ATX Vs. AT Gold On Tiny Nuggets

[N7XW]

I know this is an apples to oranges  comparison and don't  intend to determine which is "better" as each is better suited for certain specific tasks.  That being said, I do want to find out which machine would do better (deeper) on tiny small gold.  I suspect the AT Gold would be stronger on less than 0.2 gram nuggets but I know the ATX is quite good on small nuggets also (better than the Infinium).  I've recently watched a couple of videos where the AT Gold hit a one grain nugget at about an inch and the ATX found a 0.16 gram nugget near the surface in bedrock (thanks Bearkat4160 and DetectorComparisons).  So, has anyone compared these two machines on tiny nuggets?  I'd appreciate any info.

 

[Steve Herschbach]

The answer highlights why it is apples and oranges. It depends on the mineralization.

In an air test or "no mineral" ground, the AT Gold will slay an ATX if you even up the coil sizes, and get signals on small gold the ATX can't even detect.

Now, turn up the mineralization dial. The higher you set it, the more depth each machine loses. But the VLF will lose depth far faster than a Ground Balancing Pulse Induction (GBPI) detector and so the ATX will catch up to and pass the AT Gold. In extreme mineralization the ATX could end up going twice as deep or deeper than the AT Gold. The small gold the AT Gold could hit in air tests that the ATX missed are now undetectable to the AT Gold also. 

There has always been this huge misperception about the depth difference in general between a VLF and a GBPI detector. People do air tests and wonder why they do not see this advantage people talk about. The difference is almost 100% predicated on the differences in ground mineralization encountered in the field, and this varies location to location, as does the nature of the gold itself.

The inherent ground canceling capabilities of a GBPI detector are accentuated by the fact that a GBPI can put much larger coils to effective use than a VLF.

This ability to snatch even tiny gold out of bad ground is well illustrated by the SDC 2300 versus any VLF. Normally a Gold Bug 2 or GMT will pull the small gold out of the ground like nothing else. In bad enough ground however a Gold Bug 2 sees its ability severely hampered, and the SDC 2300 easily punches deeper on the really small stuff.

All this is why I just shake my head at air tests. They tell you virtually nothing about what to expect in gold country for real world performance. In fact the best air testers are often the most problematic in very bad ground. Air tests have value but telling you how the machines compare in the worst ground is not one of them.

I have a little saying about it - "Use a VLF when you can and a PI when you must". You will know when that happens!

[N7XW]

Great, thank you Steve.  That info is much appreciated.

Let me ask you this though - does the ground balance on the AT Pro or auto sensitivity on the CTX give any indication as to the level of mineralization?  I would think that it does.  

My AT Pro typically ground balances at 94 and my CTX can usually run in the low to mid 20s, maybe up to 27 when set on auto +3.  This is of course in the areas where I coin hunt but assuming the same level of mineralization in gold detecting areas, would you take the AT Gold or ATX?  This may be a difficult question - or maybe not, I don't know.  But I would certainly like to know what you think based on how my AT Pro and CTX run.

 

[Steve Herschbach]

Ground balance numbers are only loosely related to the level of mineralization. The ground balance number indicates the type of mineral being encountered, not the amount of the mineral. Maghemite is about as bad as it gets, but it will deliver low ground balance numbers. There is a huge thread on the subject at http://www.detectorprospector.com/forum/topic/1599-gb-numbers-mineralization/

The auto sensitivity indications on the CTX are a better indicator, and mid to higher 20's (max is 30) indicates normal to milder ground. In general I would say ground for a VLF. Many gold bearing locations will be worse.

Even this can be misleading. Our ground at Moore Creek, Alaska was quite mild, but had lot of magnetite laden hot rocks buried in that mild ground. Actually a bad scenario as the difference between the rocks and the ground itself really accentuates the hot rocks, which really are nothing but rocks that are significantly different than the ground they occur in. So while the ground was mild the hot rocks called for a GBPI detector.

If you only look for nuggets once or twice a year than it may not be worth it, but for any serious prospecting I am a big believer in having both a VLF and GBPI along at all times. If nothing else one provides a backup for the other should a hardware failure occur.

For what it is with the ATX is a great salt water jewelry detector for me at least, providing extra reasons for ownership.

[N7XW]

Thanks again Steve.  I am seriously considering both of these machines and appreciate the info.  I'm going to read up on mineralization.  The term is always thrown around but I want to know more about it and in particular exactly what it is that makes it difficult to deal with.