He found 1 orientation where the nail masked a coin on the 6" but not the 11" coil. What percentage of the nearly infinite arrangements of coins and trash will a 6" coil provide better separation than a 11" coil? If it's more than half, than the 6" coil is better for that purpose.
I guess now you know the 6" coil might struggle when we have a 5-7" dime in his soil and a nail (old? bent? rusty?) on the surface about 8 inches away, and on the left hand side of the coil (receiver side?), and using whatever settings he had at the time.
Also, he would have hit it fine with the 6" coil if he was gridding the property and approached from 90 degrees more or less. In fact, the 6" coil would have have hit it in the middle of the coil whereas the 11 inch coil might have only hit it on the nose or heel.
Good reply, and some of those things that are obvious to more savvy detectorists when we watch some of the vireos that get posted. They
(the poster) try to make it sound like the smaller coil
(a 6" DD here) is a terrible choice. If I had an Equinox, the 6" DD would be the most-used coil for me. Why? Because I devote the majority of my search time working sites with an over-abundance of ferrous and non-ferrous trash. Plus, many places have very rough terrain or piled / pushed-up soil, sagebrush, weeds, and other brush. And I can't forget the many conditions where I'm encountering building rubble.
In the many decades I have been detecting, and for the bulk of my chosen sites, smaller-size search coils have been my preferred pick. Time and time again, when I have been evaluating a new detector with a 'standard' coil and then continued checking them out with an available smaller coil, the advantage has almost always been in my favor when a smaller-size coil was used.
Since we're referring to a Minelab model here, I'll do the same using their Vanquish 540. I liked it so well I bought a 2nd 540 ro Pack unit. It is only one of two models in my Detector Outfit that I use with a 'standard' or to me a 'larger-size' search coil on. I keep the 9X12 DD on one V-540 because I like the performance in a more open environment with a limited target level.
But I use the other V-540 much, much more with it's smaller-size coil, the 5X8 DD
(which to me is a mid-size coil), simply because it fits in some areas better and does a better job of handling most of the densely-littered sites compared to the bigger 9X12 DD.
Now you talked about the Equinox specifically. I have both the 6" and 11" coils for it and I've experienced similar situations where the small coil missed stuff that I got with a bigger coil. One site in particular I hunted a nail ridden strip with the 6" coil and got frustrated with all the nails I dug that sounded good. Not one good artifact or coin was dug with the 6" coil. I later returned with the Deus and 9" HF coil pulled out 1 small coin and again with the Equinox 11" coil finding 2 additional small coins. I'm not a real big fan of the small coil but it is useful in some spots.
What some readers ought to note is that you had better success on a return hunt, not just by using a 9" DD instead of a 6" DD, but they were different designs, used on different brands and models and most likely at different operating frequencies.
That's an example of why I also maintain an Outfit that has more than one detector brand or model and different coil configurations and sizes so that I might select the combination to best handle a site environment. And then to re-hunt a site using a different search coil, or better still a different detector & coil combination.
All coil decisions are based on LOCATION! I have tripled my finds with the small coil mainly because most of my sites are trashy and surrounded by things like playground equipment,benches,etc. Sooner or later a playing field or huge play area forces another machine with larger coil. One FYI,however-it's really easy to forget to overlap a larger coil!
How true, with regard to factoring in the LOCATION in a detector or coil decision, and Location also includes the amount and proximity of both unfavorable and desired metal targets there are to deal with.
You bought up an important point, and I have seen it happen all the time for many years, and those re the folks who go to a larger-size coil don't overlap much, and very often do not over-lap at all! Combined with the fact that many of them sweep too briskly in the first place and all of that 'bad behavior' leads to a lot of missed targets.
I do use two models with a bigger coil, but the rest of my Outfit keep a 5" or 6" or 5X8 or 5X9½ mounted all the time. Smaller-size to mid-size coils, and they easily handle 95% of all the terrain I like to cover.
Monte