Testing 16" Round Nugget Finder Mono (GPX5000)

Hi all,

I received the big 16" Round Nugget Finder Mono (lightweight open coil) last week. I have done a quick preliminary test with a 1.97gram nugget at eight inches depth running all different settings/timings along with a 0.20gm shotgun pellet at the surface. Doing this made me think of all you fellow 5000, and even 4500 users and whether or not you would like me to test anything settings-wise with the 'Sweet 16' and share the results. Maybe you're looking at getting a larger coil in the future or may have even used one of these previously and never got to see it's full potential?

I really enjoyed doing the first test and look forward to pushing the limits of the 16"/GPX5000 combo some more over the coming days.

The area I test in is an old white Quartz gravel pit about nineteen kilometres out of town. The ground is harsh, slightly salty and chock full of ironstone/red sands. It makes for a perfect testbed, albeit somewhat interesting. It seems similar or even slightly more mineralised than most goldfields. I figured if I do another few tests and could get good depth on a three gram nugget (biggest I have unfortunately) out there, then I could gain slightly better depth and signal response in the field -going off previous tests I had done with gram and sub-gram nuggets using the Minelab 11" Commander Mono at shallow depths around the three inch mark in comparison to my actual finds on the goldfields.

I understand these tests can be so-so due to the Tx-Rx difference on the PI machines in disturbed ground with air gaps and target size/shape etc. but I would imagine you'll have a nice little depth increase percentage over these tests in undisturbed virgin ground most times. I figure that's a plus for all of us

All suggestions and pointers are most welcome as always.

I'll be heading out there for the first deep target tests with a notepad, ruler and the iPhone camera tomorrow afternoon.

I hope everyone has been well and keeping warm out there!
Kindest regards,
Shauno.

That's the most smooth running coil in my arsenal

Keen to see the results with that one Shauno, It's one I've never run. Mainly run the NF17 x 11 and swear by it, then jump to an 18". Always room for an extra coil i say,(bit like fishin' lures). Let us know what you think.

Cheers Wal.

Hi guys,

Well some interesting results from a few hours out testing the new Sweet 16" NF lightweight coil with some very simple changes to the timings, audio and gain. The reason for this was to keep it as simple as possible (something even a newcomer could do on the fly) but still gain a little knowledge that will help tremendously for locating nuggets deeper in the field with these larger coils.

First set of tests: My findings using a three gram nugget buried to exactly twelve inches. Running the stock speaker with Threshold Level at 2 O'clock. Audio Tone at 60. Coil Rx: Mono. Tracking: Fixed.



1. Timings: Normal. Audio: Deep & General. Rx Gain: 12 through to 16. All else in factory preset [FP]. =Very clear, bright signal and good target response all round.

2. Timings: Enhance. Audio: Deep & General. Rx Gain: 12 through to 18. All else in [FP]. = No response at all even with Rx Gain increases.

3. Timings: Special- Sensitive Extra. Audio: Deep & General. All else in [FP]. = Clear bright signal and good target response all round.

4. Timings: Special- Fine Gold. Audio: General. All else in [FP]. = No response at all even with Rx Gain increases.

5. Timings: Special- Sensitive Smooth. Audio: General. All else in [FP]. = No response at all even with Rx Gain increases.

Note: Normal Timings might react to variable minearalisation on the fields now and again but gave a good test base. It seemed quite stable to me due to the size increase and sensitivity decrease of the coil, no doubt.

The second set of tests: The three gram nugget buried to exactly ten inches. Running the stock speaker with Threshold Level at 2 O'clock. Audio Tone at 60. Coil Rx: Mono. Tracking: Fixed.
1.Timings: Normal. Audio: General. All else in [FP]. = Very clear and bright target response; almost an overloaded signal.

2.Timings: Enhance. Audio: General & Deep. Rx Gain: 12. All else in [FP]. It seemed to be right on the limit here at ten inches as far as signal response and target response goes. Even taking the Rx Gain to 18 hardly improved response and just broke the threshold apart. It would take an extremely experienced and thorough operator to hear it over normal ground/threshold changes.

3.Timings: Special- Fine Gold. Audio: General & Deep. Rx Gain: 14. All else in [FP]. Very good bright response with Deep Audio. Needed to take the Gain from 11[FP] to 14 to bring the target response in clearly.

4.Timings: Special- Sensitive Smooth. Audio: General & Deep. Rx Gain: 14. All else in [FP]. Very slight target response in Audio: General that improved nicely once I set it to Audio: Deep.

The reason for the depth is that the coils around the fourteen inch mark and under will all pull much finer gold out from anywhere more shallow than the ten to twelve inch mark without a worry. These larger coils are for much deeper/larger targets. If I had an even larger nugget I would take these tests to the extreme depths and see just what this detector/coil combination could do. You'll also notice I didn't test Sensitive Extra Timings at ten inches due to the already quite loud and clear response at twelve inches.

I hope this was helpful in some way to everyone. This was a very basic test but I actually learned a lot. There would be a bit of give and take in virgin ground, different shaped nuggets, even different NF coils and GPX5000's. Those of you who understand Target Volume and using the Stabilizer correctly may get an even better response overall? I'm not comfortable knowing how those work as yet. Give me time though...


Great to be caught mid swing unawares of a photo opportunity! Didn't even get time for a smile
Very nice to be out enjoying the quite warm weather here today though.
Kindest regards,
Shauno.

Great test report Shauno, By far the best way to get familiar with the different timings of the 5000. Not too sure about those snake proof sox of yours though mate.

Cheers Wal.

WalnLiz said:

Great test report Shauno, By far the best way to get familiar with the different timings of the 5000. Not too sure about those snake proof sox of yours though mate.

Cheers Wal.

Click to expand...

My pleasure Wal!

Haha! Yeah, you wouldn't catch me wearing these in the long grass through the warmer months that's for sure!

Not many snakes out here at this time of year so it's all good on that front.

Cheers,
Shauno.

Keep safe up there mate and love to see a "Depth" report, using your first "One Ouncer".....I'm sure it's not far away.

Cheers Wal.

Hey Shauno, cool tests. I wonder if headphones would have
made the more subliminal responses clearer?

I think this is where ear training comes into the equation. When
testing different settings with the 5000, usually just air tests I
try to lift the coil to the point that the signal is almost inaudible
and listen to how it behaves in different settings.

I've seen some youtube vids where people claim they can't even
hear the signal that the operator has just dug. Where to me it was
a good clear signal. I've done thousands of hours of editing audio
listening for the most subliminal clicks, pops, glitches, pitch variations
and other noises under layers of sound. It's amazing how much our
brain filters out during the normal course of a day, also understandiong
the way our ears actually work can make big difference in hearing
things.

A renowned mastering engineer I know claimed he could hear his
power points chirping at night, I never truly believed him until I
heard it myself one night. It's amazing the things we never hear.

Learning to trust your ears is the main thing, some people hear
things but it never registers or gains thier attention.

G'day Heatho,

Cheers!

Yeah, that's a very good point! I will probably give it another go running the headphones. I'd say it would be very similar overall due to the basic nature of the tests. The wind and other variables can also limit the ability to hear faint targets now and again if you aren't careful. These responses were quite good, other than the 10" test in Enhance which was right on the limit of that timings ability to hear the nugget. That will be the first one to try again.

It's funny you mention the careful hearing (coinciding from a form of audio/aural training) as I've been discussing that at some length recently with a good friend of mine (he'll join up here soon) who's run a 4500 and had some very tiny finds over time that he believes he wouldn't have heard if not for many years of musical training. He is an extremely good musician (he plays guitar at a semi professional level). We've now realised that having the ability to recognise very slight tonal variables in the threshold is key with the Minelabs. Even though I spent all my life studying drumming in various forms, also taking up guitar/bass to a decent degree in the 90's which helped me expand greatly tonal and notation-wise. Learning to hear subtle pitch variation from many years of tuning instruments etc. could now really pay off

This has been my daily space for thirty two years now (when I'm not on the electric kit)-


Who would've known the correlation between music and gold would've become so important?
As soon as I get a clear day I'll head out and put the headphones to the same tests and report back to offer up the findings.
Kindest regards,
Shauno.

Nice kit mate, yeah I played guitar for a long time also before
I started working in audio, having a good recognition of pitch
is key to great playing as you would know, so yeah you nailed
with the slightest pitch variations being key to these machines.

Also I've noticed minute threshold volume changes can indicate
a deep target, kick a bit off and you get the inverted deep tone,
dig deeper and the tone becomes normal again. Even a slight
smoothing in threshold over an area can indicate a target too.

I love the wayaudio and gold hunting go hand in hand. I got sick of
the lack of audio work and thought "what else can I use my ears
for", found myself typing in google "Worlds Best Metal Detector"
and bought it, heh.

I went for a swing today on Long Reef Beach, plenty of black sand
there and set the GPX to the deepest it will go on Deep, Coin/relic
and used the 11in DD, 1 target I did'nt even finish it was so deep
and the tide was coming very close, must have been almost a metre
deep. Had to keep doing GB because of the black sand.

Another target was a key that came out of this hole. Must be
600mm down.





2 dollar coin out of this hole. They were deeper than they look I guess.



I'm going to try the speaker next time and see if I can hear anything
really subliminal, wind is a huge factor, it does rotten things to sound.
Will be great to see what difference HP's make for you, out of interest.

Someone was using a camera one time at the beach and you could
hear the flash discharge as a false signal and then the capacitor
charging up again, freaky.

Yeah I meant to say also, that was DD, I've noticed the
monos run so much deeper and more sensitive, a mono
in this setting in perfect ground may go near twice the
depth, I think, at least an extra 50%.

Hi all,

A little update for the tests on the three gram nugget and the Sweet 16" NF.

My good friend Bill is up here visiting currently and he has never detected before (though he's been on a panning/sluicing trip with me previously) so I figured I'd repeat the test and push the nugget to a point where it was just audible via the speaker and see if even he could actually pick up a target response through the minor threshold variations.

After a good demonstration of how it all works it was time to re-plant the target down past my previous 12" depth tests. The ground is an extremely hard and conglomerated ironstone/quartz silicate gravel mix which made life difficult without the crowbar on hand. I managed to get the pick down through the ground to the 16" range and buried the nugget tightly and compressed the ground to keep any air gaps to a bare minimum.

It was still nicely responding at the 16" mark. I was definitely more than impressed with that for a small-ish target at that depth.
I made Bill close his eyes and simply listen for the response and sure enough he could make it out. (I had made a few swings over the target set much shallower beforehand so he could hear what was what, sweet non-ferrous response vs iron overload signal etc) I then repeated the test moving a few metres away and walking slower and faster towards the target just to keep him on his toes while he still looked the other way and he managed to hear it okay.

I still need to repeat these tests with the Koss UD30 headphones to see if I can actually get a clearer, cleaner response. I'll also test the little 8"x6" NF Mono and both the Minelab 11" and 15"x12" Commander Mono's fully on a range of targets to be well prepared for all scenario's that the gold fields can offer up on my first trip into Vic around September.

Kindest regards,
Shauno.

Great reports Shauno. Are you using a booster? If not it would be interesting to see how much deeper you can push it with one.

DD

Hey Shauno which settings were you using? General and Normal for this test?

Diggerdude said:

Great reports Shauno. Are you using a booster? If not it would be interesting to see how much deeper you can push it with one.

DD

Click to expand...

DD, I'm not sure if a booster would do anything for depth,
would be the same depth just a boosted signal. I'm really
not sure what is in these boosters, but they are more than
likely just a basic equaliser and/or audio compressor/limiter.

Sometimes compressing and boosting any audio signal
will raise any unwanted noise also such as ground noise.
Would more than likely make a faint good signal stand
out, but could also mask an even fainter one.

Horses for courses with these. I always prefer a pretty
clean audio signal path, less processing equals less noise,
just me though. If you suffer from Tinnitus or a similar
condition from years of loud noise a booster could be
a good thing. Not beeing cheeky, it happens a lot and
is irreversable hearing damage.

I find a booster helps you hear the very faint signals, especially on tiny nuggets. I get loads more with the booster than without.
After 15yrs operating drills and rocks breakers though there is a fair chance my hearing is shot.

DD

Fair call, I'd give one a go, if you find more with it
I guess results speak for themselves.

I've got slight damage to my hearing, years of
playing guitar through Marshall amps turned up
to 11. Lucky it's not worse, drinking and loud
music are extra bad again.

Probably yours not shot but yeah some sensitivity
and high frequency loss maybe would be there from
rock crushers and drills. Same happens as we
age too.

I'm going to try a few different sets of headphones too,
they all have a different fequency curve, some accentuate
mid feqs, some accentuate lower freqs or certain dips or
bumps throughout the bandwidth.

Headphones which accentuate around 1khz to 2khz would
be ideal as that's where our ears are most sensitive.

Best you can do to come close to real type scenario is to find a little erosion gutter or edge of some surfacing and then drill, somehow, a few holes at varying depths into the side. Did that with a mate a number of years ago to test out coils and new machines when they came out. When you dig a hole you can at times get what used to be called "hole slap" which can and does affect the target or perceived target sound. I have seen blokes dig holes and keep going deeper and saying "yep I can still hear it" when all they were getting was hole slap and the target was actually lost to hearing way before that. Some ground doesn't do that as bad as others but its something to be aware of. Best way to make sure its not happening is to wave the coil over the empty hole and be sure there isn't so much as a hint of false sound when you do. If there is it will affect the outcome.

That's interesting Jon, had not heard of this, would that be
VLF machines or PI also that are more affected by this?