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Adjustable Tone Break


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Like many nugget hunters I cut my teeth in this hobby on PI machines. If it beeps you dig it. As time goes on we may not have the physical attributes we once had. I know if I dig 6 DEEP nails I am about done for awhile with the PI. I am likely to start using a VLF if one is handy (or take a nap LOL).
 
The Question is- which VLF to grab?  Every detector has certain attributes that make it more or less attractive for nugget hunting. I had been pondering this subject because I was contemplating buying another detector, specifically a Notka Fors Core. I need another detector like I need a hole in my head but I just like detectors and find them interesting.  Recently I sold my MXT to my Brother-in-law  so he could start coin and relic detecting,  so I have room in the RV for a new detector. I hardly used my MXT as I would grab either my Deus, GBII, or GB Pro along with my GPX  depending on what I had in mind for the day. Frankly, the MXT is just too heavy when there are light weight alternatives available.
 
So let's talk about my  possible purchase. I had a laundry list of features I hoped to get. Light weight, dependable, VID in All-Metal Mode, fast target separation in trash, and adjustable low tone break. I would love to have accurate VID in hot ground but that's just wishful thinking. I have been closely following the informative discussions on this forum started by Steve H. and on the Nasa Tom forum posted by some smart coin and relic detectorists about tone breaks, target separation, target masking and mineral degradation of targets. What is sticking in my mind is the adjustable low tone break. Just how important of a feature is it for nugget hunters? Obviously not very important if you only hunt in All Metal when using your VLF. Myself, I love to hunt around the old habitation sites and mines in gold country. A lot of times these are the only areas that have not been beat to death due to the extreme amount of trash. Plus I enjoy finding old coins and relics right along with the gold, it's all treasure to me.
 
Due to the amount of trash around most of these sites All Metal Mode even with a VID on the screen is not my preferred option. I just do not enjoy detecting with eyes glued to a screen  so a mode with two tones is my choice. But we know that gold co-located with ferrous or small gold in hot dirt can read down in to the ferrous TID range. So we need to adjust our low tone break somewhere into the upper ferrous range to ensure we don't miss co-located or deep gold.
 
 If the detector you have purchased does not have an adjustable break point and is factory set at ferrous/non-ferrous how much gold will you miss because it gave a low tone on those nuggets in the midst of trash? Or the DEEP nuggets at the fringe of detection in hot dirt? I do not think we can answer that question in a quantifiable manner but we should be aware that it is occurring. How high should we put this feature of adjustable tone break on our laundry list of detector attributes? How much will it drive up the price of the detector to get it?
 
By thinking about the tone break and weight issues I believe I  talked myself out of buying a detector and saved a grand. LOL The Notka is kind of heavy and does not have adjustable tone break to my understanding from reading the manual. If I am mistaken please correct me. I may have to wait for Notka's promised PI before purchasing from them.
 
Obviously I  put the Tone Break Issue near the fore front of my desirable attributes I would like to see a VLF have. I may just have to stick with the GB Pro and the Deus as my VLF nugget machines for now as they both have that feature. There must be other mid-frequency detectors with adjustable Tone Break, is the CTX one?
 
Merton

 

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I prefer to hunt dual tone when using audio discrimination for a ferrous/non-ferrous decision. That feature should be adjustable for the reasons you have described. Off the top of my head:

Fisher Gold Bug
Fisher Gold Bug Pro
Fisher F19
Minelab CTX 3030
Teknetics G2
White's MXT versions (not MX5)
White's V3i
XP DEUS

There are more of course but these are the more familiar. You have two at least that are on the list so you are set.

A nice feature I am craving is the ability to adjust the volume of the ferrous response, also called iron volume. Not the overall volume, just the ferrous. This is nice because in heavy trash there is a barrage of ferrous noise and turning it down while still having a loud non-ferrous response would be nice. The DEUS allows for this as does the Fisher F19

Two models I have that do not have the adjustable break are the non-upgraded F75 and the Nokta. Of the two the Nokta has the better preset tone break. The FA Mode of the upgraded F75 addresses that somewhat plus adds iron volume, but in either case you are stuck with what the factory has decided is best for the ferrous break point. Not the optimum solution but then again it can work.

No matter what machine you use there has to be a point you choose where the target VDI tips between ferrous and non-ferrous. No matter where that may be, and especially on factory preset models, you always want to try and put the signal in context, and if you are ever suspicious, investigate further. This is why I prefer to hear a ferrous signal as opposed to just having ferrous signals totally blanked out. You know they are there and can maybe decide you want to dig it anyway. If the detector never alerts you to the target in the first place that opportunity is missed. With factory preset models you may simply have to know to investigate more often. Investigate can mean nothing more than a quick scrape of the surface to double check before moving on.

To answer your question in the post though - yes, we are always missing nuggets. It is not about what you miss however, it is about what you take home. The real question is "what method maximizes your investment of time for the best return possible in that time?" If there are 500 trash targets and one decent nugget, digging every target may not be the best answer to that question. If that nugget is under a nail, digging every target may be your only answer.

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For those new to this here is what we are talking about. I am going to use the Garrett AT Pro visual display here as an example:

garrett-at-gold-vdi-display.jpg
 
 The graphic on top illustrates the Garrett 0 - 100 range of possible target identification numbers. White's called these Visual Display Indicators or VDI numbers and so you hear them called that a lot. Note that ferrous targets fall on the left and non-ferrous on the right. Ferrous items because they have magnetic properties are unique as opposed to non-ferrous items which are not magnetic, allowing for this basic separation of metal types. They also usually have a low conductivity and non-ferrous items a higher conductivity, but some ferrous items are very conductive and so will trick these systems and read way up in the non-ferrous range. Items with hole like washers and nuts are big offenders along with flat steel plate materials, including bottle caps.
 
Notice that 30 and lower would generally be considered ferrous, and 50 and above non-ferrous. The range from 30 to 50 overlaps ferrous and non-ferrous. This is quite a spread! That range is the entire problem because there is no clean break between ferrous and non-ferrous. A numeric reading of 42 could be a small flat flake of steel, a small gold nugget, a piece of aluminum foil, or a bit of lead.
 
Garrett has rather predictably chosen 40, right in the middle, as their preset location for the machine to make basic ferrous and non-ferrous decisions. The LCD area below the graphic has blocks in the non-ferrous range and a separately adjustable ferrous range from 39 on down to zero. The example shown has 35 set, which means 35 and lower will not sound off at all. 36 to 39 will make a ferrous low tone. 40 and above higher non-ferrous tones depending on the scheme chosen.
 
In theory you can monitor the VDI numbers and if you get a low tone reading of 38 decide to dig it anyway. The main issue brought up in this thread however is that Garrett has chosen 39 as the place where tones flip from ferrous to non-ferrous and you can't change that. That means the range from 30 - 39 is always at particular risk of being ignored. The Garrett solution would be to set the ferrous discrimination point at 30. that way 30 -49 would give a low tone but you would know that might mean ferrous and it might mean gold.
 
Instead of 39, would it not be nice to just set your own point anywhere from 30 to 50 for the tone to break? You would then go strictly by the tone, never referring to the display. The choice would  depend on your mood and how aggressive you want to be. Set for 30 and you will dig more ferrous stuff but but have less chance of missing gold. At 50 you will dig almost no ferrous stuff but also miss some gold.
 
Fisher has this feature in the Gold Bug Pro and other models and they have called it V-Break, for Variable Tone Break. You just turn the knob and decide at which point you want the tone to flip from ferrous to non-ferrous. The new F19 also lets you adjust the tones themselves and the volume of the tones. The DEUS and a few other models offer the same ability. White's has had it since day one on the MXT - this is not a new feature.
 
Finally, I should mention some people just do not want to hear it. Traditional discrimination systems have always had the ability to set the ferrous/non-ferrous break point, but it was so that anything below the break point is totally eliminated from signalling. You do not listen to constant ferrous tones and just dig anything that beeps. This actually can work and you can hunt like this and find gold. The Gold Bug 2 has the simplest system of all. Just flip a switch, and all ferrous signals below what would be the Garrett 30 mark are eliminated. It is conservative, simple, and works. I have dug thousands of nuggets using a Gold Bug 2 in disc mode. The theory again is that I also missed a lot of gold and no doubt did, but as I said in the earlier post, it is about what you go home with, and I do pretty well.
 
I want to emphasize that I do not believe there are specific right ways or wrong ways of going about all this discrimination stuff. The only sure thing is to dig all targets, but there are all sorts of reasons people may not want to do that. Mine is usually a time thing. If I only have an hour I am going to cherry pick. The more time I have, the more digging everything makes sense. The type of discrimination system a person employs is very much a personal choice. I am keenly aware that many people just hate digging junk and so if using discrimination makes for a more pleasant experience, that is a good thing. Seriously, for most people this is a hobby, and a hobby should be fun. I would rather a person enjoy themselves and stick with it than just give up in frustration.
 
The goal here is just to inform so that you understand the choices you are making and the possible consequences. Everyone who uses discrimination eventually will have somebody come right behind them and dig a target they passed up, and have it be a nice gold nugget. Use it when you feel you must, but try to not become reliant on it as eventually it could cause you regret.
 
See also Metal Detector Discrimination Really Sucks and Metal Detectors With Reliable Target ID Numbers plus Tune Out Nails, You Will Miss Gold

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OK, lets flip this around. Lets say you have a Fisher F75 or AT Gold or X-Terra 705 where the tone break is preset. Is all lost?

Not at all! You just end up with three basic zones. In the case of the Garrett AT Gold above, you set the ferrous reject point at 30. Everything under 30 is simply rejected, and you get to pick exactly where that rejection point occurs. The low tone from 30 -39 would be treated as a ferrous/non-ferrous overlap tone so when you hear it you know it is probably ferrous but may be gold. The idea is just like in the case of setting low tones conservative and digging them because they might be gold - do the same here. The 40 - 50 range is going to be called non-ferrous by Garrett but it could also be a ferrous target.

My F75 automatically splits tones at 15 but anything from 1 - 15 could be gold also even though it is more likely to be ferrous. I can still just like the Garrett set a kill point for the low tone to go silent. For instance, I can set the discrimination at 0 so everything 1-15 has a low tone that I would dig.

The point being that this idea of V-Break or having a variable break point for the tones is nice but it is not that big a deal really. It allows you to have a set tone that says "Dig" and a tone that says "Don't dig unless you feel like it". Very easy to mentally process. But when you think about it you get nearly the same thing with a factory preset. Maybe the break point is not exactly where you want, but if you are being conservative it really does not matter. In either case you will dig a lot of low tones, most will be ferrous, but a few will be gold.

What I think is most important is far more basic. Which machines just make the right call more often? I really want to just dig gold and not dig nails, so which machine will give me the most accurate answers as to which is which? Sadly, like all things in detector land, it appears to depend on the ground itself more than anything, and so what works well in one location can not be depended on to work exactly as well someplace else. And that is why the debate never ends on the internet as people compare notes from all over and find they get different results in different areas with different machines. There are no cut and dried solutions. If there were, everyone would own the same detector.

Still, some detectors are better than others. The goal in the past has been to eliminate junk, and so detectors were more aggressive in rejecting junk targets. The problem is good finds got missed. Newer detectors are sliding the scale to be less aggressive in rejecting junk and so more good finds are being made. The dirty little secret nobody likes to talk about is more junk is also getting dug as a consequence. New people buying these latest greatest detectors for pulling goodies out of the junk are getting a big surprise when they are discovering they are going to dig lots of junk targets also.

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PI detectors miss gold too. In this case, it is a result of their method of ground balancing. What follows is my limited understanding of how that is.

They don't use phase shift to detect targets like VLF IB detectors do, they use the decay time of the target signal. The GB point is set to eliminate the ground signal based on it's decay time, but sadly some target signals have the same decay time as the ground signal. This makes a "hole". ML uses multiple pulses so that the hole in one pulse is at a different value than the hole in another. This information is combined to try and eliminate the effect of the holes, but it is clearly not perfect, thus the multitude of "timings" on the GPX-5000. TheTDI doesn't have this patent protected feature andit is easy to demonstrate the hole effect on it my manipulating the GB knob.

Why this is interesting right now is that ML's new Super Detector, details of which are due to be released late this month, is apparently not a PI machine at all (or at least not anything like current ones). Also, according to leaked information which may or may not turn out to be correct, it is All Metal. This won't help it solve the problems discussed in this thread, but if it can ground balance while offering depth in highly mineralized ground without the "holes" which plague current PI detectors, then it may be a SuperDetector indeed. Time will tell.

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I wrote this before I viewed your other replies so I apologize for any duplication of opinions.

Merry Christmas to you and your family Steve. I agree that both the Gold Bug Pro and Deus are fine machines but in this world of detecting there does not seem to be any perfect machines. It is all about compromise yet achieving the desired end result. Because I like to nugget hunt and do coin and relic I prefer VLF machines that can do all three well. 

The GB Pro I don't like to use in areas where there is too much modern trash for coin and relic as it has no notch option and limited tone options. Maybe I should switch to the F-19?. The Deus is so programmable it does most coin and relic jobs well but the jury is still out when it comes to nugget hunting in my mind. To me the Gold Field All Metal program is too noisy in bad ground. The ground grab does not set the GB close enough to the actual ground phase when in hot soil necessitating using the manual ground balance. In rapidly changing mineralization I find myself becoming annoyed with the Deus in this mode. I liken it to using a GBII under those conditions, too much time spent GBing and not enough time spent swinging. Dial in some discrimination and everything settles down considerably. Recently I had just a few minutes time to detect at an old cabin site over serpentine bedrock and was impressed by how quiet it ran using some discrimination and a higher reactivity setting. Given more time on the Deus I may very well come to understand how to tame it in all modes over any ground but I am not holding my breath.

If I could prove to myself where a Fors Core or any other machine in 2 tone mode for that matter would smoothly provide me 1 additional inch of depth in the ground I run in I would buy one. I would forsake the adjustable tone break and super light weight of the GB pro and the Deus figuring the extra gold from that 1 inch was worth it. This is not at all out of the realm of possibility as neither the GBP or Deus are touted as depth demons. 

Disclaimer- I am a mere rank neophyte compared to many on this and other forums. If you take issue with anything I have posted please feel free to correct me. I merely seek knowledge and have no brand loyalty.

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Ground and hot rock elimination is just another type of discrimination with all the same problems of target overlap. There is no doubt we are seeing vast improvements in battery technology and microprocessor based signal analyses that is narrowing the range over time. We have come a long way since 1970 in metal detectors and we are not done yet. Seems like we got a whole new crop of bright minds looking at the problems in recent years and that is sure to lead to some advances.

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Merton, you are sharper than you let on when it comes to detectors! I never have issues with anyone seeking knowledge. I wish I had great answers for you but after 40 years of detecting I still worry the same old problems around in my head and chase my tail trying to find perfect machines. I have exactly your same issue with the Gold Bug Pro and just sold mine. I want more options. I am hoping the F75 is going to do it for me. The Nokta actually works great, but again, limited options. I am eyeballing the F19 but to show you how I can be about things I just do not want camo so I am waiting for the new Teknetics version of the same machine, an improved G2. I am trying to stay with AA detectors so again prefer the F75 to win out over the F19 but in the end performance will tend to sway me. Maybe. I value lots of things in a detector and the fact is I am going to have to compromise somewhere and I just can't say yet what will win me over. I really like the F75 on my arm so it is its game to lose.

I am hard on the same quest as you. I am doing it purely for my own purposes but if I pass along my findings it may help you or others. I have to say though there is a reason I ultimately bite the bullet and get the detectors and do it myself. I read all the forums also trying to glean information but in the end to get the answers I want IN MY GROUND I have to try it myself. I could swear the Nokta is sliced bread working for me, and you get it and put it on your ground and it sucks. That is why I try to be careful to not get pinned down with absolutes because in detecting I can't seem to find any.

True story about the Nokta is I am trying not to like it! I don't really like the overall physical layout and would just as soon toss it and use the F75. The problem is I am taking the "not upgraded" F75 and Nokta out and the Nokta simply runs cleaner for me. It is pulling up non-ferrous targets better than this F75 - so far. I have an upgraded version on the way slow boat going the wrong way around the world but sooner or later I will get it. And if I have to the F19 or new G2. A new MX version if one appears. Eventually I am going to beat this down to one unit but it is going to cost me some bucks to sort it out and I am ok with that. All I can say about the DEUS is good luck with that. Absolutely great detector but just not my style. I will very much appreciate any new thoughts you get about it as you use it in return for all the typing I am doing here! 

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This is just the kind of discussion I was interested in and many of my questions have been answered. I really appreciate Steve's insight and knowledge of iron volume, V-break, "to dig or not to dig" thoughts, etc. Most of us just do what the detector tells us to do...it's just not that simple! So we just keep buying the latest and greatest detector as a magic bullet to calm down our gold fever. I'm going to "nominate" Steve as our detector tester/reviewer and make purchasing decisions based on his detailed analysis. Do I hear a second?

 

Bill

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