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goldenoldie

A Sensitive Question

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G'day all,

Been some time since I posted on this site and have followed the GPZ threads with interest and how it now compares to the GPX. 

In one particular thread I read the GPZ Audio Smoothing when set to its OFF position is similar to a Stabilizer setting of 20 on the GPX.

Therefore my question is in relation to the GPZ Sensitive setting, which is like the Gain setting on the GPX, and since both detectors have their range between 1 and 20 would you say the GPZ Sensitive default 9 setting be the same as running a Gain of 9 on the GPX 5000?,

Thanks in advance. 

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IMO Smoothing Off is more like a Stabilizer setting of ~12-14. I can't detect most places with the stab at 20, but I can detect most places with Smoothing off if I'm feeling patient (barring storms, salty ground, and right next to cities).

I think the Sens/Gain is close but not equal. To me changing the Sens makes more difference than changing the Gain, especially at higher levels.

Also, (especially with the 4500 but also with the 5000), upping the gain at higher levels seems to only increase EMI and not actual depth or sensitivity to small targets. Upping the Sensitivity on the GPZ at high levels seems to keep increasing the depth and sensitivity to small targets in a way that doesn't happen on the GPX.

Also, I can't help but feel that 14-15 on the 4500 and 18-20 on the 5000 just make it noisier, but I find 18-20 on the GPZ to be actual useful settings.

It's almost like GPX gain is logarithmic (think ln(x)) and the GPZ sensitivity is linear (think x) to me when looking at depth/target sensitivity, and both are linear when looking at noise.

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Thanks jasong for your opinion and you have raised some interesting observations.

 

Who came up with the Stabilizer 20 figure being equivalent to the Smoothing Off setting unless Minelab has stated it somewhere?

 

In regards to the GPZ Sensitive setting in comparison with the GPX Gain setting then I would now think the default setting of 9 on the GPZ would be equivalent to the default Gain setting of 11 on the GPX ? 

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I don't think direct equivalence in the gain can be determined except in the loosest way. They are different detectors and what happens at different gain settings varies dramatically depending on the nature of the gold used as a test target.

The Smoothing off equals Stabilizer at 20 thing is mentioned by JP at http://www.minelab.com/usa/treasure-talk/using-the-gpz-7000-in-high-emi-conditions-and-audio-smoothing

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It"s a big mistake to compare the GPXs to the GPZ and try to opperate one like the other. It's like comparing Apples to Orangatangs.

Using very high sensitivity settings on the Z works very well if you tweek everything else to keep it quiet and I have yet to confirm a significant loss of depth by doing so. With the GPXs I always think there is a big compromise between depth, sensitivity and smooth opperation.

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Using very high sensitivity settings on the Z works very well if you tweek everything else to keep it quiet and I have yet to confirm a significant loss of depth by doing so. 

 

Yep have to tweek everything else also if using a high Sensitive / Gain setting on the GPX although the Timing and different Coil sizes can regain any significant depth loss. Have some in-ground test results between a GPZ and GPX using one of the newer coils which showed the GPX to hold its own on smaller nuggets that were out of range previously. Therefore for me personally I will stick with the GPX.

 

Again thanks fellas for your replies.

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