Getting Large Gold With The GPZ

[Northeast]

6 hours ago, Jonathan Porter said:

The GPZ/ZVT tech thrashes PI resoundingly on big gold if your prepared to let go of the high frequency stuff for a bit and go chase the heavy gold.

Maybe a new thread if you have the time JP.  "How to target large, deep gold with the GPZ?"  Is it your conservative settings or something different again?  How does the audio differ, etc? 

There are bits and pieces (linked below) that maybe all add up to an answer but if there are any other secrets you want to add JP,  I'll listen 

 

[Jonathan Porter]

I did a Treasure Talk Blog on the differences between the GPZ 14" and GPZ 19 and included a video on a nugget signal I found using the GPZ 19" coil. I got a fair bit of feedback from people commenting on the less defined signal response of the nugget, this is typical of large coil use with any detector. When a nugget is being sensed right at the very edge of detection the response is extremely swing dependent and requires VERY careful coil control to manifest a recognizable signal.

Also key to the GPZ is the inbuilt SLOW motion filters and the ability to turn off the Audio Smoothing, anyone half serious about finding extreme depth nuggets will super glue that control on OFF no matter what!!

• Guess what gets worse with slow Motion filters and larger coils? You guessed it SALT!
• Guess what happens if you lift the GPZ 19" coil suddenly whilst detecting? You introduce varying degrees of salt signal!
• Guess what happens to an edge of detection deep target signal when you inadvertently introduce salt signal due to poor coil control? The target gets lost in the salt response.

JP

Apologies for the crazy eyed screen shot grab Minelab used for the video!!

 

[auminesweeper]

Spot On JP, great post,

people often comment when talking small coils how sharp the signal is but seem to forget about that effect when going larger and they appear to be a bit down hearted when the signals don't boom out, They seem to confuse sharpness and depth increase and because the larger coil is not as sharp they seem to think that the depth is not as described.

John. 

[Norvic]

In the ground I do, I`ve found like in this and all endeavors nothing can be written in concrete, an open mind helps a lot. Currently I do not use audio smoothing, instead of turning Volume up on the Z I leave it on 8 and use an audio booster, general, semi-auto GB, normal and sensitivity 20 if the ground allows and I switch into Extra Deep on reruns over the ground. Extra deep has scored quiet well in some deep black soil which just sucks the depth right out of the MD.

I reported in a earlier post of a 19 gram solid that was only 12-15" deep, I had missed it with the 14Z, with the 19Z  until I switched to Extra Deep 19Z, (I would think I should`ve got it 35 plus years back with a A2B, but that was my thinking back then) just a note here whilst this confirmed Extra Deep was not a setting to not use, maybe the fact I got it in extra deep may have been that I hit it at a slightly different angle, I was listening better or a host of other reasons. I just know the open mind approach is the go.

My appreciation of the Z19 and JPs advice was made after a frustrating goldless first Z19 day on ground I knew had deep gold, I followed JPs advice on the 2nd day same ground it was not a goldless day.

[Northeast]

Thanks JP.  I have watched that vid before but had forgot that you had tried Normal and the response was no better. 

I have seen for myself on an 11 gram piece that General/Difficult was way better than General/High Yield.  G/HY simply didn't hear it at all. 

It suprises me that Normal ground mode was actually detrimental to hearing your signal. I was always of the belief that Normal would make every signal better (regardless of size, density, etc).  But the increased ground response with Normal is masking the signal??

I know it is only a guess, but what do you think your particular piece would have done in Difficult/Extra Deep?  Improved signal, same or gone?  I've read that Extra Deep was going to be more useful when the 19 came out - has that been the case?  I only have the 14" - is extra deep worthwhile at all for the 14"?   

Thanks for the response and the vid link. Always pick up something on a second watching.  

[Northeast]

Thanks too Norvic - just read your comment that popped up while I was writing. 

Normal and a sensitivity of 20 - you're a lucky fella.  I struggle to get mine to run in Normal down here at anytime without 172 hot rocks per day 

[Norvic]

NE, I note you use the 14, I`m talking normal with the 19, with the 14 I mainly use difficult although that is slowly changing as I learn how to use semi-auto and better coil control(slow down with age). My grounds up here vary from quiet to noisy, from my time spent in Victoria or any other state I`ve worked not a lot of difference in grounds although you do have more such challenging ground then NQ. Certainly we have ground that yields 172 hot rocks/day.

Of course this is my take

[Jonathan Porter]

The key to remember on any deep target is the signal you are trying to capture is from the target itself and that can be incredibly weak. The deeper the target is the wider the signal can be which makes sense when you consider the target is now in effect a coil itself. Therefore the Tx of the target has to get wider and broader the further away the Rx of your coil is. You also need to imagine the targets field as being sphere like not 2 dimensional, at the very center the field is at its strongest, the further away you get the weaker it is, therefore the receive coil has to be almost dead center over the strongest part of the field (where the Coils Rx is at its most sensitive) to get the strongest response.

If you then allow for the way a Super D coil manifests its signal it makes sense that a Slow Motion filter and a wide accurate sweep is required to generate a recognizable response, the key here is repeat-ability and accurate movement of the coil through the targets field. Can you get the response to repeat when careful controls are in place to prevent Saturation and Salt signals? Having a VERY low noise floor in combination with minimal self inflicted noise input is vital in this process.

JP