GPZ And Salt

[jasong]

One the easiest ways to knock salt response down on a PI while still maintaining or increasing sensitivity to the sub 1 gram stuff is by using a smaller coil. I guess it remains to be seen if that holds true with ZVT or not yet.

 

[cobill]

Jason, 

I agree with your smaller coil idea and have seen it firsthand...a GPX 5000 at Rye Patch with torrential daily rains. That guy just picked up a nugget out of old push piles with a small coil, while everybody else was listening to extremely bad ground noise with their Zeds!

That's why I have a 10" X-coil on order.

Bill

[cobill]

52 minutes ago, flakmagnet said:

I agree Cobil, the people who buy a 7000 are generally not novices. It stands to reason that deeper information beyond the set-up manual would be a huge head start to understanding the true measure of this detector. JP's dedication to providing his detailed and hard-won knowledge to a huge segment of the detecting population is well documented - I suppose it is asking too much to hope MineLab would contribute to help fill this information void. 

Flakmagnet, 

Yes JP would the best choice for this tasking. Maybe we should put together a "pre-order" list or poll to show how much interest there would be. A local guy put together the "Book of Jack", an electronic cut & paste collection of best posts on the White's V3i and Earthsurfer then organized it into a 63-page book. Maybe JP would rather do this than another expensive & time-consuming video.?

Bill

[jasong]

Awesome Bill! Please do report back. Fingers crossed the smaller coil cuts into the salt instead of making it worse. I have no guess either way, and have been hoping a brave soul would test it out.

If you find it cuts the salt down quite a bit I'm going to have to reevaluate my no warranty-voiding decision post haste. And a lot of other people too I'm sure.  

[Andyy]

1 hour ago, jasong said:

Awesome Bill! Please do report back. Fingers crossed the smaller coil cuts into the salt instead of making it worse. I have no guess either way, and have been hoping a brave soul would test it out.

If you find it cuts the salt down quite a bit I'm going to have to reevaluate my no warranty-voiding decision post haste. And a lot of other people too I'm sure.  

A warranty is only good for 5 yrs, anyways, right?  I am near the end of my warranty, anyhow.  Now it's just working the approvals through the wifey .. lol

 

[Jonathan Porter]

3 hours ago, flakmagnet said:

I agree Cobil, the people who buy a 7000 are generally not novices. It stands to reason that deeper information beyond the set-up manual would be a huge head start to understanding the true measure of this detector. JP's dedication to providing his detailed and hard-won knowledge to a huge segment of the detecting population is well documented - I suppose it is asking too much to hope MineLab would contribute to help fill this information void. 

There is always going to be deeper information available on any detector as is evidenced by Andy Sabisch’s new book on the Equinox. To be fair to Minelab they do invest in my continued involvement in the development of their detectors so its not like my experience and knowledge are wasted. The GPZ 7000 is by far and away a much simpler detector to use out of the box than any other High End detector they have ever built, if we could address the weight issue there would be even more happy users out there world wide.

For my part the effort required to put together material in written form or in video format is a mammoth task I am no longer willing to undertake, I prefer to just focus on our customers in the shop and continued involvement in this forum when I have the time. Moving forward I intend to continue on giving feedback to Minelab for as long as they need me, hopfully this will be in parallel with my getting out detecting more frequently or one day even full time again if I’m lucky.

JP

[Jonathan Porter]

Getting back to Salt signals, as Steve has mentioned there can be a moaning sound created in the bed of gullies especially when the coil goes from the bed of the gully too the sides. This is caused by the gully bed having wet clays when the sides have a layer of wash over drier deco (decomposed bed rock which is what the clays are), the GPZ is by its nature worse on salt signal than MPS machines and then you add the complexity of the Super D coil where the two receive points are quite a distance from each other.

Careful coil control is especially important on the GPZ because it is very easy to throw the two recieved windings ‘Out of Phase’ from each other, in the creek bed scenario one receive winding will be transitioning onto the dry non salty ground whilst the other is on the wet clay section of the gully bed, this then creates a signal across the dry winding that causes the Semi Auto GB to try and compensate, this action also tends to force the operator to lift the coil which exacerbates the salt signal, combine the two and you end up with a noise that will drown out targets especially on the interchange between the two GB states.

Steve has mentioned detecting the gully bed without crossing into the drier sides which is a good idea, another way to go about it is to GB to the gully floor then place the GB into Manual mode (I select Ground Balance Mode as my User Button function to speed things up), you can then cross the interchange section with predicable results without upsetting the Semi Auto GB function, this cuts back on a lot of noise. I will then do another pass over this ground by GBing to the gully sides then Fix the GB for that Ground Balance scenario. In essence you can make three passes over this type of area, one in Semi Auto GB, one in Manual fixed to the gully floor and the other Fixed for the Gully sides.

Salt signal has a nasty way of throwing or drawing the GB away from optimum, this is often heralded by a twitch or signal like response that is not repeatable but causes you to stop or pull up to investigate, in worse areas there is also the one sided of two sided moaning sound. Salt signal also messes up the Ferrite balance which is what I advocate using Semi Auto mode. Careful coil control in both pivoting of the coil from side to side and slowing down the speed have a huge effect on the amount of salt signal experienced, as Steve has said quite often with the GPZ you can work quite nasty ground very effectively without resorting to use of the Ground Smoothing filters which kill depth simply by controlling your coil movement. 

JP

[cobill]

2 hours ago, Jonathan Porter said:

There is always going to be deeper information available on any detector as is evidenced by Andy Sabisch’s new book on the Equinox. To be fair to Minelab they do invest in my continued involvement in the development of their detectors so its not like my experience and knowledge are wasted. The GPZ 7000 is by far and away a much simpler detector to use out of the box than any other High End detector they have ever built, if we could address the weight issue there would be even more happy users out there world wide.

For my part the effort required to put together material in written form or in video format is a mammoth task I am no longer willing to undertake, I prefer to just focus on our customers in the shop and continued involvement in this forum when I have the time. Moving forward I intend to continue on giving feedback to Minelab for as long as they need me, hopfully this will be in parallel with my getting out detecting more frequently or one day even full time again if I’m lucky.

JP

JP, 

I think what we're looking for is more "Knowledge Base" type articles on the GPZ 7000 with your style of in-depth analysis of when and why to make adjustments on the different Ground Types, Volume, Volume Limit, Threshold Level, Threshold Pitch and Audio Smoothing, and the impact of those adjustments on ground noise, detection depth, coil speed and control, etc.

The GPZ 7000 manual only has 5 pages devoted to these CRITICAL ADJUSTMENTS with a basic over-view style of writing. These are detector operator decisions that can make the difference of finding gold nuggets or constantly being skunked and selling the Zed.

Minelab must realize that most GPZ 7000 owners have very limited actual hours using this complex detector. I have attended a 3-day dealer training and they setup the detector with mostly default settings.

Bill

[Northeast]

2 hours ago, Jonathan Porter said:

Salt signal also messes up the Ferrite balance which is what I advocate using Semi Auto mode.

Morning JP. 

This might be obvious to others but not me. 

Auto GB allows constant changing of G and X signal. 

Semi auto locks X and allows changing of G signal. 

Manual mode must lock G signal and ??? lock X also?  

Is there any benefit to locking the X signal in the ground at these salty locations or should the Ferrite ring be used in every situation? 

With regard to a document over and above the GPZ manual.  It is slightly time consuming but well worth creating your own document    by going through every post by JP and Steve (and anyone else on here you feel has good knowledge).  Cut and paste into a word doc, stick stuff under section headings to make it easier to read, add in extra bits whenever new threads turn up (like this one). Just be mindful of copyright and keeping it to yourself.  

[cobill]

55 minutes ago, Northeast said:

Morning JP. 

This might be obvious to others but not me. 

Auto GB allows constant changing of G and X signal. 

Semi auto locks X and allows changing of G signal. 

Manual mode must lock G signal and ??? lock X also?  

Is there any benefit to locking the X signal in the ground at these salty locations or should the Ferrite ring be used in every situation? 

With regard to a document over and above the GPZ manual.  It is slightly time consuming but well worth creating your own document    by going through every post by JP and Steve (and anyone else on here you feel has good knowledge).  Cut and paste into a word doc, stick stuff under section headings to make it easier to read, add in extra bits whenever new threads turn up (like this one). Just be mindful of copyright and keeping it to yourself.  

Northeast, 

I'm already cutting & pasting everything available. Most posters don't go into enough detail like JP & Steve...so there isn't much available. I'm also on 2 Aussie forums and learn bits here and there. Still lots to learn.

Bill