Mild Ground - Normal at high Gain, or Sharp at lower Gain?

[steve herschbach]

Just curious if anyone has been able to use the Sharp settings effectively? Yeah, I realize it will not work in bad ground. I have used Sharp and found gold with it, in fact on my very first outing with the GPX at GPX 5000 gets Alaska Gold but have not had much time with that particular timing since then. I am going to revisit the Sharp setting again this summer.

Kevin Hoagland has a nice article on the subject at http://www.minelab.com/treasure-talk/orange-and-culpeper-virginia-mineralization-not-as-bad-as-people-think

 

[narrawa]

Hi Steve,
I often use Sharp with the 4500 when working creek beds. I use it with the 10x5 commander and most of the time im using it in mono. This combo is deadly on the small bits that are wedged down in the bedrock. With the simply flick of the switch im in DD mode able to disc with some degree of acuracy when targets are fairly close to the coil. Mono mode will disc to some exstent but its less reliable.
The use of mono on the small DD coil with the Sharp timing, gives it a field much the same as a NF 12x7, and only God himself could tell the difference, but as we know, the 12x7 has no ability to disc....and thats where the little DD shines if you like to use discrimination occasionally.

The other thing is the ability of the DD coil to tame some areas of mineralization build up thats present in creeks.

Hopfully the GMT will take over this style of detecting for me now. ?? Some testing this weekend passed showed me its certainly up there when cranked up.

 

[Jonathan Porter]

Narrawa, I would have thought Sens Xtra would have been a better timing for finding little tiny bits in the sorts of areas you describe, Sharp is similar to the old SD2200's running a higher voltage whereby the transmit field has more oomph compared to other timings (uses more battery power and creates more ground noise too), however Sens Xtra starts to sample at an earlier stage which as we all know on a PI is paramount if you want to hear the little bits. Do not confuse the louder sounding response of Sharp as being an improved response over other timings on gold targets, it also generates a louder response on ground too. I would suggest if you want to lift the audio response of the smaller gold when using your DD coil method in a timing like Sens Xtra that you try experimenting with the Audio filters like Boost. Lastly I would not be relying on discrimination when in the Mono mode with a DD coil, DD mode is the best mode for discrimination.

Sharp does generate a slightly louder response on deeply buried large objects over Normal, so if in the right ground conditions Sharp can be advantageous for outright depth, it would also suit a large DD coil which as Narrawa has described irons out a lot of the surface mineral noises especially the ones that will be created by the aggressive nature of the Sharp timing.

When Steve and Chris were with me in WA a couple of seasons back we had a lot of fun chasing small gold with the Fisher GBII and GB PRO, because we only had 2 VLF units on hand I was using one of the NF Sadie coils on my 5000 and was picking up my fair share of small pieces in the same areas albeit somewhat larger, one occasion stood out because I heard a distinct response under a piece of banded Iron Stone, calling Steve over he called it for a Hot Rock with the GBII (which is was as the Banded iron was making a response on the VLF), however my GPX 5000 was ignoring the Hot Rock and was signalling a gram plus size piece under the rock.

JP

[size=small]Some pics of our fun VLF times in WA.[/size]

 

[steve herschbach]

Thanks JP, that is real meat and potato information. It would be nice to have a technical explanation like that of each timing and what makes it different.

The day we chased little stuff with three detectors proved a couple things once again. You tend to get what you look for, and big gold adds up faster than small gold. In other words, your few bit larger nuggets weighed more than our more numerous smaller nuggets. The trip as a whole, I focused on larger finds while Chris tended to focus on more common smaller finds. My fewer larger finds ended up weighing more than his more numerous smaller finds.

The VLFs may be hotter, but at the end of the day hot rocks will hide gold from them that a PI will find. I do think I have pretty well mastered finding tiny gold with a VLF but this summer I plan on working hard to better my skills at finding small gold with a GPX 5000. In the past I never put any serious effort into it. I always reverted to a VLF if I wanted to chase small gold. However, I do think that the GPX has a better balance of small gold AND deeper, larger gold capability when using small mono coils and in the end that means more gold.

I have the Commander 8" mono. Do you think it is worth getting the small Nugget Finder or is there so little difference as to not matter?

 

[narrawa]

Jp, i hear you with the use of s/extra...yet the depth when dealing with large bedrock, deep cracks, big rocks just isn't there....the use of Sharp was an accidental find combo'ed with the Commander DD some time back for me. Since than the release of a few smaller mono coils became available, but offer no disc as you know.
The small coil when working such areas lacks the reach on small gold being used as a pseudo mono, Sharp extends that reach. Just as you say, it gives it that oomph that has the ability to pick up a tin can well outside what you would expect for such a tiny pseudo mono coil. Yet the small nature and design of the Commander DD coil used in pseudo mono, pings those tiny bits with ease.

Boost and a high gain i feel bring back that sensitivity lost in the timing.....EMI is of little concern which for me means im able to use the stabilizer above FP...(never thought id say that ), but that timing even though its set up for grunt, is less susceptible to the effects of EMI when coupled to such a small coil. Some rock cavities will react, but if there is metal in there, its reaction is well noted above the build up of minerals due to the DDs ground canceling abilities.

One such cavity produced around 9g of the right color mixed with small bits of ferrous junk. If only they were all that full. looking for those glory holes for me in trap rock areas is like letting a child lose in a candy shop.

I do hear what your saying about experimenting with the other timings/filters, and with each timing comes a sort of trade off as you have mentioned in the passed. In some areas the use of s/extra would be the better choice, yet having to continuously raise the coil over rocks causes some timings to lose their ability to reach. Sharp i feel has the edge here.


The GMT running flat out has some pretty good sensitivity, it wont compete depth wise, but will add a more reliable disc with the sampling of targets with each pass of the coil. That alone means more time swinging. One big discrepancy with the GMT running flat out......the volume/gain control are combined, meaning not even an enhancer will suffice without a compression circuit.

PS. Don't suppose you wont to build me a B&Z with a variable compression circuit.?