Air testing metal detectors, Does it work?

[wheres_wheatie]

I air tested my old Bounty hunter Lone Star against the BH Land Star I just got and the Lone had 1in. more depth. Does anyone know if the results of an air test are dependable?

 

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[Old Town]

My observations are these:

Air testing will show a machine's depth potential. So if one machine air tests at 8", and one tests at 11", the 11" machine will always test deeper in the same soil. I've tested this a million times and it was true every time.

Your machine will not detect coin-size objects in the ground beyond its air-test depth. You might get improved depth due to halo effect on iron but in such cases you are actually detecting minute metal particles inside the original air-test depth. Not extra depth.

All machines lose depth in the ground compared to air tests. How much depth lost is dependent on soil makeup and density.

Last of all - nobody will agree with all above statements. This is a highly debated issue in metal detecting.

OT

 

[m bryan]

I seem to get a little more depth if the ground is wet at times.......

 

[Sandman]

Air tests are not reliable for depth. It is only good for comparing sounds of various targets and numbers of VDI's. Minelabs and some PI's are extremely deep but air test badly.

 

[Tnmountains]

My observations are these:

Air testing will show a machine's depth potential. So if one machine air tests at 8", and one tests at 11", the 11" machine will always test deeper in the same soil. I've tested this a million times and it was true every time.

Your machine will not detect coin-size objects in the ground beyond its air-test depth. You might get improved depth due to halo effect on iron but in such cases you are actually detecting minute metal particles inside the original air-test depth. Not extra depth.

All machines lose depth in the ground compared to air tests. How much depth lost is dependent on soil makeup and density.

Last of all - nobody will agree with all above statements. This is a highly debated issue in metal detecting.

OT

 

[jeff of pa]

All machines lose depth in the ground compared to air tests. How much depth lost is dependent on soil makeup and density.

I Disagree (I'm convinced I Get at least Twice the depth in ground
But only on Long buried Items)

Last of all - nobody will agree with all above statements. This is a highly debated issue in metal detecting.

OT

I Agree

 

[SteveP (NH)]

I think air testing has very little usefulness other than to confirm target ID numbers. The reason I say that is that one of the hard tasks a metal detector has to do is to separate the signal from the target from the stronger signal from the ground. The air doesn't have any response so you are not really testing how well your machine can pick up a weak target signal from a comparatively much stronger ground signal.

So air testing a detector to see how deep it will go, is kind of like jacking up the drive wheels of a car and then stepping on the gas to see how fast the car will go by looking at the speedometer. Sure the speedometer goes up to 120 with the wheels off the ground but will it go that fast on the road.

 

[TerryC]

Air testing is a valuable tool when taken IN CONTEXT. That is to say, test one machine against another, one id against another. Air testing is a good way to start with a new machine. Air test against ground test is a good way to bring your anticipations "down to earth". Pun intended. Just another tool to round out your experience with your machine. TTC

 

[Digger]

I agree with Old Town.

My experience has been that an air test gives you a detectors potential. Under rare conditions you might see slightly better depth in the ground, and I do mean rare, but for the most part don't expect to get any better depth than you get in the air test.

I've used a lot of detector and they ALL have proved this concept to be accurate.

 

[bigscoop]

Air tests are not reliable for depth. It is only good for comparing sounds of various targets and numbers of VDI's. Minelabs and some PI's are extremely deep but air test badly.

What he said.

 

[Old Town]

I think air testing has very little usefulness other than to confirm target ID numbers. The reason I say that is that one of the hard tasks a metal detector has to do is to separate the signal from the target from the stronger signal from the ground. The air doesn't have any response so you are not really testing how well your machine can pick up a weak target signal from a comparatively much stronger ground signal.

So air testing a detector to see how deep it will go, is kind of like jacking up the drive wheels of a car and then stepping on the gas to see how fast the car will go by looking at the speedometer. Sure the speedometer goes up to 120 with the wheels off the ground but will it go that fast on the road.

I like this analogy.

 

[George (MN)]

Air test are a good *beginning* for testing a detector. I don't feel air tests should be skipped, but I also believe nobody should give up on a detector based on an air test. Some mfrs have a guaranteed air test result in the manual. If you don't get those results, you know right away it's probably defective.

I had a White's Coinmaster (the current $179.95 model) that got a strong beep & accurate ID on quarter at 10.5" in air test. In ground it could not detect a 5" deep dime. Have a Whites Prizm 6T that can't detect a quarter beyond 8" in air test but does detect the 5" deep dime.

I do air test first, then planted coin test next, then actual detecting & will read manual first if detector seems complex. If others choose to do it differently, that of course is their right.

As for the claim that Minelabs do bad in air test, my Safari gets a strong beep on a dime out to 11" in air test, discriminate mode, sensitivity 18. I don't think that is poor, & haven't heard of anyone claiming beyond 12" in ground on any coin, stock coil.

I could probably write 10 to 12 paragraphs about what I learned in dozens of hours air testing my Fisher F70 (what else could I do in the winter?). Many people just sell this detector right away as they don't understand the interaction of the threshold & sensitivity controls. Best wishes, George (MN)

 

[Digger]

I'm curious, for those who believe a detector can go deeper in the ground than in the air, what science would that be based on? How can that be scientifically explained? I understand the "hallo effect" theory but then that only applies to certain targets that have been buried for a long time. For this to be possible you would need to be in perfect soil conditions(completely mineral neutral) AND have a target that has been buried a very long time. A possible scenario for sure, but not likely and surely you're not basing the claim on such a rare condition.

 

[jeff of pa]

the science of air testing my sovereign,
And Field use of my sovereign.

I'm not talking Freshly buried targets
Versus Air testing.
You break the ground the sovereign
dosn't do the same job
as when the ground is Naturally packed over years.

These numbers arn't double checked
but used as example. guessed from 1999 memory
on the first 2 . I don't air test or fresh bury anymore

air test quarter 6"
fresh buried Quarter 5"

Long lost Quarter 9"

ever dig a taget & Loose it ?
you broke the ground & added air.
repack the ground
walk away and come back later.

(I Am talking Minelab Sovereign BBS expierence.
Not saying all detectors are the same. perhaps
some are made to detect coins floating in air,
or on top of the ground from 8 inches away
I'v seen newbies detecting with the coil in the air )

 

[Iron Patch]

Air testing is a great tool and don't anyone even think about saying it's not!



It tells me my detector is on! Very important to know.

 

[jeff of pa]

Air testing is a great tool and don't anyone even think about saying it's not!



It tells me my detector is on! Very important to know.

it also tells me if my Sunray switch is on
Probe or Coil

 

[Silver Searcher]

My observations are these:

Air testing will show a machine's depth potential. So if one machine air tests at 8", and one tests at 11", the 11" machine will always test deeper in the same soil. I've tested this a million times and it was true every time.

Your machine will not detect coin-size objects in the ground beyond its air-test depth. You might get improved depth due to halo effect on iron but in such cases you are actually detecting minute metal particles inside the original air-test depth. Not extra depth.

All machines lose depth in the ground compared to air tests. How much depth lost is dependent on soil makeup and density.

Last of all - nobody will agree with all above statements. This is a highly debated issue in metal detecting.

OT

Totally agree with you there, nothing beats getting out in the field. Air tests are a waste of good detecting time, how can a air test be the same as field testing. And like someone else said damp conditions give deeper signals than dry conditions.
I think air testing is a depth issue with people...bit like mines bigger than yours

SS

 

[Iron Patch]

Air testing is a great tool and don't anyone even think about saying it's not!



It tells me my detector is on! Very important to know.

it also tells me if my Sunray switch is on
Probe or Coil

I used to but don't have to anymore. I haven't changed my settings in about 6 years and if I leave my probe on I know it just with a few swings of the coil. It's a subtle difference, probably noticeable because I run my detector a little hot so there is a bit of noise to judge it by. The probe left on is just different.

 

[jeff of pa]

I'v walked the length of a football field
already wondering why the ground was empty of
targets. Then realized I Had the switch on probe

 

[Digger]

Ah yes, and Bigfoot exists because others have told me so.

As I said I understand the hallo effect concept because it can be scientifically explained to a point. The concept that a detector would get better depth in the ground, having to deal with mineralization, trash, etc, just seems to be lacking in a scientific explanation. In this case it would make it more theory than fact. Again, I understand the hallo effect concept that applies to coins that have been in the ground a long time, but this phenomenon is limited to certain conditions, and since it is limited to ONLY certain conditions, it sure doesn't seem honest to make a blanket claim that detectors go deeper in the ground than the air, so air tests are worthless for depth testing.

Generally I find these claims made by people who get crappy air tests on their favorite detector.

But hey, I know Bigfoot is out there somewhere just waiting to be found.