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Someone Convince Me The Nox 800 Is The Machine To Buy!!!


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22 hours ago, kac said:

Went to order the Nel Super Fly for my MK but the dealer is only doing pre-orders. I have a good feeling that it will do very well on the MK and give the depth in the range of a Nox.

Can't compare TID accuracy between an 11" Nox coil and the MK stock 7x11. I have accurate TID's to 7" when I keep the gain <89. Beyond that the numbers will drop and how much depends on the soil. That doesn't go without saying I can tell a dime at 9" with the stock coil despite the numbers dropping.

I have tested the Nox  with the 6” coil, Vanquish 10 x 6” coil against the Deus/ORX  9” coil and Multi Kruzer 11x7 DD, 7” concentric, and 9x5 DD and the Simplex with the 11” coil vs the Nox with 11” coil.

Nox has the best target ID accuracy at full depth of detection, 11” for 11” coil and 8” on the 6” coil on wild US coin targets in my area and the Vanquish is right there with the Nox. The Deus comes in second. The Multi Kruzer was a distant third for target ID accuracy on ALL targets, shallow to deep in my area.

The Nox vs Simplex was a toss up for overall depth. The Nox had far better target ID accuracy even though the Simplex was as good as the Deus and 9” coil as far as target ID accuracy.

I don’t care about raw depth. I care about knowing what I am going to dig, whether it is likely to be a low-mid-high conductor.

 

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Keep in mind the Nox has only 50 id segments counting the -9 iron range and most other machines have double that so if there is a 4 number jump on a target on most other machines the Nox would have half that so it may appear to be more accurate.

I don't dispute that the cross referencing of frequencies can help in many conditions. Some machines have the ability to push the limits and often make the machines inaccurate when gains are set beyond the optimal balance of the machine and it's coil like the Kruzer for instance. The Gold Racer can hit a US clad dime at 10" in mild soil with a spot on ID and it's narrow 5" wide dd with barely a hint of something there. The AT Pro with latest firmware similarly has a descent ID to it's detection depth (older firmware you could hear a fringe target yet have no or low id).

One of the reasons I tried to get a larger coil for my Kruzer was so I could get better depth without putting the pedal to the metal and push the machine where ID's are not accurate or the machine becomes noisy in lousy ground.

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2 hours ago, kac said:

Keep in mind the Nox has only 50 id segments counting the -9 iron range and most other machines have double that so if there is a 4 number jump on a target on most other machines the Nox would have half that so it may appear to be more accurate.

You are mixing up accuracy and stability here.  The nox will appear more "stable" because it has less resolution/precision therefore less variation at the edge of ID detection because it can only bounce between a smaller range of IDs. Accuracy is simply whether or not the displayed number is correct for the given target vs. up or down averaged.  I personally prefer stability and repeatability to resolution/precision (i.e. the ability to discern between different targets with similar target IDs.) as long as the ID is accurate.

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Not mixing it up, didn't say it well. Nox has fewer id#'s so it has less precision to display. I assume it would be possible to have a 100 block id system on a Nox but there is a reason they deliberately used half that.

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10 hours ago, Chase Goldman said:

You are mixing up accuracy and stability here.  The nox will appear more "stable" because it has less resolution/precision therefore less variation at the edge of ID detection because it can only bounce between a smaller range of IDs. Accuracy is simply whether or not the displayed number is correct for the given target vs. up or down averaged.  I personally prefer stability and repeatability to resolution/precision (i.e. the ability to discern between different targets with similar target IDs.) as long as the ID is accurate.

Can you give some examples?  The first couple sentences made sense to me but the farther I read the more confused I got.  🤔

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13 hours ago, GB_Amateur said:

Can you give some examples?  The first couple sentences made sense to me but the farther I read the more confused I got.  🤔

OK - you are going to be sorry you asked, Chuck.  :smile:  This will probably raise more questions than it answers but I will give it a shot.  I am sure there are going to be parts that are confusing but I will do my best...

Let's say we have the Nox at -9 to +40 and the Deus at 0 to 99 (it actually goes from -6.8 to 99 but I am just going to ignore that for this discussion).  I chose Deus because it is a 100 point detector for which I am most familiar.  So lets compare these two detectors against each other using the defined terminology below:

Accuracy is the ability of a detector to give the correct target ID under the greatest range of conditions and targets that work against the detector giving the correct ID.  Mostly, depth is the biggest culprit here.  At some maximum detection depth, the detector knows a target exists but cannot give a definitive ID.  It will either just give an audible tone with no ID or give a wildly inaccurate and/or variable target.  Other factors influence accuracy including nearby targets that might cause down averaging (typically iron) or ground conditions such as mineralization that will affect depth at which an accurate ID can be obtained.  The other thing that affects target ID accuracy is the composition of the target itself.  Most hobby detectors are designed/calibrated primarily to most effectively ID symmetric, coin sized objects.  Differences in metallic composition, shape, and orientation in the ground will affect the accuracy of detecting say an aluminum "coin" shaped object or an irregularly shaped aluminum object of similar metal mass.  Square pull tabs are notoriously difficult to discern as junk due to their compact square symmetric shape and the fact that they ring up similar to gold jewelry (rings) or nickels.

Resolution/Precision is the total number of segments/pixels/or points used to define the ID range.  The more points the higher the resolution and precision.  Just like high resolution displays have more pixels.  High resolution can enable a detectorist to more readily discern the difference between two different targets that have similar IDs (e.g., a nickel and a pull tab)  In the extreme case of a 0 to 99 resolution vs. a 0 to 9 resolution range, if a desirable target rings up as a 53 on the high resolution display, if you swapped the display out for lower resolution (0 to 9) it would show up as "5", but so would a target ringing up as 46, but a 57 might ring up as 6 on the low resolution display.  This is typically manifested in tone ID  where folks can be perfectly happy with 5 tones others swear by 50 tones.  So you can see the advantage of precision But precision does not necessarily mean accuracy.  A high precision ID display is worthless if it displays a target at 57 when it should accurately be displayed at 53.

Stability - stability is the ability of the detector to provide an ID that does not bounce around.  It is somewhat related to accuracy but stability can also be a function of resolution/precision.  Typically higher resolution detector scales - e.g., 0 to 99 suffer more severe ID stability issues than lower resolution detectors because the numbers will bounce around more due to whatever might be causing the stability issue (depth, nearby targets, target orientation, etc.)

Repeatability.  The ability of the detector to give the same ID for a given target repeatedly under the same or even variable conditions.  Again, similar to precision, a repeatable ID is not necessarily an accurate ID.

Let's look at some practical examples:

Nickels and pull tabs.  

On the Nox a clean nickel will ring up 13 if the Nox is accurately detecting it.  On the Deus let's say it rings up as 55.

Let's say that it is also detecting a pull tab at say 15.  On the Deus, say 63.

Notice how the higher resolution of the Deus spreads out the ID numbers between the Nickel and Pull Tab, making it much easier to ID the pull tab vs. the Nox.  Presuming they are both displaying accurate IDs, you can see where precision/resolution has an advantage.

A look at stability:  Now let's presume we are at the edge of ID detection and we are getting some variation on the nickel signal and the pull tab signal.  Say on the Nox the nickel is varying between 12 and 14.  This would equate to a variation of 51 to 63 on the Deus.  A much higher variation.  Let's also say that the pull tab is varying between 13 and 16 on the Nox and which would correspond to 55 to 68 on the Deus.  You might still say more highly varying pull tab signal is still a pull tab, despite the fact that it is dropping into the nickel range but if you are getting a lot more discrete numbers popping up at you due to the bouncing, it might be more difficult on the Deus to get a good reading because of the higher resolution.  In these examples I was assuming a direct ratio of target IDs between the two detectors and also assuming the filtering was the same, resulting in the same relative variation in target ID.  Improved filtering combined with other signal processing can improve stability up to a point.  But lower resolution target ranges just inherently look more stable.

A look at repeatability - let's say that you have a stable detector but it is not highly repeatable.  You may have a situation taking the above situation where a nickel on the Nox reads 13 in one spot, then 12 in another (exact same conditions, orientation etc.) and then 14 in another.  That would certainly not be desirable.  On the Deus that might look like 55, 51, and 63.  So with the higher precision detector but high variability (low repeatability), the numbers vary greater (just as they would in the stability examples).  So a higher resolution display with poor repeatability is worse than with a lower resolution display.

I rarely need the precision that the 0 to 99 scale provides.  The fact that the Nox can reliably differentiate between a pull tab and a nickel is good enough for me and I will take the smaller variations in target IDs under conditions of lower stability.  Most modern detectors have pretty good repeatability, so that is not typically an issue, but it can be and here too, the lower resolution display works for me..  If I could be guaranteed rock solid stability, than the higher precision would be welcome.  That seems to be what the FBS detectors provide and that is enhanced by the use of a two-dimensional FE-CO target ID number.

On the Deus things get really complicated when you up the frequency but don't normalize the target IDs to a specific frequency (18 khz IDs is what Deus will normalize IDs to if you select ID normalization).  In that case IDs get shifted up with higher frequencies.  The problem is that the scale endpoints do not change (still 0 to 99) so the higher conductive/higher ID targets start getting jammed up and compressed at the top end of the scale.  BTW ID normalization is not an option for the white HF Deus coils so things get really interesting at the super high 56 khz and 72 khz operating frequencies.

 

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Thanks, Hugh!  I hope you didn't have evening plans (worse, with family) that you blew so you could write this.  I need more time to absorb it, but on first reading I understand it, I think.  I'll comment more tomorrow.

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Thought I blew up the post with my wimpy post, well said.

That is good to know on the HF coils that you can't normalize the id scale.

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    That was probably one of the best comparison's I've ever seen Chase!!  I will try and commit this to long term memory! (And print)!! Definitely useful as reference material, when things get cloudy!

Thanks!👍👍

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