AT Pro 9" x 12" Concentric Coil Machine Competes With AT Pro 5" x 8" DD Coil

[John-Edmonton]

A great day to be out! My buddy and I did a hunt today. Same detector, just different coil.

And neither coil is better, but just better under certain circumstances
.

Here's a couple of finds. Both found with the 5" x 8" coil. Silver is always good.

My 9" x 12" Coil got these 2 old cast metal toys. These are starting to be my favourite types of finds.

Both coils managed to get silver coins.

And yes.....lots of Wheat cents are found up here!

 

[an khe]

John, thanks for the post. I think the concentric coil found more coins then the double d or was it that it was in the right place at the right time? It seems to me that the concentric would be better for coins.

Is the double D over rated and does it fit everybody's condition in the field concerning the minerals in the soil? I live in Iowa, I have two double D coils for my AT Pro and they work good. I have thoughts

on getting a concentric coil do you think I would increase my coil count?

I think if I live some place where the soil was red with iron that the double D would be a better choice. Any thoughts on this subject would be helpful.

Thanks

 

[Turak]

I find DD vs Concentric choice more a matter of target separation.......

I find the DD coils more useful in 'trashy' areas. It doesn't look at as big of a chunk of soil, so its easier to separate the targets.

As far as depth, yeah the soil mineralization plays a factor. Highly mineralized, the DD reaches a little deeper.

Low/neutral mineralization and the concentric reaches a hair deeper, but not much, only an inch or so.

When explain the difference to people, I tell that that for a concentric coil, image a ball cut in half. Place the half
of the ball under the coil, flat side against the coil. The half of ball now represents the shape of the concentrics coils
magnetic field under the soil.

For the double D coil...image 2 plates. Lay one on top of the other facing down. Then cut them in half. Now place that
half, standing on edge, with the flat part against the coil. That is the general shape of a DD coils magnetic field under the soil.

 

[FrankG]

My $.02 worth.

I use both concentric and DD and and feel that once you learn to uses each type properly it becomes simply a matter of personal preference.

My soil here is pretty neutral and feel that either type will fine everything equally well if used correctly. I had never used a DD until I got the AT Pro a few years back and think that the only significant differences "to me" is that the DD offers far better separation in the trash areas and also allows you to detect much closer to metallic objects. So DD is the best choice for me for "most" places I hunt.

As far a pinpointing with either type.... They are both equally easy once you learn the techniques.

Some folks believe that the concentric is better because it's magnetic field covers more area and thus detects more/better. I think that's very debatable and I don't buy it!

I believe what's really happening is the concentric "appears" to be better because as you sweep it, the target is under the coil for a longer period of time because of the shape of it's field. The DD has a very narrow field "slice" so the target is in that field for a lot less time as you sweep. So it appears that the concentric has the edge. Also, "less time" over the target while swinging a DD has even a larger negative impact when you hunt in Pro Mode with because proportional audio volume can get quite low due to size of target or time over the target. The one thing that works well for me is to swing the DD slower and you'll get fine coverage results.

I would agree that it takes more skill to hunt on Pro Mode with a DD than it does with a concentric because of the varying audio levels and time over target variables.

Bottom line... The ideal thing anyone can do is spend significant time with each coil type and then decide for yourself which works best for you (understand the pros/cons of each), What's best for me or anyone else is very subjective based on their soil conditions and personal hunting skills. Both are different but both are excellent and don't disappoint.

 

[fongu]

Nice finds with both coils, John.

 

[Grilled Scallops]

I personally feel the small DD on the pro leaves it lacking too much depth. There's a video out there that shows the pro with the small DD in mineralized ground can't get a walking liberty half dollar at 8 inches (yikes), even after it's been buried for a few months. It's not a coincidence that the mono got more coins and the DD got the bigger targets. In my opinion, the 8.5 x 11 DD coil is the best all around coil for the pro. You get the depth and separation with it. There exist huge aftermarket coils for the pro that will give you insane depth but will also sacrifice separation. Gl and HH, nice finds.

 

[an khe]

Thanks, for all the input on the coils. I think I will stick with the double d and go slower in the field. A interesting note, I was out coin hunting, I was using the 8.5x11 and pull about $4 out of the ground, then I switch to the 4inch small coil and pull out $6 out of the ground. I think the reason was that I was going slower with the smaller coil.

 

[FrankG]

Thanks, for all the input on the coils. I think I will stick with the double d and go slower in the field. A interesting note, I was out coin hunting, I was using the 8.5x11 and pull about $4 out of the ground, then I switch to the 4inch small coil and pull out $6 out of the ground. I think the reason was that I was going slower with the smaller coil.

That 4" coil isolates targets so well it can sure make a huge difference in isolating and identifying targets worth digging, especially in particularly trashy areas.