Air Testing The Best In 1991

[Steve Herschbach]

I just finished scanning and uploading the rare Engineering Guide to the White's Eagle Spectrum from 1991. A true innovation in detecting, one of the first digital models, and the first with what became the White's SignaGraph display. 28 page free download so check it out.

Page 17 caught my eye as something we do not see these days. And actual factory produced air test/calibration chart for the Eagle Spectrum. It gave owners an easy way to see if their detector was performing to factory spec. It better serves here to show just how far we have come since 1991 in detector performance. Or not, depending how you look at it. 

[Joe Beechnut OBN]

That's great!

I might be one of the few who believe air test can play a roll in comparing the same machines or testing head phones. And it can help in learning your machine I believe when it comes to settings, it really helped me on the AQ seeing how you can go from 1 to almost 8 on the ATS setting with out much difference then just a hair more it can knock out clad and small iron. And with that I learned it could knock out some gold if you go much further. And I know many other things can come into play once the targets are coming out of the ground but airtest for me have really helped in my learning and improving performance.

 

[Steve Herschbach]

1 hour ago, Joe Beechnut OBN said:

That's great!

I might be one of the few who believe air test can play a roll in comparing the same machines or testing head phones. And it can help in learning your machine I believe when it comes to settings, it really helped me on the AQ seeing how you can go from 1 to almost 8 on the ATS setting with out much difference then just a hair more it can knock out clad and small iron. And with that I learned it could knock out some gold if you go much further. And I know many other things can come into play once the targets are coming out of the ground but airtest for me have really helped in my learning and improving performance.

 

I’ve never disputed air tests can play an important role in detector testing. I’m also adamant that air tests reveal almost nothing about competitive performance at depth in anything but the mildest non-mineralized soils. It seems it always must be black and white about things these days, good or bad, useful or useless. Life’s a little more complicated than that. 

Air tests are great for determining max performance under ideal conditions. In the tests above it would be unrealistic to expect an Eagle to hit a quarter deeper than 14 inches. And they are great as in this case as acting as a verification that the detector is running within spec. I love air testing to determine what target id to expect on a nickel and a zinc penny under ideal conditions. I air test to learn tones.

But I have done lots of testing for manufacturers over the years and my specialty is putting detectors in tough ground. I hear all the time how well this thing tested in the lab (air tests), only to have it fall on it's face in the field. Countless detectors that worked great in the lab never made it to production simply because they failed on the ground. That's just the facts of real world detector testing. If all that was needed was air tests there would be no need for the engineers to send detectors to me.

But I still like air tests for lots of things!

[Knomad]

I like Head to Head Tests under identical conditions as much as possible, either air or in ground, at least it gives an idea of how detectors compare on those particular targets in those conditions, better than having nothing but good or bad days in the field and trying to use chance as some indicator.

BTW, my Eagle 2 had performance comparable to almost any modern detector, BUT under a more limited range of ground conditions.

53 minutes ago, Steve Herschbach said:

I’ve never disputed air tests can play an important role in detector testing. I’m also adamant that air tests reveal almost nothing about competitive performance at depth in anything but the mildest non-mineralized soils. It seems it always must be black and white about things these days, good or bad, useful or useless. Life’s a little more complicated than that. 

 

 

[Joe Beechnut OBN]

30 minutes ago, Knomad said:

I like Head to Head Tests under identical conditions as much as possible, either air or in ground, at least it gives an idea of how detectors compare on those particular targets in those conditions, better than having nothing but good or bad days in the field and trying to use chance as some indicator.

BTW, my Eagle 2 had performance comparable to almost any modern detector, BUT under a more limited range of ground conditions.

 

Over the years I have done a few head to heads and they can really be enlightening on many things, first.. comparing two different machines in the environment you normally hunt in and they can reveal your competition's abilities. 

I do have one lined up this summer with the Manticore and my Excalibur, I'm very interested in seeing how both fair. And it is with one of the hunters I normally hunt with, got to keep a eye on them to..😄

[Jim McCulloch]

Steve, your posting was a nostalgic flash back to the early days of digital detecting.  The field test report I did for "Treasure" magazine was the very first detector field test I performed. I spent a lot of time and effort trying to reconcile analog into digital. Thanks again buddy.

[Steve Herschbach]

On 6/18/2025 at 8:48 AM, Jim McCulloch said:

Steve, your posting was a nostalgic flash back to the early days of digital detecting.  The field test report I did for "Treasure" magazine was the very first detector field test I performed. I spent a lot of time and effort trying to reconcile analog into digital. Thanks again buddy.

I am putting too much work into getting these old engineering reports up for what is obviously almost no interest. I get it, people have moved on, think this is just ancient history. Truth is the concepts laid out clearly in the Spectrum/Vision and MXT/GMT engineering reports is a real solid foundation for anyone wanting to know how modern digital metal detectors work. I will do one more at least as these old reports deserve to be easier to find. In that regard the effort is worth it, even if only a handful of people are interested.

 

 

[JCR]

I certainly appreciate having these types of material to study. They fill in knowledge gaps we don’t realize we have.

[Rivers rat]

Someone must have (for a good reason) believed in it,i mean they  were the 1st correct me if i am wrong then come Minelab with the EXPLO XS if my memory is right...

 

 

RR