Depth comparison between 14"GPZ coil and 19" GPZ coil. *** More Air tests Added***

Have spent the last 2 days testing the difference between the two Zed coils WITH 3 GPZed's, 2 more days of testing to go. Minelab claims up to 30% improvement over the 14" by the 19" coil.
Unfortunately (IMHO) this is staggeringly incorrect  This claim by Minelab is totally overestimated !
Some will come on and say air tests aren't accurate, but since there is no mineralised variables in between the target and the coil, air tests should be regarded as a fair comparison. All we are comparing is the depth difference between the 2 coils on varying sized gold nuggets.
Air test results between 14" and 19" GPZ Coils. All tests on both coils were conducted in Factory Preset.

Nugget        ........        14" coil       ..............         19" coil      ...............   % difference

1.2 gram                        8"                                     8"                         0 %

3 gram                          11"                                   10"                     minus 10 %

6.6 gram                        13"                                  12"                      minus 9 %
 
16 gram                         16"                                  16"                         0 %

41 gram                         17"                                  18"                      + 6 %

89 gram                         20"                                  20"                          0 %

192 gram                        14.5"                               16.5"                     +9.9 %
----------------------------------------------------------------------------------------------------
                            In General Mode                    In General Mode

192 gram                         17.5"                                18"                         + 4 %
-----------------------------------------------------------------------------------------------------
                           In Deep Mode                           In Deep Mode

192 gram                        17.5"                                      19"                  + 8.8 %

*************************************************************************************
Hi all, we decided to try a different set of nuggets, as some people suggested the lack of depth was due to the stealth shape of the first set of nuggets. LOL.

All tests were performed in factory preset on low mineralised soil.

Here are the results.

Nugget size                                       14" coil                                     19" coil               % Difference

2 gr                                                  9"                                                8"                 Minus 8 %

3.2 gr                                               7"                                                6"                  Minus 12 %

5.3 gr                                               13"                                              14"                    + 9 %

6.7 gr                                               13"                                              13"                     0 %

8.7 gr                                               8.5"                                             8.5"                    0 %

10.3 gr                                              13.5"                                           15"                  +12 %

1/10 oz. Gold coin
99.99 % purity                                   15"                                               16"                 + 7 %


Sadly, as you can see from the above new test results, even with the new set of nuggets, nothing has improved. The 19" coil is still a dog. ( Good onya Reg !)

Photos of nuggets used.

Interesting results there, No doubt we will see more results from other testing done over this week end. Thanks for putting your time consuming testing out there for us all.

Cheers
Ashley

Were the tests conducted with the coils 90 degrees from the ground, as they normally are during air tests? Reason I ask is because ground noise may be less of a factor in air tests - but air noise (EMI) increases. And a larger coil is much more effective antenna, and when you flip it up normal to the ground you are pointing it right into the transmission plane of many signals, that effect is greater with a bigger coil, which makes it harder to pick a subtle signal out of the fray.

Also, for any people conducting tests, it would be very useful to post all relevant settings, otherwise the test lacks context for those of us who weren't present.

For me, the question is how much mineral immunity does the coil have, it makes a difference if its enough to allow you to switch into normal. Air tests won't demonstrate this.

Thanks for spending the time doing this though, from those of us like myself who can't afford to do it themselves this time around.

G'day Jasong, all our air tests are performed with the coil horizontally flat over the ground, (just like in actual detecting conditions) The tests were performed over and in average to high mineralized ground conditions.
The GPZ's were balanced and tuned to run the 14x13 & 19 inch coils smoothly over this ground, which they did. There was no EMI present during the comparison tests.

All tests were performed in "Factory Preset" High Yield, Difficult, low smoothing, 27 threshold, 9 sensitivity. After concluding testing in Factory Preset, out of interest, we also tested the 192 gram nugget in
"General" & "Deep" mode, with the incurring, disappointing results.
We did not test in "Normal Mode" but will get back to you latter on this one. Here in Victoria, we can never run our GPZs in normal mode, due to excessive ground mineralization.

Cheers, Harry

Ok thanks for the additional info, interesting so far and looking forward to your results in the coming days.

Thanks for posting your findings Slim, unfortunately, your testing is flawed to make the claims you have below

slimpickens wrote:
Unfortunately (IMHO) this is absolutely FALSE.  This claim by Minelab is totally overestimated !

Some will come on and say air tests aren't accurate, And they'd be accurate

All we are comparing is the depth difference between the 2 coils on varying sized gold nuggets.

There-in is the flaw in your methodology to make such flagrant announcements. If you want to discredit something, you have to do so by 'trying' to REPLICATE the manufacturers process, not some other arbitrary method removed from how the original results were obtained.

I don't know you, and this is not personal, i'm only highlighting the flaws in your premise. I see at least 5x threads about this on various forums (and that's without trying) and for you all to make strident claims about ML "LYING" (ie; misleading/overestimated/Flase Claims), that's serious right there... just because you can't 'replicate' ML's performance figures..

Sorry, but that's how it is. If you set out to discredit, at least do it honorably.

Gypsy

Thanks Slim, not looking rosy at all, MINUS %. What on earth are Minelab playing at!
Kudos to Reg.

Good on you Slim ' takes guts to tell it as it is !  

Hey gypsy ' that last comment was you made about Slim was below the belt , suggest you withdraw it while you can .

jack .

GypsyGoldAu wrote:Thanks for posting your findings Slim, unfortunately, your testing is flawed to make the claims you have below

slimpickens wrote:
Unfortunately (IMHO) this is absolutely FALSE.  This claim by Minelab is totally overestimated !

Some will come on and say air tests aren't accurate, And they'd be accurate

All we are comparing is the depth difference between the 2 coils on varying sized gold nuggets.

There-in is the flaw in your methodology to make such flagrant announcements. If you want to discredit something, you have to do so by 'trying' to REPLICATE the manufacturers process, not some other arbitrary method removed from how the original results were obtained.

I don't know you, and this is not personal, i'm only highlighting the flaws in your premise. I see at least 5x threads about this on various forums (and that's without trying) and for you all to make strident claims about ML "LYING" (ie; misleading/overestimated/Flase Claims), that's serious right there... just because you can't 'replicate' ML's performance figures..

Sorry, but that's how it is. If you set out to discredit, at least do it honorably.

Gypsy

Gypsy

I am quite sure that someone asked Minelab a while back what was wrong with his coil and the techo from Minelab told him to place a 5 cent coin on the ground and do a simple air test to get a specific depth reading. Seems Minelab doesn't mind doing air test.
It's very simple to do an air test Gypsy, and I'll be hanging out for your results. Just grab your GPZ 7000 and the 2 coils in question and a few nuggets and let us know if your figures match ours or do they match Minelab's 30% claims.
As far as replicating Minelab's testing methods, I would love to. We await you or Minelab putting their method up on this forum so we can achieve the said 30% extra depth advantage over the 14 " coil.

All prospectors out there will do their own testing and in their own prospecting ground hence your claim here Gypsy that we need to replicate Minelab's testing conditions is a bit confusing.
We all bought the new coil in great anticipation and with great enthusiasm to work some of the old gold producing ground. We did not initially doubt all of the findings and results released by Minelab.
We believed and had a lot of faith in Minelab but when we put the coil to the ground we saw the disappointing results and lack of depth improvement.
I want to work ground that gives me depth increase and that is why I have invested time and money on the new GPZ and 19 inch coil.
I do not at this stage emphasize ground coverage which the 19 inch gives.
I also think it is wrong to try and sell my coil on the basis that it gives the prospector greater depth, who is going to be the misleading trader when I sell my coil - 'Me or Minelab'
Bill

Jack outwest wrote:Good on you Slim ' takes guts to tell it as it is !  

Hey gypsy ' that last comment was you made about Slim was below the belt , suggest you withdraw it while you can .

jack .

Firstly Jack...there is no honor in publicly slighting a person/business/product using contrary testing to base a claim upon. I stand by it.

Just an FYI Jack....that was a generalization, and footnote to those following the same flawed methodology, not directed to Slim personally.

Second, I will take your suggestion with the disdain it deserves and ignore the veiled threat.

Gypsy

jasong wrote:Were the tests conducted with the coils 90 degrees from the ground, as they normally are during air tests? Reason I ask is because ground noise may be less of a factor in air tests - but air noise (EMI) increases. And a larger coil is much more effective antenna...

Yes indeed: Air tests are usually pointless - most especially with a coil over 16" -  due to EMI.  Many of these prospectors are experienced with larger coils. But .. using Factory Presets?  Surely the goal would be to use the ideal settings for the larger coil and to be running the appropriate settings/modes in the appropriate environment/conditions.  Just based on the relative sizes alone, the 19" should by default achieve greater ground coverage... and deeper penetration on targets over a certain size.

As for the fine print from the big 'M' : "The information displayed in this diagram is a coil-for-coil comparison, is indicative only, and is based on the results of laboratory measurements and field testing undertaken by, and for, Minelab, using appropriate and identical detector settings. Please be aware that the depicted results give a relative and realistic comparison of the two GPZ coils 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 always be achieved, as performance of the two coils will vary depending upon prevailing conditions. Relevant factors in detector plus coil performance include, but are not limited to, detector settings, ground type, mineralisation levels and type, electromagnetic interference, gold nugget size, shape and composition, and operator skill level."

....Even ML state they don't Warrant you to acheive the same results (always)...not hard to see why no ASB, ACCC, ASIC or ASX charges pending....Broken expectations based on not reading the fine print...

slimpickens wrote: [snip]........[snip]
As far as replicating Minelab's testing methods, I would love to. We await you or Minelab putting their method up on this forum so we can achieve the said 30% extra depth advantage over the 14 " coil.

The precedent to this is nullified by your last.

How can you make strident claims of performance, when you don't even know how or what ML measured?...

For those with dashed expectations, i'm sorry you laid down, what for many is a lot, of $$$ and didn't get what you'd hoped for...i hate that for me too. But i don't cry foul when what i paid for doesn't 'perform' as advertised.

I refer to a post i placed elsewhere re;

#FOOTNOTE#

My final in this discussion ...

For all those using advertising figures to support their grievances......

How many of you have still got a fridge that uses more than advertised energy usage??....how many driving cars not meeting the advertised fuel consumption??...how many still using Equipment/Appliances/Accessories that are NOT performing to "specified advertised numbers"??......    

How long will it take to realize you are NOT replicating the TEST conditions, nor know, from what it is they are measuring, to arrive at the advertised figures??. So to attempt to REFUTE any such result without that replication is an exercise in FUTILITY  & disingenuous imo.

Like all diversions in life, some will attract Lovers...others Haters....be what you are, as both are right.  

I say again,...IF it were to be ML is being 'deceptive' in their advertising, they would/have be/been in front of the ASB, ACCC, and possibly ASIC & the ASX......soooo? (remember,...these allegations are not new, so where's the 'evidence'?)


*crickets* *crickets*........


.
.
.
.
Soooo, who's finding heaps with the new 19"?....Very Happy

Gypsy

GypsyGoldAu wrote:

Jack outwest wrote:Good on you Slim ' takes guts to tell it as it is !  

Hey gypsy ' that last comment was you made about Slim was below the belt , suggest you withdraw it while you can .

jack .

Firstly Jack...there is no honor in publicly slighting a person/business/product using contrary testing to base a claim upon. I stand by it.

Just an FYI Jack....that was a generalization, and footnote to those following the same flawed methodology, not directed to Slim personally.

Second, I will take your suggestion with the disdain it deserves and ignore the veiled threat.

Gypsy

Gypsy you were just starting to be accepted as a good contributor here '  all you had to say was you disagree & give the reasons why .

There was no veiled threat mate , just trying to stop you shitting in your own nest   so now be a good boy & say sorry Slim .

Jack .

[quote="Jack outwest"]

Miscomprehend much?

*Ignored*

I'm onto you Gypsy. You are after JP's job.

Reg Wilson wrote:I'm onto you Gypsy. You are after JP's job.

He said you would say that....

I've copped a pretty savage kicking from some people over this fiasco, and it seems those who are keenest to put the boots in are the ones who have found the least gold.

Reg Wilson wrote:I've copped a pretty savage kicking from some people over this fiasco, and it seems those who are keenest to put the boots in are the ones who have found the least gold.

i'm presuming that's directed to me, and my response is who's kicked you?
Certainly not I, all i have done is question how you attained the expectation you had, and how you managed to determine your expectations were ill founded.

You on the other hand have done your fair share of kicking as well, ...kettle/pot...

As i've said before Reg, i only know you from online so it's not personal, and neither of us 'knows' each other, just our perceptions from our interactions online. Each of us is more than we reveal online, so no need to get miffed if one questions elements of your scribes eh?

If you need a punching bag to feel better over your disappointment Reg, go ya hardest cause it really is water off a ducks back to me.

Cheers

Gypsy

nero_design wrote:

jasong wrote:Were the tests conducted with the coils 90 degrees from the ground, as they normally are during air tests? Reason I ask is because ground noise may be less of a factor in air tests - but air noise (EMI) increases. And a larger coil is much more effective antenna...

Yes indeed: Air tests are usually pointless - most especially with a coil over 16" -  due to EMI.  Many of these prospectors are experienced with larger coils. But .. using Factory Presets?  Surely the goal would be to use the ideal settings for the larger coil and to be running the appropriate settings/modes in the appropriate environment/conditions.  Just based on the relative sizes alone, the 19" should by default achieve greater ground coverage... and deeper penetration on targets over a certain size.

As for the fine print from the big 'M' : "The information displayed in this diagram is a coil-for-coil comparison, is indicative only, and is based on the results of laboratory measurements and field testing undertaken by, and for, Minelab, using appropriate and identical detector settings. Please be aware that the depicted results give a relative and realistic comparison of the two GPZ coils 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 always be achieved, as performance of the two coils will vary depending upon prevailing conditions. Relevant factors in detector plus coil performance include, but are not limited to, detector settings, ground type, mineralisation levels and type, electromagnetic interference, gold nugget size, shape and composition, and operator skill level."

Pitty you just cherry picked the wrong bit of the Blurb Nero

Go down the page a little and you will see this statement
"For those of you that buy the GPZ 19 coil, you should expect it to be 30% deeper, on average, compared to the GPZ 14 coil"
source
http://www.minelab.com/anz/go-minelabbing/treasure-talk/the-gpz-19-coil-does-it-really-detect-30-deeper

Now regardless of anything else, this is a promise to the consumer
If you buy our coil You (the consumer) should expect blaa blaa blaa
This Statement alone is enough for action to be taken if you not seeing your expected 30% av result

Philsgold wrote:
Now regardless of anything else, this is a promise to the consumer
If you buy our coil You (the consumer) should expect  blaa blaa blaa
This Statement alone is enough for action to be taken if you not seeing your expected 30% av result

 

Fair comment Philsgold, so tell us, how did you obtain your figures to refute ML's?....and just what was it you are 'measuring'?

Cherry picking?...re-read the ML disclaimer Nero placed above....then claim cherry picking.  

What part of this;..."but do not represent performance under all conditions, and should not be regarded as conclusive...." doesn't make sense, perhaps we can help?.

Gypsy

Gypsy, you did your share of kicking on another forum. You say I don't know you, well we can rectify that at your convenience by meeting somewhere of your choice, where we could have a quiet beer together, and discuss the pros and cons of this coil. I would be happy to show you what my problem is with this product first hand. This should not be too difficult as you do not live far from me.

Reg Wilson wrote:Gypsy, you did your share of kicking on another forum.

Now you just take that back Reg Wilson   ,  i have not, & did not kick you,... just your methodology...simples.

Sorry you feel too indignant to consider others viewpoint, but i'll get over it.  

That you built expectations based on a false premise is not of my doing, i just tried to illustrate where you may have gone wrong.

Again, sorry your not happy with your purchase, ....i'm moving on...

Gypsy

GypsyGoldAu wrote:

Philsgold wrote:
Now regardless of anything else, this is a promise to the consumer
If you buy our coil You (the consumer) should expect  blaa blaa blaa
This Statement alone is enough for action to be taken if you not seeing your expected 30% av result

 

Fair comment Philsgold, so tell us, how did you obtain your figures to refute ML's?....and just what was it you are 'measuring'?

Cherry picking?...re-read the ML disclaimer Nero placed above....then claim cherry picking.  

Gypsy

I have and the disclaimer is in relation to the diagram and starts thus
"The information displayed in this diagram is a coil-for-coil comparison"

The statement, If you buy our coil Blaa Blaa has no Disclaimer, ML would be gone in Court
People are expecting 30% on ave improvement in depth based on ML's promise, and are not seeing it.
Easy

Philsgold wrote:

GypsyGoldAu wrote:

Philsgold wrote:
Now regardless of anything else, this is a promise to the consumer
If you buy our coil You (the consumer) should expect  blaa blaa blaa
This Statement alone is enough for action to be taken if you not seeing your expected 30% av result

 

Fair comment Philsgold, so tell us, how did you obtain your figures to refute ML's?....and just what was it you are 'measuring'?

Cherry picking?...re-read the ML disclaimer Nero placed above....then claim cherry picking.  

What part of this;..."but do not represent performance under all conditions, and should not be regarded as conclusive...." doesn't make sense, perhaps we can help.

Gypsy

I have and the disclaimer is in relation to the diagram and starts thus
"The information displayed in this diagram is a coil-for-coil comparison"

The statement, If you buy our coil Blaa Blaa has no Disclaimer, ML would be gone in Court
People are expecting 30% on ave improvement in depth based on ML's promise, and are not seeing it.
Easy

Fixed that for you.
Easy.

Gypsy

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The GPZ 19 coil – does it really detect 30% deeper?
October 26, 2016 10:05am
Phil Beck
Phil metal detecting

With the imminent release of the GPZ 19 accessory coil, I thought it was worth discussing its depth capability and how our 30% performance statement was derived. Typically these types of claims are commonly greeted with much concern and doubt, before many are even able to get their hands on the product and test it for themselves. Even then, there are a wide range of settings to choose from and soils to test in, so results can vary greatly depending upon the test conditions. Also, larger objects will typically be detected deeper for the same size coil. Anyway, some background information first…

We all basically know that large coils detect deeper than small coils. Why is that? The relationship between the size of a coil and the detection depth depends on a number of factors related to both the construction of the coil and the particular target itself. Starting with the coil itself, to compare the relative sensitivity of a large coil to that of a smaller coil, we need to determine the strength of their respective transmitted magnetic fields and the receiver sensitivities. These can be calculated by applying the Biot-Savart law, which describes the magnetic field produced by an electric current.
For this, we need the exact geometry of each winding, the number of turns and the size of the wire. Once we chose a shape, the number of turns and the wire size depend upon the constraints we apply to the design. For example, we usually require the inductance and the resistance of the transmit winding to be the same regardless of the size of the coil, such that the transmitter electronics operates optimally with any size coil. This leads to a reduction in the number of turns as a coil gets larger or conversely an increase in turns as a coil gets smaller.

Based on this, we can understand that a small coil with more turns creates stronger localised fields, while a large coil creates a field that is weaker in the immediate vicinity of the coil, but decays more slowly with the distance from the coil. Thus, further away from the coils, a larger coil has a stronger field.

We now need to consider the target, for example a particular nugget: if we use one coil as a reference, at what depth can we just detect the nugget with it? Once we know this, we can utilise the previously calculated relative sensitivity to determine at what depth we can detect the same nugget with the other coil. Doing this for a range of nuggets, we find that small coils are better suited for very small nuggets near the surface, while the larger coils are better for intermediate and deep nuggets.

Is this all there is to this comparison? Of course not, there are other second order effects that come into play and, while they do not alter the conclusions dramatically, they nuance the previous calculations. As an example, the ground noise that each coil picks up depends on the detailed geometry and construction of the coil, but also on the composition of the soil (e.g. how inhomogeneous it is, on what spatial scale, etc.). For example, larger coils tend to have less ground noise, due to their reduced sensitivity close to the coil and this means even greater depth than the sensitivity calculations alone would imply.

Now, to the practical test info everyone is after – comparing the large GPZ 19 coil to the standard GPZ 14 coil. We’re derived a composite graph from our test results. This is shown below; and also on the back of the product carton and the product webpage.


*When compared to the average performance of the GPZ 7000 detector with the GPZ 14 coil in typical environments. Actual performance depends upon prevailing conditions.

The information displayed in this diagram is a coil-for-coil comparison, is indicative only, and is based on the results of laboratory measurements and field testing undertaken by, and for, Minelab, using appropriate and identical detector settings. Please be aware that the depicted results give a relative and realistic comparison of the two GPZ coils 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 always be achieved, as performance of the two coils will vary depending upon prevailing conditions. Relevant factors in detector plus coil performance include, but are not limited to, detector settings, ground type, mineralisation levels and type, electromagnetic interference, gold nugget size, shape and composition, and operator skill level.

Let’s take a more detailed look at what this shows. These results were obtained from 8 specific gold nuggets ranging in weight from 1.9g up to 60.5g. Each nugget was tested in both low and high mineralised ground, with the GPZ 7000 detector set in High Yield Gold Mode and General Gold Mode. Therefore the results in the diagram above are an averaged combination of 4 data sets:

   High Yield setting, lower level of ground mineralisation
   High Yield setting, higher level of ground mineralisation
   General setting, lower level of ground mineralisation
   General setting, higher level of ground mineralisation

Also, these particular results show that there was no ‘crossover point’, with the GPZ 14 performing better at depth for the smaller nuggets, and there was not a uniform depth increase across the nuggets – it did vary up and down, with some results less than 30% and some greater. This is likely due to the individual characteristics of the nuggets under test. Here are some more detailed measurements.

As you can see, there’s a lot of comparative information here, hence the simplified version shown in our marketing materials. We carry out significant testing and all of the results build up to give an overall picture of a new coil’s performance. This includes verifying computer modelling, taking measurements from our four test lanes and a large variety of results from field testers around Australia and overseas. For those of you that buy the GPZ 19 coil, you should expect it to be 30% deeper, on average, compared to the GPZ 14 coil. It will also cover more ground and pick up less ground noise, but it is heavier and can also pick up more EMI. As with choosing any coil for any detector, it is still a trade-off decision, but you should find that the GPZ 19 really will unleash the full power of the GPZ 7000 detector!

Why do people not see some of the statements made by ML representatives.
Also read the writing on the box of the 19' coil. We have got 3 of them.
Do you feel me ............

vasilis wrote:Why do people not see some of the statements made by ML representatives.
Also read the writing on the box of the 19' coil. We have got 3 of them.
Do you feel me ............

Yes i think we were all expecting a

Are Volkswagen sharing their IP with Codan?