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Ground Balance Offset


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Hey guys, 

Can someone explain to me in simple terms what is it and what we accomplish by using a slight ground balance offset (either positive or negative) on our machines? I remember for example that when using an Xp Deus in the past, whenever I needed some little extra depth boost I was manually set the GB a little lower than the actual ground phase of my area but in the expense of greater ground noise and instability...the opposite when I needed a more quiet run....However I never deep dived into this concept and never understood how and why this really worked.  Would be great to understand this now, and in order to help me (and because each machine has a different GB scale), let's assume a Ground Balance scale of a Makro Multi Kruzer (which I'm expecting soon).

So...In a Makro M. Kruzer, let's say that machine grabs (via pumping) a Ground Phase of 70 in our area...

1) What if I manually set my GB slightly HIGHER than 70 (eg at 75) regarding ground noise, depth abilities and targets detection? Will the effects be the same for both low & high conductors or tiny & large targets?

2) Same as above, what if I manually set my GB slightly LOWER than 70 (eg at 65) regarding ground noise, depth abilities and targets detection? Will the effects be the same for both low & high conductors or tiny & large targets?

3) Will this GB offset apply also in the salt water the same way? (I recently whatched a guy reviewing and using a Multi kruzer in the salt water, and he manually increased his GB value on purpose while he was trying to detect a small gold chain underwater...never understood why he did such a thing and how this works) 

4) Lastly, please define which side is "positive GB offset" and which side is "negative GB offset" in Makro machines..... May sound obvious but, in some machines higher GB Phase means hotter ground but in some other machines higher GB Phase means milder ground (the opposite). So to tell me that "a Positive offset means moving the GB value to the hotter side of scale & the effects wil be that..." may mean nothing if I don't know which side is hot and which side is mild...hope that makes sense. I don't have a clue which side is hot & which is mild in Makro GB Scales so would be nice to enlighten me and correlate your answers with this!

Hope my questions makes sense...

Regards,

Argyris

 

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This is a good question and should garner some great discussion, I hope members will also comment on their relative ground as far as degree of Mineralization. GB #s & # of Bars on any scale.

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For the benefit of most of us who have never used a Kruzer, this is the pdf of the operating manual on NM's website:

https://www.noktadetectors.com/wp-content/file-download/kruzer/manuals/kruzer-user-manual-en.pdf

A quick scan shows that it very closely copies the GB readings and range of the Fisher F75 / Tek T2 ( probably intentionally ).
So '90' is your safe setting, balanced to ferrite. It will adjust to '99' if you need to quieten down troublesome ground, and adjusts to '00' for very salty beach conditions.
'90' would be OK for zero mineral/iron conditions, like clean freshwater sand beaches. It's also where dirt with very strong iron will GB, where the iron vastly outweighs the mineral component.

So ... setting Mr A's machine to '75' should give less sparkiness, but less depth, I'm thinking the 'lowest conductors' will be worst affected.
And setting GB to '67' etc will make it sparkier, but the benefits ... hmmm not so sure.
Likewise, I'm not so sure what misfortune will afflict the machine if you set it to '50', for example.

Be aware the 'F75' scaling of GB is GROSSLY non-linear, for user convenience. '90' through to about '45' represents probably a ground phase of Zero through 25 degrees lag, respectively. The range '45' to '00' represents 25 through 90 degrees lag. ( my opinion, based on using an F75 and tinkering with it )

Over to the experts ...

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30 minutes ago, PimentoUK said:

So ... setting Mr A's machine to '75' should give less sparkiness, but less depth, I'm thinking the 'lowest conductors' will be worst affected.
And setting GB to '67' etc will make it sparkier, but the benefits ... hmmm not so sure.
Likewise, I'm not so sure what misfortune will afflict the machine if you set it to '50', for example.

That's exactly the effect I remember having with my old XP Deus when using GB manual offset from the real ground phase. Setting a little higher from the actual ground phase (eg from 70 to 75 as in my example for the Kruzer) was causing less noise but a 9'' silver dime had much more difficulties to be detected. Instead, when setting the GB a little lower than actual ground phase (eg from 70 to 65 as in my example for the kruzer) the 9'' Dime would become crystal clear and strong, but I had a little more ground noise and sound spikes...

So, taking into account the first part of your answer, Multi Kruzer would behave the same (correlating with my experience as described above with the Deus)...meaning that, a GB offset higher than actual ground phase => less noise but less depth....and a GB offset lower than actual ground phase => more noise but increased sensitivity/detectability.

Based on that, the guy in the video who was trying to hear a gold chain while in salt water, Raised his Multi Kruzer's GB value a little higher than the actual (from 0 to 7 as you will see) in order to have a less noisy machine, and not to run the machine hotter & increase its sensitivity to the gold chain...right?

*I'm attaching the video for reference.....watch at 3:10 when he says "I'm gonna put the GB slightly positive like I also did with the Makro Impact"

Thanks for the answer PimentoUk 🙂

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It was an introductory explanation, you really need the opinion of folks who actively do tinker with GB settings.

 

I can't comment on the video, really, I've never hunted on a saltwater beach.


I do recall from discussions on Tom D's forum, that having the correct GB setting becomes more important the stronger the ground signal is. This also means that how far above/ below ideal GB you go will vary with the ground. In mild ground, you may adjust it from 65 to 75 and see no difference. In strong ground, 69 and 71 may be the useful tinkering range.

 

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6 hours ago, Rick N. MI said:

Analog detectors like Tesoro could be set hot and go deeper with a negative ground balance. It was called power balancing. It worked very well with my Tejon and with an internal adjustment on my Lobo ST.

New detectors I haven't seen this working so well.

On the Vista X, which is not a true Analog but a sort of hybrid, the GB setting needs to be spot on for best stable operation & depth. If the ground changes you know it quickly. On my NM Anfbio & AT Max you can run a slight offset while in Disc modes but then PP will be a bit wonky. I have not seen any real benefit to trying to hunt with a GB offset. Most of my sites seem to be mild to moderate ground. Sandy areas GB 55-60, about 1 bar on the mineral scale and my hotter red clay sites 65-70 GB & 3, rarely 4 bars on the Anfibio. The GB values on the AT Max will be close to 20 points higher. I still experiment some on the hotter ground trying to get the most stable operation.

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I know that for many old timers, GB offset (positive/negative) was a common practice from what I've read so far... my experience is really limited but I do recall different results when messing with the ground phase value with some of my previously owned machines in difficult targets (like the 9'' dime detectability in hot ground as stated in my first post).

Anyway, thank you all for you answers & comments. It's not a very popular subject but would be good to know the theory behind Ground Balance Offseting...at least the basics of it. As I understand it, is like fooling the machine (via positive/negative GB offset) to believe that the ground is hotter/milder than what the actual ground phase is telling... For very deep targets or tiny low conductors that may blend with the surrounding ground due to their depth or their low conductivity, this minor GB tweeking maybe is just a little trick to make those target signals stand out more against the ground signals... but really don't know how and if that works. 

All I know is that, since I'm expecting my multi kruzer soon, it would be nice to be able to understand on my own the reason behing GB tweeking, like the one shown in the attached video where the guy set a slight positive (higher) GB offset in his Multi Kruzer while in salt water to detect the gold chain. 

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I recall reading about this in books and articles on (metal detector) gold prospecting.  But I never really understood the 'why it works' part.  It might fall into that category "I don't know why it works; I just know that it does and that's all that matters to me!"  And also in line with comments on this thread, it seems to no longer be a technique used with the latest detectors (at least not one that's mentioned, from what I've seen).  I hope we get more resposnes.

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