Jump to content

Ground Balance Offset


Recommended Posts

Truth is that I wouldn't even remember this Ground Balance Offset thing if I hadn't watch the formentioned video...but as I was seeking for Multi Kruzer reviews, the video that I posted earlier with this positive GB Offset trick in the salt water grabed my attention, so I brought it on the table for further discussion and explanations.

I would also suggest to watch another video (attached below) where the same guy (!!!) shows what happens in salt water when he doesn't ground balance his ATX for salt, vs what happens when he does ground balance it to substract the salt signal...result is he looses detectability!....I guess that this video is also very much correlated to the subject....but not 100% sure since it's for a completely different machine (pulse induction).

However, I'll copy a Steve's comment from the same thread which includes the ATX video: "...in very low mineral ground savvy VLF operators can sometimes gain depth by purposefully offsetting the ground balance control. If the ground is not signaling over a wide range when you change the setting, is it better to set lower or higher? It depends on the targets sought and knowing how your machine performs inside and out." original thread below:

Food for thought!

 

  • Like 2
Link to comment
Share on other sites


I will also add some interesting comments via other sources (DD forum) regarding the same subject, that I just found and may solve the Ground Balance offset mistery:

From Keith Southern: "I adjust my ground balance negative in disc mode till I get some ground noise feed back then set it back up slightly till it just barely makes noise....this helps when running it in disc mode to obtain more depth....
Do a simple test in your yard...bury a target to the fring depth so you just cant hear it on your machine when properly ground balanced.....say a dime at 9 - 10 inches..then turn you ground bal back CCW till you get some ground noise coming in on a sweep or even a coil bob...the go back a tad CW till it gets rid of the ground noise...do this in disc mode not all metal mode....
Now go across the dime and there should be a marked increase in the ability to all of a sudden hear it...
now this works best with a DD coil especially of the elliptical type in the 5x10 range up to say a f75 size 7x11...
The Elliptical DD's see less ground and allow for more negative ground bal than a concentric...yet still have excellent depth ...
Now the target's when heard will sound a little different than what you are accustom to maybe...what happens is when you get a signal it opens the gate and allows the ground noise to come in at the same time of the target so if you are running 2 tone you will hear more of say a iron buzz on the edges of the target.. on the approach and the departure..get used to it.. you might think it's deep iron to begin with ..There is other techniques also for hunting bad dirt maybe I will list one in another thread..
Keith"

Further comments in the same thread: 

"Negative offset for minerals/bad dirt/depth - positive offset for smaller low conductors.....old school stuff that still has merit"

"This is an old rule of thumb in detecting circles. By balancing the machine slightly "hot", meaning a slight increase in threshold as the coil approaches the ground during ground balancing, some believe it will give you a bit more depth. A filter is set up in conventional ground balancing to ignore the ground signal (filter it out) and sound off to anything that goes above that filter. By balancing with the ground signal almost breaking through (slight increase in threshold as the coil approaches the ground during balancing) you can push the ground signal right to the edge of the filter and so a target is more readily able to trip over the edge of that filter and sound off.
Now, there is a fine line here. Too "hot" of a balance and now the machine will false too much, and so you might ignore or miss a real deep coin as being ground chatter."

***All comments above are from this source for anyone that needs further reading (and I hope that it's allowed to post here): 

http://www.dankowskidetectors.com/discussions/read.php?2,33662,33674

  • Like 2
Link to comment
Share on other sites

Based on all the above info, and in order to conclude:

- slightly negative GB offset => slight increase in noise as the coil approaches the ground => machine runs hotter => more depth in bad hot soils

- slightly positive GB offset => slight increase in noise as the coil is lifted off the ground => machine more quiet/steady => increased detectability of smaller low conductors

Makes sense?

Lastly, Multi Kruzer's manual states that: "If the sound gets higher when lifting off the search coil above the ground, the ground balance value is too low, in other words, the effect from the ground is negative and the ground balance value needs to be increased by using the ( + ) button. On the other hand, if the sound gets higher when lowering the search coil to the ground, the ground balance value is too high, in other words, the effect from the ground is positive and the ground balance value needs to decreased by using the ( - ) button."

So based on the manual, it seems to me that for the Kruzer everything is vice-versa??? negative is above ground phase & positive is below ground phase?

pfff....I thought that I almost got it but it's way more complicated for my head right now... 🤪 gonna grab a beer and call it solved!

  • Haha 1
Link to comment
Share on other sites

Your best bet is to run the machine as balanced as possible. I ran my Tejon little positive but depth wise it made little or no difference maybe it is already hot so now I run all my machines as balanced as possible. If you do any all metal hunting having a balanced smooth threshold is easier to follow. With the Kruzers they get too chattery if you hear too much ground, they run smoother when properly balanced. I don't think there would be an depth difference or worth the effort doing anything more. In a long shot some hypothetical test of some sorts you gain a fraction of an inch?

In regards to pi machines with ground balance from what I have read here the ground balance can be used as a crude discrimination in the sens that it creates a tone break point. In other words you can ground balance on iron so tone break will indicatate iron/not iron targets.

Higher number is more ground, lower number is less and I believe that is pretty much the same on all VLF machines.

  • Like 2
Link to comment
Share on other sites

The Tejon in my mild ground the depth increased 1"+ with a negative gb. It would hit my 10" test dime w/ 8" concentric coil. The AT Gold also increased depth to about an 1" with a neg. gb. With the 8x5 coil it would hit a 9" test dime but not 10".

How you adjust your gb depends on what king of ground your in.

  • Like 4
Link to comment
Share on other sites

Thanks Kac & Rick

Yes, I quited overthinking about it since I don't see further interest in this thread... Was just this Kruzer's salt water-gold chain test video which made me curious to search about it, and wanted to understand why he increased his ground balance value.

Based on your replies and some further reading from multiple resources, I thought I've grabed the basics of the GB offset...Most seems to conclude that:

- negative offset (lower value than actual ground phase) means slight increase in noise as the coil approaches the ground => some extra depth abilities but more ground noise......

- positive offset (higher value than actual ground phase) means slight increase in noise as the coil is lifted off the ground => less ground noise while sweeping so tiny signals would standout more....

Is just that the Kruzer's manual statement on "positive vs negative" confused me... manual states that "if the sound gets higher when lowering the search coil to the ground, the ground balance value is too high, in other words, the effect from the ground is positive"... which is the exact opposite from what I've read and wrote above...I expected this do be the "negative" offset instead.

Anyway, I'll wait till I have my new M.Kruzer in my hands to do some real testing with it, but in any case it seems that it isn't something to overthink about.

Thank you all for participating...I guess that this Covid & Quarantine situation leaves me with enough free time to overthink about things...not good!!! 🤪

  • Like 2
Link to comment
Share on other sites

Do have to say that my AT Pro I would kick it down 5 clicks from machine gb and gain depth but after I had it repaired and they put in the latest firmware I don't gain anything so stock gb works good. My Tejon it doesn't seem to make a difference either way.

Possible it is just a tweak that may work on some machines as there may be slight variations from the factory?

I do have to say that manual gb on the Multi Kruzer is a little tedius because it has fine adjust that cycle through so the process is slow when compared to a quick twist of a knob or in Garretts case a couple of clicks of buttons. One the reasons I use tracking on my Multi Kruzer in beach mode on the beach (tracking does not work on the beach in any mode except beach mode on the Kruzer series).

  • Like 2
Link to comment
Share on other sites

Negative ground balance is setting ground balance number lower.

You have it backwards. It is positive ground balance when the coil is moved to the ground and you hear a sound. Negative is when you raise the coil and you hear a sound.

  • Like 2
Link to comment
Share on other sites

2 hours ago, Rick N. MI said:

You have it backwards. It is positive ground balance when the coil is moved to the ground and you hear a sound. Negative is when you raise the coil and you hear a sound.

Oh...if that's the case, it could explain my frustration (and will also correlate with the manual)... maybe I had missunderstood some posts from the other sources and got it backwards indeed...thanks! 

So...if wanna give a little depth boost for fringe deep targets (especially for high conductors like silver coins) => put GB in a slightly lower value (this is "negative GB offset" & ground noise will increase when raising the coil of the ground). Exactly like Kac was experiencing with his AT Pro as mentioned above, and as I also remember experiencing with my Deus....slightly lower (negative) for a slight depth increase and boost in fringe depth targets.

Based on this, and to end the confusion, the guy in the "DetectorComparisons" video who raised the GB value while in salt water (positive offset) instead of lowering it, wasn't doing it to gain some extra depth... but to somehow help the gold chain's signal stand out better. Now, how this "positive offset" while in salt water helps with low conductors, I can only assume that a slightly higher GB (positive offset) while in salt, allows to include some salt signal back in (instead of completely cancelling it), which helps detecting very week gold signals since tiny gold signals from chains, earrings etc are really close/embeded to the salt's range itself...if that's the case, seems interesting enough.

Thank you both

  • Like 1
Link to comment
Share on other sites

2 hours ago, kac said:

I do have to say that manual gb on the Multi Kruzer is a little tedius because it has fine adjust that cycle through so the process is slow when compared to a quick twist of a knob or in Garretts case a couple of clicks of buttons. One the reasons I use tracking on my Multi Kruzer in beach mode on the beach (tracking does not work on the beach in any mode except beach mode on the Kruzer series).

ps....nice to know that Tracking will work ok on the beach...will definetely try that, (but will also check if there's any risk of cancelling staff when using it), thanks

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...