Buying a DD coil for an X terra

[reffitt20]

Can anyone give me an idea of the differences in performance between stock 9"concetretic coil for X-terra 705 and a MINELAB X-TERRA 10" ROUND DD 7.5 KHZ COIL or any other DD coils that go with the Xterra 705?

Is the $165 or greater worth the investment if I am going to stick with the 705?
Also how well is it at separation?

 

[petew]

I think if you buy that 10.5 dd could you will never think about getting another detector. It separates great and depth is awesome. Me personally,I'd get it.

 

[michaelosully]

To be brief: If your soil is moderately to highly mineralized...a DD coil is an absolute must AT ANY PRICE.

 

[reffitt20]

I live in NorthWest Ohio so I have no idea how mineralized the soil is.

So A DD is far superior to a stock coil I take?

 

[Digger 45]

The 9" coil will not work at all in my high mineralized soil, went to the 5x10 DD and love it, i have to run the sensitivity at about 18 to 22 but i gets good depth and separates very well, just go real slow in trashy areas and it will tell you what is there.

The balance is much better with this coil over the 10.5 and it is great for gold along with all the other coins.

After six detectors this is my favorite detector and favorite coil.

If you are having trouble with the digital numbers jumping all over the place and have high mineralized soil you must have a DD coil-!!

 

[Old Longhair]

In NW Ohio it won't get you any additional depth, but the separation capability make it worthwhile.

 

[mapper65]

These guys are all correct.

Here is a sort of strange analogy that I like to use when people talk about this.

Before someone jumps on me, this is really just my explanation of coil detecting patterns and their advantages. No detectors, coils, coins or your feelings will be hurt during this analogy.

With that being said. let's say for conversation purposes that we have two coils (concentric & DD) and they are both 10" and for this example we will say that they are the exact same frequency.

The concentric coil has a maximum detection depth of 8" and a DD that has a maximum detection is 8". Being that the pattern of a concentric coil is conical like one of those paper drinking cups at a water cooler, the concentric coil's maximum depth will only be 8" only in the center of the coil.

The DD coil that also has a maximum depth of 8". It's detecting pattern will be about 1/8" wide nearly the entire length across the center of the coil varying just slightly near the outer edges. Kind of like a hockey stick blade.

Let's say you had 50 pennies scattered on top of a flat 4'x4' surface and your goal is to push all of those pennies off of that surface with the detecting pattern of either coil hovering just under 8" off of the surface and your eyes are closed. Kind of impossible to do it perfectly but in my example we're also all perfect. If we look at the detecting patterns of each coil as a physical figure, it's going to be much easier to push those pennies off with a hockey stick than the point of a cup. Remember we can't see coins when they are underground just like this example with our eyes being closed. The more surface that we have to work with to slide those coins the better. Of course in reality we are running over the coins with the signal and not sliding them.

Granted this is kind of a hair-brained analogy but not far from the truth. If we turned this analogy into reality, the depth of a DD coil in most soil conditions would be deeper than its similar sized counterpart. Sure if the coils were nearly touching the surface that changes things a little with the concentric at least giving you a semi-wide detecting pattern near the top but if you are going for old deep coins you want every advantage that you can get at greater depths. The DD coil besides helping in mineralized ground has a much more forgiving detecting pattern being that it covers more area over the entire depth of the signal. A concentric may be a little easier to pinpoint with and a DD is a little more subject to picking up parallel targets but I think increasing your chances of running over an item with the signal greatly out numbers the ability to pinpoint better. I've often times found trash right next to the treasure signal that I was digging using a DD coil.

It's my opinion that everyone should own the 6" Coiltek coil first and then some flavor of the Minelab 10.5" DD second.

Have fun!

 

[reffitt20]

Thanks guys

this forum is filled with good people. thanks

 

[Coin Rescue Inc]

Hey mapper65 that is a very good analogy. I like it.
(anyone) I am new to the 305 x terra and picked up a 10.5 MF DD. In two one hour hunts with the DD I was fooled by Aluminum Bottle Caps and Steel Bottle caps. Each one hitting numbers identical to copper penny/dimes (36) or Quarters (40).
I thought the Concentric brings up the ID a bit better with less caps being dug. Been out 4x with Concentric. I was working in All Metal and 99 tone. I read Randy's Blog on testing for an Iron Grunt and that helped a bit.
For 6 - 1hr hunts I found 4 dimes 8 pennies and one quarter. Would the 705 with it's wider range of ID numbers put some distance between the caps and coins on the ID scale?
Any help or suggestions would be appreciated

 

[mapper65]

Would the 705 with it's wider range of ID numbers put some distance between the caps and coins on the ID scale?
Any help or suggestions would be appreciated

Hey CR! I've never used a 305 but I'm sure that the wider range would be somewhat helpful with IDing certain targets. I find myself relying on the sound of the target in detect and pinpoint mode to help me distinguish between trash and treasure. One example would be between a pull tab and a nickel. Although they may often ID the same, in may cases the sound of them in pinpoint mode is completely different. The pull tab will have a sharper sound an a nickel will have a lower sound.

Most of detecting once you are comfortable setting up your machine is remembering four things. What the target ID'd as, what it sounded like in detect mode, what it sounded like in pinpoint mode and remembering what you are holding in your hand after digging based on those first three details. Once you get that down then you should be able to distinguish between a quarter and a bottle cap and a nickel and a pull tab. Not always, but most of the time.

 

[Coin Rescue Inc]

I do have a vision in my mind at times when I here the duration of the tone in relationship to the swing that relates to the size. of the target.
A coin seems short and quick. Maybe I was at some parks that were void of coins. I am not giving up but asking for advice.
I like your story on the DD. It makes some sense that I was killing the bottle caps by the virtue of sweeping a wider area with each swing