I still need help, problem not solved with my Gamma 6000... :thumbdown:

[aSaSSino]

I'm sorry for re-posting but no-one is looking my old post with new videos of my Gamma 6000 problem.

In this video I tried to put a nail a 12 o clock over a18k gold wedding band, using D1 or D2 tones and discrimination set to minimum (1), sens to 80.

As you can see in my video, the gamma is totally muted and no target id is shown. It should make some beep (iron or good target) but nothing.

When in All Metal mode (AT) the gamma makes a sound but no target id is shown.

[video]http://www.youtube.com/watch?v=zmpeiPOnNus[/video]

My reseller changed in warranty the CPU, but the problem still remains and he told that he asked to First Texas... I wrote to F.T. too, enclosing my video, but still no reply...

A friend of mine tried the same experiment with the same metal, here is the test:

[video]http://www.youtube.com/watch?v=z1ZvCyJwJuo[/video]

The test is better, but sometimes the metal is mute or goes in overload.

I'd like to know something about this issue... I made this test because I feel that I'm missing several targets using this metal in trashy places....

Thank you

Luca

 

[TerraDigger]

What you may be experiencing in the gold ring test is that the metal mass/signal effect of the iron nail is greater/stronger than the gold ring. Try the test with a smaller nail or piece of iron, and see if the ring is detected. On my Omega, sometimes depending on the size/shape of a nail, the Omega will not register the nail either in audio or target ID. Even though the Omega's discrimination is set at 1, its lowest disc setting.
If the mass/signal effect of a discriminated target is larger than a non-discriminated target, the detector won't register the non-discriminated target. At least thats the way it works with the Omega.

 

[:Left4Dead]

My delta 4000 does the same thing with giant Bolt and small gold ring. I would never, know it was their.

 

[aSaSSino]

I've put a smaller nail on the top of the gold ring (or coin) and the gamma shows the VDI of the ring, lowest than in air tests. And this is absolutely correct. The problem is that near a big rusty nail, the metal seems to not see any target, even with disc at minimum (1, not zero on this metal).

So it seems to me a programming error, because my cheap gold century catch the target, sometimes like iron, sometimes like good target, but it makes a sound to let me know that there's something under the soil...

I bought another search coil, I hope that this issue will disappear because I hunt often in trashy sites with big iron nails, and I'm absolutely sure that the cheap metal detector can detect more targets.

 

[BJ in Okla.]

n/t

 

[aSaSSino]

I know that the 5" will be better (but I like larger coils, not smaller), but this don't solve my question: why no sound and no vdi ?

 

[Dave J.]

I know that the 5" will be better (but I like larger coils, not smaller), but this don't solve my question: why no sound and no vdi ?

All discriminators exhibit masking phenomena. Because of different searchcoils and different ways of processing the signals, different models exhibit different masking behaviors.

As you've noticed, it's a particular arrangement of ferrous and nonferrous that is causing the machine to go silent even at low discrimination levels. If you take away the coin you'll hear the nail, and if you take away the nail you'll hear the coin. With most arrangements of the nail and the coin you'll get from one to several "hits" and by the sound and ID numbers you'll know it's probably co-located targets.

With the specific arrangement you've got, and the signals being processed the way they are, it's possible for the combination of the two signals to put the apparent phase into the negative loss half-plane where no real target exists. All motion discriminators are designed to not respond to signals in that half-plane. (As a detector user you don't have to understand the trigonometry involved in signal processing, it's the design engineer who has to understand it.) When that design principle isn't adhered to or the user adjusts the machine in such a way as to defeat that principle, you get a machine that's very noisy on the dirt and has poor iron rejection characteristics.

There's no bug in the software, it's just a peculiarity of how the signal processing in the Fratbros machines responds to that particular arrangement of targets. Overall the Fratbros series is well known for both silence in iron trash, and ability to pick out nonferrous targets in iron trash that most other machines miss.

With any discriminating metal detector, in a trashy area you're going to leave some good targets in the ground that another machine that processes signals differently might pick up. The only way to "find it all" is to use a ground balanced all metals mode and dig everything. And even then you're limited by ground noise and target depth.

--Dave J.

 

[aSaSSino]

oK so this is a pecularity but in some omega videos I've seen on the tube, the omega seems to react better to iron, do you think that another coil may solve this problem?

Some other problem: why when lowering the volume under level 5 I cannot hear high tones? why when lowering volume at minimum I can still hear the overload and the iron tones at very very high volume? I hate using earphones in summer

 

[wildeagle77]

hey asassino stop askin 'bout this coil...the whole world is bored...

buy a real one md...

 

[Dave J.]

Aquila77, the moderators may use a shillelagh on that shenanigan.

--Dave J.

 

[aSaSSino]

Something like an AT-pro? hmmhmhm maybe I prefer a GTI 2500... I love the female talking voice that tells me "COIN" when I dig rusty nails LOL

 

[wildeagle77]

hi Dave
i personally know asassino. I'm jokin .as i use to do on our forum over Italy. i fix tile so i have no need to use a shenanigan. and moderator can use that hammer...would not harm my soul.
i appreciate how u explained how to solve that problem on his md and the issue bout the iron mask...


take care Dave .

 

[Monte]

First and foremost, Dave J. provided the best and easiest answer to your questions with his comment that not all detectors are made the same or process signals the same. There are a number of dynamics to metal detector design and, regardless of the brand or model made, none of them are 'perfect'. As he stated, too, the technical side of engineering designs are not concepts that most of us would really understand. If we did, then there wouldn't be all the questions we read.

I'm sorry for re-posting but no-one is looking my old post with new videos of my Gamma 6000 problem.

The 'problem' isn't really a Gamma-specific issue, or a coil related issue (although a smaller search coil, like the 5" DD, might provide somewhat better response at times). The 'problem' is really just a matter of trying to make a detector and coil combination do what it isn't capable of doing. I use a set of four different 'testing examples' when I do my seminars or give any instruction which can demonstrate the strengths, and weaknesses, of almost every metal detector the hobbyists might use.

The 'problems' that many people also encounter is when they try to make a detector provide a 'proper' visual Target ID display or numeric VDI number, or even an expected audio Tone ID for a desired target .... but they are not using ONLY the desired target. This is exactly what I am seeing in your videos.

In this video I tried to put a nail a 12 o clock over a18k gold wedding band, using D1 or D2 tones and discrimination set to minimum (1), sens to 80.

As you can see in my video, the gamma is totally muted and no target id is shown. It should make some beep (iron or good target) but nothing.

In your first video I noted a few things. One was that you didn't do a proper Ground balance adjustment. That nutty rat-a-tat-tat noise you hear when you pushed the Ground Grab button indicated that you were trying to balance over very low or non mineralized ground. Something less that a ground Phase of '40.'

That's in the manual and is there to help those who might be hunting on a salt water beach, as an example. it tells the user to make a manual Ground balance adjustment when this occurs. However, in your case and others who have had this problem, they press the Ground Grab touch-pad/button with the search coil held in the air and away from any mineralization. Thus, the rat-a-tat-tat noise!

To achieve a 'proper' Ground Grab adjustment and eliminate that noise, I suggest you start with the search coil positioned on the ground. This introduces the ground mineral signal to the detector's electronics and then, which a brisk bobbing of the coil from surface up to maybe 6" or 8", maximum, you ought to get a good Ground balance setting without the noise.

Next, we have the 'problem' of trying to hunt in a site that abounds with iron nails (or an iron bolt in one close shot). If you are trying to find a desired object, such as a coin or ring, that is made of gold, silver, copper, or some other non-ferrous (non-magnetic) metal mixture, but you are hunting in a site that has a lot of iron nails, you have to use the smallest coil you can, sweep the coil slower and more methodically around the iron trash, and use ONLY enough discrimination (rejection) to just slightly reject the annoying junk.

In addition, you have to appreciate the fact that any good target can be masked from detection by any junk target that is too close to the desired find, or is closer to the coil (shallower) than a deeper good target. Target Masking might mean totally ignoring the good target (total rejection due to the trash rejection), or it might throw the visual and audio response off and make a desired target 'read' or 'sound' less conductive (produce a lower VDI number) than if it was tested alone and without nearby junk.

I also mentioned using a slower sweep speed when hunting in trash as well as a smaller-size search coil. In trash, or any site with a lot of targets that need to be 'processed' by the circuitry, a sweep that is too fast or brisk can easily cause target masking because it hasn't had the ability to deal with all of the mixture of targets present .... as well as the ground signal.

If you know trash is there, sweep accordingly.

Even with a Discriminate setting of '1' (which I usually use) and with the Tone ID set at 'd1' or 'd2' (and I favor 'd2' when hunting in iron), one reason you might not have been able to hear a target response was because the overload from sweep the coil too close to the larger-size nail or bolt. Remember that when searching most sites, especially whose with shallow/surface iron junk, it is best to keep the search coil about 2" from the target, and possibly more if the nails and bolts are large.

Finally, even though I have found a lot of good targets close to smaller iron trash, such as nails, I see that you positioned the ring very close (too close, perhaps) to the larger junk metal. Also, it was positioned close to the elongated end of the ferrous object and that is even worse to try and find. As Dave J. stated, the only way to get all the good stuff in a heavily littered site is to remove everything ... good stuff and junk.

When in All Metal mode (AT) the gamma makes a sound but no target id is shown.

It might not provide a TID for the ring, but that's because the greater (larger or stronger) TID is from the iron trash.

My reseller changed in warranty the CPU, but the problem still remains and he told that he asked to First Texas... I wrote to F.T. too, enclosing my video, but still no reply...

You have now received a reply from Dave J. and that ought to sum it up.

A friend of mine tried the same experiment with the same metal, here is the test:

The test is better, but sometimes the metal is mute or goes in overload.

The same problems. Ferrous object it too large and perhaps the sweep speed was too fast to handle the size of the junk and closeness of the desired object.

I'd like to know something about this issue... I made this test because I feel that I'm missing several targets using this metal in trashy places....

You are always going to miss good targets in trashy areas because that's what happens when trash masks a close-by targets response. Usually the ferrous junk is larger than the desired object, and ferrous has a different effect on an electromagnetic field than a non-ferrous object anyway.

The best way to work a very trashy site is to hunt in All metal and recover every target, good or bad. Since we don't always want to do that then the 2nd best approach is to use a smaller-than-stock search coil, ONLY enough Discrimination to just barely reject the most common lower-conductive trash, and search the site slowly and methodically. Slow, short, overlapping coil movement and then dig any target that produces a non-ferrous audio response. Forget the Tone ID and VDI, just recover all targets that do not produce an iron audio response.

The 3rd method would be to simply hunt it helter-skelter like an typical coin hunter might and only dig the targets that produce a rock-solid, lock-on target ID and Tone ID. This is the group of hunters who have left the good finds in the trashy sites for us to find today.

oK so this is a pecularity but in some omega videos I've seen on the tube, the omega seems to react better to iron, do you think that another coil may solve this problem?

The Omega and Gamma will have very similar performance. The main differences will be in the search coil selection, along with the settings used.

A 10" eloiptical concentric coil might help locate some good targets in trashier sites and is the general-use coil I prefer compared with the round 8" concentric. However, when the trash conditions are a challenge, I simply opt for the round sub-5" Double-D coil and slow my sweep speed. I work in and around trash, using a Disc. setting of '1' and the 'd2' auto Tone ID, I can hear the presence of iron trash and then carefully work the coil around it and recover all good or reasonably 'iffy' responses.

Some other problem: why when lowering the volume under level 5 I cannot hear high tones? why when lowering volume at minimum I can still hear the overload and the iron tones at very very high volume? I hate using earphones in summer

That's just the way the Gamma and delta were designed and, personally, I wish they would eliminate that feature and leave them peaked at the maximum volume level. It's not like using a traditional volume or loudness control.

I always use headphones unless I am demonstrating a detector to someone. Why? Because I want to be in control of finding the most I can and hearing responses better w.o bothering anyone near me.

I know that the 5" will be better (but I like larger coils, not smaller), but this don't solve my question: why no sound and no vdi ?

The 5" coil would be the right coil to use in a trashy site. A larger-size coil is definitely NOT the right coil to use in a high-target location with a lot of trash. it will cause too much masking.

The No sound and No VDI is usually due to an overload type situation from the coil being too close to a larger target.

I've put a smaller nail on the top of the gold ring (or coin) and the gamma shows the VDI of the ring, lowest than in air tests. And this is absolutely correct. The problem is that near a big rusty nail, the metal seems to not see any target, even with disc at minimum (1, not zero on this metal).

Your metal detector (the Gamma) will produce a proper VDI when no trash is present, and a lower-than-proper VDI with a nail on top of the ring. That would be correct. But as you stated, the BIG rusty nail might just be too big and/or too close to the search coil for the detector to function as best it can.

So it seems to me a programming error, because my cheap gold century catch the target, sometimes like iron, sometimes like good target, but it makes a sound to let me know that there's something under the soil.

Okay, and I am certain that your Gamma will do things that your Gold Century model can't, and this just proves the point I stated earlier.

There is no such thing as a 'perfect' detector. That is why I have always owned more than one detector, usually keeping 2 or 3 on hand, because one might compliment another. I select the detector and search coil that best fits the needs I have for a particular site. I do this rather than try to make a detector do what it can't.

I bought another search coil, I hope that this issue will disappear because I hunt often in trashy sites with big iron nails, and I'm absolutely sure that the cheap metal detector can detect more targets.

If you bought the 5" DD then that is good. I suggest you position the ring slightly farther away from the iron nail. I also suggest that when hunting in an iron nail infested site, you increase the Discrimination only to the point where you'll cleanly just reject the iron nail. Then, using the 'd1' or 'd2' Tone ID options, work the coil over the samples, slower and at maybe 3", and see what the outcome is.

Happy Hunting,

Monte

 

[BJ in Okla.]

Maybe he needs a GPR unit and not a metal detector....

Or a shovel and a sifter.....

One thing I look for in buying a detector, do they make other coils.
5"dd,8" con. 10" con. and 11"dd..what more do you need..

80 % of my hunting is done with a small coil,like a 5" or 6",,, a 8" coil is big to me..
But if in a big area with not to much, I will use a 11" dd.
But we don't all hunt the same type of places..

So use whats works for you....
The best Disc. is your digger.

HH...Bj

 

[aSaSSino]

Thank you as usual, Monte for long and detailed reply.

I don't think to an overload issue, i tried to put the coil even at 4, 5, 6, 10" but the metal is always mute. When I will found a friend with a 5" coil I will try it, hope it will be better.

Another issue I've discovered today is that, even with DISC at 41, and D2 tones, in trashy sites the metal still sounds often the lower tone of the iron. I hate listening this buzz because it makes me crazy, even when I put down the metal detector while digging... the metal, while the coil is not in motion and the sensitivity/threshold is high, start chattering and listening that chaos in the earphones is not confortable... as well as the overload tone volume while searching in the dug soil... volume is too high respect to medium / high tones even using the headphones, and I'd like to eliminate it.

I'm sorry but I haven't understood what is the "nutty rat-a-tat-tat noise"... are you talking about the "space invader" sound while ground balancing? It seems to be the sound that the gamma emits when the coil is far from the ground, and manual tells to start in the air... I will try to start from the soil as you are suggesting, and I will make some other test, thank you!

Luca

 

[dioramix]

Omega on the coil 8''and objects of the same size falls significantly better than the Gama.
Another algorithm ?