Jump to content

Help Me Choose


Recommended Posts

I need some help in Choosing which big Mono Coil to purchase for the Axiom

I currently have the 13x11 DD and the 11x7 Mono which were in the package I purchased, I also picked up the 11x7 DD

I am wanting to add one of the big Mono's for the Axiom, but can not decide if I want the 13x11 mono or the 16x14 Mono 

Someone please sway me one way or the other LOL


How much depth will I gain with the 16x14 Mono over the 13x11 Mono if any, I know this depends on several things ???

how much sensitivity to smaller gold will I loose with the 16x14 Mono or the 13x11 Mono if any ???, I also know there is to many factors to consider on this one also

price is only like $20-$30 more between the two so not an issue in my opinion

So there is my dilemma, so again give me some reasons to choose the 13x11 mono or the 16x14 mono 

for me it keeps coming down to (if I am going to go big go the biggest I can currently purchase) LOL


Thanks for reading my RANT

Link to comment
Share on other sites

Each coil size made has an optimum target size that gets max depth. Smaller or larger targets than that optimum will not get as much depth as other coils better optimized for those sizes. The larger the coil, the larger the optimum target size. So a small coil will get more depth on small targets than a large coil. Large coils get more depth on large targets than small coils. So you pick the coil that best fits the size targets you are after.

This is VLF but the principle is the same and this chart illustrates it well:

Coil Size vs Depth Fisher Gold Bug 2

Source - Field Testing the Gold Bug 2 by Gordon Zahara

Eric Foster used a chart he made that showed the same thing in a more technical way for PI detectors. Here is the chart, with details at this thread:


As far as specific numbers to your questions the fact is there are too many variables to consider. All I can offer is the above and generalities. Ground mineralization can largely negate depth gains with larger coils depending on the exact circumstances and flatten the results. But in general if you are looking for fist size stuff the largest coil is the way to go. Personally I don't really use the 16" coils because I am usually focused on coin size targets and the larger coils offer minimal if any gains on those, or at least not enough for me to care to swing the extra weight. But if I was looking for a 6 ounce gold nugget I'd put the 16" coil on.

  • Like 3
Link to comment
Share on other sites

My friend Steve summed up the situation well, all of this has to take into account the soil situation in your region, if it is very mineralized the Mono coil will not do well because it will cause a lot of interference with hot and ferrous stone, ending up losing a little in depth. The DD coils end up doing well and dealing with smaller mineralized soil, but it works a little shallower.

Now if the soil is low mineralized then yes the mono coil can work well and go very deep. In your case, I noticed that you have the 13x11 DD coil, this coil with the 13x11 Mono will make little difference.

I advise you to get the Mono 16x14. Because, you can use the DD 13x11 another day you go to the same place and switch to 16x14 mono, that way you will get the thick gold that the DD couldn't locate.

  • Like 2
Link to comment
Share on other sites

Thanks for the replies @Steve Herschbach and @Joel - cacadordereliquia greatly appreciated, I will go ahead and pick up the 16x14 Mono and then keep an eye out for Steve's reviews on the X coils when they come out since Mr H is going to be testing that 8 inch X Coil, I will be keeping an eye out for that also

Sometimes for me it takes a little ranting or debating myself before I can finally make up my mind so this has helped a lot for me to choose

And Yes I always go out with the thoughts in my head that I am going to find something big or small and always hope for that big big nugget, either way it just comes down to having fun, that is what dreams do for you, without dreams what do we have, going to go big and then hope I swing across a big deep target LOL either way I will be prepared for what ever the situation calls for. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...