Did I say BOTH environments? I sure did, because there are only
two different environments we make use of for 'testing' the performance of a detector or a search coil. That's right, only two.
1.. A
'Controlled Test' which is where an individual gathers whatever coins and other ferrous or non-ferrous sample objects they wan and contrives or imagines some sort of scenario they might come upon, or specifically what they might want to do to test the performance of a particular make and model detector, or a selected size and shape and internal type of search coil. At times a controlled test can intentionally be designed to bring out a strength in one chosen model or to point out a weakness in some competitive models.
2.. A
'Naturally-Encountered Test' which is simply an exact duplication of some sort of in-the-fil challenge we have actually encountered while out detecting. We then make use of that
exact duplicated Test Scenario for future comparisons. That is then, in my opinion, a more valid testing method because it wasn't
imagined, it was
actually an in-the-field encounter!
Example? Sure, I have one that that has been used for over a quarter-of-a-century and to this day remains a very fair comparison for any make and model detector or search coil. It started on memorial Day Weekend in 1994 in the ghost town of Frisco Utah. An annual gathering Outing for a couple of Utah metal detecting club members. A great time to get-together to visit, "talk shop", meet new people and, if all goes well, make some rewarding finds.
I made it a stop on my way to Prescott AZ to teach a week-long class on Recreational Metal Detecting at Yavapai College, and also evaluate the Discovery Electronics Treasure Baron in an iron-infested ghost town. I was making my way along with that model and my notebook to record my results and impressions, and when I got to the top of the school hill, where the old school had been long gone for decades, I looked at the ground to find a spot to Ground Balance.
The site was covered, and I mean
covered with Iron Nails. And looking down at the ground right in front of me, I spied a round-shaped object that was on the surface and surrounded by four different sized Nails all in a random orientation. Not human-aligned to try and achieve something
(as in #1 above), but a
naturally-encountered, in-the-field experience
(as is #2 above)..
I brushed off the object to see it was an 1800's Indian Head 1¢, and I naturally figured this would make an excellent way to test how well this new-to-me detector would handle the conditions if I used the Discrimination to reject the Iron Nails. As I had already concluded from some Bench Tests before I hit the road, the detector failed to do well when swept from several directions. With this excellent example of a ghost towns hunting environment can be, I called three fellows up to check out their detectors .... knowing ahead of time what wowuld happen to make it an 'educational moment' as they learned about this great sport.
They were all city coin hunters on their first trip to work a ghost town and all were using a White's upper-end detector with the earlier fast-motion Discrimination circuitry, and also using an 8" or 950 coil. The evening before at a campfire we were chatting in a group with some of my friends and I asked if the had a slower-sweep model or a smaller-size coil because most of the ghost towns we search are heavily littered with ferrous debris. In the soft, loose dirt I made some marks on the ground around this coin& nail encounter to indicate four sweep directions for them to try, going both ways. They were all surprised that their detectors couldn't get a hit on the coin that was in plain sight.
I told them the newer model I was checking out couldn't do well, either, but for "educational purposes" I called to my friend, Debbie, who was detecting down the slope a little. She came walking up to us, looked at the three fellows standing around, and figured out what was going on. She looked at the grounds and spotted the Indian Head and Nails, then walked all the way around, sweeping her original Tesoro Silver Sabre w/7" Concentric coil back-and-forth over the Nails and coin getting a solid 'beep' on every pass over the Indian Head.
Then she looked up at me and finally spoke ....
"Is that what you wanted?" I said,
'Yep! Now get back to finding stuff.' Those fellows learned a bit, and I took a few minutes to use some of my note paper and lay it over the coin and four Iron Nails to get an
exact measurement of their orientation, their different sizes and such, and the position of the Indian Head 1¢, then picked up my new-to-me old coin as well as the four Nails. I figure this would make an excellent true-test example of some of the challenges people can face in a Nail Infested site..
I then got a piece of cardboard and used my lay-out paper to mark the
exact positions of the targets and drew a circle where the coin was. (Oh, I forgot. After I made the impressions and picked up the Indian Head first, I paused to place it along side one of the larger Iron Nails just to test it with a lengthwise and crosswise sweep. Before the college course started I placed the Nails in the proper orientation that had been when encountered, marked them on the board in ink, then used a glue-stick gun to hold them all in their proper orientation. That was the start of
Monte's Nail Board Performance Test, and to this day it is still an excellent 'Test Scenario' of the #2 category above, and is very useful.
Another 'Natural-Encounter' I make use of is with One Brass Button Front, the size of US small 1¢ coin, and One Iron Nail it was under. Both eye-balled on the surface, and again I thought I spied an Indian Head due to the size. But while exactly the diameter, it doesn't have the back-piece and is just a thin-brass button-front with a RR train on the front. Another challenging 'Test' because the button-front is smaller-size, thin, and has about a 3½" Nail right on top and centered.
With the
NBPT it is possible to get 8 good hits. With the Nail on Button-Front, a left and right sweep Lengthwise and a left and right sweep Crosswise can produce 4 good hits. Using Double-D search coils and Concentric search coils can produce interesting results, but it isn't only the search coil involved, it is also the particular detector circuitry. That includes operating frequency, Discrimination level, and how it processes the iron and non-iron in the way of Separation or Recovery Speed or Filtering or Reactivity or Iron Bias .... use whatever terms the manufacturer chose to label things. It gets interesting, so look at these models I have used with the search coil and operating frequency I also use
on a regular basis for Coin or Relic Hunting sites or have tried:
Fisher F44 w/7" Concentric coil @ 7.8 kHz
Garrett AT Pro w/5X9 DD coil at
Makro Racer 2 w/7" Concentric coil @ 14 kHz
Minelab Equinox 800 w/6" DD and 11" DD coils @ Multi-Frequency
Minelab Vanquish w.5X8 DD coil @ ? Multi-Frequency
Nokta CoRe w/
'OOR' 4.
7X5.
2 DD coil @ 15 kHz
Nokta Relic w/5" DD coil @19 kHz
Nokta / Makro Multi-Kruzer w/5" DD and 7" Concentric coil @ 14 kHz
Nokta / Makro Anfibio Multi w/5" DD and 7" Concentric coils at 14 kHz
Nokta / Makro Simplex
+ w/11" DD coil at @ 12 kHz
Teknetics Omega 8000 w/5" DD and 7" Concentric coils @ 7.8 kHz
Teknetics T2
+ w/5" DD @ 13 kHz
Tesoro Bandido II µMAX w/6" Concentric coil @ 10 kHz
Tesoro Silver Sabre µMAX w/6" Concentric coil @ 10 kHz
XP ORX w/5X9½ DD HF coil @ 14.4 kHz
White's modified IDX Pro w/6½" Concentric coil @ 6.59 kHz
White's XLT w/6½" Concentric coil @ 6.59 kHz
Question #1: Which set-ups as shown got 2 good hits ONLY when the Nails were swept Lengthwise?
Question #2: Which set-ups as shown got 2 good hits ONLY when the Nails were swept Crosswise?
Question #3: Which set-ups as shown got 4good hits when the Nails were swept BOTH Lengthwise and Crosswise?
Naturally, the detector & coil and frequency advantages can help establish the better detector(s) to achieve
Question #3 results and, therefore, make the better choice(s) for taking on some serious Iron Nail contaminated sites. One of a few in-the-field Test Scenarios that serves a purpose, as does my
NBPT.
Quote
glabelleMonte has gone over to the darkside! Multi-IQ! 
Just a diversion for some evaluation time and see if the Vanquish might have a 'fit' in my Outfit since I am thinning out a lot of 'extra' and 'duplicate' models.
.
Quote
glabelleI know the Nokta Fors CoRe is a proven performer in the nails. Therefore, assuming similar software was used in the Nokta Impact, I drug it out the other day to test it on nails. Using the 7-1/2"X4" DD coil, it passes all of the tests except the parallel nail test. (see attached pic. for detail) (The stack of silver was not tested, since I don't have one....yet 
• Yes, the Nokta CoRe does a great job in Iron nails, but keep in mind, there is a lot more ferrous debris to contend with other then only Nails.
• Just changing the size
(thickness and diameter) of the Test Target can make a lot of difference. When I first got the Impact test unit Pro Pack it came with the 4X7½ DD coil. It worked for urban Coin Hunting, but was unacceptable when taking on some challenging tests. At the time, I had been using different coins on my
Nail Board Performance Test, and changed the coin to an 1836 Capped Bust Half-Dime I found in my favorite ghost town. The Half-Dime is half the size of a regular Dime, making it much thinner and narrower across than an Indian Head Cent. The Impact w/ 4X7½ DD was a terrible performer!
Because of that test that was published on a Forum, Nokta design engineers made a 5" DD that would work on all three Impact Frequencies. The result was a combination that then worked about on-par with the Nokta Relic w/5"DD, going 7-out-of-8, and those two were
slightly edged-out by the CoRe w
/'OOR' DD hitting 8-for-8..
• The 'short-stack' of Silver Coins I use, 5 Silver Halves on top of 1 Silver Dollar, can be duplicated pretty much by 2-Silver Halves on top of 2-Silver Dollars. There are a LOT of detectors that will not hit on it well, or at all, and that includes most of the Simultaneous Multi-Frequency detectors when used in their M-F function. Some don't produce a good, clean hit or they might give a fair audio response, perhaps a little broken or choppy, but the visual TID is terrible and reading Iron. Some models won't give an audio OR a visual response at all.
Oh, and if you don't think you will ever encounter a small 'stash' of coins like that, then forget about hunting old home sites, out-buildings, barns, cellars, etc., etc.. In Portland, before they had an I-205, they had to vacate people from all their homes and property to clear the way for construction. Some places dated to the latter 1800's and some newer, but the bulk of them seemed to fit in that 1910 to 1940 era and not only did their removal provide a lot of really good Coin Hunting opportunities, but those before, during and after Depression era places held a lot of 'stashes.' But huge 'caches' of which there was one I definitely know about, but the smaller-quantity 'stash of money' people had because they didn't trust banks. I came up with three 'stashes' and I'm sure there had to be others as well.
Quote
glabelle
I believe it failed for the same reason the EQ800 fails - the DD coil. When passing vertically over this arrangement, the blade like field emanating from a DD coil simply picks up too much iron to respond to the coin. Its pattern would encompass BOTH nails in this vertical pass. Works fine, swung in a horizontal side-to-side direction.
By 'Vertical' you mean 'Lengthwise' on the Nails and 'Horizontal' you mean 'Crosswise' to the Nails?
Quote
glabelle
So I put the 7" concentric coil on the Impact. Passes the test! The more pointed "cone" field shape can get in between the nails to see the coin.
You're talking about sweeping the 7" Concentric
across the Nails or
with the Nails?
Quote
glabelleThe EQs as of this press time do not have a concentric coil available. Too bad. This rules out the EQs for ghost towns, for me. I still think it may be the best park/school/grass detector out there. Given a small concentric coil, the EQs would pass the test, I'm certain. On the stack of silver test, the EQ sounds off as "can slaw", or like a bottle cap. Not a problem - switch to 10KHz and it reads good - a known trick. I wouldn't expect to run across a lot of silver stacks anyway 
• I'm not so certain the Equinox would be better for a ghost town with heavy Iron contamination with a Concentric coil or not. It's how they behave and that's a circuitry design issue. I would guess, however that it might work better if taken out of Multi-IQ and used with a single selected frequency.
• I'm sure the Equinox will work OK in fringe-areas or parts of ghost towns that are not heavily littered with ferrous discards. It's just that most of the old RR townsites and mining era ghost towns seem to have more trashy spaces than they do cleaner spaces. I determined in shot-order than the Vanquish has its limitations for really serious ghost town used compared with the much better iron handling models.
As I adjust my Detector Outfit and do more thinning out, I know I have 4 models that are my dedicated, dense Iron Relic Hunting tools. Then I have my 4 models to serve as urban Coin Hunting units. In both cases some can be used for the other tasks, but have their strengths in the category I assigned them to.
Monte
Hey, for anyone, here's a quick question: Not as a Relic Hunting device but for a Coin Hunting model in urban sites, we can encounter Iron Nails fro where buildings were built, or torn down, or have burned down. Just looking at the list above I showed for taking on the 1-Button-Front and 1-3½" Nail you will see models that have a Concentric coil mounted:
Fisher F44 w/7" Concentric coil @ 7.8 kHz
Makro Racer 2 w/7" Concentric coil @ 14 kHz
Nokta / Makro Multi-Kruzer w/7" Concentric coil @ 14 kHz
Nokta / Makro Anfibio Multi w/7" Concentric coils at 14 kHz
Teknetics Omega 8000 w/7" Concentric coils @ 7.8 kHz
Tesoro Bandido II µMAX w/6" Concentric coil @ 10 kHz
Tesoro Silver Sabre µMAX w/6" Concentric coil @ 10 kHz
White's modified IDX Pro w/6½" Concentric coil @ 6.59 kHz
White's XLT w/6½" Concentric coil @ 6.59 kHz
Can you guess which of these might have provided the best audio response and why?
"Your EYES ... the only 100% accurate form of Discrimination!"
Stinkwater Wells Trading Post
Metal Detector Evaluations and Product ReviewsI'm now located in Clyde, Texas monte@ahrps.org ... or ... monte@stinkwaterwells.com 325-481-8147Detector Outfit: A selection of my favorite makes and models, with the best coils mounted, for the tasks I'll take on.Pinpointers: Pulse-Dive & ProPointer AT .. Headphones: 'Hornet' & 'Wasp' .. MS-3 Z-Lynk .. N/M Green edition*** All working well today to make memories for tomorrow. ***