk. But, both the VDI resolution
> as well as the audio detail ability of your
> machine can play big factors in this, and so you
> might have to further adjust your VDI or audio
> "tools" to compensate...
>
> ...OK, one more thing to thing about and then I'm
> off...Part of that strategy also involves the
> "sex" of the rings you expect to find at a site.
> More than likely a female lost a ring there (say
> behind a baby swing in a park)? Then dig the foil
> range. More than likely a "male" ring in that it's
> being found at a horsehoe pit, then dig say from
> nickle on up. Then again, both male and female
> rings of various sizes can and do read low or high
> for any number of reasons, including being "white
> gold" or having certain levels of copper or other
> alloys affecting both the K value as well as the
> general conductivity of the target.

This is it. This is all the knowledge that is needed to hunt for gold. Period.

Excellent post.

Pinpoint twice, dig once

Actually, no, not everything. This is just about trending gold readings on a metal detector. To be complete you also have to include site reading. The two combined make up "everything"

Good site reading skills will let you hunt gold jewelry using google maps before you ever break out your detector.

You hunt gold with your mind. You recover gold with your detector.

HH
Mike

Tom; It may be true that 97% of gold jewelry id's as foil, esp. small 10k. ( small chains, earings, er backs and small pendants) but most of the larger gold (mostly rings) id higher and are much easier to detect, at least where I water hunt and one large band or class ring contains a lot of earings. I know er'c can have precious stones, but so can rings. I do like hunting for gold chains, Ithink there must be a few zillion of them lost especially in the water.

Correct. Large gold rings do (usually) ID as 'pull-tab'.

Mike Hillis Wrote:
-------------------------------------------------------
> Actually, no, not everything. This is just about
> trending gold readings on a metal detector. To be
> complete you also have to include site reading.
> The two combined make up "everything"
>
> Good site reading skills will let you hunt gold
> jewelry using google maps before you ever break
> out your detector.
>
> You hunt gold with your mind. You recover gold
> with your detector.
>
> HH
> Mike

I stand happily corrected

"You Hunt Gold With Your Mind. You Recover Gold With Your Detector" This should be on a bumper sticker!

Pinpoint twice, dig once



Edited 1 time(s). Last edit at 06/14/2012 02:01PM by pulltabMiner.

I went out this morning with the V3i to hunt pull tabs. My goal was 100 pull tabs but I only managed 83 in about 2.5 hours.

I don't know if many people here use the V3i but I came to work after my hunt with a little bit of hope in that the Polar Plot analysis screen showed great consistency on 81 out of the 83 pull tabs and that is that the frequency lines were all either loopy or squigly or both. Only two pull tabs gave me nice straight lines.

Now if I can only find 83 gold rings to test!

I have three gold rings right now to test with and all three give nice straight lines on Polar Plot. I've only tested the rings on top of the ground and not buried.

Pinpoint twice, dig once

Interesting ptminer, were they round tabs........ or the square ones (tabs that are supposed to on with the can)?

i guess you saw this .....

[www.findmall.com]


47% gold rings fall in the foil range ....

Here is a new condensed thread of the final results of the orignal huge long novel of a thread about splitting hairs on gold rings. This thread is an attempt to bring the final data right to the point and is listed in generic numbers via a chart as to the foil, nickel, tab, and coin ranges, and exactly what percent of the rings we tested fell into those four most common conducitivity "zones" people classify on a detector. By using that chart posted in this new, more to the point thread, you can easily apply the percentages to any detector if you find that the data *might* have merit in certain situations. I realize that there are many who believe that the only true way to recover rings is to dig it all. I, however, feel that just like in Vegas, I want to "bet" on certain hands and not others given the nature of the site and thus it's specific "zones" of trash content. Of course of also primary importance is location, via targeting areas where there is more potential for rings to be lost, but fueled with the percentages of conductivity ranges you can at least *perhaps* tilt the odds even a little more in your favor.

In additon to the more "generic" conductivity zone data found in this new/condensed thread that should be useful to any detector, we also have compiled the information in VDI specific ways for the Sovereign, the Etrac, and the M6/MXT. Links are provided in the below thread to those more specific threads for those machines elsewhere. The tabs were also graphed for those machines as well, so you can know for the most part exactly where the tab zone starts and ends on those machines, as well as see the specific VDI numbers listed in a chart for the rings scanned on those machines. However, the more "generic" data found directly in the below new condensed and to the point thread, should still be more than enough for the information to be applied to any detector. You simply need to know where the foil zone starts and "ends" on your machine, where the nickle zone starts/ends, where the tab zone starts/ends, and where the coin zone starts just a hair below zinc penny (which means right after where tabs end, as there is a small gap between the highest tab (usually) and zinc pennies) and goes all the way up from there. Based on knowing that on your machine, you can easily apply the percentages of rings graphed in the generic chart provided to know exactly what "odds" you have on your specific detector.

Hope at least some find this information useful...

[www.findmall.com]



Edited 2 time(s). Last edit at 06/14/2012 06:01PM by critterhunter.

Steve, wow...you are the first person I've ever see raise that point. I have read and knew of course about noise cancel changing the VDI # of mid conductivity targets. On the Sovereign we see a similar thing. On the GT if you use noise band 1 nickles and other lower end targets will be a bit off from the ID charts compiled on older Sovereigns. Noise band 2 matches the old ID charts, so for that reason just about all GT users use band 2. In fact, I compiled my own custom ID chart using the target ID data from all the charts I could find, and then added targets to this new chart that I scanned, but made sure to use noise band 2 to build the chart so it would be useful to older Sovereign model owners. No charts exist that I'm aware of for the GT using band 1, as everybody wanted to match the ID of lower targets with the older Sovereigns by using band 2 all the time.

Anyway, despite knowing that the noise band can change the VDI of low/mid level stuff on any of the Minelabs, it NEVER even occured to me that this would pretty much render the learn accept/reject function on the computerized models pretty much useless, unless you did that after noise canceling, and then you'd have to use the same channel for future hunts if you've compiled and saved a discrimination pattern. Luckily, it doesn't appear to effect the higher target ranges such as coins, so the VDI charts for the FBS machines on at least copper coins and higher should be valid I would think. But, in terms of some gold coins or other old coins that read lower on the scale, the VDI might be highly suspect based on the channels an FBS machine is running at. WOW, I'm surprised that never occured to me before. Very good point, Steve!

I wonder if Minelab could have adjusted the VDI based on the channel being used so that targets would be adjusted to continue to read the same VDI #? That seems like a very logical (and easy) software trick, and would also mean that the learn accept/reject ability would be fully functional despite the noise channel it's running on. I think I've heard the CTX will allow software upgrades via a data link. Perhaps they'll include that in a future software version so it's no longer and issue? Seems like a good idea to me. Somebody should shop it to Minelab.

NASA-Tom Wrote:
-------------------------------------------------------
> critterhunter............. Your findings about
> audio tonal signatures are correct. I may add....
> the less audio pre-processing/filtering that is
> employed......... the greater the differential in
> 'audio signature' will be presented.

Yes, I agree. There is something "lost in translation" when the audio (or even the VDI to some extent) is sent through layers of electronics or in particular software. Often the final report is sanitized or sterilized into something a bit different than the true original nature of the target. I'm also not a big fan of short reports, as is often the case on digital machines.

That's one of the things I love about the Sovereign. While though it is in fact a digital machine (but with analog controls), the audio on it has a long drawn out analog quality to it. Of course, being digital, it still has numerous levels of tones that are well beyond most if not all people to hear the subtle differences between certain "steps up" in close proximity in terms of conductivity, but there are still enough variances in different tone/conductivity levels that most people can hear so that many people even prefer not to use a meter with it. The audio is that good in both quality (detail) as well as informative from the various tone alerts to acurately judge the conductive nature of targets all across the scale.

I can say that of all the machines I've owned, it's audio is more analog (meaning detailed). The only digital machine I have personaly used that had nearly as good of "analog" nature to it's audio was the QXT/QXT Pro. The audio on it was very telling in terms of the nature of the target (like say being scratchy on a bottle cap as one small example), but as good as the QXT was it's still not nearly as long and detailed as the Sovereign, and of course the Sovereign has vastly more alert tones where as the QXT was limited to a high or low tone (or 3 if you count all metal using mixed mode). The only strength to the QXT that the Minelabs don't have is the ability to set high or low (or thirdly all metal) to each and every one of it's 8 zones. For that reason it was deadly in trash looking for specific targets, or I should say at least easier to use in that you could train your ears to only look for a high tone regardless of what the target was you wanted.

I would also add that in terms of layers of processing for a VDI, the Sovereign may be a slow machine, but it has the fastest VDI response I ever used. The VDI is just a voltage output from the control box to the meter on I think a 2V scale. For that reason you instantly see what you hear on a target with it. There is no VDI lag, as where lag is the case with several computerized detectors, including my Explorers, I would guess due to the processing and display of the VDI. That's one of the reasons why Explorer users say to listen to the audio and ignore the VDI, in particular in heavy trash, as the audio can be saying one thing and the VDI another.

Some Sovereign users prefer certain analog needle meters for use on it, being used to analog meters on old machines of yesterday. However, I prefer a digital meter readout for two reasons- No lag time as the needle moves, which makes working through trash harder. And, with a 180 digital scale there is more fine lines (or splitting hairs) that can be done on targets of very similar conductivity values. With an analog meter used on the Sovereign I feel I'd have a much harder time trying to see these differences in close targets.



Edited 2 time(s). Last edit at 06/14/2012 06:18PM by critterhunter.

Guys, just want to say that I appreciate all this info...this has, for me, turned out to be an incredibly informative and informational thread. I have to go back through and re-read all this info, as there's so much good stuff here that I want to remember...

NASA-Tom, I'll look into getting my hands on a small 10K ring...this whole noise cancel channel thing has me really intrigued, and the implications regarding the way it affects the "learn" function are something I think would be very interesting information for Explorer users to have...but, I'm also intrigued about the depth thing. I think dewcon has maybe on that "rabbit trail;" he found an inch less depth capability on a small gold ring when moving from channel 1 up to channel 11...this is just amazing stuff, and I still don't know why this is all left COMPLETELY up to the user to figure out -- which Minelab has been so silent on all of the implications of the noise cancel channel changes puzzles me...

Steve(MS) -- I will check out the "audio 1," which I believe is the same as what is called "long" on an SE. But yes, I'm sure an Explorer is not the best tool for this job...

dewcon -- I'll also check out the response in "ferrous sounds," I did not do that, but will check that out.

Mike -- I have a LONG way to go, in terms of learning to "hunt gold with my mind." I have been STRICTLY a silver coin hunter, and always will be, first and foremost, but I DO want to learn to hunt gold jewelry as well...and given my inexperience at doing so, at this point, the "mind" part of it is dreadfully lacking...

pulltabminer -- incredibly interesting information there regarding the V3i...I'd like to see if some further testing with rings confirms your initial hypothesis, regarding the lines on the Polar Plot...if there is even ANYTHING there, that requires some attention IMO...

critterhunter -- again, an incredible amount of good info you have posted. YES -- you are right that this VDI change with noise channel change is much less significant on high conductors; one digit or so is about it. But on the LOW TO MID conductors??? WOW. You are right, some "software programming" should have been able to have been done that would have "corrected" the VDI back to some "baseline" such that any noise cancel channel would give the same VDI -- and thus allowing the "learn" function to have more utility. The way it stands, it seems to be a major issue that I'm surprised Minelab has never addressed...YES, the idea needs to be brought up. I'd say on one hand that I'm sure Minelab is aware of this issue, BUT -- at the same time, they haven't apparently done anything about it, so who knows...I think this deserves a call to Minelab...which I think I just might do. Anyone know how I might get in contact with someone (an engineer or R&D type), versus a customer service rep, over at Minelab?

Steve

steveg = That's 10Kt small WHITE gold.

steveg Wrote:
-------------------------------------------------------
> An update...
>
> I dug a couple of rectangular tabs that ID exactly
> like my wedding band. So tonight, I set my
> wedding band (14K large men's band) on the ground,
> next to the rectangular tab -- both IDing at 08-19
> on the Explorer. I swung over both targets for
> quite awhile, over to the tab, back to the ring,
> etc. I could tell ZERO difference between the two
> tones, on my machine. I listened as closely as I
> could, and they were identical. If I rotated
> around the targets, I did notice that the pull tab
> was less consistent, tonally -- i.e., more changes
> in tone, than the ring. The ring was very
> consistent. This is the same tonal "clue" I use,
> when digging nickels. I think this is the
> "roundness" thing some folks speak of -- in that a
> round ring will give a consistent tone from any
> direction, whereas a rectangular tab will give a
> very slightly different tone as you hit it from
> different angles. BUT -- without rotating, and
> just doing a few east-west passes across the tab,
> and then a few east-west passes across the ring,
> there was ZERO difference in the tone that my ears
> could hear, on my Explorer.
>
> One other note, and this SHOCKED me...on noise
> cancel channel 11, my ring consistently ID'd at
> 09-13. Every pass. On noise channel 1, it's
> 08-22 -- every pass. That is INCREDIBLE. On the
> middle channels, it's 08-19. This is an INSANE
> amount of difference, just by changing the noise
> cancel channel. And for what it's worth, the
> rectangular tab that ID's the same way as my ring,
> changes exactly the same way, ID-wise, when
> changing the noise cancel channel. In other
> words, it ID's the same as the ring no matter the
> channel chosen. Anyway, there appears to me to be
> a VERY SIGNIFICANT amount of things going on by
> simply changing noise cancel channel, and this is
> something Minelab does NOT discuss openly, for
> some reason. On a related note, I was reading my
> manual tonight (trying to remember how to save a
> user-defined discrimination pattern), and it is
> funny to me how Minelab really touts their "learn"
> function, where you can take a particular target,
> sweep the coil over it, and then choose to "learn
> accept" or "learn reject" that target. They say
> that this is perhaps one of the most important
> features on the unit, i.e. the ability to "learn"
> and then "reject" a particular type of trash item
> that is prevalent at your site (say, a particular
> type of rectangular tab). However, it appears
> that the noise cancel channel being used could
> render the "learn" function COMPLETELY useless!
> If I wanted to reject a tab, and so I employed the
> "learn" function (when my machine happened to be
> using noise channel 11), and the machine thus
> "cancels" the 09-13 ID that's all fine -- UNTIL I
> NOISE CANCEL MY MACHINE! If my machine chose
> noise channel 1, let's say, that 09-13 tab is now
> IDing as 08-22 -- ENTIRELY different than my
> discriminated 09-13 target, and thus my machine
> would NOT discriminate that tab! While I don't
> use the learn function as I don't depend on ID or
> discrimination given the complexity that all of us
> on this site understand, I still find this whole
> issue of differing ID based on noise cancel
> channel to be very intriguing.
>
> Perhaps I should make a phone call to Minelab to
> discuss this...
>
> Steve


I don’t know the audio capabilities of the Explorer, but on the E-trac, you might be able to set the audio setting to differentiate that ring from that pull tab. Maxing out the tone ID limits, tone ID variability, and increasing the threshold pitch above 20, you might start to hear a slight difference. But increasing the threshold pitch will affect the target audio pitch. For my personal hearing, a pitch of 30 has a tendency of expanding the low tone signals, making them more differentiable, but makes the high tone signals blend together. Perhaps experimenting with the threshold pitch can help you differentiate those low tone targets to your own particular hearing range.

Hunting nickels in a high trash area:
Thoroughly learning the nickel signal while using a threshold pitch of around 20 or above, (I use a pitch of 30 to beach hunt for those very low conductive small gold jewelry items), and using a small coil, was able to dig a high percentage of nickels in a high aluminum trash area in a park. It was the combination of thoroughly learning the nickel signal, and discriminating by the nickel’s target ID range (around 12 up to around 15) that limited the trash dug. If it sounded like a nickel, simply checked the target ID value to see if it was in the nickel range. Also, a small coil has better target separation, (less multiple target audio blending), and has a sharper, narrower audio response to a coin.

Some aluminum trash can sound like a nickel, but have a lower target ID value. Some larger, thicker objects can have a target ID in the nickel range, but have a wider, lower tone than a nickel. I think it has something to do with the “mass” of eddy currents in a particular target that allows the E-trac to have variations in conductive tones and target ID values, and Minelab’s conductivity/ferrous (inductive) mapping algorithm.

So far, I’ve only dug 4 gold jewelry items in parks, and only dug those because I thought they were nickels!

Unfortunately, there is a particular variety of rectangular pull tab that sounds just like a nickel, and reads 12-13 like a nickel. But it has a tendency to “double hit” like a coin on edge.

Steve - there is a video where a gentleman is discussing ways to increase depth on a explorer. At one section he discusses the effect of noise channel selection. If I remember correctly he used a simple freq detector and read the freq produced by each channel (I know it's a multi freq machine) each channel produced a different freq. Again if I remember correctly as the channel number increased so did the detected freq. This makes sense with the numbers you were getting in that higher freq are more sensitive to low conductors. Whites address this by normalizing there VDI numbers but also giving you the option of turning it off. There standard was based on their older 6khz machines and how the responded. So the tip from this video was to select the lowest usable channel for silver hunting and the highest for low conductors like gold. What did not understand from this video was that Minelab does not normalize their VDI numbers.

Now I have a Safari it picks the channel and never tells what channel it chooses. Know this I kind of wish I did.

You did your it was with low conductors. Maybe you should try it with the Silver my guess is your conductive numbers will average up with Channel 1 and average down with channel 11.

I will look for that video again and post the link if I find it.

Bryanna

NASA-Tom -- gotcha, 10K small WHITE gold...

Digs_alot -- interesting, about the threshold pitch. I run my threshold pitch at the lowest setting (with limits and variability maxed out). This works well for silver; I believe these settings are what give that nice "silver warble" that the FBS units are known for. HOWEVER, it's interesting that you think running threshold pitch to the max (or close to it) might "expand" the tones on the low conductivity end of the spectrum. Very interesting. I have NEVER touched the threshold tone, as I have wanted to "train my ears" in what to listen for, but you are right -- there seems to be little tonal "definition," for lack of a better word, on low conductors. Interesting to think whether cranking up the threshold tone's pitch (and the corresponding increase in pitch of all the tones) might more "definition..."

Yes, there are a few objects that sound and ID exactly like a nickel...a "beavertail" is a tad lower, but one type of "ring tab/beavertail," with the beavertail folded into its round tab, can ID just like a nickel. There are one or two other things that really mimic a nickel, but otherwise...I've been following a similar approach to years, with respect to digging nickels in aluminum trash, with some success (and yes, those tabs will sometimes "double beep," but so did some of the rings I tested). BTW -- it's interesting that you've dug a few gold rings thinking they were nickels...I keep thinking I'm going to dig a ring at some point "by accident" like that, but hasn't happened yet...

Bryanna -- I'd like to see the video if you can find it. But I have heard that too -- low noise cancel channels for silver hunting, higher ones for gold...but dewcon's results showed a decrease in depth on small gold, at higher noise cancel channels, which doesn't line up with the "high channel for gold hunting" thing. NASA-Tom is talking about depth results on that small 10K white gold when changing channels...and so I'm interested to see what I find, to see if it matches dewcon's results on the 14K yellow gold...

As for silver, yes, I do need to test it, but I don't think silver conductivity values change much no matter the channel. I know that there have been days that I've found copper memorial pennies to be "reading high" -- just a bit higher in tone and ID than usual, but it's small...a quick air test on those days showed the pennies ringing up at "29" CO instead of the usual "28." Now that I know what I know about noise cancel channels, it makes sense that THIS may be the reason. I plan to do some testing of MANY targets, at the different noise channels, and will post the results when I do. I plan to do depth testing, too...

Steve

Supposedly, the way to use the learn feature on the Explorer is to make adjustments at site.
I did tests when I first got the Explorer and realized the noise channels could slightly move up or down the
conductivity scale.
The only times I used tight patterns was when I first used the Explorer, after that I decided to go by tone alone.
It's really not a big deal but running tight disc patterns is risky to start with....