Have I Done The Right Thing Here? Advice On 6” Coil.

[Fossiker]

Hey all hope you are faring well during these times.

I’m a long time lurker looking for advice. Any is welcome.  I’ve bought a NOX 800 and mainly detect parks. I find I’m getting a heap of trash and expect that, but after a year would like to try the 6inch coil. So today I bought one from the miners den and will fit it tomorrow. I'm curious as to see how it performs and would appreciate

a. Any tips or advice for using this coil

b. Would like to hear what you think of the coil

c. Your experience with the coil in comparison the the 11inch coil in parks.

i know there are plenty of you tube reviews and I’ve been watching a lot of them, but would like to hear from the forum.

thanks

[Steve Herschbach]

Great coil for tiny bits and tight areas, but you will move at a snails pace. In general I prefer the 11” coil for park detecting. The 6” is my gold nugget and micro jewelry coil.

If it makes you feel any better I dig a ton of trash also unless I am severely cherry picking for coins. I like gold jewelry and to find it you have to dig volumes of trash.

[Chase Goldman]

You never really described your objective (unless you were inferring that you want to dig less trash) so it is hard to advise on "whether you did the right thing".  So instead, let's talk about small coils in general - they are typically specialty coils designed for very specific conditions.  Like most things having to do with metal detecting - equipment and settings are all about balancing or biasing competing principles to optimize the desired effect for the targets of interest.

Small Coil Pros

• Light weight
• Normal target detection requires coil swing motion and the smaller coil allows you to have Increased maneuverability around obstacles like shrubs, fence lines, playground equipment, or other situations where your ability to swing would be hindered by a coil with a larger width.
• Great sensitivity to smaller targets because of the increased density of the magnetic field produced.  So they are great for small nuggets or micro jewelry.  They will of course detect larger targets (albeit at reduced depth vs. larger coils)  but the smaller targets mentioned can be missed by the larger coils.
• Ability to have less targets under the coil main active area (the center spine region of a DD coil) in thick density target situations which can improve your ability to pick out individual targets.
• Less "antenna area" so they tend to be less susceptible to EMI noise, in general, meaning you can usually run with higher sensitivity to compensate somewhat for the lack of depth performance.

Small coil Cons

• Small swing coverage which really slows down your ability to cover an area in a given time period.  Think of the coil as a broom your are sweeping from side to side.  if you want to ensure you sweep the entire floor while still moving forward then you must take overlapping sweeps which means each increment of forward motion is limited by the width of the broom.  A six inch coil means I have to tip toe across the site to ensure I have overlapping coverage whereas the 11" coil allows you to take more natural length strides as you sweep your coil back and forth and then move forward.  As a result small coils are good for grass curb strips or if you really want to focus on every square inch of a very small area.
• Depth is limited because the denser magnetic field doesn't penetrate as far into the ground before it's field strength drops off due to the smaller physical dimensions of the coil.
• Might false more on shallower small iron bits than the larger coils.

Bottom line is that unless you have a specific situation where the coil is designed to excel such as a limited swing area, focus on micro targets, or a small area of high density targets (e.g., a curb strip), you are not necessarily going to dig less trash (and may increase hits on micro trash foil bits and other annoying debris) and unless you are patient and have the time to go slow and focus on swing coverage, may miss some targets because you didn't get the coil over the target and you will also lose your ability to get some of the deeper targets.  I have the 6" coil but pull it out only occasionally for very specific situations like meticulously going through the pile of dirt dug out of a large relic pit to look for small, missed targets like buttons.  HTH.

[Fossiker]

Thanks Steve and Chase. Really appreciate the feedback. From what I’m gathering it’s still a balance and perhaps using the 6inch coil requires good sweeping technique partnered with patience as I’ll be covering less ground in comparison to the 11. I think I might need to factor in iron bias with the 6 now as well.

again gents a big thank you, definitely got me thinking🤔

[Chase Goldman]

11 minutes ago, Fossiker said:

Thanks Steve and Chase. Really appreciate the feedback. From what I’m gathering it’s still a balance and perhaps using the 6inch coil requires good sweeping technique partnered with patience as I’ll be covering less ground in comparison to the 11. I think I might need to factor in iron bias with the 6 now as well.

again gents a big thank you, definitely got me thinking🤔

Excessive falsing on nails was a knock on the 6" coil by several when it first came out which was around the same time as the first Equinox software update.  That observation appeared to be a function of the "hotter" software update 1.75 causing several to revert to the original software when using the 6" coil.  That appeared to be better resolved in the Equinox 2.0 update and perhaps that had something to do with the new F2 iron bias settings.  Definitely experiment with the iron bias settings at your sites to get your desired response and to balance falsing against masking of keeper targets (in other words don't overcompensate for iron falsing by increasing iron bias too high because that can result in masking of desirable targets - yes, another detecting balancing act).

[GB_Amateur]

2 hours ago, Chase Goldman said:

A six inch coil means I have to tip toe across the site to ensure I have overlapping coverage whereas the 11" coil allows you to take more natural length strides as you sweep your coil back and forth and then move forward.

I agree, but there is another (related) issue (which I'm sure you, Chase, are aware of as are all experienced detectorists).  The light weight of the small coil means less momentum during the swing and thus easier to get the coil off its intended trajectory.  To experience this to an extreme, remove the coil and try swinging with just the control box and shaft.  Without walking forward (as you normally would), attempt to 'swing' the detector in the *same* arc repeatedly.  You'll find it very difficult (transate 'impossible') to perfectly repeat over the same arc every time.  You will end up making an erratic, unrepeatable multi-S shaped path.

2 hours ago, Chase Goldman said:

Bottom line is that unless you have a specific situation where the coil is designed to excel such as a limited swing area, focus on micro targets, or a small area of high density targets (e.g., a curb strip), you are not necessarily going to dig less trash (and may increase hits on micro trash foil bits and other annoying debris) and unless you are patient and have the time to go slow and focus on swing coverage, may miss some targets because you didn't get the coil over the target and you will also lose your ability to get some of the deeper targets.  I have the 6" coil but pull it out only occasionally for very specific situations like meticulously going through the pile of dirt dug out of a large relic pit to look for small, missed targets like buttons.  HTH.

This is similar to Steve's advice regarding IB/VLF vs. PI, paraphrased "use a VLF when you can and a PI when you have to."