Minelab X-Terra 705 vs Garrett Ace 250 - Do Metal Detector Air Tests Have Any Value?

[Goldgrabber]

Here's an air test video comparing a Minelab X-Terra 705 with a Garrett Ace 250. Now I am fully aware that metal detectors react differently when out in the field compared to in an air test environment and I also know that air test's aren't a true reflection of a detectors abilities, however, I still found them useful when I was looking to upgrade my detector so hopefully other people will also find this video useful. The test is carried out using a variety of UK coins and jewellery. The Garrett retails for around £200 where as the Minelab retails for £450-500 so it's more than double the price so I wanted to know, in a really simple test, how much more sensitive the Minelab would be compared to the Garrett at half it's price.
Anyway, I hope you find the video useful and informative like I found them when upgrading detectors:

[Steve Herschbach]

First off, let me say welcome to the forum, and that I appreciate the effort you put into the video. So do not take the following personally because it is not aimed at you personally. It is just that perhaps with good intentions your video is doing something I see far too often.

In my opinion air tests are completely worthless for evaluating in ground depth performance of metal detectors. In fact, in my opinion when used to draw conclusions between two detectors they can be extremely misleading and this video is a perfect example.

Right in the beginning of the video the test is set up as seeing if for twice the money the X-Terra has any advantage over the Ace. Now, if you were just showing an air test of either machine separately all is well. It is the fact this is supposed to reveal how one compares to the other where it all falls apart. The rest of the video is simple misdirection. All the tests after that are air tests, ending with the conclusion that the Ace is just as good as the X-Terra that costs twice as much because it air tests as well.

Now that is nonsense and you say as much when introducing your video in the post above. In your post you say "Now I am fully aware that metal detectors react differently when out in the field compared to in an air test environment and I also know that air test's aren't a true reflection of a detectors abilities". So why then make the video and in it not make those exact statements in it? Any person watching your video gets exactly the opposite impression. You imply heavily in the video itself that these air tests have meaning.

Air tests only serve a few purposes in my opinion. They allow a person to learn basic things like what the target id numbers and sounds are for various items under perfect conditions, and they tell you what a detector will not do. If a detector cannot detect a small gold nugget in an air test, it is unlikely to do so in the ground. Air tests reveal maximum possible performance under ideal low to no mineral conditions. I do not expect detectors to do better in ground than in an air test. Air tests can reveal how well detectors deal with adjacent trash targets. Air tests can also reveal by comparing two of the exact same model of detector if one is possibly malfunctioning, but even then just because one air tests better than the other it may not mean what people think. It could be the one that air tests better is the one that is malfunctioning!

Certain forums obsess over air tests. Yet I do in ground tests on a regular basis that completely reverse the air test results people are getting so excited over. A high frequency detector will often air test better than a low frequency or multifrequency detector, with opposite results in ground. A VLF can easily do better in air tests than a PI detector, with vastly opposite results in ground.

The key to all detector performance is ground handling capability. Removing the ground from the equation removes the single most important thing people should care about, and that is evaluating the efficiency of the ground balancing method the detector employs. This ties into target id accuracy, which also can only be evaluated in ground. Target numbers that are nice and solid in air tests skew badly and jump all over the place in real ground conditions.

In fact, I can easily misadjust a detectors ground balance to make it perform better in the air, while that very same adjustment will make it perform worse in the ground. I have seen people take detectors with factory preset ground balance settings, and attempt to get better performance by setting it themselves. They usually do so by using air tests to set the internal pot to get the best air test possible. They are then usually surprised to find out the in ground performance actually got worse. Well of course - you can only ground balance a detector over the ground! The ground balance setting that works best for mineralized ground will often hurt performance in an air test. That is why a Pulse Induction (PI) detector air tests so poorly compared to a VLF - a VLF has far less inherent ground handling capability than a PI and that ground handling capability is what a PI is all about. It does not make them air test well - BUT WHO METAL DETECTS IN THE AIR?

Air test videos work best for people with low mineral ground, and so are halfway valid for turf hunters or white sand beach hunters. The guys back east love them. For nugget hunters or anyone hunting bad soil conditions, hopefully they know better. VLF detectors in my ground get about 50% of the depth or less than all these air tests that get published all over the place as meaning something. Machines that air test the best are often the absolute worst detectors to put in really bad ground conditions.

Now to this video in particular. The Ace 250 is a factory preset ground balance detector. And in low mineral ground conditions your video is halfway valid. The Ace 250 in my opinion is one of the best bang for the buck detectors ever made, and a real credit to Garrett for having produced it. However, the simple lack of a ground balance control means that in bad ground it is seriously out of adjustment and there is nothing you can do about it. Depth of detection is severely impacted and target id accuracy is ruined. The X-Terra because it can be ground balanced easily outperforms the Ace in bad ground to a very large degree, the degree depending solely on the ground conditions. Further, the Ace lacks a true threshold based all metal mode, which mode on the X-Terra is one of the absolute best made. The X-Terra 705 Prospecting mode combined with its iron mask function truly puts the Ace to shame in the hands of a serious operator. Simply no comparison at all.

Interestingly, in this video you have an optional 10" DD on the X-Terra vs the smaller concentric on the Ace. Another common error of course is comparing two detectors with vastly different coils. What is interesting in this case is that if compared with proper in ground tests you could show why that DD coil blows the Ace concentric coil away in any sort of bad ground. The concentric will overload more easily and misidentify non-ferrous items as ferrous more readily than the DD coil you have on the X-Terra. This DD advantage of course is completely lost in air tests and in fact concentric coils will usually outperform DD coils in air tests.

The best videos are those that show a single detector and show a user how to get the best performance out of it. Nearly all the worst videos are those air testing two or more detectors seeking to determine which is best. Videos of that type must be done in the ground with a great deal of effort expended to explain the conditions and settings and also the inevitable caveats involved in the testing. The main caveats being actual ground conditions relative to where the actual end user is and what types of targets it is that they are seeking. I can show well why one detector perfect for Florida is a poor choice for Arizona, and also the exact opposite. It is all about the ground conditions where a person hunts and that changes from location to location.

As far as I am concerned if people are interested in true detector comparisons the only ones that matter are in ground tests on found targets. That is how I test when I get serious about it. I use air tests and contrived buried item tests to reveal certain basic facts (can this detector detect a one grain nugget?) but for serious testing I have to haul two or more detectors into the field, go find targets, and compare the detectors on the found targets. Most top of the line detectors will find 90% plus of found targets just as well, so it takes a lot of time and effort to find the small percentage of targets that reveal true differences between the best detectors. And even then those results are only valid for me in my ground conditions and must be taken with a grain of salt.

[LipCa]

Well put...

[Jonathan Porter]

Steve your post should be pinned permanently on every detecting forum world wide.

 

JP

[Lanny]

A great write-up indeed, and I like how you've put to bed a lot of nonsensical notions that seem to always perpetuate.

 

Nicely done, and all the best,

 

Lanny