Rising vs. Falling signals w/GPX detectors

[aksafari]

So, let's start with a couple basic assumptions: 1) Mono coil 2)Normal signal response (as opposed to inverted) 3)Minelab GPX detector

When I'm detecting, I've noticed an extremely strong correlation between a falling type signal, and a ferrous target that isn't shaped like a thin disc or wire. I don't have an irregularly shaped lump of gold or silver large enough to bury a foot or two down and experiment with to listen for the signal response.

My question: Have you any similar experiences, and what would you expect a quite-large gold signal (not lacy or crystalline) to sound like? Would an analog of a melted down lump of copper be a suitable experimental piece? Would various timings (all other things being equal) affect the rising vs. falling nature of the signal? I haven't noticed a difference on my GPX5k, gold sounds like gold, whether it's Fine, Normal, Enhance, etc...

Thoughts? My point is this: I'm a little averse to digging to CHINA for a giant bolt or a railroad spike, so I typically avoid whopping, detector swamping, falling signals. Would the nugget of a lifetime sound like a humongous iron target? And what do you think that 1/2 kilo nugget they just found in Aussieland sounded like? Too bad they don't show them actually detecting that sucker...

p.s. What do you typically set your gain to in a relatively EMI quiet area?

[Aquilauno]

I am a WWII relic hunter, but hope that my experience can be of some help.

I have a GPX 4000 and an SD2200V2. These metal detectors have a composed tone, or better a sort of multitone...

Depending of target conductivity sounds will be HI-LOW or LOW- HI.

I noted that hi-lo tones are low conductor or tiny objects, low-high are high conductor, or big stuff...approx...

I.e. Big iron - silver coin, brass, bronze, copper = low- high

Gold nuggets, tiny pieces of iron or nails, mixture alluminium, some 12 cal shells = high-low

Also long nails or iron have a low-high-low tone. Squared or little nails have a hi-low tone.

A bullet has a low-high-low-high tone, that sound is a radiography of the material of the shell, copper with capsule and lead bullet at the top.

Just my two cents.

Take r.

Ale

P.S.

i guess that in USA you have tiny nuggets, that will sound Hi-low...

[Jonathan Porter]

The way a target behaves depends on the size, shape and density of the target and how it presents to the coil and the timings used. Every timing has a cross over point on gold nuggets relative to depth on where the Low high kicks in or High Low. Fine Gold and Enhance can do it on a nugget as small as a gram if the nugget meets the criterion.

I would not advise leaving faint deep sounding low high targets in the ground especially if the ground seems undisturbed because most of my largest finds have been just that, low dipping grunty type responses that were at amazing depths. Problem is a lot of small ferrous junk like nails and elongated pieces of wire generate the exact same signal response so it does make it difficult determining what's what. Good couple of things to keep in mind is ferrous targets have two components to their make up relative to the detectors behavior, one is the traditional response as per any target reacting to the field generated by the coil but there is also another aspect or component to ferrous as well and this is the fact that ferrous is attracted to a magnet which will add an extra element to the audio response which can be identified in the right circumstances to a savvy operator.

Quite often I will know when a target is going to be non ferrous because it sounds sweet, whereas a ferrous one will sound quite harsh in comparison. Another trick to ferrous items especially small ones is they will generate a much sharper and louder response compared to a non-ferrous item of the same size and more importantly can be difficult to pinpoint, a sure sign that it is most likely ferrous.

Hope this helps,

JP

Pic of a 4 ouncer found with the GPX 5000 that gave a dipping response in both Fine Gold and Enhance but more importantly in Normal as well, which indicated it had a decent amount of gold enclosed.

[frank c]

HEY MR. JOHNATHAN PORTER, thank you very much for finding the time to post here on one of the forums I frequent. I am ALWAYS looking for a word from you on any forum I read. I VALUE your input anywhere it can be had. I have learned a great deal from trying to read between the lines when you make statements. My overall detecting ability has GREATLY improved from watching your DVD's and trying to suck up any posts or responses to posts that you find the time to make.

I sincerely understand how short every day, week, and year truly are as I have aged. And know what a busy lifestyle you must have between work, prospecting, and family life. Therefor seeing you post is like CHRISTMAS for a little kid every time I see one of yours.

Please keep us avid enthusiasts on the North American Continent updated and aware of you actions as best you can.

Thanks, your'e the best in my book. Frank C.

[Paseclipse]

In the past I used to frequently pass up the low-high signals because where I normally hunt most likely it's going to be a piece of trash. That is until I nailed a 3/5 ozt nugget 18" deep that gave off a low-high signal (I was 100% convinced it was a piece of trash while digging!). I've found larger nuggets in the past and all sounded off with the high-low signal and over time I just assumed that most nuggets did this (not counting multi-ounce whoppers). Boy was I wrong and I hate to think of how many potential whoppers I could have passed up because I chose to be lazy and not dig.

Jonathan is spot on in his assesment with Ferrous targets peaking a little higher than non-ferrous targets. If you place a nugget down on the ground with a similiar sized ferrous target right next to it, it's easy to hear the difference. Ferrous targets definately peak a little higher than a non-ferrous targets. However at depth they all sound the same, at least to me. It's a very good idea to dig them all regardless of the signal response because that one target you pass up could be the big multi-ouncer we all dream of finding.

Del

[nvchris]

i'm convinced that Mr Candy, an audiophile, has made the Ml PI sound on gold (in the right conditions) the same as the sweet note of a french horn and iron sound more like a harsh brassy trumpet. Or like the difference between a acoustic guitar and an electric.

That said my largest nugget (surface area wise) was a booming harsh signal that I almost walked away from.

"p.s. What do you typically set your gain to in a relatively EMI quiet area?" I'll up the gain till I start to here "noise" then back it off.

I like a smooth threshold and will do whatever it takes to achieve it, try this next time you get a faint target, adjust the gain from low to high just to see where the target disappears or is hidden in the noise.

i still dig them all, and if its a tin can I'll move it and check the spot it was laying. It's paid off more than once.

[ellukay]

as a beginner, I to am very interested in the different sounds the ML PI detectors make and am hoping there is a way to "discriminate" by using sound variances.

in my limited experience it seams like low>high targets are usually somthing large, or has a large surface area likre a coin lying flat or a large iron bolt. small iron gives off a kind of worbeling signal and brass just screams.

solid lead gives a sweet high>low signal like gold although I have found a few large cal. bullets that give off the low>high sound.

That said... I'd like to subscribe to the "dig all signals" theory, but there is no way a guy could follow that advice and cover a 20 sq foot area in an hour. At least in and around where the oldtimers worked.

You "old" hands at this must discriminate somewhat when your working a new area, no? if so what targets "Don't you dig???

[minerjoe01]

All i can say is the first big nug i got i was sure it was just another dang box nail! After 200 of them it does get old. BUT, i was thinking that being our northern load is so junky, my niche might be just having the desire to dig all targets just in case. I was in a old mining camp today and was discusted over all the trash. But all it takes is one nice nug and you forget the rest! In our area i can only run around 9 to 10 gain running in special smooth, general. stabilizer around 11. running the mono 8in commander.

[oldies1955]

All i can say is the first big nug i got i was sure it was just another dang box nail! After 200 of them it does get old. BUT, i was thinking that being our northern load is so junky, my niche might be just having the desire to dig all targets just in case. I was in a old mining camp today and was discusted over all the trash. But all it takes is one nice nug and you forget the rest! In our area i can only run around 9 to 10 gain running in special smooth, general. stabilizer around 11. running the mono 8in commander.

One thing that helped me out a lot with getting iron/steel out of the ground is that I bought a super magnet from Rob and put it on the end of the flat part of the pick.

It "sucks" the trash out as you dig.

Dig a little and hit the area with the detector.....usually its stuck to the end of the pick. If it starts to move around in your dirt and its not on the pick...you get kind of excited

Tom

[aksafari]

There's either a great misunderstanding going on, or everyone but me runs on 'inverted' signal. When I say rising or falling, I mean relative to the pitch or frequency of the baseline threshold. Now, I'm kind of an audiophile myself, and I'm always striving toward perfect pitch, so I'd like to think this isn't in my head, but I have several small variously shaped pieces of gold, and every single one of them produces exactly the same type of smooth, intense rise from the threshold tone, falling back to baseline as you sweep past. This is almost identical to a coin or small bit of iron. I would tend to draw it on paper looking like a steep-sloped mountain with a slightly rounded top. Other larger iron targets that are NOT wire-shaped typically have the same mountain shape, but UPSIDE DOWN, like a valley. This visual analogy to sound is the best way I can clarify my confusion with so many answers on here, including J.P. (an obvious expert). I'm POSITIVE I'm not running in 'inverted' signal, i.e. I typically use 'Special'/'Fine Gold'/Gain=13/Iron Reject=Off/Mono Coil/Signal=Normal.

What would be behind so many others describing the exact opposite of what I hear?

I'll post a link to one of Rob's videos illustrating the exact tone I'm trying to describe...

Not Rob, but came up with this example of a seeming novice, but it illustrates the type of 'rising' signal I'm talking about.

[aksafari]

As a further reply; After watching several more YouTube videos, it seems as though it's kind of random whether the signal is what I'm used to hearing, or what J.Porter is describing as 'normal'. I'm slightly confused about this revelation, and wonder if someone has an easy explanation such as 'Most people prefer an inverted signal'. Obviously somebody does, since it's a factory option. Any other possible answers?

[nuggethunting]

Hey Guys,

My best advice is to dig everything, if possible. I have found thousands of gold nuggets and only a percentage of them give you the "typical" normal WEE-WOO or WOO-WEE depending on if you have normal or inverted signals on you Minelab. That being said, more than half of the nuggets have dug over the years have given signals that would sound like iron rubbish or garbage.

The density, size and shape play a huge role in what the signal will sound like, then the depth at which it's hiding at.

The double hits, broken type targets signals and such have been my best nuggets and some of the largest to date.

Conclusion: Don't get locked up into only digging the typical signals or you will walk over gold.

Take care,

Rob Allison

[nvchris]

'Most people prefer an inverted signal'.

I'd say that 99% of users do not run in "inverted" if thats what your thinking. It is an option when hunting a site thats littered with surface trash.

The reason we like an inverted response is simply,

The inverted signal, a falling then rising, indicates the possibility of a large deep target.

Nothing beats experiencing digging a whopper at depth and you'll never forget the sound.

Good luck and dig them all!