Minelab GPZ 7000 Depth Tests And Charts - Looking Back

[goldenoldie]

***Editor's note - the following thread was split off from one about air tests and their reliability or lack thereof at http://www.detectorprospector.com/forum/topic/1472-minelab-x-terra-705-vs-garrett-ace-250/*** Steve H


How are we then to believe the depth charts released by ML comparing the 7000 with the 5000 and 2300?

[Steve Herschbach]

You don't have to. Having used all three I can draw my own conclusions and anyone else can do the same.

[goldenoldie]

Okay thanks Steve as from what I have observed those charts do not reflect the same.

[Steve Herschbach]

I guess when in an information vacuum they had to start someplace but even for people unable to test the machines themselves there are more than enough operators using the various Minelab models under various conditions worldwide for one to draw some fairly good conclusions with Google and a lot of reading. No need to rely on marketing material at this point.

The key words in all the Minelab comparison charts are "up to". Understanding that phrase and what it means in marketing terms is all a person really needs to know.

[Jonathan Porter]

How are we then to believe the depth charts released by ML comparing the 7000 with the 5000 and 2300?

 

Because the Minelab tests were not conducted in air! 

[goldenoldie]

Because the Minelab tests were not conducted in air! 

 

I never said they were however do you know how they were conducted? 

[Steve Herschbach]

Well, let's take a look....



UP TO 40%* and UP TO 30%* and UP TO 40%*

*When compared to the average performance of the GPX 5000 in typical environments. Actual performance depends on prevailing conditions.

The information displayed in this graph is an out-of-the-box comparison, is indicative only, and is based on the results of laboratory measurements and field testing undertaken by, and for, Minelab using a GPX 5000 with the 11" Monoloop coil, an SDC 2300 with attached 8" Monoloop coil and a GPZ 7000 with the GPZ 14 Super-D coil.The nominal performance for GPX 5000 with the 11" Monoloop coil is used as the baseline for comparison of the other detectors. The performance of the GPX 5000 on larger nuggets with a larger comparable accessory 15" x 12" Monoloop coil is also depicted. Note that a GPZ 7000 with a GPZ 14 coil will also typically further outperform a GPX 5000 with larger accessory coils on small and medium nuggets.

Please be aware that the depicted results give a relative and realistic comparison of the three detectors for typical goldfields conditions for detecting the weight ranges of gold shown, but do not represent performance under all conditions, and should not be regarded as conclusive.

Minelab does not warrant or represent that the performance levels depicted will actually be achieved, as performance of the three detectors will vary depending upon prevailing conditions. relevant factors in detector performance include, but are not limited to, detector settings, coil size and configuration, ground type, mineralization levels and type, electromagnetic interference, gold nuggets size, shape and composition, and operator skill level.

[Steve Herschbach]

From Basics Of GPZ 7000 Technology: Zero Voltage Technology (ZVT) page 3

Performance advantage of the GPZ 7000

To measure the performance of any detector depends on many factors, such as: particular detector settings, coil size and configuration, ground type, mineralisation levels and type, electromagnetic interference, gold nugget size and composition, and of course, operator skill. Figure 3 shows the percentage increase in depth of a GPZ 7000 compared to the GPX 5000, using the same sized coils (14‐inch). This data was obtained at several different soil locations and conditions in Australia.

For these measurements:

• A GPX 5000 using a Monoloop with Fine/Enhance timings is used when testing in (highly) mineralised soils.

• A GPX 5000 using a Double‐D with either Normal or Sharp, whichever gives the best depth for each nugget tested (referred to as ‘GPX 5000 Normal’), is compared to the GPZ 7000 Difficult + General in moderately mineralised soils.

• The GPZ 7000 General is compared to the GPX 5000 Sharp or Normal (again referred to as ‘GPX 5000 Normal’) using a monoloop in moderately mineralised soils.

Here the vertical Y‐axis is the percent advantage, and the horizontal X‐axis from left to right, is for a steadily decreasing mass of the nugget tested, going from number 1 being for a 20 ounce nugget, to number 30 for a 0.13 gram nugget.

The X‐axis is not drawn to any scale, merely listing nuggets that were available for testing in decreasing weight order. The depth advantages of nugget numbers above 30, (30–35 being between 0.13 and 0.05g) are off scale; above 60%, and thus not shown on this graph.

The reason why the data is so scattered is because the two different technologies respond differently to how fast the eddy currents change; due to different Time Constants (TC). The Time Constants vary considerably between nuggets even if they have the same mass; that is, whilst the X‐axis list decreasing nugget mass, this does not necessarily correspond to continually decreasing Time Constant. As can be seen, the depth advantage varies considerably from nugget to nugget, and setting to setting, but the general advantage of ZVT is clear; mostly distributed between 0–40% improvement, and even more.

[Steve Herschbach]

Finally, at least some of the GPZ comparative testing was done in a test pit as shown in this video starting at the two minute mark.

 

 

 

Anyway, there is all I know on that subject, people can draw their own conclusions and judge this all on what time has revealed as fact in the field. I guess I am way too jaded from my years in sales to see anything but the words "up to" and so I know what I am seeing in the field clearly fits into at least that category. In fact I can say I have seen performance from my GPZ on the order of several hundred percent better than a GPX on certain specimen gold.

 

Others no doubt feel otherwise.

[LuckyLundy]

Steve, no dought the chart above was formulated with Australian soil conditions which I've never swung on, but hear they are nasty for detectors to say the least. I know, my hunting partners and I, dig up nuggets weekly that are way off this chart. And that's in some tough mineralized dirt of our Western States. The GPZ, is what it is...Expensive & Awesome!

LuckyLundy