Splitting Hairs On Ring VDI Numbers

[Critterhunter]

This isn't intended as an arguement over "dig everything". That's very realistic on the beach and in some other areas but not in a large area with tons of trash. I'm compiling my own chart with percentage of various gold rings from a test pool of about 100 to 200. Still, I would be very much interested in hearing what number ranges others tend to key in on when gold ring hunting based on your own personal experience. Is it below nickle, in nickle, or above? Be specific with your number range if you can. Are there any other strategies you use when doing this, such as only digging "pulltab" numbers deeper than a certain depth to avoid them, or can you/do you listen to the sound of the target to try to hear a possible gold ring versus a piece of trash? Although I haven't conducted specific audio tests yet, I'm finding in my air testing to record VDI numbers that gold rings even with very close VDI numbers to a pulltab have a distinct warm, smooth, round sound to them, while the pulltab tends to sound harsh, hollow, or tinny. This tends to hold true with a few detectors out there that I've owned in the past but the difference seems more pronounced on the GT.

Anyway, I'm hoping at least a few people will find posting specific number ranges interesting or useful in discussion. If you are a beach hunter or a die hard "dig it all" kind of guy that's great, so am I in the right places, but this discussion is tooled more to strategies for selective hunting. If you have specific ring find numbers to list please do so as well, but try to include K value, general size of the ring (small, medium, large), and if it's a man's or woman's (big difference between a "medium" man's ring and a woman's. Here's a few of my own...

GOLD RING (WOMAN

 

[Ron from Michigan]

Critter hunter,interesting,I think the GT requires a recalibration with the meter when bands are switched? HH Ron

 

[Critterhunter]

I haven't tested the shifting nickle numbers but I've read that band 1 will cause them to move compared to band 2. Also read that most prefer band 2 as the numbers jive better with the charts already out there from older Sovereigns that couldn't switch bands. Interesting to also read that they say only nickles do this. I would suspect at least gold rings near that range would also move?

I have noticed that auto sensitivity will vairy the numbers a bit, or cause them not to lock on in my air testing. Since I never use AUTO I figured it'd be best to use the lowest manual setting. The machine is stable enough in my garage at that level. I also noticed that if the machine was turned on with the coil in the air the numbers would drift off a little, so I always make sure to turn it on with the coil flat on the ground. I always sweep over a clad quarter to insure the meter is staying at 180 before doing my air tests while compiling my custom chart. I tried sweeping targets over the coil with it stationary but the numbers also drift some. Best to place all test targets on the ground and then sweep over them as normal.

 

[crazyman]

This is the same old debate that always reaches the same conclusion in the end. First I would suggest picking up a book called "Taking A Closer Look At Metal Detector Discrimination" by Robert Brockett. When it comes to gold the dig everything argument applies no matter where your hunting I'm afraid. Your own testing shows that gold rings can read anywhere depending on size and kt. wt. If your primarily looking for gold your better off focusing on areas where gold is lost, beaches. tot lots, sports fields etc. and digging it all as opposed to selective digging using VDI numbers. The percentage of gold rings found is small even when digging everything. For general hunting If someone was determined to dig less junk and pick up an occasional gold ring while out coin hunting the nickel range would be your best bet as a large percentage of gold is found in this range give or take a number or two and even then your going to be digging a lot of square tabs in newer areas.

 

[Critterhunter]

I ran some tests on the notch, it's width, and target masking and am very happy with the results. I also scanned in 121 gold rings that were found with an Excalibur water hunting and digging any signal, so the test pool is not biased. Same thing I did with the test pool of pulltabs to create that graph. We loaded the rings into a spreadsheet and the numbers are looking very good. It's going to be possible to cut out 84% or more of all pulltabs while only looking about 32% of medium (most common) gold rings. I'd say that's a VERY good trade off when you consider the amount of pulltabs in some spots versus rings, so the good to bad ratio can be tilted highly in your favor by setting the notch correctly.

Have to get off the computer for a bit but I'll be posting the spreadsheet chart and other information soon...

 

[Critterhunter]

My notch testing has found the notch to be about 12.5 digits wide on my GT. This may differ on others so do your own tests to confirm things. If I raise the notch to just kill a 169 vdi tab a 155/156 tab will sounds off but not a 156/157 tab, so the breaking point is 156.5. This setting should kill about 73% of all around/square tabs. Killing up to a 169 vdi reading has my notch dial at halfway between the last two dashes on the dial. Notching out 152.5 to 165 (most highly recommended notch setting as this should kill about 84% of all round/square tabs) has the notch dial right on the second to last marking on the dial.

In my random round/square tab sampling I arrived at the conclusion that 84% of all tabs fall between 153 and 165 on the vdi scale. 8% ranged from 149 to 152, and roughly 8% ranged from 166 to 169. I would recommend notching out 152.5 to 165 by using a 165 target and slowly bringing the notch up to where it just kills that target's response. If you find a site has a large number of tabs in the 149 to 152 range, but not as many in the 166 to 169 range (or vise versa) you can adjust the notch up or down to better eliminate what is being found in that area. I'm finding thus far that the 152.5 to 165 setting is doing very well for me at some really trashy sites. Of course an alternative way to set your notch, lacking the highest vdi target you want to kill, would be to raise it above say a 153 target and then slowly lower it until that target is silenced. Your notch should now be roughly set at 153 to 165.5. Don't make the mistake of raising the notch to kill the lowest desired #. For example, raising it to kill a 153 target would eliminate the nickle zone and a lot of potential rings. I feel this is the reason the notch gets a bad reputation among some hunters. They simply don't know what they are doing when setting it.

Notch Masking Test:

Raised to just kill a 169 tab. Nickle VDI: 142. Tab placed over nickle I still get a positive response with a VDI of 172. Tab placed over a dime I still get a positive response and a VDI of 177. A 156 VDI tab placed over the dime still produces a positive response and a VDI of 171. It appears that the nickle masked will raise in vdi while the dime will drop. More precisely, the VDI value of the tab is always raised when it's masking a target.

Hopefuly I can get this chart up with no problem. As you can see from the percentages of rings rejected with the two listed notch ranges (157-169 is highlighted as an example, but again I'd recommend the 153-165 range), the numbers are very encouraging. Eliminating 84% of all tabs while only rejecting 35% of all medium sized gold rings (most common lost, with small gold rings being second and only 6% eliminated...or 20% of all large gold rings, which is the third most common type of ring lost) is a very workable percentage of good to bad targets. When you consider the amount of pulltabs in some areas it isn't even worth digging for rings unless you've got some way to increase your odds. Properly setting the notch will do that for you.

I also plan to set my discrimination at around 90 to 95 to eliminate most bits of foil or aluminum, which will greatly quite down the machine in real trashy spots. It'll cost me 25% of small gold rings set at 95 for a total of 31% with the notch going, or 14% of small rings set at 90 for a total of 20% with the notch. Still very good odds while eliminating a lot of junk. The trick is that the VDIs of foil and other trash tend to be jumpy, while most small rings will lock on to one or two VDI numbers when sweeping over them.

(UPDATE): Once again I'm stumped by the limited file formats that Findmall will accept. I have this file in a PDF but it needs converted into something it will allow.

 

[Critterhunter]

OK, I think I got a JPEG file format that should work here...

 

[UtahRich]

Thanks for the information. I am heading over to my test area after work today for an hour or so and am tempted to put your numbers to work for a bit just to see if I can pull something out of my pulltab garden before I clean continue cleaning them out.

Rich (Utah)

 

[Critterhunter]

You're welcome, and I just updated the above chart with some more information to help make things more clear. Remember, I'm not saying that digging it all isn't the best solution on the beach or in low trash areas. The whole concept is to tilt the odds in your favor when in a large trashy area that would take years of work to dig all the pulltabs. Eliminating 84% of round/square tabs while only loosing 35% of medium rings and even less of the small and large yellow is stacking the odds much more in your favor. I'm not as much worried about the white gold numbers as they are much less common, but even then they are pretty darn good. I plan to run discrimination at around 90 or 95 to eliminate most of the small foil/aluminum. That'll only reduce the small ring numbers a bit.

 

[Critterhunter]

Once again I've updated the chart with more information. Hopefuly it'll be the last update for a while. Just wanted to include some related information that can all be looked at at a glance on one page with the chart.

 

[Critterhunter]

Notice in the chart that the "nickle zone" (for me that's 140-147 in my testing of nickles so far, but that may change) isn't showing a huge number of rings in that area compared to others. What that tells me is that the old saying of "dig the nickle zone" to hunt gold rings isn't really true. I would guess that with most of the VDI meters out there featuring much less resolution many people would see rings read in the "nickle" zone as that window of targets that fell into this area was wider on their machines. This might be one of those myths that people just assumed and followed without question without doing the research on a more capable machine. See, sometimes good things can come from challenging authority.

I welcome any and all remarks, negative or positive, to the working theory above and related data. Nobody learns without debate so feel free to set me straight...

 

[ToniSteve]

Hello Critterhunter,
Nice body of work! And thanks for your tenacity. I do not have a Sovereign yet too bare out your findings but hopefully that will be remedied soon. Your theory and work toward proving it have been quite interesting and informative. You did not have to share your findings and testing along the way but I for one feel fortunate that you have done so, not only for the tentative results but for the fine example of your organized way getting there. The challenge was worthwhile even if it had been a total failure. It will be interesting to see how it works out in the field.

 

[kered]

32% loss on gold, nearly a 1/3rd thats not for me, especially at todays prices, i'll stick to 0 disc 0 notch

 

[UtahRich]

On my XS-2a Pro, a newer nickel on the ground comes in at 145. I tried several, all the same. While hunting this evening, I finally found a pulltab that came in right at 165 with a solid signal. I adjust my discrimination knob until I just lost the signal for sure. As I swung my coil around over the multitude of pulltabs, I found several that came in solid at 155-6. There were a lot of discriminated targets. I wasn't able to find any higher target that came in under the notch. I double checked with a couple quarters that I was calibrated on 180. My discrimination knob was pointing at the 2nd to last index line when knocking out 165 and below.

I have an XS2 meter that I've rescaled to 180.

Rich (Utah)

 

[Critterhunter]

It'll take time to see how all this plays out in actual field use. I still feel that 152.5 to 165 is the best all around notch setting to eliminate most tabs, but again that's in my testing with random tabs from the areas I hunt. You may find that 149-152 is a problem in your area, or that 166-169 is more common at the sites you are hunting. Slightly adjust the notch up or down to compensate and see how things pan out if need be. One area I hunted for about an hour the other day is an old park loaded with tabs, more so than any other place I've ever hunted. I found with the notch adjusted from 156.5 to 169 that there was only one particular tab reading 153 that showed up on a consistent bases. It was a smaller than usual round tab. Still, considering the thousands of tabs and wide variety found at this site it was a joy to only dig 5 or 6 of those odd 153 ones. I produced 4 or 5 nickles in that hour's time but no rings or older coins. I can't wait to get back to this location and give it a very long hunt and test my 152.5-165 notch setting.

I think my unit (check above) also has the dial on the second to last mark to kill up to 165, and halfway between the last two marks to kill up to 169. Still, it's better to carry a test target with you, place it on the ground, and calibrate the notch at the site. I found that having it set at home and then hitting a site was producing a signal from my test 165 target when I got there. Not sure if this is due to the ground minerals or what but it's clear that it needs to be fine tuned in the actual site before hunting.

 

[Critterhunter]

Hello Critterhunter,
Nice body of work! And thanks for your tenacity. I do not have a Sovereign yet too bare out your findings but hopefully that will be remedied soon. Your theory and work toward proving it have been quite interesting and informative. You did not have to share your findings and testing along the way but I for one feel fortunate that you have done so, not only for the tentative results but for the fine example of your organized way getting there. The challenge was worthwhile even if it had been a total failure. It will be interesting to see how it works out in the field.

Thanks. I was anxious to see the final results once the rings were grafted in comparison to the tabs. I was very happy to see only 35% of medium yellow gold rings would be lost by eliminating 84% of all tabs, and that small and large yellow rings do even better percentage wise. It's important to remember what these percentages show. Take a typical high tab location and a general number of say 2000 tabs being present. That's 1680 eliminated with proper notch setting. In trade you are giving up 35% of medium size yellow gold rings. Let's just throw out a number of 10 rings in this class being present at the site. This means you are giving up 3.5 rings but still can recover 6.5, while only digging 320 tabs. Now, if you would dig it all you'd be digging 1680 more tabs just to recover the other 3.5 rings. Like playing cards there are certain percentages you can play to tilt the odds in your favor.

 

[wag]

I've already seen from the comments that some folks don't get it. This is about playing the percentages in trashy areas, folks, and NOT talking about the beach, et. al.. Personally, I think the data collection and analysis is great. There is a lot of work here that he didn't have to share with y'all. I'm glad he did, I got something valuable out of it. Just gathering up all the rings and pulltabs must have been a job and a half, much less testing them all. He spent a lot of time on this, and the results show it. Well-done, critterhunter.

The most valuable resource you have is your time. Playing the percentages and not wasting it is the smart way to spend it. But...

I also think the next logical extension of this work is to move on in Phase Two to something like the E-Trac, with two-factor discrimination capability, i.e., FeCo. That might be an even more interesting study. Especially if it provides a way to eliminate pulltabs without also eliminating the "35% of rings" trait that some folks objected to so much.

I tend to say little and listen a lot. Less hassle that way. Critterhunter's data analysis was worth saying something. I hope it continues.

WA

 

[Critterhunter]

I've already seen from the comments that some folks don't get it. This is about playing the percentages in trashy areas, folks, and NOT talking about the beach, et. al.. Well-done, critterhunter.

The most valuable resource you have is your time. Playing the percentages and not wasting it is the smart way to spend it. But...

I also think the next logical extension of this work is to move on in Phase Two to something like the E-Trac, with two-factor discrimination capability, i.e., FeCo. That might be an even more interesting study. Especially if it provides a way to eliminate pulltabs without also eliminating the "35% of rings" trait that some folks objected to so much.

I tend to say little and listen a lot. Less hassle that way. Critterhunter's data analysis was worth saying something. I hope it continues.

WA

Thanks. At least I won you over. It's all about odds like I said, when the trash would take a lifetime in an area to dig. As far as the E-Trac goes, one day I'll get my hands on one and will try this testing with it as well. However, I tried something similar on the Explorer and found the dual ferous/non-ferous numbering to offer too much resolution. Identical tabs would often produce variations. Maybe just slight ones but by the time you scan enough of them in you've blocked a huge area, much more than what I did with the GT. As I said before, some ID averaging can be an advantage in that it helps you see patterns easier. Look too close with too much resolution and it becomes a blurry mess. On the other than, most other machines don't offer near the resolution of the GT's VDI scale, not enough to split hairs as well. What inspired me to try it on the GT was I felt it might offer just the right amount of resolution to make if work much better. Only extensive hunting with the notch set properly will tell if the theory has merit.

 

[Critterhunter]

Just about all the same rings used to create the above GT chart have been scanned into a chart for the M6. The M6 chart has I think 7 more rings scanned, but just about all the rest were the same used for the GT. It's interesting to note if you place the two charts side by side that the patterns look almost identical. A few of the rings sizes might have been placed in one or the other category this time but you can still see a distinct pattern of notched targets. Once again digging "the nickle zone" proves to not hold a lot of merit (nickles range from 16 to 20 on the M6/MXT). There are no more rings in that zone than any other for the most part. The trick and purpose being to prove that by avoiding the most common tab numbers you can still dig the vast majority of rings without having to dig billions of tabs.

Right now we have only scanned in the entire sample pool of random tabs we used for the GT percentages. The M6 chart shows all the tab numbers blocked, rather than what happens if you just block where say 84% of them fall by using the GT's notch. We have not charted where the vast majority of those tabs will fall on the M6 yet but that information is coming. For that reason it's chart will show more rings rejected simply because it's rejecting all the test pool numbers instead of just where 84% or so of them fall. Even if you don't have an MXT or M6 it's useful to compare results from that data to what I posted above for the GT.

Interesting enough, the Sovereign found a 20 digit wide window for all the test tabs while the M6 found this window to be 17 digits wide. It's obvious that the GT has better resolution at the lower end of the scale than the M6 or MXT. This is saying a lot because the M6/MXT have a reputation of being good ring machines. On the other hand, the M6/MXT have better resolution at the top end of the scale. They seperate some coins better than the GT that puts a lot of them in the 180 number. Still, the M6/MXT don't appear to have as good of coin resolution as some other machines out there.

http://www.findmall.com/read.php?31,1139039

 

[Critterhunter]

Somebody out of the blue just PM'd me and offered to send me a book written for the Sovereign that details finding rings and such, with I think he said over 100 or 1000 rings scanned and compared to various settings and such. I'm looking forward to reading that book and will post a report on how their findings compare or differ to mine in this thread. Thanks again for the offer! Name with held in case this person doesn't want to be associated with me in public.