Finding when more is too much

[Southwind]

I when to the city park for some testing last night after work and was a little surprised at the results.

Our city park is possibly the perfect test bed for detector testing in the live environment. It(Wright Park) was established in 1883 to host 1 of only 2 authentic Mexican Bullfights ever held in North America. It also happens to sit along side the Arkansas River which used to flood on average every 30 to 40 years which would deposit from 3" to 6" of mud in the park grounds. Some areas in this park you can plainly see where at least 24" of soil covers the original ground level. It slopes gradually from one side to another which means the coins get deeper as you move from the south to the north. This works great because you simply hunt from the south as far north as a detector will pick up coins and you get a good comparison of depth abilities. At least in this hunting environment. I have done this for years with many many different detectors. Some did much better than others. After 30 some years there is currently only 2 detectors that can still consistently pull deep coins out of the reach of the others I have tried. The V3i is one of them.

In my never ending pursuit of looking for the deepest, for me, detector I am finding the V3i second to none. Right now I am trying to maximize the depth of the V3i for this park and was doing some testing of sensitivity and boost and was surprised at my results. I find a target which I am 99.9% sure is a deep coin, roughly 8 to 12" is where I am now, anything less than 7" will be clad, and I run that target through all kinds of different settings to see how it changes the response. What I find odd is that so far boost mode has NEVER increased the hit on a deep coin. Also, it seems my optimum sensitivity settings are 10, no boost, discrimination at 90, all-metal at 95. If I go higher on sensitivity than 10 the signal gets worse. In boost mode the deep signals practically disappear which I find very odd. Currently I am running with the stock Coin program with discrimination opened up to accept +93 down to -20. reject the rest.

Now I am very happy with the depth I'm getting on the V3i right now, which is as deep as any detector I've tested so far bar none, but I was surprised at the results of increasing the sensitivity and especially boost mode. Just thought I'd pass on my experience.

 

[Southwind]

Just wanted to add last nights test target turned out to be a 1942 merc at roughly 9".

Also, when testing the E-Trac in the same park I got the same type of more is too much. When I ran in auto +3 I got good solid repeatable signals, but when I went to manual sensitivity and turned it up, the coin signals got worse not better.

 

[Larry (IL)]

Too much sensitivity or Boost ON goes back to the old analogy of "bright lights in a fog". By putting your V3i "brights" on, you are lighting up everything in the ground and not just your target. If you think of the fog as minerals in the ground and the car ahead of you as your target, it is easy to see why too much is not better.

 

[earthmansurfer]

I've heard it mentioned that a sweet spot for the V3i is an Rx of 10 - 12 and disc of 90 - 95 (or even less). Of course if you have mild ground with few targets it probably won't matter much but the brights in the fog example is a perfect analogy.

It does seem that adjusting the RX changes the footprint of the coil (from air tests). With my 5" coil and Rx at 10 - 15, the footprint (edge effect) goes out to 2" beyond the coil. With Rx at 6 it is roughly even. So, you are just putting more ground and hence targets under your coil by upping the Rx. There is clearly not a linear increase in depth with Rx, where as Disc seems to do much more for depth.

Thanks for doing your test as it helps to get other perspectives. Could you give us the ground probe readings (soil mineralization and type of mineralization) as well as the EMI (zoom + sensitivity) as this will really help to understand your findings. Also, is there a lot of iron, trash, etc?

With the varied ground it would seem to me that you either have to update your GB often or perhaps just run it in auto track and adjust its setting for how often it checks the ground.

 

[corvair]

Most guys I know only use Boost mode when they had to reduce RX gain due to poor ground conditions in an attempt to improve target signal. I have yet to use it other than just to test for improved signal like you at higher RX Gain settings.

I wonder what would happen to your depth and signal in that stock Coin program if you set your disc. to accept down to -40 to -60 range, then set VDI number tones to 5 or 0 for all VDI's below +10.Should see some depth increase.

 

[Rob (IL)]

Why would that give him a depth increase? Changing tones will have no affect on depth.

One of the moderators on another forum runs TX boost all the time but his soil allows him to do this. His posted programs all include TX boost. I don't run TX boost in my regular programs. I can in my soil without overloading but it is too noisy.

Southwind is looking for deep coins not small gold jewelry. Setting negative number to 5 was intended to let guys know of the presents of iron. The 0 to - 20, 0 to -40 range etc. was usually set to an identifiable tone so they could identify small gold jewelry.

 

[Rob (IL)]

Why the 95 on all metal? Is it for deep pinpointing? Try setting your base threshold like the high pro program. It wouldn't actually make the detector deeper but it will allow you to see fainter signals. You will have to adjust this for your soil conditions. Setting it too low and it will get noisy.

Another good report. I'm not surprised on your findings. It just proves what I have been telling the guys who are copying programs from guys on the forums. What works for me doesn't mean it will work for you.

The rule of thumb is that, to gain another inch of depth the gain must be doubled. This means that increasing the gain from 14 to 15 will not improve depth much at all whereas increasing the gain from 2 to 4 should gain another inch. So 4 to 8 gains another inch and 8 to 16, oops no 16, another inch. So don't get crazy on setting the RX at the upper levels because it provides diminishing rewards, ( higher noise to signal ratio). In some cases the added noise will actually negate the increase. So in my opinion, higher RX and more noise and signal loss would be about the same as lower RX with less signal loss. If you are hunting in a clean area with only deep targets, then run the gain just below the overload point for max depth. But if there are a lot of shallow targets, then this will result in a lot of audio overload signals which might be annoying. The bottom line is, with any coil, run the gain as high as you can for stable operation, just as you'd do with any detector.

By the way my signal doesn't start sounding bad at 12 where I run it most of the time, many times I'm at 13. I will still back it down though if I can't see improvement. Love to see your experiment results.ROB

 

[Giant056]

My RXgain is usually always 10, I use 5khz bandpass, all metal at 70 but this can change temporarily when pinpointing the ultra deep targets. In Michigan most of the older coins are always deep especially in a manicured sod type situation, there's a ball park I've been hunting for years and my brother won't even hunt it anymore with his Minelab SE cause he has never found any of the super deep coins like I still do with my V3i. Some of you might have seen my last post with the seated dime at about 10 inches. Anyway when I got this signal I turned my all metal up to 80 to get a good pinpoint, it was hitting hardest on the 2.5khz and the VDI was 67-68. Usually this kind of target is a small silver ring fooling me a little on depth but not this time, it was a silver coin. About the last time my brother agreed to meet me there he told me that if I came across another one of the deep Indian type signals he wanted to check it with his SE before I dug it and I actually managed to find one. He could tell there was something down there but couldn't pinpoint it and it read junk. It was indeed an Indian cent very deep that VDI'd 50-52 consistently and this coin too also required having the all metal turned up to around 80 to pinpoint.

 

[Southwind]

I run with my all-metal so high because it is the only way I can pinpoint the very deep ones. With the stock all-metal level I'd get a good signal in motion but nothing when I went to pinpoint.

I ran some tests on the park soil and this is what I got.

Signal = 37.5% to 44.6%
Noise = 4.4% to 27% a lot of fluctuaconsistentlyently.
When I lower the coil to the ground with the trigger pulled I get a 4 1/5 to 5

The ground is very littered with trash and iron. 128 years of it. So much so it took me quite awhile just to find a spot clear enough to run tests.

 

[Neil in West Jersey]

If you want to squeak out a bit more depth, try single frequency 7.5KHz. In certain conditions I can eek out a bit more and 7.5 is good for all around coins and jewelry. If you are only interested in silver, then try 2.5Khz.

 

[Rob (IL)]

Southwind has a new V3i but it is not his first. He's got experience. Southwind keep up the comparing with your buddy.

When Larry and I went relic hunting I hunted in single 7.5 kHz. Larry tried both 7.5 and 3 frequency. In our soil he noticed no difference. ROB

 

[Southwind]

I did try 2.5 khz single frequency on the 9" merc and also saw no difference in performance from the 3 frequency. In fact, I felt the 3 frequency gave the better sound. The 2.5 khz did seem to have a more tight VDI in the upper range, whereas the 3 frequency had a wider VDI spread, but I liked the 3 frequency response better.

Yes I bought a Vision back in the end of the 2009 season and my first E-Trac for head-to-head testing. I sold both over the winter, which I generally do with my test units, and bought a V3i and another E-Trac at the start of the 2010 season to continue my testing. I determined that while the E-Trac out of the box very good at telling the user when deep coins, especially silver, were present, I felt the V3i had the potential to go even deeper. I decided I couldn't give a fair evaluation of either detector while trying to learn two full featured machines so I put both up for sale figuring I'd do more thorough evaluation with which ever I didn't sell first. The V3i happened to sell first. I spent the next year putting the ET to the test and found it to be one heck of a machine for pulling those deep coins from hard hit locations, but didn't really care for it as a tot lot machine or relics. I bought my current V3i just about 3 weeks ago and have already determined it fits my likes better than the ET did. I am getting the same depth and pulling the same extremely deep coins from a park that doesn't give the goods to just any detector, plus it make one heck of a tot lot machine being just as sensitive to gold as my Garrett AT Pro was.

I like to start all my testing out with stock setups because it tells me what someone new would be experiencing. If I need to do all kinds of tweaking to get a detector to perform at all then I won't recommend it to someone new to detecting. That would just be irresponsible.

I will be headed back to the park this weekend for some more testing. I'm hoping to get a few videos done to show the V3i hitting on some of those extremely deep coins and what I have found to watch for.

 

[wvrick]

I really enjoy reading test and head to head reports, to use a phrase from the 60's sit-com "Very Interesting" ... now I'm telling my age. I really liked my E and it was a good detector, and my new V I think the same "DEEP", plus with more flexibility. All you have to do is run thru the menu to see all the possibility's, plus you can see the screen in the sunlight.

( Southwind, is that your youtube user name also? I'd like to see your videos. )

HH Rick

 

[Southwind]

( Southwind, is that your youtube user name also? I'd like to see your videos. )

No my Youtube name is DCDetector

 

[earthmansurfer]

Nice writeup Southwind. The E-Trac came out in the summer of 2008 and the V3i came out a year later I think?
They do seem pretty close to eachother on coins. Many others have observed what you said - The E-Trac is often deeper out of the Box, but the V3i goes a bit deeper once adjusted. But the difference is in the flexibility of the V3i, on gold in particular. They weigh about the same but the balance of the V3i is superior. I will look at the next Minelab whenever that is released.

So far, having my V3i for a month or so I really like that I can get it running the way I want. I can put iron at a 5 tone to alert me. I can set the screens up to look the way I want. I'm pretty impressed with the machine. I'm still battling a few problems with getting the unit to correctly GB but overall I'm incredibly pleased and having fun with the controls.

Anyway to the point of your thread. I mostly hunt the same area, which is an advantage with the V3i as you can really tweak it. It is important, I've noticed to not give it too much juice. I'm pretty content with Rx at 10-12 but do usually run disc at 90 to 95 without problems. Still more testing to do regarding sensitivity - Iron sure makes things challenging.

 

[corvair]

Why would that give him a depth increase? Changing tones will have no affect on depth.

My suggestion had to do with increasing the accepted negative VDI targets in discrimination mode from the stock coin program Southwind mentioned. That will increase depth.
On my DFX and on my V3i when I accept further down into negative VDI numbers my depth does increase. Have tested that on my coin garden.

The tones comment was intended to reduce that chatter.Southwind had indicated that he was at -20 acceptance.