What are the advantages of a small coil? They have less target volume which is a plus as there are fewer targets at an instant in time to try to separate into good and bad. The lines of force are tighter and can detect a smaller target. I think of this like lines drawn on a piece of paper. If the spacing of the lines are wide I can put a BB on the paper between lines. I lines are very close together then a lot of line intersect the BB. That is the idea of centering a target in the hot spot of a double D coil. That narrow hot strip in the double D also rejects noise better as does a small properly designed coil. Where we get into trouble is a coil is not just wire wrapped in a circle. It really takes some pretty good manufacturing to get one right. George Payne, inventor of the VLF, has a post on the Internet that explains the parameters for designing a coil that is the best I have seen anywhere.
One of the thinks that impressed me so much about the X1 probe is it will ID and operate with no problems just like a coil manufactured by Minelab. That takes some pretty good engineering. Where I most often see coil problem is when it comes to proper ID compared to the stock coils. The signals presented to the receiver are not the same for all coils. That is where I have to go by the reports I read on different after market manufactures of coils and probes.
One of the thinks that impressed me so much about the X1 probe is it will ID and operate with no problems just like a coil manufactured by Minelab. That takes some pretty good engineering. Where I most often see coil problem is when it comes to proper ID compared to the stock coils. The signals presented to the receiver are not the same for all coils. That is where I have to go by the reports I read on different after market manufactures of coils and probes.