Basalt, small gold and SPP

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Roscoe

Ross
Joined
Oct 27, 2013
Messages
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Location
, QLD
Well i did some very extensive testing of the SPP over the week end and using a variety of different coils. Firstly i wish to say that the SPP will not signal off on basalt compared to my SD2200v2. A basalt rock that the SD will scream on barely makes a murmur on the SPP.

However i was able to find areas were the SPP signaled in the basalt soil. These were concentrated spots of basalt soil much like clay domes. The SPP responded on these with a very noticeable high tone signal.

After ground balancing the SPP in all conductivity (switch is install on my SPP) and gain of 5. I switched to Low conductivity and turned gain up to 10. I then adjusted the ground balance slighty positive half a notch and the responding ground disappeared only producing occasional chirps every know and again from these spots. I then buried a 0.2 gram piece of gold approx. 2" down and the SPP made a clear signaled on it . I then buried a 1 gram nugget approx 4" down and once again the SPP signaled on it.

I then tested the SPP's depth of those targets with the ground balance spot on and did notice an improvement in the signal strength on all test targets. So the off setting of the ground balance can remove unwanted signals, but there is a slight trade off on out right depth. So long as you don't shift the ground balance to much it should not be a problem.

I hope this helps, Roscoe.
 
Great testing thanks Roscoe, I do the same set-up as this on my SL to eliminate the hot spot signals but without burring targets so wasn't aware of the slight sacrifice in depth, I normally advance the GB positive 1 notch but might pay a little more attention to it now after hearing about your results.
Thanks again as it will definitely help me this weekend (finally getting out again, yah).
 
Great info on testing any coil / detector for gold signals and depth. I'd be paranoid of loosing it due to lack of confidence until the detector finds me a bit of gold and would put the gold into sticky tape attached to fishing wire so I certainly can retrieve it
 
Pete, I think by keeping a slow steady sweep speed when the ground balance is off set a bit should help, as the signal response seemed to be tighter when operated like this and slowing down it should give the machine more time to signal. This is what i found when testing it out, but i was amazed at how the machine could still pick up these small targets even though the ground balance was off set, a good feature on the machine to use that's for sure.

Atom, How did you go with your Eureka gold over the weekend?
 
Roscoe because with the SL/Pro has the delay you can GB on the Basalt and if it makes any noise by raising the Delay you can wipe out the basalt without having to off set the GB,

Well done Mate, Good Job.

john
 
G'day John, The pulse delay would be a handy feature for sure. To use the pulse delay and ground balance in conjunction together would be very handy. It took a while for the penny to drop, but i think i have the bull by the horns on this machine now. :)
 
Roscoe said:
G'day John, The pulse delay would be a handy feature for sure. To use the pulse delay and ground balance in conjunction together would be very handy. It took a while for the penny to drop, but i think i have the bull by the horns on this machine now. :)

Well thanks for making the effort on behalf of every ones questions, That is a way better result than anyone expected, and you have proved the SPP/SLs etc to be more serious and more than able to work in such places, And the thing for SPP/SL owners to do now is head for the Basalt areas where other machines won't run and clean up,

Well daone Roscoe,

john
 
Thanks for doing that Roscoe. That testing looks very promising. How much depth loss would you estimate - or more importantly how much depth would you get in this area on a say 1 gram bit do ya reckon? My SD2200D loved the basalt too but the GPX5000 handled them a lot better but you would still get the odd one here & there with it. The SDC in spots is more like the old SD's with them & if they are high enough in iron it will signal sweetly just like the gold in between them :lol:. Obviously the SDC isn't a depth monster in these areas either.

John - its not that other machines won't run in these spots - they will & I've got gold from them! It can just be a nuisance - more so in the more heavily scattered & higher iron content areas - sometimes to a point where you just move on after awhile especially if short on time & other more manageable spots nearby are calling ;). The SPP/TDI looks like it would have some advantages but, depending on the actual loss of depth, then that may be more of an issue?
Some of the basaltic areas are quite deep (basalt being a cap layer) & there is more than one gold detectorist out there that would like a machine that will fully handle basalt but still maintain SD/GP/GPX/GPZ like depth but it's probably not likely at this point in time. Also isn't it possible that by adjusting the pulse delay you may also wipe out smaller gold, 10uS being the ideal gold detecting pulse delay? "For every action there is a reaction"
I'm going to try & get my hands on a TDI (or modded SPP) to test around here but at this stage I don't think I would buy one just for this purpose.
 
People,

You are forgetting one thing and that is, if you advance the delay, you will also lose depth or at least reduce signals from small gold. So, all is not perfect if you have a delay control.

On the SPP, one should use the GB sparingly when the basalt is not a major problem. However, in areas where the basalt is a constant source of signals, then using the GB to minimize basalt signals will allow one to hunt an area normally not possible to hunt otherwise.

If you really learn the machine, you will notice small gold (less than a gram) often will be a narrow signal, way less in size than the 12" coil, but more along the lines of the smaller coil in the 12" housing if using a dual field or a folded mono.

Often small gold will signal as a small signal along the outer edge of the 12" mono coil indicating a depth of 3" or less. Basalt, on the other hand can be a much wider signal that can be quite intense if the coil is on the ground, but the signal will diminish noticeably if the coil is raised.

All mono type coils have an intense field that extends a few inches right around the coil windings. Keeping the coil closer to the ground allows you to use this feature. If you experiment with small gold, this feature will become more obvious.

Reg

PS: I forgot to mention, coin hunters can turn the coil vertically and use the outer edge to give one an idea of the depth of a target such as a coin. Usually, if you get a good signal using only the edge of a vertical coil, the object is no more than 3" to 4" in depth.
 
mbasko said:
Thanks for doing that Roscoe. That testing looks very promising. How much depth loss would you estimate - or more importantly how much depth would you get in this area on a say 1 gram bit do ya reckon? My SD2200D loved the basalt too but the GPX5000 handled them a lot better but you would still get the odd one here & there with it. The SDC in spots is more like the old SD's with them & if they are high enough in iron it will signal sweetly just like the gold in between them :lol:. Obviously the SDC isn't a depth monster in these areas either.

John - its not that other machines won't run in these spots - they will & I've got gold from them! It can just be a nuisance - more so in the more heavily scattered & higher iron content areas - sometimes to a point where you just move on after awhile especially if short on time & other more manageable spots nearby are calling ;). The SPP/TDI looks like it would have some advantages but, depending on the actual loss of depth, then that may be more of an issue?
Some of the basaltic areas are quite deep (basalt being a cap layer) & there is more than one gold detectorist out there that would like a machine that will fully handle basalt but still maintain SD/GP/GPX/GPZ like depth but it's probably not likely at this point in time. Also isn't it possible that by adjusting the pulse delay you may also wipe out smaller gold, 10uS being the ideal gold detecting pulse delay? "For every action there is a reaction"
I'm going to try & get my hands on a TDI (or modded SPP) to test around here but at this stage I don't think I would buy one just for this purpose.

Good point, the depth would be the deciding factor, I never knew that the ML machines did not like those areas, As for not rushing out and grabbing a machine, I cheated and bought one to suit different issues, and if depth remains a persons goal then I would sagest getting the Pro, But if a person has an ML that they use 90/95% of the time then the SPP (mod)/SL might be the way to go, Purely because there is no point in throwing a lot of money in to something that won't get used that often.
Adjusting the delay does not have much of an effect until you get up around 15 to 17 then you will see the difference, But From 10us to 13us it is almost impossible to tell but when you get to 14us then the signal was very quiet at the same distance using an 0.42 test bit ( cut the skirt off an air gun pellet ) and used that, lol . But at 13us I still got it at around 3 inches baring in mind mine has not been modded so it does not see the tiny targets like the OZ machines do, but it does see bits smaller than 0.10 depending on the shape using the standard DF coil. but that will change when MJ sorts out a few bits for me, (pending an Email)

PS,, and of coarse the Pro see's them a bit deeper,

hope this helps,

john
 
Mbasko, I would have to do a bit more testing and of course use different coils. I was using an 8" commander coil for that testing, i would like to try out the miner john 9 x 11 folded and maybe a sadie coil too. I will have to dig a small trench and tunnel bore into it's side and place a 1 grammer at different depths and different coils, but that would be the only way to get as close as possible to the real thing.

I agree Reg. the GB off set should be used sparingly,but half a notch seemed to be acceptable but personally i wouldn't go over this my self.
 
Reg said:
People,

You are forgetting one thing and that is, if you advance the delay, you will also lose depth or at least reduce signals from small gold. So, all is not perfect if you have a delay control.

Reg

Reg, as long as you don't take the delay over 13 it is almost impossible to tell, And as the knob is Approaching 14us and Above then you can see and hear the difference.

John
 
You can't use a single or even a couple of sizes of targets to determine how the delay affects the results. Since gold can come in all sizes and characteristics, there will be plenty of gold that will clearly display a noticeable depth loss with a delay change of a usec or two.

There is no standard results for specific weights either. As an example, I have 1 grain (not gram) nuggets I can detect with the SPP but I also have a couple of nuggets when combined weigh close to 8 grains I can't detect at all. These nuggets require a delay or 8 usec or so to detect them.

Size, shape, purity and surface characteristics will all impact how well a nugget is detected at a set delay. So, a bunch of small nuggets are required to make accurate tests. Purity makes a huge difference. Near pure gold is highly conductive while a nugget with a lot of silver or copper may act as a very poor conductor.

As another example, I have quite pure gold nuggets from an area that at about 1/4 oz transition from a low conductor to a high conductor. I also have some gold nuggets found only a few miles away that weigh a half oz each that respond as a strong low conductor even when tested together.

So, you can use aluminum ingot material to mimic some high conductive nuggets and then use lead alloys to mimic nuggets that are much lower in conductivity. This is why I recommend you know the gold characteristics where you are hunting so you can know what to expect signal wise.

Here in the US most gold found is smaller than 1/4 oz, so using the low conductor mode makes sense since pure or near pure gold below a 1/4 oz signals as a low conductor. Impure gold can weigh several oz's and still respond as a low conductor but very pure gold will easily respond as a high conductor. This is important to know and realize.

Reg
 
The whole point of this was to see If what DiggerBob shows/said In His Video Actually Works, Yes, and Roscoe kindly went and did his version of the Test by just Tweaking the Ground Balance did it Work ? Yes and he provided some useful information in the process,
So seeing as Roscoe does not have access to the TDIs with the Delay Control and I did, where Roscoe used a 0.50g test piece, I used a 0.42g test piece and so without touching the GB control I adjusted the delay from 10us up to 17 us repeatedly and then I did the same with the other TDI and the response was the same and by raising the Delay (As Per DiggerBobs Suggestion) I saw No loss in either machine at being able to detect the test piece when moving the Delay from 10us to 13us, which is what (DB) is telling people, But above that you will see a Loss in Signal Quality/Depth.

I do not see where Ghost nuggets come in to the subject (nuggets that are see through) and small flakes and having to use 8us Delay setting because the TDIs do not go down that Low when we are comparing Off the Shelf detectors,
A person can not Debunk what DiggerBob does on Video Live when he shows you it works and I have tested that it works, He and myself are talking about Normal everyday type Nuggets, The Same Type Roscoe used in his Tests, Yes there a thousands of different type nuggets out there, But when you are detecting the type of Nuggets Roscoe and DiggerBob used then it works, And you can use multiple sized nuggets to test is,

It is what it is I did not make Bobs Video, But what Bob says works.

john
 
John,

I am not disputing what Bob says works because it does, but if you have the SPP and no delay control, then, I say use what works on it. Personally, I prefer my choice of moving the GB even when using my SL or TDI. Many years ago, way before the TDI or GS 5, I used this simple technique of advancing the GB to ignore basalt and it worked great. Set and forget made hunting easy and fast. I was doing this around 2003 and later after I added ground balance to a low powered PI, so I do have a lot of experience and found a lot of small gold using the gb method.

So, my idea of using the GB never made it on a video made by me but has a lot more time of using and working under its belt. Whether you care to use it is nothing I need to know or care to know. Now, for those with a SPP, feel free to try it. Actually, you can watch Luke Lindsay's videos he made using the SPP in OZ and you will notice he uses the GB technique in his videos to eliminate "hot spots" and in one of them displays how he can still detect a small gold nugget.

So, in a nutshell, advancing the GB a little works just fine also and proven to work in OZ by lukeozdigger's videos.

Reg
 
Reg said:
John,

I am not disputing what Bob says works because it does, but if you have the SPP and no delay control, then, I say use what works on it. Personally, I prefer my choice of moving the GB even when using my SL or TDI. Many years ago, way before the TDI or GS 5, I used this simple technique of advancing the GB to ignore basalt and it worked great. Set and forget made hunting easy and fast. I was doing this around 2003 and later after I added ground balance to a low powered PI, so I do have a lot of experience and found a lot of small gold using the gb method.

So, my idea of using the GB never made it on a video made by me but has a lot more time of using and working under its belt. Whether you care to use it is nothing I need to know or care to know. Now, for those with a SPP, feel free to try it. Actually, you can watch Luke Lindsay's videos he made using the SPP in OZ and you will notice he uses the GB technique in his videos to eliminate "hot spots" and in one of them displays how he can still detect a small gold nugget.

So, in a nutshell, advancing the GB a little works just fine also and proven to work in OZ by lukeozdigger's videos.

Reg

Reg,

As far as I am concerned No One on the planet has as much Knowledge about the TDI series as you, Full Stop.

I have tried many of the tests put out there by you and you have always been right, But I did not understand why you would say to up the Ground balance to remove the TDIs response to Basalt rocks when if a person ups the Delay the True GB can be maintained,?? I understand that neither way is perfect but I can see the GB method would be desirable, But now I am wondering which method would have the Leased effect on wanted Items either by raising the GB by up to one number or by raising the Delay by 2 or 3 numbers, ??
I understand that owners of the SPP (TDIs) do not have the delay control so they will have to raise the GB in order to remove the unwanted signals, But for those people that can use the delay it does raise the question as to which method to use, Having tested both The Pro and the SL machines I found it almost impossible to tell the difference in Target response when using the delay method, And just when a person gets to understanding the machine then something like this turns up and causes doubts in the back of ones mind,
So from what you say by raising the GB to ignore the Basalt, Will the Auto Tune system of the Machine compensate for the GB off set ??
Personally I have always used your method but I can see that Bobs way works too but it retains the Grounds GB,

John
 
John, when you advance the ground balance slightly you shifting a high tone (low conductor)target to a low tone target (high conductor)and because the low tone side has been switched off by the conductivity switch we no longer hear these signals. This makes the machine run very very quiet because it only has half the work to do because its only processing half of the total ground signal.
 
Roscoe said:
John, when you advance the ground balance slightly you shifting a high tone (low conductor)target to a low tone target (high conductor)and because the low tone side has been switched off by the conductivity switch we no longer hear these signals. This makes the machine run very very quiet because it only has half the work to do because its only processing half of the total ground signal.

G'day Roscoe, yeah I understand that, Did it actually change the sound on your test piece because I just raise the GB from 6 to 8 and a limp of Lead 20mmX20mm by about 2mm thick and I still got a high tone so I tried it with w 0.30g test bit and it was high too, so now it is not doing what you are saying which is weird, I have messed around a lot seeing how different targets respond at different GB settings, but these 2 bits of lead keep making the same high tone whether I move the GB from one extreme to the other on both machines with a slight Gain/Loss in depth depending whether it is set to ONE or 10. Right when I had the machines worked out they go and do this, lol

Thanks mate

John
 
SunriseBoy said:
Well...I'm really trying to get my head around this (being an SL owner)...but it has checkmated me!

G'day Mate, the best way to deal with this is to set up in the normal way, with the GB turned on if you adjust the Ground Balance you can make low conductive targets sound like high conductive targets and vice versa, But if you lower the GB you will loose depth on low conductive targets, and the same when you are in the High Mode, but if you have it set to all By adjusting the GB setting to either low or high you can make a high conductive targets in to a low con Tone target and turn a Low Con in to a High con Tone target, so just remember if you are in Low or High if you lower the GB you will loose depth and vice versa, and if you are on the beach or mild/normal ground turn the GB off because you will gain more depth, ok

good luck,, john

PS:- The GB on the Pro does not alter the conductivity sound so drastically when you change the GB setting and it does is alter the depth, But it reverses the conductivity sound and is more noticeable on the SL because the GB seems to be Higher Geared.
 

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