I'd be curious how the DD and concentric perform on the F75 for depth on the same target. IE a test garden where the both Bp and DE are used with the same sensitivity level on known depth targets.
As a relic digger I'm all about depth particularly when detecting in farm fields or timber tracts where past events have turned items under.
Never tested in a garden but in the field using both for a ton of hours this is what I noticed.
In almost perfect soil, black loamy with very little mineralization, the big DD was deeper.
I got as far as 10" on some targets with the concentric, very happy with that since those really deep targets are rare and most of the good stuff I found were still around 6-7"...came across a few good coins at 8-9".
Got a couple of really deep targets past that in audio only using the concentric where the screen goes blank but never dug them because I hunted mostly public parks...didn't think they were good targets anyway but I will never know.
The big DD was definitely deeper and could ID pretty accurately up to the 12" or so area, dug one target at a measured 15" that ID'd in the foil to nickel area and it was a thumb ringer off of an old bicycle bell that air tested in that range.
Most other targets past 12" would give you that audio but again the screen goes blank so that one was unusual.
I moved to the SE. and usually hunt in areas with much more mineralization plus old spots that had homes and neighborhoods knocked down so lots of iron...plus due to the history of this city usually lots of extra iron.
Here the concentric found a great silver target easily at the 7-8" area in some rare good black dirt with solid non jumping correct VDI info but most of the time I can trust it to get me to where I want to be at 6" and deeper in the bad stuff maybe but the signal gets all screwed up.
Mostly all targets here past 4-5" are screwed up with jumping skewed signals using any coil, I have found a ton deeper but I had to learn a new language...use new behavior and indicators to do it.
The big DD does seem to lock on better on the bit deeper targets here than the concentric, and the 5"DD has done just as well for me here and I have dug great targets up to the 8-9" here so far in the really bad stuff.
I can get signals past that, I have used the pinpointer and gotten depth readings up to 12" with that coil, the big DD and maybe one or two with the concentric but haven't dug one of them so far as I suspect they were deep iron and even in good conditions the soil here is difficult to dig in.
In the good soil out west the sniper matched everything the concentric could do in depth, might even could get a bit deeper if you can believe that.
Here, all of them seem more equal but the DD's still find me more.
What people say about DD's handling hot soil better seems to be true.
I use all of them and also discovered that settings matter when trying to get deeper here and notice the good stuff that is masked.
DP works great, is stable and pretty deep on the DD's, the concentric doesn't penetrate really far in that tone option and everything is pretty jumpy.
Using other tones and all metal I get different results so I use many depending on the site.
For precious metals and silver coins the concentric just sounds super sweet in its response on all tone options but in multi tones especially for me.
Hunting for jewelry and coins that are not super deep I love using the concentric, the sound and response on targets is special to my ears and senses.
For going super deep and covering a lot of area efficiently the big DD gets the call.
In heavy trash and/or iron I use the sniper...since that is common for most of my sites around here I use that one more than others most of the time.
For your purposes it is a no brainer....use the big DD, that is what I would do, anyway.
