Ground Balance Revisited

[Neil in West Jersey]

I asked a few weeks back about ground balancing the CTX. The manual says don't...unless the mineralization is high. Well, I would categorize the soil in my sites as mild to moderate, but I haven't gotten as deep as I feel I should with a detector of this caliber. Today I got an Indian Head signal at around 4 inches, but it dropped down to around 7 inches when I dug the plug. The detector could not detect it. No nulls, no signal, nothing.

I decided to enable the GB, and after balancing it, the detector was a whole different animal! It added inches! Afterwards I dug buttons at 10 inches with no problem.

The find of the day was this old gold band, possibly from a 19th century dip pen. It was jumpy but settled at around 12-04

 

[GateKeeper]

On the right side of your sensitivity panel, the green number is what the CTX recommends for sensitivity. Do you remember what that number was? FYI, if that green number is registering say 14 and below, then the GB should be activated.

 

[Neil in West Jersey]

On the right side of your sensitivity panel, the green number is what the CTX recommends for sensitivity. Do you remember what that number was? FYI, if that green number is registering say 14 and below, then the GB should be activated.

14, but I think they are not directly related. I could have soft sugar sand which has almost no mineralization, and I could have high voltage power lines over it. I would need to lower the sensitivity, but I don't think a GB would be necessary.

 

[GateKeeper]

Neil, you are confusing confusing EMI and mineralization. Although they do go hand in hand, they are both different. The powerline would be controlled by the Noise Cancellation while the Minerlaization is controled by the Ground Balance feature.

 

[Larry (IL)]

I don't think Neil is confused Phil, he is a veteran with many many years experience. Although noise cancel will pick the clearest off-set frequency channel to hunt in, reducing the sensitivity is the proper way to deal with persistent EMI, like under power lines.

 

[GateKeeper]

Actually Larry, yes and no. I have been testing that theory and I've found that you can run your sensitivity higher under power lines by noice cancelling underneath them. By doing that I've been able to run my sensitivity as high as 27 in auto +3.

No doubt Neil is a vet and mean no disrespect to anyones abilities, Neil is one of our many valued members here. With the CTX still being relatively new, there are still subtle nuonces that are being discovered through constant field testing. Even I still learn something new on every outing.

 

[Digger]

First off, congrats on the finds. As to your results using manual GB in what you determine to be moderate ground mineralization...... unfortunately, the CTX does not offer the ability to measure or display the mineralization content of the soil below the coil. If it did, we could all get a better idea as to when we should implement manual GB, vs. the default "tracking" mode. As it is, when I tell folks that my mineralization levels are low to moderate, which I have many times, it really doesn't identify what the true magnetic mineralization levels are. What may be moderate to me could be considered mild to others.

Regardless, what I have learned over the past couple years of using the CTX 3030 is that, when you implement both Auto Sensitivity and the default "ground compensation" tracking GB, both "functions"constantly monitor the ground for changes in mineralization levels. As mineralization levels change, the Sensitivity is automatically adjusted to allow for maximum depth of detection. And, through electronic filtering, the ground compensation software removes false signals caused by the ground noise. This is what leads me to recommend using Auto Sensitivity (even with an offset) and default "ground compensation, to most who are new to the CTX 3030. We've now reached a point where some of you folks have a good understanding of what makes it tick. For those who understand how these two "functions" compliment each other, I have no problem saying that you may be able to increase your depth of detection by implementing manual Sensitivity. And in some situations, you may increase your depth of detection using manual Ground Balance. However, either can cause false signals and both should be adjusted regularly. Minelab recommends using Ground / Coin separation when implementing manual Ground Balance. However, in the few areas that I felt I had gained performance by implementing manual GB, I found that I could get good results with either Ground / Coin or High Trash separation. Both Ferrous / Coin and Low Trash Separation modes were designed for use in areas with low to moderate mineralization. And once again, low to moderate are too ambiguous of terms to properly identify specific applications.

As I've recommended since the introduction of the CTX 3030...... learn the detector and what each function does. Learn how one "function" may affect another. Learn what works best for you, in the sites you hunt. And don't be afraid to experiment......as Neil has clearly shown in this post, thinking "outside the box" resulted in some finds he wouldn't have made had he stuck with vanilla. JMHO HH Randy

 

[parkgt]

It is interesting that the CTX seems to suggest sensitivities that are much more conservative than many are running or seem willing to believe in running.

How often does a CTX recommend a setting of 28 or 30 compared to how often people push to run those settings.

Is the CTX wrong or too conservative? Or are we unwilling to accept that much of the time optimum detection doesn't require the highest sensitivity settings?

 

[GateKeeper]

Digger wrote this in his Xterra book. He said that the processor was much smarter than he was and that it could select a channel better than him. An example would be when he would manually noise cancel, he could select channel 2, but the Xterra could select 2.4567. Now that might not seem like much, but that might be all the difference you would need. Same thing goes with the CTX. The CTX 3030 can seek the most optimum channel to hunt in. You see the CTX in the Auto sensitivity mode with take the average of all 3 channels to get the GREEN sensitivity number in your sensitivity panel. Now if you manually set your sensitivity, all 3 channels will be the same. And if you think you need more sensitivity, you can always offset the Auto sensitivity by +1, +2, or +3. By selecting the offset, you will gain extra depth. If +3 starts falsing, then lower the sensivity to Auto +2 and so on. I myself would rather allow the processor to distinguish my sensitivity in the ever changing soil conditions for optimum capabilities the CTX is intended for. So to answer your question, is the CTX too conservative? The answer is NO.

 

[Neil in West Jersey]

It is interesting that the CTX seems to suggest sensitivities that are much more conservative than many are running or seem willing to believe in running.

How often does a CTX recommend a setting of 28 or 30 compared to how often people push to run those settings.

Is the CTX wrong or too conservative? Or are we unwilling to accept that much of the time optimum detection doesn't require the highest sensitivity settings?

I mentioned this in another post, but when I run Auto +3 at the site that I made this find, the recommended reads 14, yet the Auto display is at 25 to 27. It runs very smooth with little false signals, yet if I swithch to Manual, it will go crazy at those levels. I seem to get more depth from Manual at 23, than at Auto 27, but definitely a bit more chattery.

I'll take a bit of false signals for an extra two inches of depth. I don't need a $2500 detector that runs smooth as butter but misses Indian Heads at 6 inches! JMO

And Phil, you are correct, that there is a definite relationship between Sensitivity and Ground Balance. Any experienced detectorist who has tried to GB a detector with the Sens too high can tell you this. My point was that I don't necessarily think the recommended Auto setting is a good indication of whether or not to enable the GB.

One final note: I took the gold to my jeweler and it tested higher than 14K and lower than 18K, "probably around 16K", which confirms it's age. 15K and 16K were more commonly used in the 19th century and earlier.

 

[GateKeeper]

Neil, I do see your point. Ironic isnt it that you stated that the recommended sensitivity was at 14 at the time you ground balanced? Then after you ground balanced it ran as smooth as butter. This is ment as a starting point for operators who are wondering when to ground balance. And thank you for confirming that.