DD vs concentric coils?

[MrMikeJackie]

So we all know a concentric coil goes deeper than a double d coil, that goes without question. But is my lust for depth holding me back? A dd gives you a nice long sweeping coverage albeit not as deep but I'm covering more ground. At let's say 6inches my concentric 12 inch coil now has the footprint of maybe 4 inches? Even less the deeper you go. Yea I can hit a dime 12 inches down but I really have to be over that coin as the point of my scan is now reduced to like an inch. To get the best out of my concentric coil I have to slow down to a snails pace and overlap my swing by inches. The dd will give me say 6-8 inches of depth with a scan the length of my coil. So my question is should I switch to a dd as I might be missing targets between swings?

 

[Hot zone]

Makes sense to me, but I go back to the same old ground with different coils, different detectors and different search patterns... Still find stuff so I make the decision to first use a given setup based more on the amount of trash and the likely depth of finds... Sometimes you just have to take shallow finds and some trash off the playing field before you find those deep targets anyway!

 

[BamaBill]

DD vs concentric coils

Yep, overlapping is necessary with a concentric. But, a concentric discriminates better, pinpoints easier, and gets better depth for the same size. I think the need to overlap your swings is the price you pay for some of those advantages. However, if I have bad ground, then I'll deal with the pinpoint difficulty introduced by the DD coil, to get the depth I need. Just like most things, there's a tradeoff involved. Be really nice if someone came up with a coil that had the combined advantages of both, without the drawbacks.

 

[DeepseekerADS]

One issue needs to be mentioned. For deep targets, the cone of the concentric coil will be much smaller, and unless you were dead on the target, you would miss it and leave it for another person to find. That's one reason the locations I (and others) searched heavily in the early 80's are not searched out.

 

[bigfoot1]

I have found that target id seems more consistant with the stock concentric.Also a bit deeper but not alot.The DD seems to love bottle caps.
Bottom line for me and my favorite machine(gtax 1250)The DD is a keeper in mineralized soil...covers a ton more ground per hour,misses pretty much nothing and was the best thing I ever did for,"ol trusty"

cheers

 

[Frankn]

You have been reading all the baloney put out by the coil manufacturers. There is really not that much difference in pickup between the two coil designs. I like the concentric that came with my XLT. In the 13+ years I have been using it, it has found just about everything. I have pulled large targets from 2' down that theory says I couldn't reach. I have pulled rings and coins from 200 year old lawns. Hay, we are talking about a 9.5" 13+ year old concentric coil that pinpoints dead center. Look at it this way, a coil is just a winding of wire, It's the detector that makes it preform. Frank...

 

[Frankn]

You have been reading all the baloney put out by the coil manufacturers. There is really not that much difference in pickup between the two coil designs. I like the concentric that came with my XLT. In the 13+ years I have been using it, it has found just about everything. I have pulled large targets from 2' down that theory says I couldn't reach. I have pulled rings and coins from 200 year old lawns. Hay, we are talking about a 9.5" 13+ year old concentric coil that pinpoints dead center. Look at it this way, a coil is just a winding of wire, It's the detector that makes it preform. Frank...
View attachment 988721

 

[MrMikeJackie]

You have been reading all the baloney put out by the coil manufacturers. There is really not that much difference in pickup between the two coil designs. I like the concentric that came with my XLT. In the 13+ years I have been using it, it has found just about everything. I have pulled large targets from 2' down that theory says I couldn't reach. I have pulled rings and coins from 200 year old lawns. Hay, we are talking about a 9.5" 13+ year old concentric coil that pinpoints dead center. Look at it this way, a coil is just a winding of wire, It's the detector that makes it preform. Frank...
View attachment 988721

So you're saying the scanning pattern on the dd is the same as a concentric? This is twice now were your saying something that goes against everything I have ever been taught and have read about. I don't get it.

 

[Frankn]

So you're saying the scanning pattern on the dd is the same as a concentric? This is twice now were your saying something that goes against everything I have ever been taught and have read about. I don't get it.

Just lay a metal object on the ground and move a concentric and then a DD over to check the actual pick up pattern. It's that simple!

Hay, there are only two coils of wire in most coils. The wires are laid out either concentric or on DD's side by side or slightly overlapping. There's not that much difference.
Now on a 2 Box detector, the coils are app. 3' apart and are angled 90 degrees out of phase. That's where they get there depth, but it cost them in that they can't pick up small items which can be a big advantage in junky areas. Just my thoughts. Frank...

 

[MrMikeJackie]

Just lay a metal object on the ground and move a concentric and then a DD over to check the actual pick up pattern. It's that simple!

Hay, there are only two coils of wire in most coils. The wires are laid out either concentric or on DD's side by side or slightly overlapping. There's not that much difference.
Now on a 2 Box detector, the coils are app. 3' apart and are angled 90 degrees out of phase. That's where they get there depth, but it cost them in that they can't pick up small items which can be a big advantage in junky areas. Just my thoughts. Frank...
View attachment 989195

Sounds interesting, I'll def check it out. My buddies have them so I'll ask to borrow one and try out what your saying. If your right you save me 250 bucks on a new coil! Thank you Frank for your input, looks like you've been doing this a while. I appreciate it. Mike

 

[bowwinkles]

So we all know a concentric coil goes deeper than a double d coil, that goes without question. But is my lust for depth holding me back? A dd gives you a nice long sweeping coverage albeit not as deep but I'm covering more ground. At let's say 6inches my concentric 12 inch coil now has the footprint of maybe 4 inches? Even less the deeper you go. Yea I can hit a dime 12 inches down but I really have to be over that coin as the point of my scan is now reduced to like an inch. To get the best out of my concentric coil I have to slow down to a snails pace and overlap my swing by inches. The dd will give me say 6-8 inches of depth with a scan the length of my coil. So my question is should I switch to a dd as I might be missing targets between swings?

Mike, I believe that your interpretation of coil function is correct. The dd coils do have a long wedge of flux down the center of the coil. The concentric coils have a downward cone of flux strait under the coil. There is weaker areas of sensing on the concentric coils front and back, where the dd coils maintains the sensing depth further out near the coil edge. The field of flux of a concentric coil is the strongest near the center so it tends to sense much better in that area where the dd coil maintains a ridge of flux front to back. This is like having a household straw broom and sweeping it across a dirty area which would be like the dd, then take the same broom and cut the straw to a point and make the same pass and see the difference in the area that it cleaned. The dd two fields pull to each other and have a tendency not to reach as deep as the single concentric coil. Concentric coils do not cover as much area as dd coils of the same size but the area they do cover is a bit deeper.

 

[MrMikeJackie]

Mike, I believe that your interpretation of coil function is correct. The dd coils do have a long wedge of flux down the center of the coil. The concentric coils have a downward cone of flux strait under the coil. There is weaker areas of sensing on the concentric coils front and back, where the dd coils maintains the sensing depth further out near the coil edge. The field of flux of a concentric coil is the strongest near the center so it tends to sense much better in that area where the dd coil maintains a ridge of flux front to back. This is like having a household straw broom and sweeping it across a dirty area which would be like the dd, then take the same broom and cut the straw to a point and make the same pass and see the difference in the area that it cleaned. The dd two fields pull to each other and have a tendency not to reach as deep as the single concentric coil. Concentric coils do not cover as much area as dd coils of the same size but the area they do cover is a bit deeper.

Thank you for your insight Bow, that's what I have always understood. However I am by no means technologically savvy and love to hear everyone's opinions on the matter. I just have this feeling that I might be missing targets with the concentric coil and am almost certain of it because I have gone to small areas that I " pounded " real good but still found targets deep that nearly blew my ears off leaving me saying "how did I miss that"? 7-8 inches might not sound deep but I feel can be easily missed with a concentric coil. I don't know?

 

[bigscoop]

There is another factor you may not be factoring in. In reality, we're actually chasing "very small" targets, the signature of each growing even smaller once they are tilted or the deeper they are buried. "Miss by an inch, sometimes less, and you may have just as well missed by a mile." The amount of moisture in the soil can also effect field performance, as can other factors. Maybe, and this is just something to consider, you're splitting hairs too closely. As a very good hunter once told me, "Once you let all this other stuff get into your head it will only complicate your hunts by no positive means." He was right, by the way.

 

[Hot zone]

There is another factor you may not be factoring in. In reality, we're actually chasing "very small" targets, the signature of each growing even smaller once they are tilted or the deeper they are buried. "Miss by an inch, sometimes less, and you may have just as well missed by a mile." The amount of moisture in the soil can also effect field performance, as can other factors. Maybe, and this is just something to consider, you're splitting hairs too closely. As a very good hunter once told me, "Once you let all this other stuff get into your head it will only complicate your hunts by no positive means." He was right, by the way.

reminds me of an annoying engineering habit of proving something on paper, but there is only one problem: in actual practice it usually makes no difference! In the mean time a whole lot of energy went into it! If he is really good, he makes it looked like it worked on paper too!

 

[bowwinkles]

bigscoop is correct that even though the factories design their coils to perform, those items are now going to be put up against a variety of soil types and varying degrees of moisture by a multitude of operators. Depending on how it is used and how well the detector handles the conditions will determine the degree of success. We only know what we find, we have no way of knowing what we miss unless for some reason you or others re detect that same area later and discover those missed items. Missed items are seed to draw you back for more fun.

 

[bigscoop]

I often remind myself when hunting my saltwater beaches that the average gold ring is less then an inch in diameter, that signature being much smaller when it is sitting on edge, these signatures even growing smaller the deeper they are buried. The advantage for me, at least with a DD coil, is that i don't have to overlap as much in order to maintain good coverage, something I believe is extremely important given the size of the targets we pursue. So for me, it really comes down to, "which coil can I get the most and complete coverage from?" On any day of the week I'll gladly trade depth for better/complete coverage.

On another note, as just an example of the various factors that effect performance, the very best time to be hunting the wet sand on my saltwater beaches is immediately after a heavy rain as this runoff tends to reduce the amount of surface mineralization in the first few inches of sand, which likewise helps to improve performance, sometimes quite noticeably.

 

[bowwinkles]

Ring = 1 inch, that is pretty big when you think about the fellows with their gold machines looking for a grain about the size of a rice seed. Enjoy what you find and the process of finding. What you miss will be there for another day that may to the positive when you re sweep the area.