For Monte

[RLOH]

Monte, I read all of your posts about detectors I own or have owned and am interested in your opinions about coils. You advocate concentric coils for your style of detecting. You might just be the most knowledgeable person on the forum when it comes to technology and many including myself respect your opinions about coils usage. It seems that most mid to high end detectors are now coming with dd coils as the stock coil. It might appear confusing to a new detectorist to why these big companies would have a DD coil as their stock coil. Many companies don't even offer a concentric coil for their high end detectors. Is this practice going to be the "wave of the future"? I am not trying to "stir the pot", but it continually confuses me to why your opinions differ from the manufacturers. Many of my detecting friends seem confused by what we are buying and what you are saying. Personally, I can use either kind of coil with like results. R.L. Johnson

 

[Monte]

Monte, I read all of your posts about detectors I own or have owned and am interested in your opinions about coils.

If you read all of my posts then you're putting in a lot of reading time, and in many of my posts related to search coil selection I often add one or two important considerations. The primary one is that we also have to consider the detector the coil is affixed to and the electronic circuitry engineering designs and available in-the-field performance. Some search cloil designs are pretty good, but mount them to a detector that lacks the right design and performance and the results are a let-down.

The reverse it true as well, and you can pit a coil on a very well designed detector and experience more negative results than with a comparable size coil of a different internal design. When I work with any detector that interests me for my personal arsenal, I make sure I evaluate both the detector and the available search coils that seem to be a 'fit' for my site selection challenges. If a detector doesn't provide the level of performance afield that I want, it's gone, and the same goes for any search coils that I check out.

You advocate concentric coils for your style of detecting.

That statement is not 100% correct. Yes, I do like the performance of many Concentric designed search coils over some comparable Double-D designed search coils as far as they perform on certain makes and models of detectors, and in the very iron trash older places I tend to search.

My 'style' of detecting is to research and locate older locations to hunt. Most of them are non-urban, such as pioneer or military encampments, railroad siding and depot sites, stage stops, logging and gold mining camps, old recreation/resort sites, homesteads, and especially old town sites. Of the latter, my preferred ghost town locations are void of most structures and often not easily observed to the glancing eye. Also, they are towns that had significant activity during their hey-day and when you consider the amount of commonly lost and discarded trash and the nails that remain due to structures that decayed, were torn down or destroyed by fire, the amount and density of iron junk and nails poses one of the biggest challenges.

I started hunting these old sites with my first ghost town adventure with my older brother, Ed, on May 4th, 1969 when we were armed with White's BFO's. In '71 to '74 I did have a Garrett Master Hunter BFO in my arsenal, but my primary-use detectors were White's, Garrett and Compass models all of the Transmit/Receive design. Some used a 'Triplet' labeled coil and other names, but I had a lot of success in both my urban Coin Hunting and out-of-town Relic Hunting with some of my favorite Compass models. Those were non-Discriminating units and they were designed with different sizes of Double-D Coils.

That was mainly Don't search coil idea that helped Compass get up and going with, but they had to go with a different search coil design to get better performance from their TR's once they incorporated Discriminating circuitry. Why? Because a DD design didn't work well when it came to processing signals in Discrimination. But the Compass DD designs still live on with those who own and use some of those early conventional TR Compass detectors. I have two in my personal arsenal, both up-and-running as I keep batteries in both of them for periodic use. They are my Coin Hustler w/6" DD coil and 99B w/8" DD coil.

Looking back to the '70s, I used my DD equipped Compass models quite a bit, even though I owned many different makes and models during they fast-paced growth of the metal detecting hobby. Fast paced referring to the era of rapid interest and growth which pretty much peaked in the early '80s and hasn't been like those earlier times since. There were quite a few different or interesting search coil designs [size=small](referring to the inner windings of the Transmit and Receive coils)[/size] until we reached the late '70s and early '80s when we pretty much setting on a 'Coplaner' design which morphed into the 'Concentric' coils we refer to today.

Most manufacturers had discovered that a Concentric designed search coil seemed to perform better than a Double-D designed coil as we progressed with models that featured Discrimination, which was also during the progression that lead to hobby detectors that featured Ground Balance. Concentric coils also provided some improved depth of detection over comparable-size DD coils and that appealed to many early and avid Relic Hunters who were in search of objects that they thought might be located deeper or were perhaps larger-sized.

DD coils were seen very seldom on most hobby-based metal detectors. Even during the start of the "Electronic Prospecting" era with the gold rush in Australia and here in the USA, most detectors used Concentric search coils. That was also in an era when many makes and models had gone to the lower-end of the VLF range with models operating in the ±1.75 kHz to 7 kHz range, or some working higher at around 15 kHz.

More attention was being paid to the operating frequencies than search coil design, I believe, and it was an era [size=small](from about '77 to '85 or so)[/size] when it was popular to think that the models operating around 15 kHz were better for gold nuggets, gold jewelry and other lower-conductive metals, and those that worked down around 5 to 7 kHz better at handling 'bad ground' and being more responsive to the higher-conductive targets such as copper and silver coins.

We also saw the introduction of Coin Depth read-out on hobby detectors, then the progression to visual Target ID and then audio Tone ID. All those earlier detectors that worked so well for almost everything we did came equipped with a Concentric coil. Some Double-D coils were also offered with some brands or for some models during that period. but Concentric coils ruled. Then we had a spark of creativity with the move to slightly higher VLF detectors designed more specifically for Gold Nugget hunting, such as the Fisher Gold Bug, that came with a DD coil. The DD was promoted as being better for hunting in more mineralized ground as well as having a wider-scan coverage on the side-to-side sweep that might help when searching wide-open areas for gold nuggets.

Not all gold nugget detectors used only DD coils. The LF Fisher Gold Bug II, operating at 71 kHz, used elliptical-shaped Concentric coils, and has been known to be an excellent performer on the tiniest-sized gold nuggets. I believe credit should be shared between the higher 71 kHz operating frequency as well as the choice to design it to use Concentric search coils. The Tesoro Lobo also had Concentric coils as well as DD, and I did better with it in any hunting application when a Concentric coil was mounted.

For what it's worth, I have used many makes and models of detectors as well as both DD and Concentric search coils when I have hunted gold nuggets in several western US states, and while I am not the most avid Gold Nugget Hunter, I have enjoyed my best success using detectors in the 10 to 14 kHz range, and with a Concentric coil mounted. It still boils down to matching the detector design and coil design with the settings used.

You might just be the most knowledgeable person on the forum when it comes to technology and many including myself respect your opinions about coils usage.

I thank you for the kind comments. I won't claim to be the 'most knowledgeable' person on the forums as I know I enjoy looking for and reading reports and replies fro several others who are also knowledgeable. I think the key to my and my comments and postings is not just knowledge, but the experience I have that has helped me gain the level of smarts I might have.

I am wrapping up my fifty-first year of detecting and start on number fifty-two the first of March, and I have had the pleasure of being able to work with quite a few manufacturers, starting in 1974, to evaluate prototype units, review some testing of product revisions, and work with and for a couple of detector makers. I have also enjoyed many discussions with detector engineers over those decades, and many people involved in the marketing end of their business, which has given me a better understanding of what is happening in the industry, and that includes their personal thoughts and business thoughts with regard to search coil selection.

Most design engineers never get out detecting, or certainly not nearly as much as I do, or other avid detectorists. That's why they rely on some of us to do evaluations of prototype units for them from different areas and environments .... and harvest different points of view. I do know three engineers who are more involved in hobby-level detecting and most of the time they select a Concentric search coil to use on their personal detectors.

It seems that most mid to high end detectors are now coming with dd coils as the stock coil. It might appear confusing to a new detectorist to why these big companies would have a DD coil as their stock coil. Many companies don't even offer a concentric coil for their high end detectors. Is this practice going to be the "wave of the future"?

This 'wave' has been splashing on us for roughly fifteen years now. If you look back to about the latter 1990's to 2001, most detector makers produced Concentric coils as standard ion their detectors, and some offered while others didn't a Double-D coil as an accessory option. Maybe only the Gold Nugget hunting models really fashioned a DD coils standard.

But it was about that time that big $$$ showed up with a Minelab Sovereign that only had a DD coil, and that BBS unit was followed by the FBS Minelab Explorer with a DD coil design, and the race was on. They used a 10" round DD coil, while most makers offered 7" to 8" to 950 labeled Concentric coils. Yes, DD coils had been around a bit but that really [prompted a surge in both marketing mumbo-jumbo and general interest in search coils. Both the coil type and coil size started to confuse many average hobbyists ... and it continues to do so to this day!

A simple check of many forums or the advertising the detector makers put in magazines and other ads is what I believe has drawn so many of them to start featuring a Double-D coil design as standard, and all too often the coil is also over-sized for the detector, the type of applications it might be intended for, and the novice or less experienced user who will buy into the marketing hype and get such a contraption.

I am not trying to "stir the pot", but it continually confuses me to why your opinions differ from the manufacturers.

The manufacturers opinions are to sell, sell, sell and make a profit, cut into the market better than their competitors, and try to live fat and happy. Most of the detector company owners, marketing staff, sales staff, and assembly crew do not detect at all, or they get out detecting very little, and most of them have no clue what the more avid detectorists out here in the real world are dealing with and what we really want or need.

My opinions are based on over five decades of owning and using metal detectors, evaluating them and various search coils, in a wide range of hunting environments and some very tough challenges. Things like dense, tangly brush, building rubble, a variety of trash conditions to include especially dense iron debris. I need ample adjustment functions, especially good operator control not just preset, and I want good Ground Balance control, quick-response and fast-recovery ... to include Discrimination processing ... and search coils that allow me to work in a slow and methodical method to pull keepers out of a lot of potentially masking junk.

I also want the detectors to be Simple, Functional and have Performance to satisfy me, and the coil choice is a vital part of that pick. My goal is to get out and hunt the sites I prefer and to find oood stuff and go home happy. The weight issues I have already taken care of.

Many of my detecting friends seem confused by what we are buying and what you are saying.

What I say is pick the detector and coil you feel best suits the types of sites you hunt, and then learn the detector and coil performance well. That let the operator be in control of the settings and search coil presentation for the challenges they face.

Personally, I can use either kind of coil with like results. R.L. Johnson

I can put you in several ghost towns I have hunted since '69 where you can use one detector and switch between a Concentric coil and Double-D coils, and you will NOT get like results between them.

I use both, based on the detector and what the manufacturer has offered that works well where I want to search as noted below. I have DD coils on my Racer and FORS CoRe, a 5C10 Concentric on my FORS Gold+ with DD coils back-up, and a 6" Concentric on the Tesoro's. All of them work, and work very well and out-perform the competition in sites I select most often.

Monte

 

[Des D]

"Monte,

Many years ago Minelab received a New Concentric coil from "an after-market" manufacturer to try out...

In my hands and mounted at the time on my Sov XS 2a, it was A HUGE HIT...many small / thin / low conductive items...

Minelab "never bothered" with CC coils until I got them to consider a NEW line of "fast-use light models"...and we got the X-Terra..."

Des D

 

[Monte]

"Monte,

Many years ago Minelab received a New Concentric coil from "an after-market" manufacturer to try out...

In my hands and mounted at the time on my Sov XS 2a, it was A HUGE HIT...many small / thin / low conductive items...

As we know, their BBS and FBS series were designed with, and I guess you might say for, the use of DD coils as that was what they wanted to use. I had an aftermarket 8" Concentric coil I used on a couple of Explorer's [size=small](an XS and a II)[/size] and for the urban sites I hunted it worked quite well. Well enough that I used it for maybe 90% of my FBS hunting during that time.

I wish I had a Concentric to have tried on my Sovereign XS 2a because that was one Minelab model I really liked out of all the Sovereign and Explorer [size=small](FBS)[/size] models. Too bad the Sovereigns went by the wayside with all the emphasis on the other multi-frequency model efforts.

Minelab "never bothered" with CC coils until I got them to consider a NEW line of "fast-use light models"...and we got the X-Terra..."

Des D

Glad you called some things to their attention. When I was sent the pre-release Minelab X-Terra 30 and 50 I was not only happy to have a lighter-weight detector in-hand, but also liked having the Concentric coil. The 30 didn't handle the high mineralized ground where I lived at the time, but the 50, with manual GB, worked pretty well. When I was sent an X-Terra 70, it quickly won out over the 50 due to more GB range of adjustment and a broader Disc. range .... but still used the Concentric coils that worked better for me than the DD designs.

In about a week or so I should be on the road and heading to some warmer and driers locations to work with a few new detectors, both for nugget hunting and relic hunting, and I'll compare the Makro Gold Racer and Nokta FORS Gold+ with a mix of DD and Concentric coils against my FOES CoRe which only has DD coils. After shoveling another 2" of fresh snow this morning, warmer and drier places are definitely drawing my interest ... regardless of coil type.

Monte

 

[JJdigs]

Love the great read Monte !

 

[RLOH]

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