DD coil vs. concentric

With the recent trend of DD coils I'm wondering if they are really that much better. We've all seen the illustrations of how the narrow detection field separates like a knife but I've passed a coin a couple inches from the edge of the coil and still gotten a signal so I don't know how accurate those claims are. Another point that comes to mind about separation is, a dd coils detects the same depth all the way from the front of the coil to the rear. I would think in areas with a lot of deep trash this would adversely affect masking whereas with a concentric coil deep trash would be separated better due to the smaller field of detection. Has anyone compared the 2 different coils under the same conditions?

I'll give one plain example:
On side by side comparisons using the Eurotek Pro with both the 8" concentric and 11"DD coil.
I've found many targets deeper than 6" that the 8" concentric coil can't find regardless of sensitivity settings.
But the 11" DD coil not only found but ID very accurately.
The 11" DD coil is truly amazing.

I did a comparison a little while Back but with the Tejon and F75 so not conclusive but still shows.

Video here [youtu.be]

A 5" DD coil, and 5" concentric, (or even 8") both in trash, I'll take the DD every time.

Aaron

I think it has just as much to do with the detector as it does the coil. As an example, I can hit a silver dime at 8+ inches with both my CZ6a with 8 inch concentric, and CTX3030 with 11 inch DD coil, same strength, and ID. But with the CZ, I have to be more accurate with where the center of the coil is being swept.

With a concentric coil, in trash, the deeper targets can be hit, but coil control and overlapping is CRUCIAL, Overlapping has to be done precisely ( you can make more 'errors' with a DD, ie, not over lap as much ), and get the better results due to the DD design.

Both types of coils have their place and it all depends on the soil conditions and what targets are in the soil, and how close/far away they are to each other.

Personally all depends on the DD and Concentric of unit in hand as I don't feel all DD or for that matter Concentric coils are the same. That being said have done well with either and feel both have their place in the hobby.

It's well worth going over a site with a concentric as it will find items that the 2D just can't see. In the video I did above it hits a coin at all angles around iron just like with Keith's spider coil. The 2D hit more times in other tests when iron was placed above target.

Slower sweep speeds can really help out a machine to winkle out those awkward items amongst iron while using the concentric.... More of a precise sweep helps.



Edited 1 time(s). Last edit at 04/30/2014 05:48PM by Ziggy.

If I could have both coils for every detector I use I would love that. They are each better than the other at certain things and in this game you want to "cover all your bases".

Same reason I have several different detectors and only grab certain ones for certain hunts.

I like tight DD's...

And usually a DD does not I.D. iron quite as well as a concentric...

you can see how bottle caps sound good on a DD but can be easier to discern on a Concentric..

yet when working though iron the degrade in iron I.D. by falsing on it is actually going to allow for more targets to be heard by the audio report..plus the tight window combines to create a useful site unlocker..

now on a Tesoro the round small DDs are not really tight...and I have found more itmes in iron by using the concentric of same size....

the only DD coil's I have found a use for on the Tejon was the 5x10 and the 10x12 and it was for working though iron dirt..

the way a DD coil is designed and the machien its couple too means alot..

Im not for sure T2 or F75 would even run right without a DD or at least an elliptical concentric...

Keith

Keith