Coils,DD vs Concentric question

[Bowie]

Ive had this thought in my head for some time now and would like to know the truth of it.
I am sure all of you know the difference in the two coil designs,concentric and DD, and Im sure you have seen the diagrams/drawings of the signal that each emit.
The concentric with its cone shape and the DD with its knife blade type signal. I also know from reading, in a mild type soil the concentric is supposedly a tad bit deeper, and I know ,from reading that a DD coil is better in mineralized soil.
Ok, that being said. Heres my thought, and I need to mention Ive never used a DD type coil. If you use a DD coil ,comparative in size to a round, would the DD give you better coverage at a deeper depth than a round ,BECAUSE, of its wider signal in the deeper area of the soil vs conical. Or would it mean it is maybe more forgiving on your overlaps as you sweep.
Im sorry,lol, but I just keep seeing this picture of a cone that gets narrow the deeper it gets, whereas the picture of the DD doesnt.
Maybe someone can understand what Im trying to ask,hopefully.
Thanks,
John

 

[Shambler]

The upside down triangle picture "out there" is a little over simplified. It's more of a parabola under the concentric than a cone. In fact, some are so sensitive off the edges, it's probably more accurate to view it as 2/3's of a ball under the ground. The concentric should have the depth advantage, but ALL things equal the DD would have the other advantages. The DD should have less to information for the detector to interpret while covering more ground per sweep (and hence less mineralization). This creates another question with elliptical concentrics - are they better than round ones? I think unless you're searching for something specific (like say a cache or meteor) and using a really large concentric, you're generally going to have better luck with a DD IF your detector supports it. I read on Dankowski's forums that people have tried to develop a DD for the CZ3D and haven't been successful. That seems to indicate there's a lot involved with the detector beyond the simple "coverage pattern" of the coil.

 

[Bowie]

Shambler, thank you for your answer. I often wondered about the coverage but never wanted to ask that question. I had tried to reason that the DD would be a bit better in overall coverage,tho maybe not as deep. I never thought about the DD not having the total area of coverage like a concentric relating to the detector not having to process as much target (s) info while sweeping.
Thanks again,
John

 

[Ron from Michigan]

Bowie,I have found the DD coil has a wider scan and better depth.The pinpointing on the DD coil usually isn't much difference than the Concentric coil.I suspect the DD coil gets a bad wrap on pinpointing because of the extra depth.In the field where it counts the small 800 coil on a Sovereign will separate better than the concentric coil of the same size.

 

[Elton]

n/t

 

[BarberBill]

My experience seems to indicate that the DD doesn't need to overlap as much and does separate better than a concentric of similar size. Size for size in decent ground the concentric will usually give a bit better depth. For the larger share of my detecting, the concentrics have given me excellent results, but I've done well with the DD types on occasions as well.. My two bits.
BB

 

[Uncle Willy]

The DD detects the same depth from tip to tip the full length of the coil whereas a concentric at peak depth is only covering an area the size of a quarter which is why you have to overlap a concentric. And even if you overlap it 50% at peak depth you are still missing a lot of real estate.

Bill