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- Thread starter djbutch
- Start date
Hillbilly Bob
New member
I am not 100% sure but I think it has something to do with the way the coil windings are inside the coil, the DD coils have windings in the shape of two D's back to back. It is supposed to give you better detection and depth.
Concentric coils like your 5.3 are round shaped O and have a magnetic field below them like a ice cream cone V. As you can see as the field goes deeper in the ground the field gets narrower. That's why you have to over lap your swings. When the field gets deep enough it is only a point. If you took a pencil and mounted it on your coil and swept it back and forth the line the pencil threw would would have a lot of space between the lines. Deeper coins in these spaces you wouldn't see with your detector.
DD coils have their coils positioned like two D's with one D flipped over so the two straight parts of the D's are facing each other in the center of the coil. The field is a narrow field that runs from the front to back of the coil. The field is almost as wide at the bottom as it is at the top. Therefore, overlapping is not as critical. Put a piece of 3/4" board on edge on the bottom of your coil. You can see it would be easier to hit a coin under the coil.
DD coils aren't deeper than concentric coils. They are deeper if the ground has enough minerals.
Concentric loops like the 5.3 have the following advantages:
Can get good targets under bad targets because of their cone shaped field
They are 10% quieter regarding magnetic interference from power lines
They have 10% better trash discrimination on iron - steel bottle caps and foil
They can shape the target without walking around it
They pin point accurately
Wide Scan Loops (DD) like the 6x10 have the following advantages:
They have better side by side target separation
They are more sensitive to smaller than coin size targets
They are more sensitive off the tip area of the coil
Rob
DD coils have their coils positioned like two D's with one D flipped over so the two straight parts of the D's are facing each other in the center of the coil. The field is a narrow field that runs from the front to back of the coil. The field is almost as wide at the bottom as it is at the top. Therefore, overlapping is not as critical. Put a piece of 3/4" board on edge on the bottom of your coil. You can see it would be easier to hit a coin under the coil.
DD coils aren't deeper than concentric coils. They are deeper if the ground has enough minerals.
Concentric loops like the 5.3 have the following advantages:
Can get good targets under bad targets because of their cone shaped field
They are 10% quieter regarding magnetic interference from power lines
They have 10% better trash discrimination on iron - steel bottle caps and foil
They can shape the target without walking around it
They pin point accurately
Wide Scan Loops (DD) like the 6x10 have the following advantages:
They have better side by side target separation
They are more sensitive to smaller than coin size targets
They are more sensitive off the tip area of the coil
Rob
Hillbilly Bob
New member
Well said Rob,....
......But I have to disagree with the depth part...... I get allot more depth out of my DD coils then my concentric, matter of fact even in the western states I hunt in the DD out performs the concentric. 
Thats why Whites new 10" is a DD coil and is out performing most others.
......But I have to disagree with the depth part...... I get allot more depth out of my DD coils then my concentric, matter of fact even in the western states I hunt in the DD out performs the concentric. Thats why Whites new 10" is a DD coil and is out performing most others.
Hillbilly Bob
New member
Great that's a very good coil, its also a DD coil so when you get it check it with all your other coils and see if it's not deeper....
Bob, it's just my humble opinion and I'm not arguing. There's snow on the ground and I have plenty of time to waste typing. 
I use the 10" DD excelerator and right now it is my deepest coil. However, that's because of my soil. I use Jeff's method of determining my minerals in the soil. My soil measures a 5, with 0 the worse and 12 the best soil. In my soil my 8
I use the 10" DD excelerator and right now it is my deepest coil. However, that's because of my soil. I use Jeff's method of determining my minerals in the soil. My soil measures a 5, with 0 the worse and 12 the best soil. In my soil my 8
Hillbilly Bob
New member
Rob, isn't the SEF a DD coil also? My 9.5 only gets a inch deeper then my 6 X 10 DD but is allot nosier and my 4.5 X 7 EXcelerator gets about two more inches then my 9.5 and about one inch on my 5.3 Eclipse, and the 10 X 14 Excelerator I got off Larry puts them all to shame as long as their is no trash or very little trash. I am very satisfied with my DD coils it might just be the way I hunt low and fast.
Symmetric Electro-Magnetic Field (S.E.F.) No it's not a DD coil because the coils aren't D shaped. I was reading a post by Carl@Whites and he explained it. He was explaining the SEF disign was better because there was field distortion in the sharp corners of the DD shaped coils of a DD coil. The SEF was better because it as oval 00 shaped coils and the smoother coils have less distortion. Even better would be an OO coil with no corners. I can't remember were I read it or what problem the distortion caused. I hate that. 
Rob
Rob