Home air test on your detectors

Here's a thought. Everyone has a detector, or two, or three. Would you folks agree to do an air test on say a quarter, dime, and nickel and post your results here.

If enough people participate (including all you lurking about) the results would be interesting and marginally scientifically illuminating.

Test all metal (or whatever is zero disc) and consider all settings that will maximize the detectability within normal (usual) operating parameters (fairly quiet and stable running.) Your judgment will determine a diggable signal - if too faint such that you wouldn't normally distinquish it, then you'd be beyond the proper depth.

There must be hundreds (if not thousands) of folks on this forum with many different (or the same, doesn't matter, the more the better) detectors. Will you take a moment and air test a clad quarter, dime, and nickel?

Post your results on this thread (max distance in inches) and coil size (i.e., factory 11" DD) and detector used.

Fisher CZ3D - Los Banos model - 1021 serial number - Stock 8 inch coil.

Nickel 12.5
Dime 12.25
Quarter 13.5



Edited 1 time(s). Last edit at 06/04/2015 12:03PM by wjs.

See Keith's post on correct coil position.



Edited 1 time(s). Last edit at 06/04/2015 02:21PM by doc holiday.

Don't think air tests mean much it is the dirt that counts

LowBoy

TAKE A LITTLE TIME KICKBACK AND WATCH SOME OF MY DETECTING VIDEO'S BELOW ON YouTube

[www.youtube.com]

If you don’t dig it, then how are you going to know what you’re missing!
How can you have your pudding if you don’t eat your meat!

About the only benefit of a group of air tests is to find out if my unit seems to be operating within acceptable tolerances as compared to others with the same unit.

I have a few concerns.....

1. We all have varying amounts of EMI we have to deal with that affect air tests. Results will mostly likely vary by fairly significant amounts for the same models. I know my results will vary day by day and in some cases hour by hour.

2. Many folks will not know how to use or interpret this information and it turns into a pissing contest, or worse, used to market a particular model or brand over another based upon an air test. We have all seen this happen.

3. We also know air tests have no relation to depth in the ground for the majority of users.

3. Air tests do not highlight a particular detector's strengths or strong points.

4. Lastly, the results will not stay on this forum.

HH
Mike

I see where your coming from but would like the same done in the ground where it really counts..Certainly air tests have their place and will give you a ballpark test and should be pretty much the same for a particular units as imagine air is the same in Idaho or Texas (well you get the idea)..

Varying EMI will affect the outcome, as will differing standards of what is a diggable signal. Should enough people particapate the outliers will be averaged away.

I think most here are mature enough not to become unhinged at air test results of their favorite detector. Again, they can do their own test ... which is what I want everyone here to do, and report their results.

An all-metal air test has the least variables to deal with ... in-ground are much more time consuming and difficult with all kinds of opportunity for errors.

I would compile the results of all the tests. But you detectorists have to set aside 15 minutes to run the test yourself. I'd like to see several hundred test results in the next few weeks. Hope it happens.

There is an army of detectorists out there ... let's work for a simple goal: perform an air test on a quarter, dime, and nickel

I agree with Mike, the best reason for air testing is to make sure your specific unit is operating to design intent compared to other units of the same make and model. Also to have a benchmark for future comparisons with the same unit.

CTX - Stock 11" coil

Sens Auto + 3
Nickel 8.5
Dime 8.0
Quarter 8.5

Man + 25
Nickel 10.5
Dime 10
Quarter 12

In 9 years of detecting I have yet to find a single coin floating in the air yet....

Might I ask, please: If anyone posts results for an F75 / T2, can they do it in a regular mode (eg. Default), not just a 'boost/BP' setting.

@ JohnnyA, I think you had better start another thread with just the test results in it, and keep this one for "related discussion".



Edited 1 time(s). Last edit at 06/08/2015 12:02AM by Pimento.

Treasure_hunter Wrote:
-------------------------------------------------------
> In 9 years of detecting I have yet to find a
> single coin floating in the air yet....

LOL !!!

I once demonstrated to a group of detectorist a Whites V3 in the field (low EMI detecting), and accurately identified a Quarter at 21.5 inches. The secret was in using a 12 inch concentric coil (Whites Super12) in combination with single frequency 2.5 kHz, and a very slow recovery time (110), and moving the Quarter slowly across the field under the coil. It was a great party trick, but had no value what so ever in the actual detecting ability of the machine. In reality It's all about circumventing the nulling effect of trash, and objects in close proximity to one another, and of course the mineralization strength of the ground itself.



Edited 1 time(s). Last edit at 06/07/2015 09:29PM by CyberSage.

Quote
In 9 years of detecting I have yet to find a single coin floating in the air yet....winking smiley

Super Mario Detecting World


I use air testing to get an estimate on VDI numbers and to make sure that my detector is working properly. More than that I personally don't think that air testing means that much. It is something we do every Winter to pass the time and create forum threads, but in the dirt is where it counts. Detectors that give poor air tests will probably be poor in the dirt I would assume. But those detectors are quickly scrutinized on the forums and the word gets out. I saw a video of Peaches air test a Deus in one of the Pinpoint modes a few years ago. He was at least two feet away from the coil. Fun to watch, but the information was just not relevant to real hunting.



Edited 2 time(s). Last edit at 06/07/2015 10:09PM by goodmore.

Been detecting 39 years. Had a bunch of detectors. If a detector will not air test at 6 inches,. it probably will not be very good in ground. One that detects 11 inches does not mean it will do well in the ground. But the air test does give somewhat an idea of maybe what it may be capable of in ground.....Jack

XL-PRO / 10.5'' DIME/11'' NICKEL/11.5''QUARTER. With Proper Tone and I.D. CZ-3D same as above. My Etrac doesn't air test well less then XL-PRO.

But the air test does give somewhat an idea of maybe what it may be capable of in ground.

Yes, of course it does. But, in the ground there are too many variables too allow for, such that ten different detectorist performing an in-ground test are not in sync and the results, though accurate, would not coorelate as well. A well designed in-ground test performed with multiple dietectors at the same test bed by the same person can reduce the variables ... but we don't have that using forum people. So we'er back to air tests.

Fortunately, an air test has just a few varaiables ... much more precision is possible, even among different people.

Funny how the same folks who criticize air tests so much are so impressed with other tests made on a box indoors... lol

I bought my first detector in 1973, a BFO, and immediately did air tests to determine what it could do. I still have those test results somewhere.

An induction balance detector operates on a simple principle: a secondary magnetic field is detectable (creates an imbalance between the xmit and receive windings) when illuminated by a primary magnetic field. A quarter creates a strong secondary field in the presence of a strong primary field, and a weak one in a weak field. Pretty simple, at least in the air.

Iron also produces a secondary magnetic field as sub-domains align to the primary field (and then relax between coil polarity switches). But we don't use a nail for testing purposes ... too many variables to account for ... so
it is back to the US coin as the standard.

Even though the CTX (and E-Trac, they are nearly identical in depth) could not reliably sense a quarter beyond 9" in my air test, I've dug quarters at 12" in the soil. Not often, but it has happened. How is that possible? There is only one way it is possible (if the depth is correctly assessed) and that is because the primary magnetic field drove eddies in the coin to produce the secondary field that was 'detected' by the CTX. What's different with the air test that resulted in less depth? The air test is missing a dozen different variables that the soil possesses, a few of which can decrease the depth/sensitivity and a few of which can intensify/direct the field deeper. On that day, in that one spot in a park, the magnetic field lines were directed deeper, and the coin was exposed. Yeah for me.

But that didn't invalidate the air tests. With the few variables that couldn't be controlled, in the air, the detector still won't respond to a quarter at 12" in Auto+3. Just can't do it. The air tests are accurate, the in-ground results are accurate but only for that spot of ground, with that soil moisture content, with that iron content arranged in that particular way to duct the energy, or with that nail beneath the coin to drive current in the coin, or with a dozen other variables affecting the outcome. Leave the quarter alone, come back tomorrow or next week, and you can't get a signal - in-ground variables (plus external EMI) have altered performance again, as it does everywhere, constantly, unbeknownst to you.

Physics is laws ... everything obeys law, including wound coils and tank circuits. If you've done the air tests witih just a modium of care your results are likely to be 90% of what anyone else will receive (variables again in coil manufacturing, testing standards, etc. cannot be controlled perfectly). If 100 people test the 11" DD coil on the CTX the standard deviatioin will be small enough to yield a realistic picture of the capability of the detector, in the soil, under ordinary circumstances (there is no accounting for the extraordinary).

Not to say that depth performance is the end-all be-all of detecting ... but it is an easily measured performance indicator that is related directly to the sensitivity of the detector.

When I was younger I would study all things hunting ... and rifle performance. Bullet performance was so important ... wanted the best caliber rifle with the best bullets ... it was a passion.

When you wanted to know if a particular rifle was any good you "air tested" it, you took it to a range, removed as many variables as possible (proper rest, no wind, controlled shots) and measured groupings.

Oh, but that's just an air test, it doesn’t mean anything at all, right!? Consumer Reports tests hundreds of appliances, cars, and there test results don't mean anything, right!? You still bought that 1971 Ford Pinto didn't you.

Testing is how we uncover detector strengths and weaknesses. Don't rely on detector magazines to "field test" the detector for you. The results are always going to be fantastic, and the field report will always find the detector "a keeper" and it will always open up "hunted out" sites and make them "new again". Any detector taken to any location is going to find something iron and something non-ferrous, unless the thing won't turn on it'll find junk ... that is not a "test". Good grief.

In-ground head-to-head comparisons are the gold standard ... if the variables are controlled, one of which is subconscious bias by the testors. The problem of course is you can't compare in-ground tests with each other, too many differences between the ground and testing principles, your detector does poorly then in some other test it does great ... so which is it?

The air test is the silver standard for ease of use in making depth comparisons on identical targets. Depth is related to coil construction, circuit noise issues, and the algorithms employed in the detector. It is the end result of good or poor design engineering.

I think most detectorists are keenly interested in getting some hard substantial factual information and are generally tired of being in the dark about the varied detectors out there and their capability. This is one of the few hobbies where people will spend thousands of dollars in the hope that some YouTube video showing someone dig a ring in the park means the detector is a good one. Well, that is just cr@p way to make a decision. We can honestly say that almost no one has any bloody clue to how their "favorite" detector performance in relation to all similar detectors. The detector companies THRIVE on your ignorance and will you also pooh-pooh performance testing because it isn't real world. Good grief. You're being had at a fantastic level and will you still be content with ignorance?

Yeah OK, let's all go buy unit "X" because it found a silver dime by a field testors who recommends it, and those that have bought it really like it and I hear it's are real tiger for uncovering in iron (blah, blah, blah). But please don't air test it against a standard - that is meaningless. Just keep buying cr@p because of hearsay and paid testimonials and YouTube videos and colorful brochures full of fluff from the manufacture, that's the way to be objective. Good grief!



Edited 1 time(s). Last edit at 06/08/2015 02:19AM by Johnnyanglo.

Multi frequency detectors have a tendency to go deeper in the ground than air tests would indicate....


Johnnyanglo Wrote:
-------------------------------------------------------
> I bought my first detector in 1973, a BFO, and
> immediately did air tests to determine what it
> could do. I still have those test results
> somewhere.
>
> An induction balance detector operates on a simple
> principle: a secondary magnetic field is
> detectable (creates an imbalance between the xmit
> and receive windings) when illuminated by a
> primary magnetic field. A quarter creates a strong
> secondary field in the presence of a strong
> primary field, and a weak one in a weak field.
> Pretty simple, at least in the air.
>
> Iron also produces a secondary magnetic field as
> sub-domains align to the primary field (and then
> relax between coil polarity switches). But we
> don't use a nail for testing purposes ... too many
> variables to account for ... so
> it is back to the US coin as the standard.
>
> Even though the CTX (and E-Trac, they are nearly
> identical in depth) could not reliably sense a
> quarter beyond 9" in my air test, I've dug
> quarters at 12" in the soil. Not often, but it has
> happened. How is that possible? There is only one
> way it is possible (if the depth is correctly
> assessed) and that is because the primary magnetic
> field drove eddies in the coin to produce the
> secondary field that was 'detected' by the CTX.
> What's different with the air test that resulted
> in less depth? The air test is missing a dozen
> different variables that the soil possesses, a few
> of which can decrease the depth/sensitivity and a
> few of which can intensify/direct the field
> deeper. On that day, in that one spot in a park,
> the magnetic field lines were directed deeper, and
> the coin was exposed. Yeah for me.
>
> But that didn't invalidate the air tests. With the
> few variables that couldn't be controlled, in the
> air, the detector still won't respond to a quarter
> at 12" in Auto+3. Just can't do it. The air tests
> are accurate, the in-ground results are accurate
> but only for that spot of ground, with that soil
> moisture content, with that iron content arranged
> in that particular way to duct the energy, or with
> that nail beneath the coin to drive current in the
> coin, or with a dozen other variables affecting
> the outcome. Leave the quarter alone, come back
> tomorrow or next week, and you can't get a signal
> - in-ground variables (plus external EMI) have
> altered performance again, as it does everywhere,
> constantly, unbeknownst to you.
>
> Physics is laws ... everything obeys law,
> including wound coils and tank circuits. If you've
> done the air tests witih just a modium of care
> your results are likely to be 90% of what anyone
> else will receive (variables again in coil
> manufacturing, testing standards, etc. cannot be
> controlled perfectly). If 100 people test the 11"
> DD coil on the CTX the standard deviatioin will be
> small enough to yield a realistic picture of the
> capability of the detector, in the soil, under
> ordinary circumstances (there is no accounting for
> the extraordinary).
>
> Not to say that depth performance is the end-all
> be-all of detecting ... but it is an easily
> measured performance indicator that is related
> directly to the sensitivity of the detector.

Interesting how a thread requesting air test data for various machines, gets turned into a debate about whether air tests are legit or not. There is a simple solution to if you do not like air tests...don't read threads with air test in the title!! I came here to see some info/data. Not to get lectures on whether they are legit or not.

I'm with you Johnny on a lot of things you said:

"Testing is how we uncover detector strengths and weaknesses. Don't rely on detector magazines to "field test" the detector for you."

Absolutely! Do the homework. If you have the machine, do the air tests and see if your machine is close or up to the specs as others.

"The air test is the silver standard for ease of use in making depth comparisons on identical targets. Depth is related to coil construction, circuit noise issues, and the algorithms employed in the detector. It is the end result of good or poor design engineering."

I think air test should be the gold standard when evaluating your machine. Way too many variables in the ground and in the field(more on ground hunting in a minute).

"This is one of the few hobbies where people will spend thousands of dollars in the hope that some YouTube video showing someone dig a ring in the park means the detector is a good one. Well, that is just cr@p way to make a decision."

I made THAT decision and it was not a good one. I bought a machine based on what I saw in videos rather than do the homework because i TRUSTED the makers of those videos and got stuck with a lemon. So hard factual tests are needed.

"The detector companies THRIVE on your ignorance and will you also pooh-pooh performance testing because it isn't real world. Good grief. You're being had at a fantastic level and will you still be content with ignorance? "

Again more truth. It's the almighty dollar(or whatever currency) that drives these companies to push sub-standard products or not fully tested products. Remember the big f75 upgrade debacle? The only way to find out if you upgrade was on par, was to air test them. Since this was addressed, do we hear anything on that subject anymore? I haven't. But we wouldn't of even known about it, if it wasn't for a certain air test video that started it all. People began to air test their machines and saw the same issue. Then you have the overseas market with the most outlandish in ground depth videos I ever seen which are ABSOLUTELY worthless to the U.S. as our ground is much different than theirs. I am NOT a fan of some of the overseas markets(Blisstool, AKA, Nexus) due to the hype and price. I don't feel that their machines are worth the price point(For many reasons).

Air tests DO NOT show the best capabilities of a machine, however, they do show you where your machine stands against other machines of the same type(For-going EMI). It's also a great way to test your coil to see if it is functioning correctly. It's a great test to perform so others can get a good idea of how their machine stacks up against other machines of the same type.

In-ground tests have too many variables to test against other machines of it's type however, it is a great test to see the capabilities of YOUR machine. In YOUR ground. With YOUR conditions. THIS should be stated in all in ground test videos.

For example, My dirt is fairly inert up north. Kieth's dirt is pretty hot down south. Let's say we both have identical machines set identically(for arguments sake, let's say all tolerances are identical). We both bury a quarter at exactly 10 inches.The ground is completely free of all man made metal except for the quarter. Chances are, Kieth's machine is going to have a much harder time hitting that quarter, and if he does hit it, it would not have the same response as my machine would. Does that mean my machine is better or Kieth's machine is broken? Obviously, no.

Given the same circumstances above with an air test, both of our machines(barring EMI) should be nearly the same. Even with EMI the differences my be an inch(I cant see it being anymore than that).

Well that's my take on it.

Bey

Daniel Tn Wrote:
-------------------------------------------------------
> Interesting how a thread requesting air test data
> for various machines, gets turned into a debate
> about whether air tests are legit or not. There
> is a simple solution to if you do not like air
> tests...don't read threads with air test in the
> title!! I came here to see some info/data. Not to
> get lectures on whether they are legit or not.

Amen.

Treasure_hunter Wrote:
-------------------------------------------------------
> In 9 years of detecting I have yet to find a
> single coin floating in the air yet....

I came here to see some info/data.

Great! Let's see one air tests from each forum member (or lurker) on a quarter, dime, and nickel.

Just post your results here and the size coil used. Takes all of 15 minutes.

Use the search tool. Takes LESS than 15 mins . I've already done numerous air tests and posted results of various machines and coil combinations.

When I get the time, I'll post some results.

Here's my take on air tests: In 1973 I was at the Garrett factory and the Chief Engineer,don't recall his name,showed me how THEY did air tests to determine the variance between like detectors and if they were within specs. I have used this simple test on dozens and dozens of detectors over the years and can tell you that like detectors will vary as much as 25% on air testing.Anyone,even those of us who are a couple bricks short,can understand that YOUR local conditions,soil,emi,batteries,etc.will cause YOUR results to differ. Sooo if the guy who MAKES the detectors feels that he can get the info that HE needs from an air test---dat bees good nuff fo me.

Omega and G2
version 5/6 omega is an inch deeper on quarter with 11" DD

Racer with 11"

Digitek

Harold,ILL. Wrote:
-------------------------------------------------------
> XL-PRO / 10.5'' DIME/11'' NICKEL/11.5''QUARTER.
> With Proper Tone and I.D. CZ-3D same as above. My
> Etrac doesn't air test well less then XL-PRO.

I should add to the above XL-PRO air test I was using the stock 9.5'' coil. Also had SIGNAL at 3:00 in GEB DISC. MODE with DISC. set at SALT. and HOT ROCK /ACCEPT ON. Once again this is with proper Tone and I.D. inside a mobile home with no EMI. I think this is pretty good for a 4 filter analog detector that some consider ''old tech''.