Head to Head Comparison Testing by Thomas J. Dankowski

[Terry Soloman]

Head-To-Head Comparison Testing

One person claims 7" on a dime in one State and another person claims 12" on a dime in another State. One person hunts a particular site with Brand-X detector, then, the very next day, he hunts the exact place again with Brand-Y detector and finds more good targets, then touts the Brand-X detector as inferior. These are very common and misleading occurrences.​

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A head-to-head comparison is VERY difficult to perform. Absolutely ALL variables must be removed if any form of validity is to be ascertained. The slightest changing variable can completely void the test. --- Let's get dirty and come away clean.​

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A textbook perfect test-garden is a good start, yet it does not represent the real world dirt conditions. This includes simplex and complex test-garden scenarios. The preferred method for head-to-head comparison takes place at several different sites with varying mineralization and with several different undug, undisturbed targets in their natural settings.​

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Let's say you have selected a local park. You have located several 'items of interest' and marked their exact pinpoint location with colored plastic poker chips. You turn off Brand-X detector and swap it out for Brand-Y detector. Here is where the difficulty begins. Was Brand-X detector control panel settings optimized for each individual target? Was the level & quality of signal documented (for comparison) on each individual target..... or are you ONLY seeking to find 'detectable' or 'not detectable' (go/no-go) scenarios to each detector being tested...... regardless of signal strength/quality? How high was the coil over the target(s)? How fast was the coil sweep speed? Are you aware that one detector may like a fast sweep speed.... and the other unit resolves better with a slower sweep speed? Were you facing the exact same direction when sweeping the coil over subject target? Was Brand-Y detector coil sweeping the subject target one inch further forward or aft of the exact pinpoint location? Was only one of the units properly ground balanced? Is this type of information potentially "interpretive"? Are you slightly biased more favorably towards Brand-X detector? Does Brand-Ex detector come standard with a 10.5" coil and Brand-Z detector is factory 8" coil equipped? What is categorized as 'fair' or 'unfair'? When you went back to the car to swap detectors, did the nearby local radio station switch from nighttime 10KW to daytime 50KW transmit power? Or did the A/C compressor and pool pump cycle 'on' at the nearby building? Were your steel-toe'd shoes and steel shovel a bit closer to the coil of Brand-X whilst comparing detectors? Is Brand-T detector more resonant on low conductors (nickels) and Brand-Z detector more resonant on high conductors (silver dimes)? Does one brand detector fall flat on its face in bad ground, yet it will trump all other detectors in fairly mineral-free dirt ---- and you only gave it one chance at one location ---- and came to one final conclusion? Are you trying to compare Brand-T detector equipped with a extremely tight electromagnetic footprint bi-axial elliptical DD coil to Brand-Z detector with a concentric coplanar coil? Are you seeking to find which detector is simply the deepest unit -- or which one presents the best enhanced adjacent target separation characteristics? Are you aware that one detector may be superior at finding coins next to pull-tabs (non-ferrous) trash and another detector may be superior at finding those same coins next to nails (ferrous) trash? Is one person operating Brand-X unit and a different person operating Brand-Y unit? Can you see where this might make a difference? Did you know that you can mark targets today --- and tomorrow you may or may not be able to detect these exact same targets? If tomorrow brings different humidity, temperature, rain or electrical interference, a whole new set of parameters exists. Are you aware that one detector may find one set of targets and another detector may find a completely different set of targets in the same field? Does this make one unit inferior/superior to another unit?​

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This brings up another interesting scenario/phenomenon. Say a [very small nail] is 6" deep --- and a silver dime is directly beneath the nail, one inch deeper -- at a total depth of 7". In your hands, you have one detector and two coils; a 5" coil and a 10.5" coil. With the small coil installed, the 6" deep nail is a moderate signal strength -- and the (one inch deeper) 7" deep dime is starting to "push the depth limits" of the small coil, yet still within detectable range; HOWEVER, the dimes signal strength to the small coil is much weaker than the shallower nail --- so the detector reports "iron". A one inch deeper depth to the small coil is a formidable signal strength reduction. x-x-x-x-x Now you install the large 10.5" coil. A target at 6" and a target at 7" is hardly even a difference to the larger coil --- the field intensity at 6" & 7" are nearly the same; HOWEVER, the detector reports "coin" because the dime has a larger mass as compared to the [very small nail]. Sometimes this phenomenon is referred to as the "wrap-around" effect. So, is this apples-to-apples... head-to-head comparison? Interpretive it is! In any case, armed with this knowledge can prove to be VERY fruitful. The same detector with different coils may 'light up' completely different targets in the same area. Keep that in mind.​

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As you can see, there are many things that can alter data resultants. One of the more common mistakes is to be facing, say West (270 deg.) while sweeping with Brand-X, then repeat the same process with Brand-Y detector in almost exactly the same direction, nearly due West (say 255 deg.). This slightly different (15 deg. difference) sweep angle, in many cases, is just enough of a difference to invalidate the comparison. A tight footprint DD coil can highly accentuate this common occurrence as you rotate your body around the target. This is also to say that you may have hunted a parcel of land numerous times, always walking South to North (facing North), yet you keep finding more targets. Maybe a particular target could only be electromagnetically illuminated when the coil is passed over the target from a Northwest-to-Southeast approach angle. One day you are facing (and walking) North again, but, this particular time the target is on your Right side of your sweep (vs. directly in front of you or slightly to the Left side); hence, your coil approach angle into the target is finally the correct angle and - "Bam" you get a good hit. Upon further examination, you decide to rotate your body around this specific target while sweeping --- only to discover that this particular target is detectable in a certain window-of-opportunity of body rotation --- and is undetectable from other approach angles,,,, possibly due to a co-located trash target in close proximity to the good target. You may or may not be able to hear the culprit trash item, because of masking, silent masking or your level of discrimination dialed in to your detector. (If you have tone ID capabilities, use zero discrimination for the full intelligence package of existing dirt scenarios). Depending upon how your coil approaches into the co-located targets, dictates how the detector will respond.​

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Find the right tool for the right job. Detectors are akin to eye-glasses. There are spectacles for specific tasks such as; near-sightedness, far-sightedness, high magnification macro viewing, long-range zoom viewing, reading glasses, 3-D viewing, Solar eclipse viewing, low-light/night-vision viewing, Sun shades and shades that are specifically designed for nothing ... except to just simply look "cool". And detectors with 'flames' to just simply look ****** ,,,,, you know the rest of the story!​

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All of this information sounds like 'data overload'. There are many additional scenarios that can void a head-to-head test. Sounds discouraging and difficult, doesn't it? The bottom line is; DO YOUR BEST! Remove as many of the variables as possible. If you can have your buddy standing behind you ,,, handing you detectors and equipment,,,, whilst you have your feet planted in the exact same unmovable spot........ chances are your head-to-head testing should generate valid results --- as sweep angle direction, temperature, ground moisture content, humidity, local electromagnetic interference, local ground mineralization content and other potential "variables" become "constants". When you become accustomed to this procedure,,,,, you will learn that it was not that difficult after all!!! Your conclusive analysis may very well present a resultant that is not in accord with your initial expectations. Keep an open mind and don't be biased ....and enhanced performance will ensue. Your increased awareness and intelligence will 'magically' increase your volume of "keeper" finds!!!​

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Happy Intelligent Hunting! - Thomas J. Dankowski​

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[sprailroad]

Whoa, overload, overload. But I do agree with it all. For me, it's simply 33 1/3% machine, 33 1/3% operator, and 33 1/3% luck. I'm a simple guy.

 

[adamBomb]

I have learned a lot from Tom D. over the years.

 

[Nevada Prospector]

Whoa, overload, overload. But I do agree with it all. For me, it's simply 33 1/3% machine, 33 1/3% operator, and 33 1/3% luck. I'm a simple guy.

I agree with that assessment, Railroad Man, except that luck may be a tad bit higher.

 

[HighVDI]

Tom is a great guy and super knowledgeable! Spoke with him over the phone a couple times with some questions on my f75 and learned a ton. This write up is great like all his others.

 

[OBN]

Overload.......I can't even get past the second paragraph. Reminds me too much of my college term papers.

 

[ColonelDan]

Terry, I'm with you!

I've done a lot of testing for Kellyco providing written reports on performance on many detectors and in a variety of circumstances. I avoid putting much if any emphasis on "depth" of any detector for just the reasons you cite. The depth I can get here in Florida under the test conditions I set up will certainly not apply to someone using the same detector with the same settings in Maine...or any place else for that matter. Far too many variables impact depth as you so expertly explain. Even if all other variables could somehow be constant except that your test area had rain the next day, the depth could and very well will be affected.

I much prefer to see how a detector performs, standing on its own in terms of sensitivity and its ability to separate good targets from junk. I look at the structure and design of its user interface and its reliability under field conditions.

I then always add the following, "Just the view from my foxhole under the given conditions. Your results may well vary."

Good job Terry....I believe your missive should and will enlighten many of our fellow detectorists.

 

[3cylbill]

what it all boils down to is learn your machine , sure the $150 dollar machine won't do what the $1500 dollar machine will and your state of mind has alot to do with it .if your in a bad mood or tired with much on your mind your not going to focus . there are so many variables to consider if your machine weighs five pounds you will get tired sooner than if you swing a two pound machine . if your digging lower signals your digging and have fifty digs behind you your going to get sloppy . if you have your machine tuned and are able to pass up the junk you just might find the god target that you would have never made it to digging all the junk . it's ALL about the variables and the quality of the sites you choose to swing it...

 

[sprailroad]

Terry, I'm with you!

I've done a lot of testing for Kellyco providing written reports on performance on many detectors and in a variety of circumstances. I avoid putting much if any emphasis on "depth" of any detector for just the reasons you cite. The depth I can get here in Florida under the test conditions I set up will certainly not apply to someone using the same detector with the same settings in Maine...or any place else for that matter. Far too many variables impact depth as you so expertly explain. Even if all other variables could somehow be constant except that your test area had rain the next day, the depth could and very well will be affected.

I much prefer to see how a detector performs, standing on its own in terms of sensitivity and its ability to separate good targets from junk. I look at the structure and design of its user interface and its reliability under field conditions.

I then always add the following, "Just the view from my foxhole under the given conditions. Your results may well vary."

Good job Terry....I believe your missive should and will enlighten many of our fellow detectorists.

Colonel Dan, I'm somehow thinking you might have taken what you learned with tanks with the 11th ACR, and applied it to metal detectors. I like it, I like it a lot.

 

[sprailroad]

I agree with that assessment, Railroad Man, except that luck may be a tad bit higher.

Ya know Nevada....I'd have to go along with that, except in MY case, I'm thinking MORE then JUST a tad.

 

[GA_Boy]

I read the article in its entirety. Well written explaining the variables that can occur.
I'm not much on believing in luck, but rather knowing your machine and its capabilities.
I hunt the same area/park/yard/etc but one time North to South, next time maybe East to West. It depends on the terrain.
I want to dig only good targets, but if I miss one, so be it.
Marvin

 

[ColonelDan]

Colonel Dan, I'm somehow thinking you might have taken what you learned with tanks with the 11th ACR, and applied it to metal detectors. I like it, I like it a lot.

Thank you. I will say that the sites on our modern tanks are, in their own way, exceptional "metal detectors"...particularly at night!

Soldier on...

 

[sprailroad]

Thank you. I will say that the sites on our modern tanks are, in their own way, exceptional "metal detectors"...particularly at night!

Soldier on...

I love the sound of an answer like that in the morning, it sounds like....victory.

 

[Rookster]

I believe in virgin sites to hunt. I have some that have been pounded over the years. But to make a point. I believe it's the operator that makes it all happen. You can have the most expensive machine out there but if the owner doesn't know the correct setup, probably going to be a slower day than expected. I believe in getting as close as possible with ground balance, sens.,and disc. And silencer, and go to it. I've read that 6" is the national average for most finds. Most medium priced machine can hit that mark.

 

[Bama Billy]

Whoa, overload, overload. But I do agree with it all. For me, it's simply 33 1/3% machine, 33 1/3% operator, and 33 1/3% luck. I'm a simple guy.

That’s pretty good math but I think I’d replace luck with location. Just my two cents

 

[HighVDI]

I believe in virgin sites to hunt. I have some that have been pounded over the years. But to make a point. I believe it's the operator that makes it all happen. You can have the most expensive machine out there but if the owner doesn't know the correct setup, probably going to be a slower day than expected. I believe in getting as close as possible with ground balance, sens.,and disc. And silencer, and go to it. I've read that 6" is the national average for most finds. Most medium priced machine can hit that mark.

True, but only in perfect conditions. Add in a couple nails, mineralization, a hot rock and a 6" target becomes a very small signal.

I recently dug a 2" deep merc at a pounded county park. This dime was barely even making a peep and sometimes just a one way broken high tone. I can see why it was never dug but the point is it was handicapped in one way or another. Another was a 5" merc in the same park that was also sounding off like it was 10" down.

That's why to me a coin dropped in a hole someone digs to make a garden really isn't an accurate test. It leads someone to think that every single 6" dime will sound like the one buried. IMO the only way to compare different machines is taking every one to a spot you're hunting and see what each machine does on a real dropped target.

 

[sprailroad]

True, but only in perfect conditions. Add in a couple nails, mineralization, a hot rock and a 6" target becomes a very small signal.

I recently dug a 2" deep merc at a pounded county park. This dime was barely even making a peep and sometimes just a one way broken high tone. I can see why it was never dug but the point is it was handicapped in one way or another. Another was a 5" merc in the same park that was also sounding off like it was 10" down.

That's why to me a coin dropped in a hole someone digs to make a garden really isn't an accurate test. It leads someone to think that every single 6" dime will sound like the one buried. IMO the only way to compare different machines is taking every one to a spot you're hunting and see what each machine does on a real dropped target.

And I'm in agreement with VDI's post here, which brings us back full circle to Terry's original post of T. J. Dankowski's thoughts.

 

[HighVDI]

How many times have we went back to a spot we know for a fact we've gotten our coil over.......multiple times and out of nowhere a beautiful high tone appears out of thin air, lol.

Definitely holds some water.