Detector Air Tests and Paper Tests

[mts]

I'm wondering if there is any value in trying to come up with a simple controlled test that we could use to evaluate the different depth capabiliites of each detector. Given the variances in soils around the word, it seems obvious that doing soil tests is out of the question. That pretty much leaves air tests (and paper tests, which I'll get to shortly) as the most viable options. Unfortunately, air tests are not a very good indicator of how well a particular detector is going to work in a specific ground condition. But I think it is about the only way to really get common readings between detectors.

I've devised another type of test that I'll call the Paper Test. Basically, you take a coin and place it under a tight stack of paper (computer fan-fold paper, phone books, etc). Then you attempt to detect through it. The nice thing about this test is that it is really easy to measure and most people should be able to come up with a thick paper source that is reasonably similar. I have no idea how well paper mimics soil, but I can't imagine that it is much worse than air. If we get enough people to post results we should be able to remove any variances and get some good average numbers.

So what do you think? Should we try to get something established? If so, what should the targets be (US quarter, dime, penny)? Where should we post the results? Is this worthwhile? Would you participate? Is there a better test besides air or paper that would be consistent around the world?

Thoughts?

 

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[deepskyal]

Interesting proposition....

Just would have to watch whats under your paper....make sure all use the same kind of paper....like acid free...lol

I think measurement wise...it would be more accurate than an air test....but I'm sure there are other variables we'd miss. Different detector settings come to mind right off the bat....coil size....strength of battery power.....

I'd be interested to see how something like that would pan out....as long as bragging rights don't get in the way of it.

Al

 

[gary in idaho]

I would have to guess this may be no better than an airtest. Ground mineralization plays an important part in detection depth. How long a target has been in the ground, composition of the target, wet ground/dry ground, too many variables in the real world. I've had machines that airtested great but weren't worth squat in mineralized ground.

Gary

 

[Charlie P. (NY)]

As soon as you find a way to ground-balance in air. ;-)

Since you should be outdoors anyway, to eliminate EMI as much as possible from home & building effects (motors, wiring, electronic circuits, etc.) you might as well do it on the ground.

Some detectors don't "like" to have their coils elevated up where there are excessive signals. Most transmissions are "line of sight" and the higher you go the more you are subjected to. You can up the sensitivity if you keep the coil near the soil, so an air-test would be unfair to these types.

Besides, who hunts flying coins?

 

[mts]

Different detector settings come to mind right off the bat....coil size....strength of battery power.....

Yes, we'd have to set some guidelines. All metal mode (no discrimination), stock/standard coil, sensitivity/gain set to maximum available that doesn't cause chatter, measurements to the nearest quarter inch, and on and on. The idea of the tests would be for people to have some way to guage depth. If one person posts that a Minelab does an air test of a quarter at 12" and the best Garrett Ace 250 test gives a quarter at 6" then that tells us something. What it tells us I don't really know because as Gary said, a machine can give you a great air test but be terrible at finding things in your local soil type. Still, I would assume that an air test is the "best possible" value you can get. If a quarter air tests at 3" on your machine, there's probably no way that you are going to get better than that out of the ground. And if you can't expect to find a quarter at 3" in the ground then you'd probably want to consider another detector. Of course, it is possible to find things in the ground at depths deeper than the air test results due to the halo effect. But it probably isn't going to be much deeper (especially for gold and silver coins).

It's just a thought. I think I'll go ahead and post the results of my Bounty Hunter machines in the Metal Detector Reviews section. I'll give the details of my tests and people can decide whether or not they want to follow suit. And "bragging rights" is definitely something that we need to keep out of the equation.

 

[Nick A]

I dunno about you, but I feel confident that all good quality/high end detectors will air test well. I think where the rubber meets the road is not depth, but ID accuracy. Getting a deep signal means nothing if the signal doesn't sound like it's worth digging. Most of us are not digging everything under the coil, but trying to be selective and dig the "good" targets.

I'd rather have a detector that only had 6" depth but would nail the ID on old coins and trash in almost any hunting condition. I'd be bringing home handfuls of silver and other obsolete coins every hunt. Even better would be a detector that had less accurate ID but surface blanking - ignore the top 3-4" and only signal on targets over 4" deep.

All the evidence I need as to what detector is the best is right here in these forums. Look at the various finds posted on the different forums. Look what machines are making the best finds, the oldest finds, the deepest finds. Consistently, you'll see the same few machines. Look at the machines the tot-lot hunters prefer, look at what machines people who consider themselves "pros" prefer.

A non-biased scientific "Consumer Reports" style air test comparison of detectors would be of little use to me, whereas seeing someone pull a seated dime and a shield nickel out of a park - right in front of me - in an area I had hunted hard and repeatedly speaks volumes.

 

[deepskyal]

I think you nailed it well at1cad.

The difference of an inch or two...or even 3 really doesn't mean much.

The Vision comes with a stock 10" coil, my 6000 pro an 8". Right off the bat I would expect the Vision to air test at a greater distance. Also, the Vision is a "hot" machine...again, I'd expect deeper results. Both these machines more advanced than my original white's 3000.

But the biggest, most pleasurable difference is the target ID. The less junk I dig versus coins is what counts. Knowing a solid coin hit from a bottle cap infested area is priceless. I dug 3 quarters out of one hole with the vision, about 6-7 inches deep. A hard hit, like I'd expect from a chunk of iron maybe. Would I have dug that with my 6000 in a finely manicured lawn with the probability of it being iron? Guess I will never know because with the Vision, it nailed it as a silver object....so I dug it. Like I said...great target ID.

The park I found this find has been obviously hit before....how'd everyone else pass over such a powerful hit? Older machines, not as good ID...probably thought it was iron I'm guessing.

After years of using my 6000, I really wouldn't care if a minelab could go an inch or 2 deeper because I know my machine inside and out and know how to push it for a little extra depth. I trust it! But 3 quarters in a hole at 6-7....now I have to wonder. I almost didn't dig 2 quarters side by side before because of the double blip of a pulltab. I was showing someone how it worked and told them it was a pulltab...I was pleasantly suprised. How much did I miss because of false signals and so-so ID?

I got the Vision now, awesome target ID, probably great depth....a learning curve....and I'm learning to trust it....

It seems to be as good as my 6000 but has a much better ID that I really like and my finds are good. Guess the true test is to get it over a lost coin 9 or 10" deep...but I got to get over one first...in my conditions.

Al

 

[steve from ohio]

The Minelab machines are notoriously poor when it comes to air testing. The broadband spectrum and full band spectrum systems that are part of the technology used by a lot of the Minelab machines. They air test worse than most of the others out there. In my experience, they are deeper in the field where it counts than most others in most instances. But then again, some will disagree with that and say the Vision is better. Or the 2500. Or the F-75. Or others that are out there.

Coming up with a test for what is the best machine is really not possible. With each type of area being hunted, there is not a machine made that can cover it all. You just have to try each machine and if it does not work for you, then sell it. Get another until you find the right machine for your style and hunting areas.