Air Test Comparisons -- 6" coil vs. 11" coil on U.S. coins...

[sgoss66]

Hello all!

Based on requests from several folks who are curious, I went ahead and did some air testing with my new Minelab 6” coil, attached to my Equinox 800. I wanted to give folks some idea of the relative capabilities of this coil as compared to the 11” coil.

While all the normal caveats of air testing apply — such as, air-test results in no way mirror in-ground results, etc. etc. etc., I do think there is at least a little bit of value when doing side-by-side air testing of two different coils for comparison purposes. Anyway, how much value exists in such a test is up to each individual to decide; I simply wanted to provide the data. I also did a YouTube video, which I will post a link to as soon as it is done uploading. In the video, I did NOT record the testing of all the coins; I ran only the silver Roosevelt dime in the video to show you, audibly, what quality of signal I listened for in order to call it a “hit.” In other words, how repeatable of a signal I listened for before I assigned a depth value to that particular coin, with that particular coil. The rest of the video is just some discussion of a few points regarding the coil, and the testing.

Anyway, here is the data…

​

Minelab Equinox 800
11” and 6” coils, air-test comparison, done indoors
Park 1 Mode
Sensitivity 18
Noise Cancel Channel 7
All-metal mode (horseshoe button engaged)
Ground Balance 0
Recovery Speed 4 (on the 800, equivalent to 2 on the 600)
Iron Bias 2 (on the 800, equivalent to 1 on the 600)

Here are the results:



After this “apples to apples” comparison, where I tested both coils using identical settings, I then re-tested a couple of coins (specifically the silver dime and the silver quarter) on the 6” coil, but this time bumping sensitivity to 22. I found that I was able to run sensitivity about 3 points higher, as the 6” coil is (as expected) less affected by EMI. Since “18” is a rather conservative sensitivity for a 6” coil (but that is as high as I could go with the 11” in my indoor testing, and I wanted to keep it “apples to apples”), I wanted to see how much depth gain I would get on the 6” coil if I bumped sensitivity up some.

Here are those results:



In summary, you can see that the 6” coil (at 18 sensitivity) loses roughly 1 ¾” depth on each coin, in an air test, as compared to the 11” coil. You can also see that by bumping the sensitivity on the 6” coil up from 18 to 22, you “gain back” most of the loss of air-test depth, getting to within ½” to ¾” of depths achieved by the 11”coil, set at 18 sensitivity. SO…while you DO lose depth with the 6” coil, as expected, you may — in a real-world scenario — be able to gain most of that depth back, due to being able to run it at a higher sensitivity setting. Overall, I am thus far impressed with the coil, and can’t wait to use it “in the field,” where I can begin to get a feel for its REAL value — its ability to separate, in trashy sites.

Steve​

 

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[Truth]

Hello all!

Based on requests from several folks who are curious, I wentahead and did some air testing with my new Minelab 6” coil, attached to myEquinox 800. I wanted to give folks someidea of the relative capabilities of this coil as compared to the 11” coil.

While all the normal caveats of air testing apply – such asair-test results in no way mirror in-ground results, etc. etc. etc., I do thinkthere is at least a little bit of value when doing side-by-side air testing oftwo different coils for comparison purposes. Anyway, how much value exists in such a test is up to each individual todecide; I simply wanted to provide the data. I also did a Youtube video, which I will post a link to as soon as it isdone uploading. In the video, I did NOTrecord the testing of all the coins; I ran only the silver Roosevelt dime inthe video to show you, audibly, what quality of signal I listened for in orderto call it a “hit.” In other words, howrepeatable of a signal I listened for before I assigned a depth value to thatparticular coin, with that particular coil. The rest of the video is just some discussion of a few points regardingthe coil, and the testing.

Anyway, here is the data…

Minelab Equinox 800
11” and 6” coils, air-test comparison, done indoors
Park 1 Mode
Sensitivity18
Noise CancelChannel 7
All-metalmode (horseshoe button engaged)
GroundBalance 0
RecoverySpeed 4 (on the 800, equivalent to 2 on the 600)
Iron Bias 2(on the 800, equivalent to 1 on the 600)

Here are the results:

View attachment 1625494 [SUB][/SUB]

After this“apples to apples” comparison, where I tested both coils using identicalsettings, I then re-tested a couple of coins (specifically the silver dime andthe silver quarter) on the 6” coil, but this time bumping sensitivity to22. I found that I was able to runsensitivity about 3 points higher, as the 6” coil is (as expected) lessaffected by EMI. And since “18” is arather conservative sensitivity for a 6” coil, but that is as high as I couldgo with the 11” in my indoor testing, and since I wanted to keep it “apples toapples,” I wanted to see how much depth gain I would get on the 6” coil if Ibumped sensitivity up some.

Here are those results:

View attachment 1625495 [SUB][/SUB]

In summary,you can see that the 6” coil (at 18 sensitivity) loses roughly 1 ¾” depth oneach coin, in an air test, as compared to the 11” coil. You can also see that by bumping thesensitivity on the 6” coil up from 18 to 22, you “gain back” most of the lossof air-test depth, getting to within ½” to ¾” of depths achieved by the 11”coil, set at 18 sensitivity. SO…whileyou DO lose depth with the 6” coil, as expected, you may – in a real-worldscenario – be able to gain most of that depth back, due to being able to runit at a higher sensitivity setting. Overall, I am thus far impressed with thecoil, and can’t wait to use it “in the field,” where I can begin to get a feelfor its REAL value – its ability to separate, in trashy sites.

Steve

Hey Steve I’m in high mineralization with iron. You’ve never went higher then 22 I rarely experience high EMI. But is that still to much and does that cause more iron falsing which is a huge problem since it’s using mixed with iron nails. It’s like a crap shoot at this time. Trying to stop that falsing but not sure that possible. Even lowing iron sensitivity won’t stop the small falsing but not due if high mineralization plays a part of that. I hope you understand what I’m saying I do have a hard time articulating my thoughts in words.

 

[sgoss66]

Truth,

In high-mineral ground, lowering your sensitivity is often necessary; what you are trying to do is "optimise your signal-to-noise ratio." In other words, if you raise your sensitivity too much, you get alot of noise, and then you can't pick out the signals you are interested in, from all the noise being generated by the ground minerals. The idea of course is to lower sensitivity enough to decrease the amount of background noise enough (by lowering sensitivity), so that the good signals are easily discernable -- i.e. not "drowned out" by the background noise. But, the tradeoff of course is that when you lower sensitivity, you lose depth (as you have noticed -- based on your posts where you say you are struggling to get good depth).

The bottom line is, the effectiveness of a detector is definitely reduced when hunting in difficult soil, and there is really no way around it. You HAVE to lower sensitivity enough to hear the good signals from amongst the noise, BUT, this will cost you depth. It is just "the way it is," in bad dirt.

As for iron falsing -- if you are talking about nails and such that occasionally "wrap around" from the negative VDI numbers into the high positive numbers, i.e. 39 and 40, there is not much you can do besides -- again -- lowering sensitivity. Not sure if your high mineralization is playing a role there, or not. I'd almost have to be there, an experience it, to give you a good answer on that.

Steve

 

[Hawks88]

Steve first I want to thank you for taking the time to do the air test. That’s very useful information you’ve provided to all us Equinox users. I think I may just leave the 6” coil on all the time and crank up the sensitivity alittle. I mostly beach hunt and I don’t need to dig deep holes for resent ring and coin drops on a beach. Thanks.

 

[sgoss66]

Hawks -- you are quite welcome! I know alot of EQ users have been curious, so if some of this helps, I'm glad!

It does seem that cranking up the sensitivity on the 6" will allow it to achieve really good depth...

Steve

 

[sgoss66]

Here's the video, FWIW...



Steve

 

[Truth]

Air Test Comparisons -- 6" coil vs. 11" coil on U.S. coins...

Truth,

In high-mineral ground, lowering your sensitivity is often necessary; what you are trying to do is "optimise your signal-to-noise ratio." In other words, if you raise your sensitivity too much, you get alot of noise, and then you can't pick out the signals you are interested in, from all the noise being generated by the ground minerals. The idea of course is to lower sensitivity enough to decrease the amount of background noise enough (by lowering sensitivity), so that the good signals are easily discernable -- i.e. not "drowned out" by the background noise. But, the tradeoff of course is that when you lower sensitivity, you lose depth (as you have noticed -- based on your posts where you say you are struggling to get good depth).

The bottom line is, the effectiveness of a detector is definitely reduced when hunting in difficult soil, and there is really no way around it. You HAVE to lower sensitivity enough to hear the good signals from amongst the noise, BUT, this will cost you depth. It is just "the way it is," in bad dirt.

As for iron falsing -- if you are talking about nails and such that occasionally "wrap around" from the negative VDI numbers into the high positive numbers, i.e. 39 and 40, there is not much you can do besides -- again -- lowering sensitivity. Not sure if your high mineralization is playing a role there, or not. I'd almost have to be there, an experience it, to give you a good answer on that.

Steve

I’m planning a hunt tomorrow with the 6” at this spot. I’ve noticed in multiple videos high conductors do better in Park 2 or Field 2, but the admit they have low mineralization ground. I wonder if I should go to the 1’s in Park or Field, adjust sensitivity to a quite setting, lower my recovery speed to 3 or 4 for depth and just go slower. Will higher iron bias 0-6 quite that iron? I leave it in 0-1 is that my problem?

I hope I’m not asking to many questions. I’m just want to get the most out of my opportunity tomorrow. My son’s watching my wife, so I can swing till my arm drops off and then an hour more.

Also just curious Steve you you hunt setting 50 or 5? Do you customize your settings. I’ll put iron down to 0 volume low and still get that falsing. I think I want that totally gone, but you might be right that might not be realistic. Example I had a target falsing or possibly a iffy half dime signal because every plug basically has some iron in it, in this particular spot. It was effy 14-22 back and fourth, but 1 out of 20 in one direction I saw a 34. Good enough for me I dig. I pulled out 8 pieces of rusting nail pieces and lastly a silver fork in the side wall. It’s a gamble and I am a gambling man,no problem, I just want some more odds in my favor. Not trying to cherry pick not my style just need a little more odds to play with.

 

[vferrari]

I’m planning a hunt tomorrow with the 6” at this spot. I’ve noticed in multiple videos high conductors do better in Park 2 or Field 2, but the admit they have low mineralization ground. I wonder if I should go to the 1’s in Park or Field, adjust sensitivity to a quite setting, lower my recovery speed to 3 or 4 for depth and just go slower. Will higher iron bias 0-6 quite that iron? I leave it in 0-1 is that my problem?

I hope I’m not asking to many questions. I’m just want to get the most out of my opportunity tomorrow. My son’s watching my wife, so I can swing till my arm drops off and then an hour more.

Also just curious Steve you you hunt setting 50 or 5? Do you customize your settings. I’ll put iron down to 0 volume low and still get that falsing. I think I want that totally gone, but you might be right that might not be realistic. Example I had a target falsing or possibly a iffy half dime signal because every plug basically has some iron in it, in this particular spot. It was effy 14-22 back and fourth, but 1 out of 20 in one direction I saw a 34. Good enough for me I dig. I pulled out 8 pieces of rusting nail pieces and lastly a silver fork in the side wall. It’s a gamble and I am a gambling man,no problem, I just want some more odds in my favor. Not trying to cherry pick not my style just need a little more odds to play with.

Truth,

I know you didn't ask me, but it looks like some things have gotten totally mixed up here with time so I thought I would refresh some Equinox fundamentals for you and others. As Steve said in a previous post above, the Equinox is all about maximizing the Signal-to-noise ratio, not just the signal. So not knowing what videos you have been watching, some of what you are saying runs counter to how the Equinox is supposed to behave or you are only focusing on one aspect of the parameter that you trying to understand. Also, the default settings (especially Recovery Speed) the ML has set up I have found to be pretty good even for different soil conditions and I try not to deviate to far from the defaults. I have run through this many time before but repetition helps. Remember - the key to using any detector is being adept at balancing all the tradeoffs. There are no free lunches - for example if you want to separate targets better you need to up recovery speed, but then you lower depth. That may be ok, because in thick trash what you are looking for are the relatively shallow targets that have been masked and not picked up by folks using slower detectors as they have been cherry picking the deep lone high conductive targets.

GB

If your ground is mineralized and/or has wide variations in ground phase, then use Tracking GB. I have not experienced a downside using Tracking GB.

Mode Selection:

For example, you said above that you watched videos that indicate high conductors "do better" in Park 2 or Field 2 - well that is not consistent with how the Equinox is designed. The Park and Field "2" modes are weighted to higher "frequencies" which means they will hit small and mid to low conductive targets better. They will still hit high conductive targets, but Park 1 and Field 1 are optimized for high conductors. Bottom line - if you are going for deep silver, your best bet is Park 1 (5 tones) or Field 1 (2 tones) or 5 khz single frequency (but then you lose some multi IQ features like Iron Bias filtering and some of the advanced signal processing that comes with Multi IQ).

Recovery Speed

On the surface, lowering recovery speed will increase depth performance...to a point. That point being when the slower sweep speed required results in more ground feedback noise. This lowers the overall Signal-to-noise ratio discussed above and you will actually start losing effective depth if you lower recovery speed too much. Lowering recovery speed way down typically works best in dry sand conditions where there is basically no ground feedback. Higher recovery speeds are needed in thick trash environments when separation is key, but of course you will lose depth, but as I described above, the tradeoff may be worth it to find the shallower masked keepers.

Iron Bias

Double edged sword. First, yes it can help with iron falsing, but frankly I have not seen the minimal reduction in iron falsing it provides to be worth the trip especially considering its main downside. Being a filter, it has a huge drawback - it will tend to exacerbate masking of non-ferrous targets in thick iron even with high recovery speed settings. If you want to unmask in thick iron, turn Iron Bias settings to minimums (0 or 1).

Non-Ferrous Trash

Tnsharpsooter noticed that thick non-ferrous trash (can slaw, pull tabs, twist tops, freshness seals) really messes with the Equinox Multi IQ TID processing. He has shown some success in hitting such sites in single frequency (5 khz) and this helps some of the shallower high conductors to pop out of the mid-conductive trash muck.

HTH

 

[sgoss66]

Truth --

Vferrari gave you some great advice. I will try to answer a few of your questions as well.

I was going to say the same thing he did, about you using Park 2...if you are hunting high conductors (silver, copper, etc.), I would definitely switch to Park 1. Park 1 is designed to be a bit hotter on high conductors (but obviously it is "dirt-dependent" in terms of which mode will work best in different types of soils, for different types of targets). Still though, it is worth at least TRYING Park 1 mode, since you seem to be a coin hunter.

One thing vferrari is trying to say, is this -- until you understand the IMPLICATIONS of each setting, in other words, the TRADEOFFS (i.e., the plusses and minuses) of adjusting each setting, then you can end up having your machine set up improperly for your dirt, and your style of hunting, if you start adjusting things too much. If you don't truly understand each setting, and instead just adjust things based on what someone else says "works best," then you may end up having things set up "all wrong." Now, even with things "set up wrong," the machine will still find targets, but to MAXIMIZE your machine's ability -- to "TUNE" it to the type of ground at a given site, and to the types of targets you are searching for, you really need to acquire sort of a "holisitic" understanding of each setting, what it does, how it does it, and what the implications are. And that takes alot of time and experience on the machine, and learning how it behaves. And so, to help you understand those "implications" of each setting, THAT is why vferrari ran through each of the settings for you with a description, AND...that is why the best advice for someone relatively new to the machine is to pick a mode, and then leave the settings for that mode AT THE DEFAULT LEVELS, for awhile, until you understand the machine, and what each setting is designed to do.

If I were you, I would do a factory reset. Get all your settings back to "normal." And then, set it in Park 1 mode and simply run the settings at default -- i.e. a "middle of the road" recovery speed, a "middle of the road" iron bias, etc.

Then, the next thing I'd do if I were you is I would decide if I want to hunt in 5-tones, or 50-tones. I personally hunt in 50 tones, but I am used to this type of tone profile after hunting for 7 years with other Minelab machines in the "full-tone" mode. If you like 50 tones, set the machine that way. But, if you prefer fewer tones (and I would think that most folks who have not hunted Minelabs before, and are just starting out with the Equinox WOULD prefer fewer tones), leave the default "5-tone" setting that is associated with Park 1. Then, next step, I'd noise cancel, for sure. Then, I'd ground balance. BE SURE you ground balance over "clean" ground (i.e. no target in the ground under the coil). If your soil is REALLY bad, then tracking ground balance (as vferrari mentioned) might be the best option for you. Then, finally, I would adjust sensitivity upward or downward to a point where EMI has been largely silenced, and your ground noise is "manageable." It's BEST to manage "ground noise" by ground balancing -- FREQUENTLY if necessary (or, again, using tracking which will automatically, continually adjust to ground conditions). BUT -- if you can't get the ground silenced even with good ground balance, then some sensitivity adjustment downward can help (at the expense of depth). And at that point, you should be ready to go; I would hunt this way for awhile, and see how it goes.

Another thing -- you said that you "adjust iron volume down to 0 and yet still hear falsing." YES, you will! First though, let's talk a bit about "iron falsing," because some people define it differently. Some folks (like myself) will sometimes refer to "falsing" to mean "a nail, most often rusty and bent into a curve, that reads in the coin range." But that's not REALLY what true iron "falsing" is. TRUE iron falsing, means that an iron target like large nail or whatever, that would normally read -7, -8, -9, (i.e. down in the lowest end of the VDI scale), "wraps around" at times to read 39 or 40 on occasional sweeps (i.e. up at the highest end of the VDI scale). Think of the VDI scale as "circular," not "linear," and you will understand why it's called "wrap around." In other words, thinking again of VDI as a "circular" scale, a target that wants to read "lower" than -9 CAN'T, on the Equinox, go to -10, because there IS NO -10 on the Equinox. And so, instead, it reads "40." THAT is true "iron falsing," or "wrap-around falsing."

Now, the reason I went through all of that, is this...if you are trying to "silence" true "iron falsing" i.e. readings up around 39 or 40 that happen in very nail-laden ground, YOU WILL HAVE NO EFFECT ON THE PROBLEM WHATSOEVER if you adjust iron volume. All that adjusting "iron volume" does, is lower the volume of any tone IN THE "NORMAL" IRON VDI RANGE, which is of course -9 to 0. In other words, if you have your "iron range" set at the default, which in Park 1 is -9 to 0, then adjusting iron volume up or down ONLY ADJUSTS UP OR DOWN THE VOLUME OF ANY TARGET READING -9 TO 0. It will have NO effect on a target that reads 39 or 40, by definition! Said a bit differently...if you set your iron volume to zero, all you are doing is silencing any target ID values which read -9 to 0. You will still hear ALL targets which read with VDI above zero -- including the 39 and 40 values associated with "iron falses!"

Furthermore, I would like to point out so as to be sure you understand...unless you have depressed your horseshoe button to engage "all-metal mode," your machine will already be discriminating out -- by default -- any targets that read -9 to 1 (in Park mode). So, through your DISCRIMINATION setting you have ALREADY "silenced" the "iron ID values" -- by discriminating those values out! And if you are already discriminating out -9 to 1 VDIs, that renders "iron volume" a completely "moot" point! Because if iron IDs from -9 through 0 are being rejected by your disc. pattern, then there are no iron IDs (-9 to 0) audible to the user -- and THUS, of course, no iron VDIs upon which to adjust the volume!

If you want to silence the true "iron falses," i.e. the occasional sweeps over iron that "high-tone" up in the 39 and 40 VDI range, and if ground balance and iron bias and sensitivity are all set optimally, then the only way to do it is to DISCRIMINATE -- i.e. turn on discrimination for VDI values 39 and 40. That is an option, if you what you are referring to as "falsing" are those 39 and 40 values you will hear when working in iron.

I know this is getting long-winded, but it sounds like you might be confused on a few things, and I'm trying to help clear a few things up for you. Again, to summarize...

Put on your 6" coil. Do a factory reset. Place the machine in Park 1 mode (iron bias will default to 6, recovery will default to 5, discrimination will default to -9 through 1, tones will default to 5-tone, and sensitivity will default to 20). Then, noise cancel; then, carefully ground balance (either using the "auto" feature to set a fixed ground balance, or else turn on tracking ground balance to adjust continuously to your very difficult, hot soil), and then, adjust your sensitivity up or down, as necessary, to get the machine on the edge of "quiet" -- i.e. just barely below the "noise threshold." Also remember that by default, unless you depress the horseshoe button, in Park 1 mode you are discriminating out all targets that read -9 to 1. And then, as a last step, if this has not helped to reduce the iron falsing and you really want it silenced, discriminate out (i.e. reject) VDI values of 39 and 40, to silence the falsing.

See if these settings help you out some...

Steve

 

[vferrari]

Steve - agree with your detailed writeup, especially the going back to square one with a reset, but just wanted to point out he said that he had "Iron Bias" not "Iron Volume" turned down, two different things entirely. I believe the "falsing" he is getting is more of the nail head/bent nail "falsing" that is showing up in the coin range (small silver). Could be wrong though. It is hard to tell from his descriptions without actually being there.

 

[Professor of Engineering]

Thank you for sharing!

 

[sgoss66]

Vferrari --

I think he talked about both iron bias AND iron volume (and hence why I was discussing iron volume with him); in one of his posts, he said this...​

"I’ll put iron down to 0 volume low and still get that falsing."

​

I interpreted that to mean that he was running his iron volume to 0, trying to silence falsing. Maybe I am misunderstanding what he's saying, though.

Professor -- you are welcome!

Steve
​

 

[vferrari]

Vferrari --

I think he talked about both iron bias AND iron volume (and hence why I was discussing iron volume with him); in one of his posts, he said this...​

"I’ll put iron down to 0 volume low and still get that falsing."

​

I interpreted that to mean that he was running his iron volume to 0, trying to silence falsing. Maybe I am misunderstanding what he's saying, though.

Professor -- you are welcome!

Steve
​

Gotcha. I missed the second statement. But sometimes he gets the terminology mixed up so I read it the wrong way. Your explanation was correct, but obvious too. That's why he asked you not me. I have gone around in circles so many times on this iron site situation now I'm confused. Ha Ha.

 

[sgoss66]

I hear you, vferrari. I'm not sure either. I thought maybe, from reading his post, that he was saying in his mind "I have iron falsing, I need to turn down my iron volume," mistakenly thinking that would help...but not realizing that iron volume only affects TRUE iron IDs, i.e. down in the 0 to -9 range -- and not iron "falses" up in the high-tone, high-VDI range.

Not sure, though, if I understood him correctly or not.

Steve

 

[vferrari]

I hear you, vferrari. I'm not sure either. I thought maybe, from reading his post, that he was saying in his mind "I have iron falsing, I need to turn down my iron volume," mistakenly thinking that would help...but not realizing that iron volume only affects TRUE iron IDs, i.e. down in the 0 to -9 range -- and not iron "falses" up in the high-tone, high-VDI range.

Not sure, though, if I understood him correctly or not.

Steve

Well, bottom line you gave Truth good advice. He manages to get some great finds there regardless of settings and I hope he had a great hunt today. Can't wait to see what Truth came up with today. HH to all.

 

[sgoss66]

Ha -- he does indeed make some great finds, vferrari. Maybe I should be asking HIM for advice!

Steve