pros and cons of the DD coil

[hollowpointred]

one thing i have learned over the past two years, is that in this hobby,nothing is 100% good. eveything seems to have a trade off to it. so here is my question........i already know the benifits of a DD coil are improved coverage, and they are better at dealing with higly minerilized conditions, but what is the down side to them? some guys say that they are harder to pinpoint with, so i guess that would be one, but are there other drawbacks?

 

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[EDDE]

one draw back is questions like these just funning ya'

 

[hollowpointred]

one draw back is questions like these just funning ya'

WHY I OUGHTA!!!!

 

[jeff of pa]

The only drawback I'm aware of is the pinpointing.
& that should only be a problem on the detectors that
have pinpointing controls.

However since I'v never used a DD on one of them, it's just
Speculation.

I have no problem pinpointing with a DD

Trashy areas can be tricky when pinpointing if while your backing
the coil up you hit another buried object, but that's
when you change angles until you get it, or dig the other object first
to get it out the way.

 

[OutBack Duo]

I have a 14DD coil for my DFX and I love it. The only thing I don't like about it is the pinpointing and the weight. If you are out in the field with a good size shovel then pinpointing won't be a problem but if you are trying to keep your hole small and neat you are going to have problems. The 14DD is quite heavy but it also gives you a couple extra inches of depth so its worth it.

Just my thoughts.

Don

 

[EDDE]

i find shalow targets 1-3 a little tricky to PP on
anything deeper seems easier
make sense

 

[Beachcomber310]

You are right that everything in medal detecting is a trade-off of one kind or another.

The advantages of the DD are more ground coverage at maximum detection depth and better handling of mineralization and saltwater beaches. The dowsides are it's slightly harder to pinpoint, poorer discrimination characteristics, and less depth than the same sized Concentric coil.

Characteristics of a Concentric coil are excellent depth in low to moderate mineralization soils, ease of pinpointing, and excellent discrimination characteristcs. The downside to a Concentric coil is loss of performance in high mineral soils and poor ground coverage at maximum detection depth.

Now you maybe wondering about the fact that a DD coil that is the same size as a Concentric coil has less depth than the Concentric. It's another one of those trade-offs that we spoke of earlier. An 8" concentric coil is actually an 8" in diameter coil. However an 8" DD coil is actually two 6" coils flattened and overlapped down the center. So basically to get equal depth between a Concentric and DD coils you need to use the next size larger DD. An 8" Concentric and a 10" DD will get almost the same depth in average mineralized ground.

Hope this helps and sorry for the long Post.

HH

BC

 

[hollowpointred]

You are right that everything in medal detecting is a trade-off of one kind or another.

The advantages of the DD are more ground coverage at maximum detection depth and better handling of mineralization and saltwater beaches. The dowsides are it's slightly harder to pinpoint, poorer discrimination characteristics, and less depth than the same sized Concentric coil.

Characteristics of a Concentric coil are excellent depth in low to moderate mineralization soils, ease of pinpointing, and excellent discrimination characteristcs. The downside to a Concentric coil is loss of performance in high mineral soils and poor ground coverage at maximum detection depth.

Now you maybe wondering about the fact that a DD coil that is the same size as a Concentric coil has less depth than the Concentric. It's another one of those trade-offs that we spoke of earlier. An 8" concentric coil is actually an 8" in diameter coil. However an 8" DD coil is actually two 6" coils flattened and overlapped down the center. So basically to get equal depth between a Concentric and DD coils you need to use the next size larger DD. An 8" Concentric and a 10" DD will get almost the same depth in average mineralized ground.

Hope this helps and sorry for the long Post.

HH

BC

no need to apologize for a long post. this, as well as the other answers were exactly what i was looking for. i have found that you can learn a lot of stuff around here if you just ask! thanks for the reply!

 

[Willy]

In nasty ground, the DD will go deeper than the concentric. Up here, the 5x10" DD (MXT) will go as deep or deeper than the stock 9.5" concentric. The Reason? with the DD I can have the sensitivity maxed out with no problem whereas the concentric 'might' be able to go up to 2/3. In regards to pinpointing, I'll take a DD any day. All I do is pull the coil back till the target is right under the tip. takes all of a couple of seconds. Something REALLY deep can be PP'ed by X'ing the target. ..Willy.

 

[W6PEA]

What is a DD coil?

 

[Charlie P. (NY)]

That's whats ye gots on yer Sovereign GT. Two "D" shaped coils butted together with the flats down the center. As opposed to concentric coils that are a circle within a circle.

The DD coil has a field like a long but narrow line down the middle, while the concentric coils are more a parabola with a narrowing "tip" at about the same distance down (and up) as the coil is wide.

Now consider this:

A DD coil swept with one pass just beyond the prior searches a pattern like this:

UUUUU

While a concentric searches a pattern like:

VVVVV

The deeper targets have more "gaps" to hide in. Though it is harder to pinpoint with a DD coil. The eliptical concentric coils are a way of elongating the field to get the best of both worlds; though I don't know if they shoot as deep as the coil is wide or as it is long.

 

[OutBack Duo]

WOW, that was about the best explanation I have seen yet. I love your diagrams, they really do show what you are saying quite well.

 

[EDDE]

target seperation is great with a DD verse a concentric

 

[U.K. Brian]

Everyone should get out their coils and check with a small coin the actual detection pattern. Some DD's have very poor detection fields not the wiper/full depth from side to side as the manufacturers would have us believe whilst few concentric are an inverted cone shape. Many are like a squashed ballon and detect well outside the size of the coil a few inches in the ground.

 

[EDDE]

g d point brian 8)

 

[Willy]

There's a guy who mapped out the field on 2 Garrett GTI coils (wayne's this 'n that .. I think it's called) and it turned out to be very different from what people commonly think. Something like what Brian was saying.. but add an icecream cone to the bottom of the balloon. ..Willy.