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Penetrating Hot Rock Layer - GPZ Tuning Tips?

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Hey guys, 

I hate being the guy asking for help on the forum. But, I'm really struggling and hope some of you with more experience on the GPZ might be able to share some insight.

So, here's the scenario. I have what I think is an old equipment pad I've been working. I've nicknamed it my "trash patch" since it is just hammered with trash, probably why it doesn't appear to have be detected much even though close by areas have been beat to death. I found my first nugget in there with my GPZ at about 8", The problem, so much trash I couldn't even keep a single target under the 14" coil. I went back this week and spent 2 1/2 days (sun up to sun down) with my GB2 cleaning about a 2500sf area of trash. I can't begin to know how many targets were removed, but I can tell you my legs are so sore from that many squats I can barely walk today. Once I got the area clean, I was super excited to get back over it with the GPZ and see what I could find.

And, here's where we get to the help part. This entire pad has basically been built with about 3" of crushed hotrock. I thought getting the trash out was the biggest issue, but it wasn't. I can't figure out setting on the GPZ to get through the top layer. Either it just wobbles and whines all over the place, or you choke the settings down so hard it won't pick up anything. I can't find a working medium. Short of racking and shoveling 3" of rock off this area, which moves way outside the bounderies of enjoyable hobbie for me, I'm not sure what to do.

Anyone have some detector settings I might try, or other ideas would be greatly appreciated.

Attached are 8 little micro nuggets I pulled off the surface cleaning trash with the GB2. Everything I have got more than 2"s below the rock layer has been larger.

Thx, Beau

20191116_110417.jpg

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First thing everyone needs to know is what settings you are currently using. Factory default and if not, all adjustments you have made.

Minelab GPZ 7000 Factory Default Detect Settings

Gold ModeHigh Yield, General, Extra Deep

Ground Type - Normal, Difficult, Severe

Noise Cancel Channel Auto 1 to 256 (Preset 129) Manual 1 to 256

Sensitivity  - 1 to 20 (Preset 9)

Volume  - 1 to 20 (Preset 8)

Threshold Level  - 1 to 50 (Preset 27)

Threshold Pitch  - 1 to 100 (Preset 53)

Volume Limit  - 1 to 20 (Preset 12)

Audio Smoothing - Off, Low, High

Ground Balance Mode - Auto, Manual

Ground Smoothing - Off, Locate Patch, Salty Soil

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My general setting for the area are:

GM - High Yield

GT - Normal 

Sensitivity - 8

Volume - 15

Threshold 35

Threshold Pitch 35

Volume limit - 5

Audio Smoothing - High

Ground Smoothing - OFF

I tried High yield/GT difficult, General/ GT normal, General/ GT difficult. Also tried these settings in GS off and Locate Patch. To be perfectly honest, adjustments beyond that felt beyond my experience at this point. I have less than 50 hours on the ground with the GPZ . I didn't want to start chasing the white rabbit.

 

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Hi CCRV. 

Perhaps try a Factory Reset and start from scratch.  Just in case there is some outlier setting in there somewhere giving you an issue. 
 

My guess would be High Yield difficult as being your best bet. 
 

Threshold at 35 is a question mark for me. I would think you will be missing the little fellas with that settings.  
 

Noise cancel, ground balance and ferrite balance over the hot ground in semi-auto tracking.  

Sensitivity at 1 and bring it up until unstable and back it off 1 or 2.  

Just my guess at what will quieten things.  Audio Smoothing and Ground Smoothing would be next if that all doesn’t work.  
 

Best of luck  😉

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Beau, if nothing else works, don't be afraid to try Severe Ground Type; in the right circumstances it can be a real weapon.

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Just a general question for anyone -- I'm a complete novice at nugget hunting:  I see you on your sidebar that you have a GPX 4000.  Would that be a better choice in this difficult ground?

 

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The basics of all tuning is to find the most sensitive settings that will handle the ground and hot rocks effectively. What you have left for power when that is done is what you have. Attempting to go for more power will bring back the hot rock or ground response... that is the problem in a nutshell.

First thing I would do if Normal/High Yield is not working is try Normal/General. Next up Difficult/High Yield and then Difficult/General. In each case sensitivity to where the detector is on edge of stability. It may be that once you get the machine stable you will feel you have “choked the settings down” too far. Unfortunately that is how this game works. Some ground forces you to detune the machine, which in turn means it might not do what you want to do. As GB just mentioned the GPX may be the better option. The sad truth is not everything is as detectable as we want, and some locations are such that any detector is almost worthless. Luckily those areas are extremely rare, but artificial locations like a manufactured pad are high on that list.

Even if a machine is unstable, working extremely slowly and digging signals that are different that all the other noises can get results. Background noise and hot rocks have a certain audio pattern and a nugget will often sound slightly different. I’ll still miss a lot but I can usually pull nuggets out of some pretty bad background noise by working very slowly and patiently.

Or go somewhere else easier! :smile:

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17 hours ago, Northeast said:

Hi CCRV. 

Perhaps try a Factory Reset and start from scratch.  Just in case there is some outlier setting in there somewhere giving you an issue. 

My guess would be High Yield difficult as being your best bet. 

Threshold at 35 is a question mark for me. I would think you will be missing the little fellas with that settings.  

Noise cancel, ground balance and ferrite balance over the hot ground in semi-auto tracking.  

Sensitivity at 1 and bring it up until unstable and back it off 1 or 2.  

Just my guess at what will quieten things.  Audio Smoothing and Ground Smoothing would be next if that all doesn’t work.  
 

Best of luck  😉

Your suggestion to work the sensitivity up makes so much sense. It's funny how the obvious can avoid me sometimes. Thx.

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Hey guys, Thanks for the input. I know I'm very late to the party with the GPZ and I appreciate you taking a minute to point me in the right direction. I'm sure you guys have hashed this over many times... years ago, lol.

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I strongly suggest you adjust as many settings as possible, this is the best way to learn what the gpz is capable of.  Start by dumbing down the machine, and then slowly working in the opposite direction with the settings until you feel you have the optimum settings for the ground beneath the coil.  This will take some time and loads of patience, but you will become more efficient as time goes by. 

The hard part is over, you found gold, now you just need to get it all.  Have fun.

Brian.

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