Nexus 20' DD Low Frequency Coil Revisited

Over time the more I use a search coil the more I learn about its performance, all my Nexus coils perform slightly different to each other. Reading older forum posts some people who have used Nexus in the past, usually after selling them on, claim that the larger coils are unusable. I'd like to point out straight away that this is utter rubbish, the larger coils are lovely to use. However, if you don't set them up correctly then it's going to be a frustrating experience. If you can't run a larger coil in a stable state then you're doing something wrong and the beauty of Nexus is, everything to run the unit correctly can be found on the interface. 

The general rule of thumb for easy operation is pretty straight forward, everything stems from the ground balance, get that right and you're "good to go". The next thing to take in to account in regards to coil size is the threshold level. I have a tendency to have mine set higher on the smaller coils, it's possible to do this because there isn't so much of the coil communicating with the ground. When I'm swinging a larger coil, due to their overall sensitivity I'll suppress the threshold in accordance with the ground that I'm on. This can change from day to day or when hunting on the same section of land, the machine will tell you everything you need to know if you know what to listen for. My threshold will either be 'audible', just 'audible' or 'barely audible', the feedback I get from the ground along with the coil I'm using dictates where it will be set.

How Do You Know What To Listen For? easy, you use your machine as much as possible, listen, apply your mind and experiment. One thing to listen for is noise at the end of your swing, usually coming from the left side, this is an indication that the ground balance needs to be tweaked slightly. Each coil has it's own language and style of operation and it's up to you to figure it out. Initially it can be frustrating but with a little patience you'll eventually master it, one thing to understand with Nexus is, there are no settings, the ground you're on dictates everything so if you're 'hardwired' into using digital machines with "settings", you need to get out of that mindset straight away.

Moving on to the 20' DD coil, I've been using it a lot more recently, for its size, not only is it light to swing and easy to tune, it runs really smooth. This alone allows you to hear the deeper targets without them being masked by excess noise. Out of all my coils, with the 20' DD, you have to balance it and swing it slightly higher off the ground, at first this can be counter intuitive but it's actually quite stunning how smooth and sensitive the coil is when taking both these points into consideration. When the coil is too close to the dirt, it isn't a particularly enjoyable experience, signals are stifled and the RGB meter fires off on the ground rather than metal targets. 

Due to the size it's really really sensitive to all variation of targets including really small items, there seems to be a misconception that the bigger the coil the bigger the limitations when hunting for small coins and relics. This just isn't the case with the 20' DD, it hits hard on the small stuff at good depths, the other misconception is, the bigger the coil the more prone it is to issues with mineralised soils. The size of the coil has nothing to do with this whatsoever, it's the ground balance on the Nexus that gives both the machine and coils the ability to work really well on highly mineralised ground. Below is a video demonstrating the ability of the 20' DD coil to pick up small items at a reasonable depth. Pay close attention to just how strong the initial signal is.

The other misconception is, the bigger the coil the more inhibited to both unmasking and separation, to a degree this might be true and it's most definitely the case compared to the smaller high frequency silver scout coils. BUT all the large Nexus coils actually do a really good job at unmasking non ferrous in close proximity to ferrous materials. It was only yesterday when using the 20'DD coil on my V3 with VCO tones engaged that I found an old button in the same hole as a number of ferrous shards. 

The other benefit to using the 20" DD is the ground that you cover, due to the overall size you're obviously detecting more ground on each swing. I personally don't really use it for this, I use this coil for it's depth capabilities, with a lot of modern tech machines the largest coils you can get are 15' inch or a 17' inch for the CTX 3030. I don't see evidence of any real depth advantages with these large sized coils. I saw no real depth increase with the 15' inch Coiltek when I got one for my Equinox 800. I can confirm that as Nexus coils increase in size, there's a very clear advancement in their depth capabilities. 

To conclude, for me personally, this is one of my favourite coils to swing, it's deep, sensitive and I genuinely don't feel like I'm missing much with it. What I mean by this is, if I swing over a target I'm going to be notified of its presence down to some pretty impressive depths. Unfortunately due to peoples inability to have an open mind in regards to coil size, the 20' DD has now been discontinued which is a shame because a lot of Nexus users would've benefitted greatly having it in their collection.

Below Is A Video Of The V3 Using The 20' DD Coil To Unmask A Coin In Close Proximity To Iron.