Upon first seeing the world in 3D..... (lengthy post)

Upon first seeing the world in 3D I'll admit, I was completely taken aback.
I began swinging several years ago and owned several good machines before being forced into a period of abstinence by health related issues and selling all of my machines.

Several months ago I had a few (four) pesky discs removed from my neck and replaced with titanium plates. After a little R&R I decided it was time to start all over again and picked up an LTD. As a side note, the first thing I did after installing the batteries in the LTD was sweep my neck. The aforementioned plates ID around 21 which really freaks out the kids and some adults for that matter.

I posted here not long ago asking for opinions on a primary detector for my son/ secondary for myself. Thanks to everyone who offered an opinion.
I ended up buying a 1021 CZ-3D. It arrived a few days ago and I have been putting it through its paces both air testing and in the test garden. I paid more than I had planned but it will correctly ID a clad dime at exactly 11" with the SENS ~5, and is a pleasure to swing.

I have three poker chips that supposedly have very small amounts of gold epoxied into the center of them, 1 grain, 2 grains and 3 grains respectively but the epoxy "spheres" are extremely small. I have no idea if it is really gold or not and if it is, what size the pieces really are. I bought them on ebay some time ago where they were advertised as tools to test a detectors sensitivity to small gold.

Most of the machines I previously owned struggled to "see" them. Maybe it was my inability to properly configure the controls, maybe it was the machines themselves. With the LTD set up on the verge of instability (DISC 0, CL Mode, GB 1, SENS 55) and the 11"DD coil it will pick them all up at about 2" but the ID is not stable. Any higher on the SENS and it gets so chatty the chips are hard to discern.

The thing that amazes me the most is this; I just tried them on the 3D for the first time and was impressed to say the least. The 3D is stable with everything wide open and the 8" coil AND it IDs them all with a repeatable mid tone at comparable depth to the LTD, dare I say maybe a little more. This may be commonplace for the 3D but it sure put a smile on my face.
This was done without the aid of my normal air testing rig so I cannot say with any degree of certainty exactly how far from the coil they hit but I did try them again on the LTD to confirm my "calibrated" eye.

Over the past few years I had gotten caught up in the whirlwind of super fast, LCD screened "bells and whistles" machines on the market. Without this forum I would likely not have considered the 3D and would have never known what I was missing. I haven't had it out "in the real world" yet but I have no doubt that when I do, my opinion will not be swayed in the least. It looks like it will be a great detector both for me and my son.

Kudos to you Tom for designing a great machine and thanks again for all the advice and tutelage.

I love the scanning of the cervical plates......truly...........you are a diehard detectorist. And I wish you the best that the surgical procedure will allow you many years of swinging.

Chris,

What a thoughtful and eye-opening write-up. Appreciate the candid sharing.

Now............try the F75 again............just the way you had it set up before.........except one thing. Set the Grnd Balance on '90'.......and test those gold nuggets again.

Okay Tom,
I did as you suggested and tested the LTD again with the Ground Balance on 90. You know the result....
As I was passing the nuggets in front of the coil and trying to figure out exactly why this was happening I started thinking about the different conditions that would cause you to run the Ground Balance down to 1 or up to 90.

That's when the light switched on and I remembered reading about micro jewelry being invisible on wet sand because it is basically Ground Balanced out.

It's things like this that make want to bang my head against the wall. I had read all of the posts about gold on the beach and filed them away for recall when I get the chance to hunt the surf again, I didn't however stop to think how they related to anything other than wet sand. This is not the first time that having tunnel vision has "jumped up and bit me" so to speak and I can guarantee you that it won't be the last.

I also appreciate the way you pass this information along. Something discovered will be remembered long after something told is forgotten.

Forgive me if this has already been explained but if I have read it, it has slipped my mind. One thing that I don't quite understand is why the chatter/EMI increased as I increased the Ground Balance. Can this be explained in simple terms?

MUCH more sensitive to tiny signals......including EMI.

Funny you mention the Ground Balance issue .....I too have been G. B. lax becuse of having it done for me as I own a few ML machines that do this for me ....... Now owning an AT Pro I am more in tune ( a little play on words ) to being more aware of my Ground Balance numbers and the significance they play when looking for various targets ....Part of me says , " Wow this is great that my machine automatically Ground Balances " while another side of me is saying " I sure wish I could change this ground balance !! ".... It would be a pretty nice feature to have BOTH automatic G.B. and Adjustable !!....( I know I know ....I'm getting a little crazy here ) ......

So with this in mind .....The day on the beach in the wet salt , would it be possible that the ML machines were not reading the small gold ring because they were automatically ground balancing to the point where the ring was a moot target with enough distance between the coil and the ring in the damp salt sand ? ......Jim

Jim..............the interesting thing with the Minelab Exp/E-T's is..........they do not have auto ground-track.....or auto ground-balance. The multi-sampling complex squarewave analyzation "realizes" what the ground signal/return looks like.......and is looking for 'sharp deltas' (better known as: 'metal targets').......within/above the 'mix' of the dirt matrix. This is an advantage of a derivative-PI (w/VLF) driven unit. Units that employ a 'auto ground-track' actually adjust a phase-shift angle to compensate for the bad ground. The Minelab units do not have to change any 'phase-shift angle'.

BUT.............BUT, BUT........the Minelabs are still gold-dead to tiny and micro gold jewelry in the wet salt sand. This still remains a COMPLETELY untouched world to detectorists. . . . . and no one can fathom (or even begin to) 'realize' HOW much tiny and micro jewelry is in the wet salt. You don't know....what you don't know. You cannot 'miss' what you don't know. Tiny and micro jewelry is the type/class of jewelry that adorns the bulk of the 'stones' in this world. I own the worlds most powerful wet salt detector.......and...........at that..........it can only detect the category: 'tiny' gold jewelry....to.....at best......maybe....2". This is to say..... I can NOT detect micro-jewelry in the wet salt. I can confidently and comfortably say that......if I had a detector that could detect micro-jewelry..........even to depths of only 4"....... I could easily retire...and live off of wet salt finds. JUSTIFICATION: Nearly every time I hunt the beach (wet salt slope)......I come home with over a dozen micro-jewelry finds...............except................there's one problem. The items are gold PLATED silver (better known as) 'costume' junk/jewelry.....as......this 'highly conductive' type of jewelry is easily detectable to many detectors. Imagine all of the true/real GOLD micro-jewelry that continues to accrue.....and accrue...........and is NEVER depleted/detected/recovered.

I'd like to see a Mfr 'realize' this ""opportunity"" and capitalise/invent!

Now this is intense stuff here that I don't even BEGIN to understand , but I will be looking to understand it in the future .....This analyzaton sounds like a Psuedo Automatic Ground balance, which continues to analyze soil / metal conditions with a continuous read .... .. The Sovereign GT has a ground balancing feature and DOES in fact have a ground tracking section on the detector whereby you track for a while and when the detector adjusts to the area that iti is tracking , you switch into a more pemanent " Fix " position ...... This does have to be tested from time to time as soil conditions dictate ......

I don't understand what you are saying about the Minelabs being Gold Dead in wet salt sand on smaller gold .......I have personally found post earings with diamonds in them in wet salt sand with both my E Trac and my Soveregn GT ....My pardner has also found small Gold with his E Trac ..... The AT Pro just does not want to run quiet enough in wet salt sand and the Low Ground balance doesn't help matters for Gold much either ..... I have no doubt that the AT Pro will hit gold , but it will be very shallow as you will need to turn your Sensitivity so low to come up with anything without your ears ringing for a few days ...... I'm still baffled by the womans ring that we buried over the WInter ......That STILL has me stumped !!....Jim

I have tested a few standardized 'test-standard' gold targets in the wet salt with the Minelab........and it (expectedly) failed to detect these targets.....on a Florida wet-salt beach.

Tom, would it be possible to get your wet salt beach/micro jewelry thread as a sticky up front?

Wally......Can you do this?