Concentric coils vs DD coils

I know I know. This question has been asked a thousand times, But I hunt with a guy that uses a concentric coil and he often find coins that I have walked over. My question is this: are there scenarios where a concentric coil trumps a DD coil???? Thanks. kevin

You are usually more conscience of your coil overlap when using concentric coils. With a DD it is easy to forget that they need the same overlap. The other issue is that the object spends less time in the detection field as compared to a concentric, therefore the audio is less pronounced. The beep becomes a blip and easy to walk over.

HH
Mike

I used to be a bigger concentric fan. Bad experiences with the lousy 10" DD coils they used to put on Explorers only firmed that up for me for a while. Those coils seemed to have rather fuzzy fields, which caused instability, separation, and depth issues in my soil. Now that I've used some quality DD coils the difference is like night and day. In my soil, DDs handle mineralization better and punch deeper, not to mention give me better left/right separation at all depths.

The rule of thumb seems to be that concentrics tend to peter out in still retaining sensitivity (and thus depth gains) on coin/ring sized targets somewhere in the 10.5 to perhaps 12" coil size range. For DDs, perhaps somewhere up to about 14" in coil size before beginning to lose sensitiity and depth on coin/ring sized targets.

But, it also depends on mineralization. *In general*, concentrics tend to ride on and see more ground matrix, so in some soils even a 10" concentric might not show gains in depth on coin/ring sized targets compared to say a 8 or 9" concentric perhaps. Same deal with DDs. In my soil the 15x12 got less depth than my stock 10" coil (the 10" Tornado for the BBS units is an outstanding coil) on coin/ring sized targets, and I would guess only because of mineralization at some of my sites. They 12x10 is showing me depth gains over my stock 10" coil, and I'm guessing mainly due to it's tight/sharp field for a "12 inch" coil, which isn't riding on and soaking in as much ground stew as a round coil. For that reason, I'm not sure if a round 12" or 13" coil will even get the same depth as the 12x10 in my soil.

As to your question of when a concetric trumps a DD coil. Sure that can happen. Let's take two of the same size as comparison- a 10" concentric versus a 10" DD. If the mineralization isn't bad enough to where the DD might come into it's own depth and stability wise, then the concentric in theory should have slightly more depth right at the very center of the coil, and at that fringe edge of the field it should in theory also have excellent separation from any angle, where as a DD will have it's best at only certain angles. Contrast that though with a DD tending to have better left/right separation over more of it's vertical span into the ground.

Perks of a DD? Better stability/depth in mineralization after a certain point, better left/right separation, better coverage length wise at depth, though as said a concentric can have better depth at the very tight center of it if both coils are the same size. Easier pin pointing with a concentric too, although DDs aren't so much harder IMO to PP with as they are just different to PP with.

My choice? In my soil I prefer a DD for max punching depth and stability, along with the left/right separation thing. In a trash coil? Again, still a DD, and for the same left/right thing. I can't really say where I'd prefer a concentric these days, other than for say shallow target hunting in a nice sports field where I don't want to dig plugs and only want to pop targets with a screwdriver. By de-tuning my Whites a few times over a target I could stick the screwdriver in the ground and pop it first try almost every time. With a DD I just can't do that. I can get close, but it requires use of my Pro Pointer to find it precisely to pop out.

Are you saying a concentric will give longer target response? I don't think the two co-relate. I can say the Sovereign has the longest, most rich, most detailed response to targets I've ever seen on a detector. I can say though that the ultra sharp DD line of the 12x10 does indeed make target response more "crisp", although still long and detailed. Like plucking a guitar with a guiter pic versus your thumb.

I basically use the stock coil and I will say this:

Many DD coils are rusty steel bottlecap magnets and may be good for relic hunting in the boonies but get in a local park with them and there seems to be ways to tell a high coin from a bottlecap but in my neck of the woods you will wrap it around a tree or frisbee it into a lake..Not all mind you so do some research and Minelabs for the most part does not have this problem...

I agree w the rusty bottle cap issue w DDs, however if your really "working" a site they should be dug because they can easily mask good stuff. It's funny, I've be using my 3D a lot lately and finding stuff I missed w the Etrac. The 8" CZ coil really isn't that bad in trash an moderate iron when you get to understand its language and what's its saying. You do need to go slower than the DD though.

Indeed slow is the way to go with a CZ....

Many years ago after a long exhausting day I came up empty handed silver coin wise and my buddy had several with his Sov.
I was tired and really slowed down...yep you guessed it and got 3 silver coins in the last half hour at 8 inch plus depths..tied my buddy with 3 and he bought supper as I had the oldest silver coin..Ever since slow is the way to go with a CZ.....

Yes. For example:

Say you have a tiny fleck of rust at 3"...... and a dime at 5"...... directly/exactly beneath the fleck of rust.

A concentric coil puts out a very broad/unfocused amount of electromagnetic footprint/energy whereby the tiny fleck of rust hardly receives any energy from the coil........ subsequently...... the dime is detected.

A DD coil will put a strong/full focus narrow electromagnetic footprint (in a very tight corridor) amount of energy into the ground.......... subsequently..... the tiny rust fleck ... will then receive a fairly large amount of (focused) imparted electromagnetic energy .................. and ........... the dime might not be detected.

IF there is a bit of lateral/adjacent separation between the dime... and the fleck of rust............... this is where the DD coil attributes.

From all these awesome answers, I conclude that it would be very intelligent to acquire one of the concentric coils for the AT Pro. Not becaue I am looking for extra depth, as the stockk DD coil does that job, but for the attributes that you guys have stated. So in essence, a new concentric 6.5"x9" or a 9" x 12" coil made by Garrett for the AT pro should unlock doors previously locked.
Like Tom stated about the fleck of rust masking the dime and the Concentric coils broad electromagnetic footprint in able to SEE the dime where as the rust flake would distort the DD coil's fooftprint and hide the dime.
Of the two concentric coils I just mentioned for the AT Pro......which would be the SMART choice. The 6.5 x9???? (that's what I'm hoping you'll say). And for me, ontaining maximum depth is not my goal, or I would just stay with the DD coil in my soil. I just want to add some attributes to an already fine detector. Thanks Kevin

Kevin if depth is not a issue then get the smallest concentric coil you can especially if your working in nasty old sqaure nail territory.

One other thing...
I've seen this on more than one occasion, guys get a new machine then right away start buying all kinds of coils (including concentrics) even before they learn the machine w it's stock coil. Im sure you've already found the ATPro likes rusty bottle caps, maybe a concentric would help, if ones available. Get on the forums and find out first before you spend $$$ on something might not like or even use.

Aaron, you are the voice of reason. And I'm not being facetious or am I trying to be witty. You give awesome advice. I just want ya to know that I appreciate it. Ya know, it can't be easy giving advice to a guy like me, who has had all the well known, many of them, top of the line detectors. And ya know Aaron, I never gave myself a chance to learn any of them. By the way, I'll do as you suggested, because i rely on the wisdom of others since I wasn't born with a brain capable of producing good common sense in the amount needed for good everyday decision making. I've accepted that about myself. It's not a pretty self portrait, but it's flat true.
Check this out: In March of 2011, a friend of mine named George D., kept calling me every night telling me how much fun he was having with his detector. He called it a Garrett ACE250. He told me about some old Indian Heads, mercury dimes, wheats,....etc etc. I would just yawn as he driveled on and on about: "I tried this old homesite today and found an old iron (they would get it hot at the fireside and iron cloths with it)" He finally said: "Since you are home bound much of the time taking care of your Momma, I'll bring my detector by so that you can try it." He is a house painter, and runs a house painting crew. He's a very good one, and a highly sought after one, because they are perfectionists. They get all the BIG lakeside homes. Always has work. Never advertises. Well.....one morning at 6:30 am I hear his pick up coming up the driveway. He gets out with his ACE 250. He quickly teaches me how to use it. I quickly find some coins that was dropped when the siblings and me were children. I AM HOOKED! I run down to Corinth Mississippi to a distributor (Ferrell's Home and Appliance Center) and buy a Garrett ACE 250. George and I start going to the old school house in town. The playground is large. I find THREE MERCURY DIMES in one plug!!!!! I AM REALLY HOOKED!!!! I start joining forums. The first was the Friendly forum. I took a pic of the three dimes and related the story. Lots of awesome replies. I start reading all the forums and finally narrow it down to mainly this one. I also start reading about the different VLF detectors. I check out Youtube, and watch Bill Ladd's vids. I order NasaTom's Inland DVD. It assists me greatly and opens my eyes vastly. I have a few phone consultations with NasaTom. His enthusiaam, by osmosis I guess, rubs off and into me. So here I am. Talking with sensible people like you. Was this long essay necessary. No. I guess not. But then, I warned ya that in the area of common sense I am lacking. But still, I'm happy. And this forum keeps my thinking on the right track. And I surely appreciate it. Happy Hunting. And thank you, and the other repliers, for your replies. Y'all are a swell bunch of folks. I truly mean that. Sorry about the sentimentality in this post. It's how I'm feeling today.



Edited 1 time(s). Last edit at 11/03/2012 06:39PM by Kevin B.

Kevin there's alot of super smart guys on this forum, I'm not one of them, I've just been doing this for more than half my life and have a lot of experience and a burning passion for the hobby(?) and history.
I would like to say one thing though. I think one of the problems that alot of people have in this and other hobbys is that they spend more time buying and looking for new and different machines to buy, thinking that somehow their results and finds are finally going to improve. Some wait and wait for a company to finally release its latest flagship thinking, imagining this will finally be it, this will be the machine that will find the long sought after silver I've been longing for. Then, they take the machine out only to find its just another detector that will take time and patience to learn, and soon find themselves disallusioned and discouraged, next thing you know that $1500 dollar machine is up forsale on Finds. I think that's where the real problem is, is that most don't want to get thru the learning curve. For some reason, I don't know why a lot of guys keep thinking its gonna be different the next time with the next machine and it never is, they require their time in. Some guy was on here last summer, he's not here anymore. He poped on the forum to tell or justify was he buys and sells so much, saying that he can tell one time out within a few minutes if that machine is right for him. Well if that's the case that it appears no machines is because he's still buying and selling.

Somebody here w a CZ just said recently that they smoked someone w a Etrac I believe it, especially if that guy had his time in on the CZ. The guy w the real time on his machine or knows it will always find more than the guy w the better machine who lacks experience.
Thanks for the kind words and stick with that Deus Kevin, you have a lot better places to hunt it seems than most of us here.



Edited 1 time(s). Last edit at 11/03/2012 08:25PM by Aaron.