Double D Coil vs Concentric

[CoilFisher]

Anyone really notice a great difference in these vs the old concentric. Is it all just hype?

 

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[Frankn]

Jason, The concentric delivers all its transmit power through one coil set while the DD delivers 1/2 its power through each of two coil sets. That's why the concentric goes deeper. My concentric picks up at the extreme edges of the coil which means that picture is wrong because it only shows signal at the center hole. The picture is BS. Try any detector with a concentric and prove this to yourself, if that is possible. My detector will pick up a large object at 2' which tells me that little cone is BS. My comments are based on actual usage over many years not just wild mutterings pulled from the air. Frank

 

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[deepskyal]

I like the 5" DD running on my Vision in trashy parks. Very good seperation and pinpointing. I don't like the stock 10" DD that came with it. I use my 6000Di pro with the stock 8" concentric in a lot of places still.

The 5" DD on the Vision was the first detector/coil combo that got me right under powerlines without any EMI at all. Was like virgin territory

I know I'm not the only guy out there that switches coils or detectors, depending on the site and conditions. You use what works best where. Just like choosing bait to go fishing.

Al

 

[Smudge]

Maybe its a question of where you are at, but in this mild Florida soil I hunt in, DD coils have been a double pain in the butt for me. Overly sensitive and unstable. I don't like them down here.

I'll bet they help a whole bunch in more difficult soils though.

 

[Jason in Enid]

Jason, The concentric delivers all its transmit power through one coil set while the DD delivers 1/2 its power through each of two coil sets. That's why the concentric goes deeper. My concentric picks up at the extreme edges of the coil which means that picture is wrong because it only shows signal at the center hole. The picture is BS. Try any detector with a concentric and prove this to yourself, if that is possible. My detector will pick up a large object at 2' which tells me that little cone is BS. My comments are based on actual usage over many years not just wild mutterings pulled from the air. Frank

Oh, gee, I guess the last 25+ years of doing this means I don't know shit.

We aren't talking about detecting hubcaps, but even that will detect it's very deepest at the center. You claim the picture are wrong, but you are thinking about it backwards. Yes, the TRANSMIT coil is on the outside, but the recieving coil is the TINY one on the inside. What every coil does is transmit energy into the ground. That energy causes the metal objects to begin radiating that energy back. The recieving coil is what looks for the change in frequency away from what it sees from the transmit coil. Because the coin is a small target, it radiates a lot of energy very close to the surface. This means you can "see" the coin all over the coil. As that coin moves farther and farther away, it reads stronger the closer to center it is. Closer to center also means more of the transmitted energy is hitting the target. Closer to the center means more of it's radiated energy is being seen by the whole reciever, not just part of it. Therefore, the farther away the target is the closer to center is has to be to be detected; hence the "cone" of detection.

Oh, and BTW... That hubcap you are detecting at 2 feet is radiating hundreds of times more signal strength than a coin, which is why you can detect it so much farther away.

Maybe you should try reading a book once in a while.

 

[CoilFisher]

I had good results first time out, but I am very analytical.
I am going to re-hit some of the places I found silver on this Summer when I get a chance and see what pokes up.
If I find more in the same places I meticulously swept, I think that shall be all the proof in this pudding on my end.

 

[Frankn]

Jason, if the "little point" you vision on the coil pattern goes down 2', it must be very wide at normal coin dept. The detector doesn't measure frequency shift, it measures returned signal strength. That target ID number is the amount of transmitted signal that is returned. The detector is programed to "guess" as to what the target is by the amount of signal returned. That's why the detector always indicates a large deep target is shallower than it actually is. I don't think you have the vaguest idea as to what goes on in a detector! I have been detecting for 40+ years and have worked in electronics for 32+ years. Frank

 

[earthmansurfer]

DD's can definitely be a pain in the but, especially with pinpointing, around EMI and if you try to overpower the ground (sometimes) as they can get chatty. I remember when I first went from a concentric on my Nautilus IIB to a DD on a T2 I thought it was terrible. But two weeks later I was pulling things out of iron with no problem and it was much much easier than with a concentric (when the iron was worse). I think it takes time to adjust for any hunter.

The smaller field of detection (at depth) of a concentric is very easy to test. Just find a coin at 7" or 8" and see the window of the hit. It is quite small compared to a DD coil. I'm not saying it's better, they are suited for different conditions. But, the DD can definitely cover more ground as you don't need to overlap the swings as much. As another poster said, the concentric will go deeper but the field is quite small at that depth and you would really need to be right over the coin. So, effective depth would probably be the DD coil unless you are really good with the concentric and overlap your swings and know how to use it well.

I think a proficient/experienced detectorist will be able to use any coil they want and out-hunt an average person with the better detector and coil, no argument from me. But, for an average Joe (no offense Joe ) the DD coils might help finding the deeper coins a bit easier due to their wide field of detection and ability to see through trash and iron better (when dense). But you won't be pinpointing dead on at first.

Would love to hear from those of you who have used coils like SEF's as to how they compared in heavier iron, low or higher mineralization, etc.

EMS

 

[Jason in Enid]

Jason, if the "little point" you vision on the coil pattern goes down 2', it must be very wide at normal coin dept. The detector doesn't measure frequency shift, it measures returned signal strength. That target ID number is the amount of transmitted signal that is returned. The detector is programed to "guess" as to what the target is by the amount of signal returned. That's why the detector always indicates a large deep target is shallower than it actually is. I don't think you have the vaguest idea as to what goes on in a detector! I have been detecting for 40+ years and have worked in electronics for 32+ years. Frank

You have to be full of BS! You don't have a dang clue how detectors operate. Just give up and go play in the tot lots.

 

[Treasure_Hunter]

I have been using large DD coils on my Minelabs Excals, and my Sovereign GTs for over 4 years. I have no problem pinpointing with them what so ever. I use them in parks as well as at the beach. I can pinpoint a coin with it with no problem at all....

Frankn, your saying everything ever written about concentric coils narrowing to a point as they go down is a lie.....


I have hunted with both concentric and dd coils, used WOTS, SEF Butterfly (12x15" and 15x18"), Dietech and Sunray S-12 DD coils....I will take a DD coil everytime for the depth and coverage it gives.........

 

[bigscoop]

Anyone really notice a great difference in these vs the old concentric. Is it all just hype?

"By their design", and using the example that both machine setups had the same exact ability to hunt the same depth, it's really a question of technique. The DD allows you to use a broader overlap in your coil swing, thus letting you cover more of its deepest range evenly with fewer swings. The concentric requires more coil overlap and thus more swings to cover that same deeper surface area. Everything else depends on other factors unrelated to the coil design, primarily machine capabilities, conditions, etc. Either of these coils are only as good as the machine it is attached to and the person using it.

 

[M Scott @ FTP]

Jason, The concentric delivers all its transmit power through one coil set while the DD delivers 1/2 its power through each of two coil sets. That's why the concentric goes deeper. My concentric picks up at the extreme edges of the coil which means that picture is wrong because it only shows signal at the center hole. The picture is BS. Try any detector with a concentric and prove this to yourself, if that is possible. My detector will pick up a large object at 2' which tells me that little cone is BS. My comments are based on actual usage over many years not just wild mutterings pulled from the air. Frank

Frank is right-the picture is complete BS created by detector companies marketing departments. Far too many people believe the imaginary detector field because they saw it in a manufacturers catalog.....

Here are some facts from detector designer David J whom has also stated the drawings are BS;

http://www.fisherlab.com/hobby/davejohnson/searchcoils essay revised.htm

DD better depth in bad soil and concentrics are cheaper to manufacture-lots more infor if you read all his essays on the web site.

Mike

 

[Jason in Enid]

Jason, The concentric delivers all its transmit power through one coil set while the DD delivers 1/2 its power through each of two coil sets. That's why the concentric goes deeper. My concentric picks up at the extreme edges of the coil which means that picture is wrong because it only shows signal at the center hole. The picture is BS. Try any detector with a concentric and prove this to yourself, if that is possible. My detector will pick up a large object at 2' which tells me that little cone is BS. My comments are based on actual usage over many years not just wild mutterings pulled from the air. Frank

Frank is right-the picture is complete BS created by detector companies marketing departments. Far too many people believe the imaginary detector field because they saw it in a manufacturers catalog.....

Here are some facts from detector designer David J whom has also stated the drawings are BS;

http://www.fisherlab.com/hobby/davejohnson/searchcoils essay revised.htm

DD better depth in bad soil and concentrics are cheaper to manufacture-lots more infor if you read all his essays on the web site.

Mike

That article doesn't say anything about "pictures" being BS or anything close to it.

Geez people, are some of you REALLY that dense?!

The transmit coil puts off signal.
the metal object radiates back its own signal from the transmitted energy
the recieving coil picks up the energy
the detector compares the differences and tell you what it thinks is down there.

Now, WAKE UP! A metal object above, below, or beside a coil will still recieve and re-radiate a signal
the picture that some you are complaining about isn't a fully discriptive picture, it's a representation of DETECTION AREA for small targets, under the coil, where you will typically be seeing them.
Oh, and Frankn... if the detector wasn't seeing differences in radiated frequency, it would never detect anything. No returned signal will ever be stronger than the field from the transmit coil, therefore if it is only seeing ONE frequency, it is blind.

I'm done trying to explain such a simple concept to such dense people.

 

[RW]

The top selling brands best machines all come with a DD coil.
V3i - Etrac - F75 - AT Pro - Tesoro's best coil is the CleanSweep.
The manufacturers are all pushing DD coils for a reason.
They just work better for more people in more situations.
Most people don't start out with the top of the line detector.
They become accustomed and prejudiced towards concentric coils.
Since I made the switch to DD coils I rarely, maybe never again, find an actual NEED to pop on a concentric.

 

[Treasure_Hunter]

Frank is right-the picture is complete BS created by detector companies marketing departments. Far too many people believe the imaginary detector field because they saw it in a manufacturers catalog.....

Here are some facts from detector designer David J whom has also stated the drawings are BS;

http://www.fisherlab.com/hobby/davejohnson/searchcoils essay revised.htm

DD better depth in bad soil and concentrics are cheaper to manufacture-lots more infor if you read all his essays on the web site.

Mike

Mike you better go back and read your reference, no where in it AT ALL does he say they are BS, in fact he praises them...

"The advantages of the DD are greater depth in mineralized soil, a broad sweep pattern, and narrower target response. Its primary disadvantages from a user's point of view are multiple responses on shallow targets and poor discrimination of flat iron objects. Designing and manufacturing them is more difficult because their lack of radial symmetry makes them prone to drift which the design and the manufacturing process must minimize. Manufacturing cost is higher because the coils cannot be wound on high-speed winding equipment."

I have been using large DD coils for over 4 years, they simply rock..... I have found .06 of a gram gold rings with them, the depth is fantasitc, the foot print makes cover areas so much easier, I am have absolutely no problem pinpointing with them, or recovering multiple targets under the 15 inch footprint most of mine have......

 

[Frankn]

Hay I can go with that write up from the engineer at First Texas/Fisher.
Jason <the bounce reflected signal from the target is always weaker, I never said it was stronger. That was you putting words in other peoples mouths as usual.
RW, nice writeup, but Whites new top dog the VX3 has a concentric because of pinpointing problems with the DD on the V3i.
Scott, nice catch on that coil writeup.
I am out of here on this one, it's been fun. Frank

 

[Keppy]

Let's see you guys like that minelab wiggle so here it is..........

 

[gleaner1]

Anyone really notice a great difference in these vs the old concentric. Is it all just hype?

CoilFisher there is no hype. We all have a concentric we prefer, and a good big dd as backup. This assuming we all are tectin' for the same crap, deep old crap. To the Devil with trashy sites!!!

 

[Treasure_Hunter]

You guys keep using those concentric coils, those of us with the experience on the DD coils know just how deep and great the DD's are, keep on leaving those targets for us to find........Love the foot print on my DDs...

 

[gleaner1]

For most people the dd has endless advantages. I find them a bit heavy. That really is the only thing that kills me about them, along with the loss of depth, size for size. I think the dd's need to lighten up.

 

[OBN]

My question is, Has anyone scientifically prov-en information showing the "fields" that come off of any coil, I've seen Eric Foster, Prospector Al and several others discuse but no one can measure this type of data from what I have read......... Plus would not the Matrix of the soil/sand affect this from one location to the next?

WOT in Action, deep target? 18/19 inch's possibly, no problem with pinpointing...............