By Steve Herschbach
Which metal detectors have the most reliable target ID numbers?
Target ID is a function of depth - the deeper the target, the more difficult it is to get a clean target ID as the ground signal interferes. Other items directly adjacent to the desired target can also cause inaccurate numbers. The more conductive the item, the higher the resulting ID number, but also the larger the item the higher the number. Silver is more conductive than gold, so a gold item will give a lower number than the same size silver item. But a very large gold item can give a higher number than a small silver item, so numbers do not identify types of metal. Gold and aluminum read the same and vary in size so to dig one you dig the other. Only mass produced items like coins produce numbers that are more or less the same over the years but a zinc penny will read lower than a copper penny due to the change in composition.
In general iron or ferrous targets produce negative numbers or low numbers. Aluminum, gold, and US nickels produce mid-range numbers. And most other US coins produce high numbers. Other countries coins, like Canadian coins with ferrous content, can read all over the place.
The scale applied varies according to manufacturer so the number produced by each detector will vary according to the scale used. The 0-100 range for non-ferrous targets is most common but there are others. Minelab employs a dual number system on a 2D scale with thousands of possible numbers, but they are now normalizing the results produced to conform more closely to the linear scale used by other manufacturers.
Increasing ground mineralization has a huge effect on the ability to get a good target ID. Ground mineralization is nearly always from iron mineralization, and this tends to make weak targets, whether very small targets or very deep targets, misidentify. The target numbers get dragged lower, and many non-ferrous targets will eventually be identified as iron if buried deep enough. Small non-ferrous readings and iron readings actually overlap. That is why any discrimination at all is particularly risky for gold nugget hunters.
If you want target ID numbers to settle down, lower sensitivity and practice consistent coil control. The target number will often vary depending on how well the target is centered and how fast the coil moves.
Higher sensitivity settings lead to jumpier numbers as the detectors become less stable at higher levels. The interference from the ground signal increases and interference from outside electrical sources also increases, leading to less stable numbers.
Higher frequency detectors are inherently more sensitive and are jumpier. So lean lower frequency for more solid results. Multi frequency detectors act like low frequency detectors and tend to have more solid target numbers due to the ability to analyze a target with different frequencies.
Another issue is the number of target categories, or ID segments, or VDIs, or notches, or bins (all names for the same thing) that a detector offers.
For instance here are the number of possible target id categories or segments each detector below offers:
Fisher CZ-3D = 7
Garrett Ace 250 = 12
Minelab X-Terra 305 = 12
Minelab X-Terra 505 = 19
Minelab X-Terra 705 = 28
Minelab Equinox = 50
Fisher F75 (and many other models) = 99
White's MXT (and many other models) = 190
Minelab CTX 3030 = 1750
Fewer target categories means more possible items get lumped together under a single reading, but that the reading is more stable. Many detectors will tell you the difference between a dime and a quarter. The Fisher CZ assumes you want to dig both so puts them under one segment along with most other coins.
People who use detectors with many target numbers usually just watch the numbers jump around and mentally average the results. Some high end detectors can actually do this averaging for you! But I think there is something to be said for owning a detector that simplifies things and offers less possible numbers to start with. The old Fisher CZ method still appeals to me, especially for coin detecting. So do detectors like the Garrett Ace 250 or Minelab X-Terra 505 for the same reason.
The problem is that as people strive to dig deeper targets or smaller targets the numbers will always get less reliable. But if you want to have a quiet performing metal detecting with solid, reliable target numbers look more for coin type detectors running at lower frequencies under 10 kHz or at multiple frequencies and possibly consider getting a detector with fewer possible target segments. And with any detector no matter what just back that sensitivity setting off and you will get more reliable target numbers.
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Detectors often use tones to identify targets and often use far fewer tones than indicated by the possible visual target id numbers. The X-Terra 705 for instance can use 28 tones, one for each segment. However, most people find this too busy, and so simple tone schemes of two, three, or four tones may be selected. I think it is instructive that many people often end up ignoring screen readings and hunting by ear, using just a few tones. This ends up just being an ultra simple target id system much like the simpler units offer. Reality is that most people do not need or care about huge numbers of target numbers. For many just three ranges suffice, low tone for iron, mid tone for most gold items, and high tone for most US coins. The meter could do the same thing, but for marketing purposes more is better and so we get sold on detectors with hundreds of possible target ID numbers. Perhaps that represents a digital representation of an old analog meter with its nearly infinite range of response but the reality is we do not need that level of differentiation to make a simple dig or no dig decision.
Finally, a picture often says it all. Below we have a shot of the White's M6 meter. I like it because the decal below illustrates a lot. You see the possible numerical range of -95 to 95 laid out in the middle. Over it is the simplified iron/gold/silver range. Note the slants where they overlap to indicate the readings really do overlap. Then you get the probable target icons. -95 is noted as "hot rock" because many do read there.
The M6 can generate 7 tones depending on the target category. I have added red lines to the image to show where these tones sit in relation to the scale. It breaks down as follows:
-95 = 57 Hz (Very Low) Hot Rock
-94 to -6 = 128 Hz (Low) Iron Junk
-5 to 7 = 145 Hz (Med Low) Gold Earrings, Chains - Foil
8 to 26 = 182 Hz (Medium) Women's Gold Rings/Nickel - Small Pull Tabs
27 to 49 = 259 Hz (Med Hi) Men's Gold Rings - Large Pull Tabs
50 to 70 = 411 Hz (High) Zinc Penny/Indian Head Penny - Screw Caps
71 to 95 = 900 Hz (Very High) Copper Penny/Dime/Quarter/Dollar
Note that the screen reading of +14 is noted as being a nickel or ring but it can also be the "beaver tail" part of an aluminum pull tab or the aluminum ring that holds an eraser on a pencil, among other things.
The best book ever written on the subject of discrimination is "Taking A Closer Look At Metal Detector Discrimination" by Robert C. Brockett. It is out of print but if you find a copy grab it, assuming the topic interests you.
Always remember - when in doubt, dig it out! Your eyes are the best target ID method available.
Disclaimer: I've only really been interested in Gold hunting so I'm pretty clueless in using my Nox for jewellery hunting.
This might be a challenging one, a farmer I knows wife lost her wedding ring in a paddock and didn't realise, Later the same day they run a plough or some sort of farming gadget over the paddock as they planted it out with grass seed so the ring is likely buried. They're pretty certain it was lost in this paddock.
I have been recruited to try find this ring, it's 24k gold with about 20 diamonds on it. The guy originally gave me the wrong description of the ring, probably his ex-wife's ring he described as he said it had 1 diamond and sapphires 😄
The paddock is really junk filled, I went and swung my detector over it yesterday morning before skiing and there was iron I assume setting the detector off everywhere in all metal mode.
I know the VDI numbers are extremely useful for coin hunting but will they help for finding this ring, I really don't want to have to dig everything! Is there a range I should be targeting? I assume Field 1 will be the best mode or maybe Park 1 seeing there is a lot of junk?
Small gold when prospecting always comes up under 10 on the VDI's, I am guessing a ring will come up higher?
Would the Equinox be my best choice or would I be better off using my T2 with Mars Tiger 10x13" or 15" round Stock T2 coil for more ground coverage? I also have a Garrett Euroace with Nel Tornado 12x13" I could use if that would be best. That's the biggest coils I own.
I have a GPX 4500 with a 15x12 DD Commander I could use but I don't want to dig lots of junk and I was hoping VDI's would be useful.
I told them I'd do the hunt for nothing when they tried to pay me as it's a bit of fun for me anyway but they said they can't allow that and they'd give me a few sheep for my freezer for my efforts even if I don't find it but I'm sure if I find it they'll force me to take some sort of payment, I will try refuse as I really don't want it but it will be difficult to not take it when they're forcing it....
The paddock is about 3 hectares!!!!! Just over 7 acres so I really have a job ahead of me. The soil is extremely mild but it seems to have its share of junk. I assume rusty old nails and tractor bits and mower blades whatever else over the years.
Any help appreciated.
The following is a compilation from my Rutus testing and useage.
Very long, but anyone wanting some info, this here may help folks.
Btw to my knowledge currently no dealers for this detector line in USA.
They can be purchased from abroad.
The Rutus Alter 71 may not be very well known, but make no mistake a very good detector for what they cost.
There is some comparison info too with other detector models.
Overall weight and feel of unit is IMO nice,,not heavy feeling.
Btw. Concentric measures 8.125" outside to outside diameter.
Supposed 11" dd measures 11".
I even with little time I have run this unit,,this unit designed to be a Deus killer for the $$$. Question is, is it??
Using concentric coil user likely not to dig steel bottle caps, hodograph paints a good pic of junk target,,a backwards C in the meter. Haven't tried DD coil yet to see what happens here.
Depth is dependent on mask setting,,meaning for fringe depth the lower the better.
Interesting how they gave a user options here to have their targets ID in the meter.
Three choices real-- ID is directly reflective of frequency run and conductivity of target.
Then 2 other options,,you can select either 6khz or 12khz for target ID normalization.
So with saying all this here is some data using each of the above selections for target ID.
I should say the Rutus uses a different scale when comparing to most other detectors-- 0-120.
Real ID option selected and frequency selected on detector at max 18.4khz
Normalized setting of 6khz selected,,detector still set to 18.4khz
Normalized setting of 12kh selected,,detector still set to 18.4khz
Frequency changed on detector to 7khz,,real ID option selected
Frequency still at 7khz,,6khz normalization selected
Frequency still at 7khz,,12 khz normalization selected
Preliminary test using 3D test with coin and nails,,detector seems above average with what I see,,,Deus like results,,,not giving either detector yet no advantage,,with time maybe.
Audio,,,Rutus audio not as smooth as Xp Deus,,not as blendy sounding,,leans more toward what I call beeps. This is not meant to say Rutus audio is terrible or anything.
I am still trying to nail down how I want my tones set up using the user programs,,,not there yet.
Does take time though,,user must select each number TID wise and singularly adjust,,,no blocking of groups of tones to adjust.
I do reserve the right here to correct anything I say about this detector in the future.
From what I can tell right now,,Rutus will retain settings when turned off.
Turn back on,,user will need to ground balance though.
Also what ever you have selected,,this is where the cursor will be when you go back in and open menu-- not sure if this happens if you turn detector off though.
Now,,here is where other manufacturers like White's should be paying attention,,Xp as well.
I have read countless Internet forum threads and post associated with just when does the White's V3i and even the Vx3 model need to be ground balanced.
Rutus depending on what you change setting wise will give you ground balance prompt.
This is exactly what White's should have done on the 2 models I mention here.
Xp Deus,,you change freqs,,ground balance doesn't carry over,,should be a prompt..
Now detector companies,,if they do this for future models,,,they could offer a way to override the prompt,,so it doesn't appear in screen. This might be more handy for someone say who is more experience with the detector in question.
Emi,,this detector ranks right up there as being one of the quietest I have run for Vlf,,,even runs as quiet IMO as CTX and etrac,,and DST Fisher units.
Now this from judging in 2 different places with loads of light wires,,and a few transformers.
I should also say,,this concentric coil I received with Rutus is the very first one I have ever owned,,I did run a gents White's XLT with concentric some 6 years ago for around 15 minutes.
Navigating around using Rutus is different,,but not hard,,just gotta get used to it.
Unit seems to ground balance nicely here in my soil.
More to come.
are starting to heat up. I spent a couple hours at the sand bar this morning and managed a couple pieces. Nothing to brag about as the stones in the ring are CZ's. The hoop earring is silver plated. There were 3 other hunters out and their finds were meager as well with only one gold ring being reported at this spot so far.
The wire mesh I had welded in the scoop worked a dream. The earring back in the pic is just one of many tiny bits it captured saving a lot of time. 😉
It really felt good to get out and get started on this years "crop"! 👍
By Mike Hillis
Hunting tiny gold jewelry in inland sites is just so different from mainstream detecting methods that unless you do it you don't understand the requirements.
#1. EMI stability. Your detector has to be stone cold stable. No spurious noise. None. The signals you are after are small tight signals and you can’t hear them if your detector is making spurious noises.
#2. The detector needs to be able to keep its HOTs at low gain/sensitivity settings because:
a... You need to be able to focus on the right depth of signals and those tiny signals are not deep. Most of the time they are just down in the grass roots. You want to focus only on the top three to four inches of depth. If you have to run your sensitivity at or near max all you are doing is masking the desired signal response with reports from all the other signals surrounding it and below it. And in cases where the ground minerals are high, the ground itself will mask the response.
b... You need to control the coil foot print. In this type of hunting you don’t want coil edge surface responses. You only want to hear what is directly under your coil. Concentric coils work better at this than DD coils. DD coils are ok but you get better footprints with concentric and tighter readings on your meter.
#3. The higher the operating frequency, the more important the above become. As the operating frequency goes up, the level of discrimination goes down because the trash targets hit harder and sound better. In other words, the higher the operating frequency the better the trash sounds and responds.
#4. Notch discrimination or some other form of discrimination that will allow you to focus just on the signal range you are hunting. The only range of signals you are interested in are in the ferrous/non-ferrous boundary range and the foil range up to maybe the nickel reading. All other signals are distractions.
I'm editing to add a number #5. Tiny signal audio boost is a big plus if it can be deployed while keeping original signal response integrity.
I'll close with this.....You can take a gold prospecting unit onto a woodchip playground or a sand pit and as long as it can handle the EMI you can hunt with it on normal settings. But if you are targeting sites where good quality, tiny jewelry is most likely to be present, you will be working a lot of turf sites where a prospecting detector's normal feature set isn't going to be very helpful.
By Randy Dee
This post is mainly directed to UK field detecting where we have had social open air gatherings since Medieval times and on fields littered with coke. I used these settings yesterday and I was hopeful of finding at least one gold necklace / chain but alas none, better luck next time.
As most of us know it is almost impossible to find a fine gold chain with any metal detector and as it is a long story why but mainly due to Eddy Currents and the metal detector rejecting coke which fits into the same frequency range as thin and fine gold and as here in the UK we find our permission fields littered with coke which mostly emanates from the days of steam engines powering farm equipment and the spreading of night soil as a crop fertilizer and which was collected from house middens and where the ashes from the household coal fires was used to cover the stinking human excrement, these ashes contained large cinders which survive for donkeys years in the soil and give off wonderful signals for metal detectors.
This information on how to adjust the Tone Breaks to enhance the chances of finding gold chains during field detecting is only applicable to the Minelab Equinox 800 as it has the advanced settings capability.
To alter the "Tone Breaks" it involves making changes to three "Target Tone Dependencies" which are "Number Of Target Tones", "Target Pitch" & "Target Volume".
Here is my effort to change the settings to cover the frequency conductive range to give off a signal from thin gold chains in the discrimination zones, at present the default Discrimination zone is -9 to +2 and it is the Zero to +2 segment where gold chains show.
So first of all select either "Field 1 or 2" your choice.
Then go to "Target Tone" choose 5 tones.
Then go to "Tone Breaks" and set the 5 tones as thus T1 = -9 to 0, T2 = 1 to 2, T3 = 3 to 28, T4 = 29 to 38, T5 = 39 to 40.
Then go back to "Tone Volume" and set tone segments to T1 = 1, T2 = 15, T3 = 25, T4 = 25, T5 = 15.
Then go to "Tone Pitch" and set the tone segments to T1 = 1, T2 = 15, T3 = 25, T4 = 20, T5 = 16.
To move from from one tone segment to the next segment use the "Accept / Reject" button ( \//x ). These settings are working for me but then again they may not be every-bodies cup of tea.