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Auto sensitivity
- Thread starter Mentez
- Start date
Critterhunter
New member
Most of the time when I've tested auto against manual it seems that Auto sets it's self somewhere around the 2 to 3PM position, probably leaning more around 3PM. That's when I've flipped back and fourth between auto and manual to test the response of a buried target. Often when I can't hear it in Auto once I move the dial up (remember that the sensitivity dial goes counter clockwise in terms of lowest to highest, then into Auto when it clicks out of the highest manual setting) to around 3PM or so is when I start to hear the target in manual.
However, I think Auto calibrates it's self not on the amount of ground mineral content but also to the amount of RF noise in the air. For that reason setting it to Auto in your house will calibrate it much lower than it would if you were away from any power lines or other sources of electrical/mechanical noise. In a situation like say in the woods I believe Auto will adjust it's self higher or at least bases it's setting more on how rough the ground is to handle rather than due to the amount of noise it's picking up.
You might think that running the Sovereign in Auto in highly mineralized ground with tons of iron and hot rocks would cause it to really drop to something super low. I've not found that to be the case. In fact, there are some bad sites with all the above problems and running in Auto at least on the 15x12 coil has got me silver coins at 7 1/2" deep easily with perfect/loud audio and proper VDI. One of the spots it did this for me also has a nearby AM transmitter which along with the ground conditions has played havoc on all my prior machines including my Explorers. Needless to say I was shocked to hit on a deep silver quarter perfectly that I know I've passed over numerous times with other machines including all three of my Explorers.
There seems to be something about Auto that I feel can make it produce coins that a static manual setting misses for one reason or another. My main theory on this is that I feel Auto is much like automatic ground tracking on some machines in that it is constantly adjusting it's self to the changing ground conditions. I feel that's why it seems to some times produce coins that a manual setting missed for me when I know very well I've passed over that coin countless times in manual yet never got it. If for instance a silver coin is laying in a particular spot where the ground in days gone by has been disturbed (changing it's matrix), or say for some odd reason a band of mineral or heavy iron content (I'm not talking things like nails here, but rather soil where there is a lot of microscopic iron "powder" in the soil)...then I think under these specific circumstances Auto's constant adjustment to the soil matrix might unmask that coin.
That sounds more like what auto ground tracking does then auto sensitivity but in a sense they both work in a somewhat similar fashion. Just as ground tracking will try to track the changing ground that some sites have, I think auto sensitivity may be re-adjusting it's self when the ground gets hotter or "colder" in order to keep the machine as stable as possible. Auto sensitivity's main job is to keep the machine and thus it's threshold rock solid stable. If it runs across a band of heavy minerals, iron, or hot rocks, I believe it lowers the sensitivity so that the machine isn't blinded by those conditions. That's where a static manual setting might suddenly be too high (or even too low) for one particular spot and so blind the machine to the target.
Auto is also useful when a site is so heavily loaded with iron and other trash that it's almost impossible to find a clean spot to sweep over while adjusting your sensitivity. In a case like that you'd probably be better running in auto then guessing at a sensitivity setting which might be way off what the best should be. At least auto will get you in the ballpark. Crazyman's pump method of setting sensitivity is a good option in a place like this where there is not enough clean ground to sweep around while calibrating the sensitivity.
The main reason why I do not like auto ground tracking on any machine is that iron and other junk can cause the ground balance to get way off. Setting ground tracking statictly is always going to give you maximum depth, and an auto ground tracking can smooth out and track out a deep coin at fringe depth. For those reasons I still have concerns with Auto sensitivity. I don't trust what it might be doing to the machine due to what the coil is passing over in the ground. It might say be hitting a ton of iron or hot rocks and knock it's adjustment way down to try to keep the machine stable. On the flip side of this, though, I think Auto sensitivity might have benefits in these kinds of conditions as it's constantly tweaking the machine for a decent setting that's in the ballpark for that particular spot the coil is now over.
Another theory I have about auto sensitivity which I haven't tested yet is that I feel it's either going to do one of two things when it comes to coins masked by iron or other trash. It could possibly reveal the coin better because it's adjusting to try to bring back the threshold faster and so give the machine the chance to hear the coin. The other possibility is that in trying to keep the machine stable Auto might smooth out the signal and make the coin harder to unmask. I keep intending to test this theory both ways on several masked coins in a test bed to see if either has advantages over the other. One of these days I'll get around to it and will write up a report on the results. I need to do that anyway because I want to compare the 15x12's unmasking ability to the 10" and S-5 coil. I'm pretty sure it's going to beat the 10" but I also have a feeling it might do better on certain masked targets than even the S-5 can due to the SEF's unique morphed hybrid coil field (part concentric but mostly double D).
In summary (you probably thought I'd never get there
), I think what it comes down to is to try Auto at some of your rougher spots (hot rocks, minerals, iron, fast changing ground conditions, RF noise, etc). Re-work the spot in auto after you've gridded it with your "best" manual setting. Make sure you grid in the same direction so that variable doesn't alter the results of what is and isn't revealed. I think you may surprise yourself in that Auto reveals some targets that manual plain out missed.
One last remark about Auto- It will really stabilize target ID's and audio when the conditions are so bad due to any of the above factors that a solid locking VDI is hard to achieve. As good as these Minelabs are at excelling in the worst of site conditions (way better than the competition), even they still have their limits as to what they'll put up with. If the ID on something that doesn't sound all that deep is roaming around on you yet you know it's a coin or other target that should provide a single VDI #, my first suggestion is that you haven't calibrated manual sensitivity properly. However, I've been at spots where nothing in the way of manual adjustment would clean up the signal (rare to have sites like this that give a Minelab problem, but they do exist) try flipping over to Auto. I've personally seen it clean up the audio and ID that any manual setting wouldn't. Whether that was due to soil conditions, nearby mineral or trash, or even just stray RF noise that keeps messing with the machine is any body's guess. I just feel that there is something about Auto that works when manual won't, but I'm sure the reverse of that is true more often than not as well.
With what I've seen Auto do on the SEF (giving me silver at just under 8" deep with no problem) I'm confident it will go even an inch or two deeper. Even at 7.5 to 8", though, that's very impressive because most machines on the market max out at about that depth regardless of how high they've tweaked manual for best possible depth. That's also why I've said the same thing about the S-5 coil. It just blows my mind that that little bugger is pretty much getting the same depth as many of my prior machines from other companies using an 8 to 10" coil. Really brings a smile to my face...
OK, now I really am done with my thoughts on Auto.
However, I think Auto calibrates it's self not on the amount of ground mineral content but also to the amount of RF noise in the air. For that reason setting it to Auto in your house will calibrate it much lower than it would if you were away from any power lines or other sources of electrical/mechanical noise. In a situation like say in the woods I believe Auto will adjust it's self higher or at least bases it's setting more on how rough the ground is to handle rather than due to the amount of noise it's picking up.
You might think that running the Sovereign in Auto in highly mineralized ground with tons of iron and hot rocks would cause it to really drop to something super low. I've not found that to be the case. In fact, there are some bad sites with all the above problems and running in Auto at least on the 15x12 coil has got me silver coins at 7 1/2" deep easily with perfect/loud audio and proper VDI. One of the spots it did this for me also has a nearby AM transmitter which along with the ground conditions has played havoc on all my prior machines including my Explorers. Needless to say I was shocked to hit on a deep silver quarter perfectly that I know I've passed over numerous times with other machines including all three of my Explorers.
There seems to be something about Auto that I feel can make it produce coins that a static manual setting misses for one reason or another. My main theory on this is that I feel Auto is much like automatic ground tracking on some machines in that it is constantly adjusting it's self to the changing ground conditions. I feel that's why it seems to some times produce coins that a manual setting missed for me when I know very well I've passed over that coin countless times in manual yet never got it. If for instance a silver coin is laying in a particular spot where the ground in days gone by has been disturbed (changing it's matrix), or say for some odd reason a band of mineral or heavy iron content (I'm not talking things like nails here, but rather soil where there is a lot of microscopic iron "powder" in the soil)...then I think under these specific circumstances Auto's constant adjustment to the soil matrix might unmask that coin.
That sounds more like what auto ground tracking does then auto sensitivity but in a sense they both work in a somewhat similar fashion. Just as ground tracking will try to track the changing ground that some sites have, I think auto sensitivity may be re-adjusting it's self when the ground gets hotter or "colder" in order to keep the machine as stable as possible. Auto sensitivity's main job is to keep the machine and thus it's threshold rock solid stable. If it runs across a band of heavy minerals, iron, or hot rocks, I believe it lowers the sensitivity so that the machine isn't blinded by those conditions. That's where a static manual setting might suddenly be too high (or even too low) for one particular spot and so blind the machine to the target.
Auto is also useful when a site is so heavily loaded with iron and other trash that it's almost impossible to find a clean spot to sweep over while adjusting your sensitivity. In a case like that you'd probably be better running in auto then guessing at a sensitivity setting which might be way off what the best should be. At least auto will get you in the ballpark. Crazyman's pump method of setting sensitivity is a good option in a place like this where there is not enough clean ground to sweep around while calibrating the sensitivity.
The main reason why I do not like auto ground tracking on any machine is that iron and other junk can cause the ground balance to get way off. Setting ground tracking statictly is always going to give you maximum depth, and an auto ground tracking can smooth out and track out a deep coin at fringe depth. For those reasons I still have concerns with Auto sensitivity. I don't trust what it might be doing to the machine due to what the coil is passing over in the ground. It might say be hitting a ton of iron or hot rocks and knock it's adjustment way down to try to keep the machine stable. On the flip side of this, though, I think Auto sensitivity might have benefits in these kinds of conditions as it's constantly tweaking the machine for a decent setting that's in the ballpark for that particular spot the coil is now over.
Another theory I have about auto sensitivity which I haven't tested yet is that I feel it's either going to do one of two things when it comes to coins masked by iron or other trash. It could possibly reveal the coin better because it's adjusting to try to bring back the threshold faster and so give the machine the chance to hear the coin. The other possibility is that in trying to keep the machine stable Auto might smooth out the signal and make the coin harder to unmask. I keep intending to test this theory both ways on several masked coins in a test bed to see if either has advantages over the other. One of these days I'll get around to it and will write up a report on the results. I need to do that anyway because I want to compare the 15x12's unmasking ability to the 10" and S-5 coil. I'm pretty sure it's going to beat the 10" but I also have a feeling it might do better on certain masked targets than even the S-5 can due to the SEF's unique morphed hybrid coil field (part concentric but mostly double D).
In summary (you probably thought I'd never get there
), I think what it comes down to is to try Auto at some of your rougher spots (hot rocks, minerals, iron, fast changing ground conditions, RF noise, etc). Re-work the spot in auto after you've gridded it with your "best" manual setting. Make sure you grid in the same direction so that variable doesn't alter the results of what is and isn't revealed. I think you may surprise yourself in that Auto reveals some targets that manual plain out missed.One last remark about Auto- It will really stabilize target ID's and audio when the conditions are so bad due to any of the above factors that a solid locking VDI is hard to achieve. As good as these Minelabs are at excelling in the worst of site conditions (way better than the competition), even they still have their limits as to what they'll put up with. If the ID on something that doesn't sound all that deep is roaming around on you yet you know it's a coin or other target that should provide a single VDI #, my first suggestion is that you haven't calibrated manual sensitivity properly. However, I've been at spots where nothing in the way of manual adjustment would clean up the signal (rare to have sites like this that give a Minelab problem, but they do exist) try flipping over to Auto. I've personally seen it clean up the audio and ID that any manual setting wouldn't. Whether that was due to soil conditions, nearby mineral or trash, or even just stray RF noise that keeps messing with the machine is any body's guess. I just feel that there is something about Auto that works when manual won't, but I'm sure the reverse of that is true more often than not as well.
With what I've seen Auto do on the SEF (giving me silver at just under 8" deep with no problem) I'm confident it will go even an inch or two deeper. Even at 7.5 to 8", though, that's very impressive because most machines on the market max out at about that depth regardless of how high they've tweaked manual for best possible depth. That's also why I've said the same thing about the S-5 coil. It just blows my mind that that little bugger is pretty much getting the same depth as many of my prior machines from other companies using an 8 to 10" coil. Really brings a smile to my face...
OK, now I really am done with my thoughts on Auto.
Being these detectors are a little different than most beep and dig detectors Minelab recommends auto sensitivity until you get to know your Sovereign well, it will help learning it. After you get to know it better you will find that manual will go deeper, but the threshold will not run as smooth and if you want the deep ones you will be swinging the coil slower to hear those good targets in with the trash signals.I run mine no lower than the 12 o'clock position and mostly around the 10 o'clock position and have used auto if I want to go faster and not as deep.
Rick
Rick
On the E Trac ( sorry guys, this is the machine I'm using until my Sovereign comes ) the sensitivity works by having 3 channels built into it,lo, medium and high, and these channels all handle the magnetic ground interference that is in some grounds ..... Running Auto Sensitivity allows the E Trac to adjust as it goes along to the conditions of the ground by utilizing these 3 channels ....They AVERAGE out the ground conditions as they go along ..... You could never manually process the intereference as fast as the detector can ..... If you run your machine on the dry sand , there is not as much interference and you can run your levels higher than you would in normal ground conditions .... This being said, if you are in an area where the ground conditions have less magnetic ground interference , you can switch over to Manual as there will be less of a chance of the ground conditions changing, and you can raise your Sensitivity ....
I have many times tried to think that I could pretty much out guess the E Trac and have gone to manual mode and raise the level hoping for deepers readings .....In a short time I am shot down with noisy ground conditions to the point where if a target was right there , I wouldn't hear it ..... The E Trac would be falsing all over the place ..... The falsing sounds so much like a high toned Silver signal that you think that you're in luck when in reality , it's just a false signal .... I'm sure that there are many folks out there that can adjust better to this kind of noise and hear thru it , but I"m not one of them .....I have too many good finds just leaving my Sensitivity on Auto +3 anyway .....Why would I want to ruin a good thing ? ..... I would bet that the Sovereign runs very much like the E Trac in this regard .....I could be wrong , but these machines are too similar to be so different .....It all has to do with the ground conditions in your area too !!!...... Some conditions are much better than others , and manual can be run without issue .... As my grandmother would say ( may she rest in peace ) "Too mucha no good " .......Jim
I have many times tried to think that I could pretty much out guess the E Trac and have gone to manual mode and raise the level hoping for deepers readings .....In a short time I am shot down with noisy ground conditions to the point where if a target was right there , I wouldn't hear it ..... The E Trac would be falsing all over the place ..... The falsing sounds so much like a high toned Silver signal that you think that you're in luck when in reality , it's just a false signal .... I'm sure that there are many folks out there that can adjust better to this kind of noise and hear thru it , but I"m not one of them .....I have too many good finds just leaving my Sensitivity on Auto +3 anyway .....Why would I want to ruin a good thing ? ..... I would bet that the Sovereign runs very much like the E Trac in this regard .....I could be wrong , but these machines are too similar to be so different .....It all has to do with the ground conditions in your area too !!!...... Some conditions are much better than others , and manual can be run without issue .... As my grandmother would say ( may she rest in peace ) "Too mucha no good " .......Jim
Critterhunter
New member
Yea, I found that to be true on the Explorers I've owned as well. Trying to max out sensitivity in manual would cost you depth. Semi-Auto so that I could have it run in auto yet kick it up a bit with what I set it for was what normally worked best for best depth. Still found the machine to be much more temper-mental in terms of adjustments when I was trying to ride the edge of best performance. I'll be picking up one of those Etracs for the "backup" to my GT down the road when money allows. Either that or a T2LTD.
I agree that running in Auto for a while is a great way to learn the Sovereign. I did that a lot. Even did that when getting my feet wet again water hunting because I didn't want to be chasing targets to China or have anything other than getting my routine down to bother me. On my last water hunt I set the machine at around 2 to 3PM and man was I getting some great depth. Almost gave up on some targets thinking they must be a large can or something. I think less is more on the Sovereign. Slightly too high sensitivity will hurt you more in depth/ID than slightly lower than what might be perfect. That's how it was on my Explorers too.
I agree that running in Auto for a while is a great way to learn the Sovereign. I did that a lot. Even did that when getting my feet wet again water hunting because I didn't want to be chasing targets to China or have anything other than getting my routine down to bother me. On my last water hunt I set the machine at around 2 to 3PM and man was I getting some great depth. Almost gave up on some targets thinking they must be a large can or something. I think less is more on the Sovereign. Slightly too high sensitivity will hurt you more in depth/ID than slightly lower than what might be perfect. That's how it was on my Explorers too.
It's amazing how the E Trac cleans up when in Auto Sens .......From my understanding in Manual , the 3 channels will be different settings ....For example you might set Manual to 20 , and the middle might adjust down to 15 and the low channel might read 10 ..... The manual setting however will read 20 ....
In some soils you are constantly riding the Sens. .....unless you are in ground that is very consistant .... Going from manual to Auto really quiets the machine down nicely .... If I'm in neutral soil / sand , I will then switch over to manual ......Jim
In some soils you are constantly riding the Sens. .....unless you are in ground that is very consistant .... Going from manual to Auto really quiets the machine down nicely .... If I'm in neutral soil / sand , I will then switch over to manual ......Jim
deanosaur1972
New member
Mentez said:
Likewise I am still learning the GT - and I am taking the "that will do" approach at the moment - don't like auto settings so I haven't used it, just stuck sensitivity on 12 o'clock position which has never made the threshold become unstable on dry or wet sand. That will do for me, for now because because I am finding stuff that other people's detectors (just about every make and model) are missing - so whilst I am sure that I can go much deeper at the moment there is no need, come winter time when pickings are slim on the dry sand then I will be testing out all the other theories on getting as much depth as possible.
deanosaur1972
New member
synthnut said:
Up to about 12 inches...........even for a tiny 5p coin. If its going any deeper than that then its harder for me to gauge properly, I can tell its around that deep because my arm was almost up to my elbow in the holes. So at the moment any tinkering around to get deeper would be counter productive when there is still plenty of recent drops plus all the finds that other detectors are unable to find. Come winter time when dry sand hunting is tough going then I will play with the settings to eek out a little extra and it will be like having a whole new beach to detect.
There is a world of difference between beach hunting with the GT and hunting an old homesite built on red clay with iron ore and lots of square nails and other junk... a world of difference. On the beach, in FL, i'd never use AUTO, no need to. You can run the sens really high on a beach like that but in bad ground with iron and other junk you can't. At most places about 1:00 is about as high as Ican go and I still almost never have a stable threshold. I make the most finds in auto at most of my sites and would always use auto first, then if there is a "hot spot", clean it out in auto then try hunting it again in manual. Set it so that the threshold comes in occasionally and go really slow. Like Rick said, you can swing a little faster in auto and you can certainly swing faster in AM.
I like auto and if I use manual it is usually 2:00 to 3:00 and it is still dropping the almost all null but it still signals. You don't have to have a threshold tone to hear a signal. A lot of people hunt in silent.
J
I like auto and if I use manual it is usually 2:00 to 3:00 and it is still dropping the almost all null but it still signals. You don't have to have a threshold tone to hear a signal. A lot of people hunt in silent.
J
I'm at least 12 inches using my E Trac with a Pro Coil and that is for a very soiid tone on a clad dime in the dry sand !!.....It's almost like the strong tones will continue past the 12 inch mark, but as you said , why go deeper than that with so much more recent stuff to dig .... It will really be interesting to see what I will do in the parks ....I'm sure it will be an entirely different ball game .... The area's in the parks by me are mixed ....Some area's are trashy, while others are pretty clean ....It's funny how they divide up .....Some area's are Silver , some newer Silver , and yet others are Clad like crazy ... Jim
It depends on your ground conditions (mineralization and or iron/trash density. I live in an area with very high mineralization and I set my sensitivity to maintain a steady audible threshold at all times no matter where it ends up on the sensitivity setting. Your sensitivity setting will have a big affect on the sweep speed needed to maintain a steady threshold. If your hunting with a threshold null from mineralization or to fast a swing speed your loosing depth. If you need to use auto sensitivity to maintain the threshold you will still get better depth than using manual and hunting in the null. In my ground I use auto sensitivity with a medium sweep speed most of the time using the stock 10 inch coil when hunting large open areas like parks and beaches but use manual sensitivity between 1:00 - 2:00 with a slower sweep speed with the Sunray S-8 coil for woods hunting in old ghost towns and logging camps. There are some places that I have to use auto even with the smaller 8 inch coil. Even using auto sensitivity I get better depth in my mineralized ground than any detector I've used in the past and with much better target ID.
Crazyman,
I remember reading some of your threads about the soil conditions in your area ..... Too bad they didn't make a 6 x 8 SEF coil for the Sovereign ....The 12 x 15 that my buddy uses on his E Trac is way more stable than the Pro Coil and the Pro Coil is no sloutch ....If you can borrow a 12 x 15 SEF coil , you may want to try that out on your Sovereign ......It can seperate very well , and can hit some pretty small targets .....It hits Gold like a hammer !!....I'm suprised that you can get up to 1:00 with the soil conditions the way they are by you .....Good Luck ...Jim
I remember reading some of your threads about the soil conditions in your area ..... Too bad they didn't make a 6 x 8 SEF coil for the Sovereign ....The 12 x 15 that my buddy uses on his E Trac is way more stable than the Pro Coil and the Pro Coil is no sloutch ....If you can borrow a 12 x 15 SEF coil , you may want to try that out on your Sovereign ......It can seperate very well , and can hit some pretty small targets .....It hits Gold like a hammer !!....I'm suprised that you can get up to 1:00 with the soil conditions the way they are by you .....Good Luck ...Jim
Jim, I've had my eye out for a 10X12 SEF for a while now. I'm still not sure about the bigger 12X15 in my ground. I can use as high as 1:00 sens. in some areas with the 8 inch coil only if I go real slow which I usually do hunting my ghost town sites if the coins are deep but 2:00 seems to be about right without to much iron falsing and sometimes auto is better.
Crazyman,
When KellyCo get's the SEF's back in stock again, I will get the 12 x 15 .....I will be running some tests with it , and will also go to a couple of bad grounds that I know of around here, and will let you konw how it reacts ....I'm basically geting the 12 x 15 not only for depth, but more for coverage as I am going to outfit my Sovereign as my main beach machine ....If the wet, black, sand is any indication , I know it runs pettty quiet there on an E Trac ....A lot mroe quiet than the Pro Coil does in the same sand .....Jim
When KellyCo get's the SEF's back in stock again, I will get the 12 x 15 .....I will be running some tests with it , and will also go to a couple of bad grounds that I know of around here, and will let you konw how it reacts ....I'm basically geting the 12 x 15 not only for depth, but more for coverage as I am going to outfit my Sovereign as my main beach machine ....If the wet, black, sand is any indication , I know it runs pettty quiet there on an E Trac ....A lot mroe quiet than the Pro Coil does in the same sand .....Jim
Critterhunter
New member
crazyman said:
SO TRUE! I don't think my soil is quite as bad as yours but I'm finding the same thing. The 10" or 15x12 will get better depth in Auto than most machines on the market, regardless of soil.
Critterhunter
New member
jbow said:
I've done the same thing and it's a great strategy (hunting in auto first at rough high mineral/iron spots). I've also done the reverse, hunting in manual at a site griding it and the re-hunting it in Auto and Auto *will* find coins that I somehow missed in manual probably for the stated reasons I already posted and won't re-hash to the relief of everybody. Otherwise it might cause something like this to happen...
uke: I just noticed that graphic and I love it.Critterhunter
New member
crazyman said:
Based on my experience so far with the 15x12 in my mineralized soil (but probably not as bad as yours) I would suggest you go with the 12x10. It might be that the 15x12 for me is past the point of providing more depth with the minerals I'm dealing with at least at some of my sites. It's still smooth as butter, though, but I have yet to prove it's deeper. It's deep, but deeper than the 10" dealing with that kind of matrix? I'm still tossing that coin in the air and need more field time to see. Put it this way, most people say the 12x10 is for sure deeper than the stock 10" and even the 11" Pro Coil, and it's for sure going to see less ground minerals than the 15x12, so it might get deeper than the 10" even in high minerals. I'll be picking one up sooner or later if that proves to be true. From the sound of your soil I'd be highly suspicious that the 15x12 just won't get as deep as say your 8" or 10". Not saying that's a fact yet, but I'm leaning that way for myself in my soil until I see otherwise. It might turn out that the 12x10 is just as deep as the 15x12 in high minerals. In that case the 12x10 would be the better choice for being less weight, unless you are looking to max out coverage with the 15x12.
Based on the worst of worst spots for me (even higher minerals and hot rocks, etc, than the norm) the 15x12 is still smooth in operation. I have no doubt it will run smooth for you, even smoother than the 10" from my experience in spots like this. But will it be deeper? If that's important then I'd put my money on the 12x10 for now. What I can't figure out is that the field tests I've read on these coils were done in some pretty bad ground and the 15x12 beat the 12x10 on most coins. The 12x10 was deeper than the 10" stock coil but the only thing it was deeper than the 15x12 on was a cut quarter penny, which is very tiny. If that's the case (testing in high minerals) then this coil should be deeper in my soil. Just waiting for that to happen yet.