My Tips On Nugget Detecting With The Minelab Equinox

[schoolofhardNox]

Thanks Steve for the insight on the gold modes. I may try that on the beach and see if that system works there. I really want to try gold 2 and get it stable on the beach.

[Mark Gillespie]

I'd love to have one for the super trashy areas around an old homestead.  But I guess I'll keep using the F75 with the 5" coil for that purpose.  In the future I might see into trading other coils for a used one for the Equinox.

 

[alaskaseeker]

Wow, well done Steve, I'm going to have to sift thru this info carefully, Thanx again for a well written synopsis...lol....

[strick]

Thanks for this post I still have not hunted in the gold modes for gold nuggets and this is going to be a big help when I finally do.

strick 

[Chase Goldman]

1 hour ago, phrunt said:

Is the iron bias a pointless setting if I dig virtually everything anyway?

Does it do more than just adjust the cut off point where the Equinox thinks a target is ferrous or non ferrous with the VDI numbers?

I tend to dig everything -7 or higher and have found a significant amount of my gold reporting in the negative numbers.

I'm trying to understand what Iron bias actually does, so if a nugget is coming up as -1 on the VDI's in the default 6 iron bias being tiny would an Iron bias of 0 try nudge it up to 1 on the VDI's?

I used to set it to 0 but I haven't noticed a difference leaving it at default and can obviously find tiny specs of gold without adjusting it.

 

Iron bias simply increases the ferrous weighting that Equinox gives a mixed ferrous/non-ferrous target response.  This is fine if you simply want to reduce the likelihood of getting fooled by a ferrous target such as a rusted nail that tends to give both a ferrous and non-ferrous response as you swing the coil across the target.  I won't get into the nitty gritty of why that happens, but we all pretty much have experienced it.  There are two other target possibilities, however, that will give you a similar mixed response.  One is a an actual target of mixed ferrous/non-ferrous composition such as some crown caps and the other is two separate targets in close proximity, one being ferrou and the other non-ferrous.  Increasing iron bias simply tells Equinox to more heavily weight the ferrous component of the mixed response giving you a more pure ferrous response and de-emphasizing the non-ferrous response.  Great if you want to avoid digging nails or rusty crown caps but not so great if you are looking for partially masked non-ferrous, mid to high conductors amongst a bed of ferrous targets.  In that case, those partially masked non-ferrous targets will become totally masked as far as the detectorist is concerned because iron bias will emphasize the ferrous target.

I have never seriously prospected for natural gold with a metal detector nor do I have any detecting buddies who prospect, so all I know is what I have read and that has been posted by Steve and other pospecters such you that have posted on various forums.  From what I know, typically a gold prospector is neither concerned about ferrous masking nor ferrous falsing, because, as you described it ferrous target density is typically, relatively low and the variability in gold target ID based on nugget mass means that desirable gold targets can fall well into the ferrous range of target IDs.  Since neither masking (favoring a lower iron bias setting) nor falsing are a concern (favoring a higher iron bias setting) , the iron bias setting is largely immaterial for the prospector.    Since gold does not "false"  and may indeed ID around the breakpoint of the ferrous-non-ferrous range and since masking is not of great concern, then keeping IB at the default higher setting on the 800 (IB 6 out of a maximum of 9) is probably a reasonably sound choice because at least you will avoid the falsing that might occur when you sweep over the occasional ferrous target (e.g., nail)  that might be giving you a mixed ferrous/non-ferrous signal and IB may help "emphasize" a repeatable signal for those nuggets that ID in the ferrous range that may be in the near proximity to a non-gold, non-ferrous target (this latter point is dubious at best but theoretically true).  Seems to be pretty consistent with your actual experience experimenting with IB, Simon.  That's my take, anyway based on my understanding of how iron bias works and my limited knowledge of typical prospecting conditions.  Perhaps someone else with prospecting experience can chime in.

[Steve Herschbach]

I have yet to explore this question in depth. I just set iron bias at 0 and go detecting. I have not recovered any gold that read as low as what you are reporting but that could be for several reasons besides the iron bias setting. My recommendation is you spend some time finding those negative number targets that have been coming up gold, and on quite a few of them run the bias to both extremes and check the target before digging to see if there is any difference. I keep meaning to do this but have just been too busy.

[Steve Herschbach]

What does the nugget air test as?

There are many things that might pull a nugget negative, like an adjacent hot rock or ferrous, hot ground, or mineral in the nugget matrix.

If the gold air tests negative it would be the last one. I saw a nugget once a Gold Bug 2 insisted was ferrous. It would disappear when iron disc was engaged.

If the nugget air tests positive then it has to be something in the ground or the tuning. I am going to put a test bed together and see if I can force a negative response on a tiny nugget.

[EL NINO77]

Simon ....one of the gold benefits of the one-tonne-mode is if you have enough open discrimination still a nice ton though you are getting minus-vdi. Can it be mineralization .... Have you tried other 2 ton mode like Park2? .If the program isn't as deep as the Gold modes.
 
It's a bit out of the way, but it has a definite ... well with gold prospectus ..
Today I am at 7 bar Fe3O4 -extremne mineralization for Black-sand tests.
-tested several detectors and coils between the other and Equinox ...

Tested item "N.4 " was 1.2grams gold pendant about 12cm deep in Black sand.

When testing equinox, I noticed a non-ferrous audio signal - which was sometimes a bit worn out ... but Vdi is almost still in the minus VDI numbers -2, -3, sometimes at 1a just occasionally jumping to the right 11-12 ID ..

So I tried all the programs and the best work here was Gold Programs .. enough better audio and more correctly VDI 11-13 ... but it was still not 100% OK ..
  
So I changed the 11 "standard coil on a small 6" coil. The signal detection work was further improved, but Vdi on a small coil was still very often on minus VDI ...

So I tried to change my discrimination that I use / accept -3 to + 40 / to +1 to +40.
After such a change in discrimination, Equinox detection has improved dramatically and I have been practically + VDI .. very often with the correct VDI 11-12.

  At the end I put on the Equinox standard 11 "coil and tried to test Equinox again on the new discrimination settings. The new discrimination setting worked great ... even on the 11" standard coil.

Lessons learned from the test - in too harsh conditions, it may be too open to discriminating and allmetal has a great impact on working and displaying the correct VDI on Equinox.
 

[EL NINO77]

Something else, .... in this 7-Bar Fe3o4 Black Sand test my optimum setting Equinox 800   on programs Park1 and Park2...  was .. :

1."Discrimination"  from +1 to +40 ..-you get a great and exact ID.=reading "11-12"ID -for  small gold  pendant its - perfect..

If you only discriminate on accepting from +0 to +40-you get too much reading or "0 ID "or "+1 ID"- for small gold pendant   to mean non-accurate read ID ..                                                                  

 

2. "Correctly set the Recovery speed 7-or 8".-very important setting .. -to make miracles
At lower settings ..Recovery Speed 1-6 ... you will not get almost any number ID even at the highest sensitivity -...25 .. even if you still get the correct audio signal ..
On optimal recovery speed 7-8 ..
 you get right number 11-12 ID and good signal..from sensitivity 15.... and it works well on sensitivity up to 25-max ..

3 ."Sensitivity ".. good signal and correct ID I got at the sensitivity of 15 I tried it on both 11 "as well as small 6" coil.
What is more interesting ... Equinox correctly detected 1.2gram gold pendant up to a maximum sensitivity of 24-25 in this test.

 This is a difference from other detectors where you have to reduce the "Gain" or "Sensitivity" setting so that you can properly detect the 7-Bar Fe3o4 mineralization.

4. "I tested 11 "and 6" Equinox coil" - ..and found the correct Equinox detector correctly and the same for 11 "standard and small 6" coil.

5.. Another observation ... it is definitely good to change ground balance - again in such a rough terrain when changing the Recovery speed.