The first thing to explain is that not all iron is the same. Iron targets, as we consider them, are man-made objects of various sizes and shapes, so it is not only the ferrous content that we have to deal with. Although iron metal is a lower conductive product, the size and shape can add to the
conductivity and result in a target which can produce a response that reads higher than any indicated display or control knob adjustment that suggests an upper limit for iron. You can usually use a simple technique or two to easily 'classify' most of that type of high-reading iron in the motion Discriminate mode, both audibly and visually, but that is simply learning some detecting skills.
Another thing to know is that iron targets have a different effect on the electromagnetic field [size=small](EMF)[/size] than do similar size & shape non-ferrous targets. Many, perhaps most, of the modern-day motion-based Discriminators are used in that mode, not a conventional Threshold-based All Metal mode, so the operators often don't benefit from hearing some of the audio subtleties between ferrous and non-ferrous targets [size=small](especially smaller sizes like coins, buttons and bottle caps)[/size], plus most are designed as 'silent-search' operation and that can also inhibit some of the subtle audio we can hear between ferrous and non-ferrous objects.
Then we need to remember that some ferrous metals are easier to reject, such as a common iron nail which is all I set my Discrimination to deal with, while other types can be more challenging, such as rusty tin or the old crimp-edge bottle caps. Again, useful search techniques can help us audibly and visually 'classify' most of those pesky hunks of annoyance.
Metal Monster said:
Hello everyone. I am new around here and to metal detecting and have been going over the many informative post new and old throughout the forums to see if I could find an answer to my question but nothing found yet.
Welcome to the Findmall Forums and especially to the exciting hobby of metal detecting.
Metal Monster said:
I have a Garrett Euro Ace 350 and also have a Tesoro Vaquero on the way. Should be here by Friday.
Well, it is now Saturday so you should have your Vaquero in hand and have probably tinkered with it a bit. If you're newer to the hobby, there are some terms you may or may not know, so pardon me if I describe some along the way.
Your Garrett Euro Ace is essentially the European version of the Ace 350 here in the USA and comes standard with a bigger-size 8½" X 11" Double-D search coil. Some manufacturers use the term 'Wide Scan' which is the same as 'Double-D.' The Tesoro Vaquero comes standard with an 8" X 9" Concentric search coil. Since you asked about "Iron Discrimination," let me suggest that for any serious hunting in a very challenging iron littered site, a smaller-than-stock search coil of Concentric design will usually be the better coil selection to have in your arsenal.
Metal Monster said:
Anyway, my question is, does the Euro Ace have more notches of iron discrimination than the Vaquero?
'Notch' or 'Segment' Discrimination is found of some models, such as your Garrett Euro Ace, and provides pre-determined design amounts of Discrimination. The Vaquero doesn't have 'Notch' or 'Segmented' Discrimination, but a variable Discrimination control. I only have a couple of 'Segmented Discrimination adjustment model in my personal detector arsenal, preferring to have more operator control with a Variable Discrimination to help me fine-tune iron rejection [size=small](if the Discrimination control adjusts below iron nail acceptance)[/size].
Metal Monster said:
I just finish reading the book, "Mastering the Tesoro Tejon and Vaquero", and it seems to indicate that the Tejon has more iron discrimination than the Vaquero.
Tesoro detector models have used different ranges of 'acceptance' adjustment in the Discriminate mode. Older, early Tesoro Discriminators in the '80s had a more limited range that, at the minimum Disc. setting, would only be accepting the upper 90° to 100° of the target conductivity range. They worked well, but in some bad iron littered sites there was more target masking from using too much rejection, even at the minimum Disc. setting. Also, they had a little more challenge trying to respond to very low conductivity targets, such as thin gold jewelry like earrings or thin gold chains.
To address that, in 1990 Tesoro brought out their original Bandido and introduced a new Discrimination adjustment range that Jack Gifford called "ED-120." This described the Discrimination control's lower-end range as being
Expanded
Discrimination, and described it to include the upper 120° of acceptance. That meant it adjusted lower at the minimum setting. As such, models with an ED-120 Discrimination adjustment will adjust lower to accept more smaller and thin gold jewelry, but even at the minimum setting they are still slightly above most iron nail rejection.
Therefore, on models like my Bandido II µMAX or Outlaw or a Silver Sabre II or Silver Sabre µMAX, I never run the Discrimination control higher than the absolute minimum Disc. setting because I want to be as close as I can to just barely rejecting common nails. Tesoro also had some models, like the original Lobo or newer models such as the Eldorado µMAX, Euro Sabre, and even the little Compadre or the higher-cost Téjon, which feature a fully-expanded Discrimination called "ED-180." That means these models can adjust all the way down to a minimum setting that will accept ALL metal targets spanning the full 180° of acceptance. These are sometimes called All Metal Discrimination or Zero Discrimination as there is no target rejection, be it ferrous or non-ferrous.
Then there are some models that have a Discrimination acceptance range such that at the minimum Discriminate setting they are accepting roughly the upper 160°-165° range of conductive targets. That means the ED-165'ish models can be set below iron nail rejection and respond to nails and a a lot of iron, but are still rejecting at least some iron targets. This includes models such as the Vaquero and Cibola, Golden µMAX [size=small](pronounced microMAX)[/size].
Please pardon my lengthy explanation, but this shows why the Téjon, with ED-180 Disc. has more lower-end adjustment range of iron than the Vaquero with an ED-165 Disc. range, so 'yes' the Téjon has a little more Iron Disc. range of acceptance than the Vaquero. I will add, however, that due to more of the Low-Noise/High-Gain circuitry design used in many of their models since about late 1997, some of their models have a little noisier or raspier rejection handling that earlier models that had a cleaner iron rejection.
Metal Monster said:
I was thinking of selling the Euro Ace but I may just hold on to it for relic hunting if I have better control over iron. What do you all think?
I think the Euro Ace can work fairly well, but it is more limited in the way it processes and responds to higher-conductive targets, plus it has a factory preset Ground Balance and that can limit some performance in a challenging mineralized site. I would easily part with such a unit in favor of a detector that gives you a true Threshold-based All Metal search mode [size=small](the Euro Ace doesn't have it)[/size], plus the ability to Ground Balance the detector for peak performance regardless of the site environment. The Vaquero wins that decision, easily.
Now to review the replies you received from 'kimbershot' that I know left several people scratching their heads as I was contacted about it to explain. Here are his two posts with my comments.:
kimbershot said:
i have the stock, 5.75 concentric and widescan. most of the sites i hit are trashy--renders the widescan basically useless. my favorite is the 5.75--great on trash, very manuverable and depth is very good and excellent at pinpointing. one thing i noticed is that the 5.75's signal in the all metal mode also emits and receives it's signal parallel to the ground, resulting in threshold pitch change. when that happens--i shift the coil until i get a solid hit--then utilize the discrimination,
i dig a lot of signals just above iron (discriminates square nails) and dig a lot of junk--and some interesting relics.
'Wide Scan = Double-D.
In dense trash, especially ferrous junk, DD coils are "basically useless" compared with a similar-size Concentric coil because they do not handle iron rejection quite as well. You can also get a mixed response in such troublesome conditions.
The 5.75" or 5¾" coil actually measures right at 6", and I keep my 6" Concentric coil mounted full-time on my Outlaw. I am getting another 6" Concentric to use on a Bandido II µMAX, or some other Tesoro I might acquire, such as a Silver sabre II or Silver Sabre microMAX [size=small](µMAX)[/size]. This coil is light weight and very maneuverable in trashy and brushy condition, plus the depth of detection is very impressive and pinpointing with it is a exceptional.
His description of the EMF is a little off in explanation. He made it sound like a different 'signal' is sent out parallel to the ground, but you have one 'signal' or EMF. The EMF is an induced magnetic field that flows out and around the Transmit winding. Too often we see goofy drawing or hear folks say the DD 'signal' goes straight down and the Concentric 'signal' is shaped like a 'V' but those are both incorrect. The EMF is simply a field that radiates out and around the Tx coil. It is happening all the time.
The difference, however, is that in the All Metal mode you can hear subtle changes in the field from near-by target response, but usually in the motion-based Discriminate mode you don't. In that mode you usually need to have the search coil swept more directly over the metal target, thus the targets is in the stronger portion of the EMF and there is greater reaction for the Rx coil (receive coil) to process.
There is no Threshold 'pitch change'
unless you are operating in a VCO audio function. That can produce a variable pitch change. Without VCO all you will have is a loudness change. Often you will only have a VCO audio in a Threshold-based All Metal mode, but some makes and models do respond with a VCO audio in the motion-based Discriminate mode. Often I will hunt a more open site in a Threshold-based All Metal mode for the same reasons he related, and that is to hear even a subtle response from a target close to the search coil during a sweep that I was close to but didn't sweep over. Then you can redirect your sweep to pinpoint, switch to the Discriminate model and re-check the target using some rejection,.
kimbershot said:
the best way to describe what i am experiencing with my 5.75 concentric is to view metaldetectingworld.com and the article on depth penetration page 1.
my coil senses metal out to it's side and i hear slight changes in threshold (all metal). when that happens--i swing the coil and listen for the highest tone--(pinpoint).
another great article on the same site is "search coil secrets and tips"--it will show how a electomagnetic pulse might be influenced by a particular target--and that ties into threshold tone modulation.
again, i use the all metal mode and flip back and forth for target discrimination.
after reading the articles--i decided to dig more targets that hit above iron.
hope this helps. 
He basically explains what I broke down above, but I will caution that some sites you might be referred to still have errant diagrams of what an EMF is and how they describe the 'projected signal' of Concentric and Double-D coils. There is some other info at that site I disagree with and find in error, but that often comes from people picking up on the incorrect information early on and believing it. That happens.
Best of success with your Vaquero, and I hope you can find a 6"
Concentric coil for it for iron littered places.
Monte
