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Comparing the TDI SL and The MXT Pro (12")

I was wondering if anyone as Compared these Two Machines, Because the SL is an in between machine, Between it and the ML 5K,

I have been wondering about these two machine Because I have Read Stories about people Pulling One Ounce Nuggets at 18" At Gains Creek with the MXT fitted with the 12 inch Coil, And I have seen Coins come up at over 13" with the same setup with the Gain set between 6.5 to 7, Yet I have never heard about Deep Nuggets found with the TDI SL, and I have heard about people digging Bobby Pins on the beach with the TDI's at 16" to 18", In Air Tests My GMT with the standard 5X9 coil versus the TDI SL, On a Round Flat 1 1/4ozt Lead Nugget TDI SL = 18" and the GMT = 21" set at 7'5 (pre set mark) So I could do up to 10 if conditions Allow, But considering the SL has a 12 DF mono I would never of expected that to happen, Like The MXT when you Turn The GMT up you Can hear it Changing Gears so to Speak as it Multiplies the Gain,

Has anyone here found any Deep Nuggets with the SL, I know that someone in OZ found a 5.6ozt nugget AT 32" using a 20 NF Coil,

I have picked up Large Iron at have 4 foot deep and the subway Tunnel at over 6 feet deep, But as winter is all but over I am hoping to get out and do some testing ect,

Thanks Guys,, John

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This answer is not aimed specifically at you John, just generic readers.

 

Whenever you are looking for nuggets suspended in mid air it is very important to turn the ground balance off when running the TDI or TDI SL. The ground balance system is designed for in ground use and robs depth when working in very low mineral or no mineral situations. This is easily seen by testing a target with ground balance off and ground balance engaged.

Raising the age old detector question - why use a setting that degrades performance?

Ground balance exists to compensate for ground conditions. Any pure all metal machine without a ground balance system, including VLF detectors, gets more depth in no mineral or low mineral ground than a ground balancing detector.

In order to properly test ground balancing metal detectors you cannot remove the main component the system was designed for - the ground.

A VLF ground balancing system cannot handle extreme ground as well as a PI based ground balancing system, because PI has an inherent advantage in ignoring ground signals.

As ground conditions get more severe a VLF loses depth faster than a ground balancing PI and so eventually conditions are encountered where the PI can get twice the depth of the VLF. This chart tries to illustrate this. I no longer have either of these machines and so this is for illustrative purposes as I cannot attach exact numbers to the chart. It all depends on the ground and the target as to what the exact difference are and what machine is the best choice. Notice that as ground conditions get worse both detectors lose depth. A PI just does not lose depth as quickly as the VLF.

vlf-vs-pi-ground-balance.jpg

In low mineral ground like at Ganes Creek a VLF is the detector of choice because it gets maximum depth while having superb discrimination. In extreme bad ground a PI is a much better choice.

Long winded way to get to the real question. Big nuggets found deep here with the TDI. Chicken or the egg problem. So few of the people most likely to find that kind of nugget are running a Minelab that the TDI is at a distinct statistical disadvantage. On top of many big nuggets here being found at shallow depths. My 6.5 ounce nugget recently could have been found with a TDI but I was swinging a GPX. But the MXT would have found it also, as would an Ace 250.

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Thanks Steve,, So in Low medium Ground would the MXT with the 12" setup Be Deeper??

I understand there is no point in using a PI in mild ground, But if I wanted to search for deeper Targets would the SL be able to do that over the 12"MXT, Because after A Person has used the 12" concentric coil you would have to go up to an 18" DD to beat it and even then it would make that bigger difference,

My GMT seems to be Possessed by Evil Forces, It Has awesome power compared to the last one I bought and they have moved the GB setting from 77 down to 50, So I wonder if that is the Reason??

John

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"So in Low medium Ground would the MXT with the 12" setup Be Deeper??"

 

Probably. The TDI is not exactly a powerhouse detector and it requires pretty bad ground to look good compared to a good VLF running in all metal mode. In most ground I found a Gold Bug Pro in all metal did just as well or better than a TDI.

 

The caveat being, if the ground is mild enough, can you turn the ground balance off on the TDI? Now you have a very powerful "straight" PI about as powerful if not more so than most you can buy. It is perhaps the best beach PI you can buy when run with ground balance off.

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"So in Low medium Ground would the MXT with the 12" setup Be Deeper??"

 

Probably. The TDI is not exactly a powerhouse detector and it requires pretty bad ground to look good compared to a good VLF running in all metal mode. In most ground I found a Gold Bug Pro in all metal did just as well or better than a TDI.

 

The caveat being, if the ground is mild enough, can you turn the ground balance off on the TDI? Now you have a very powerful "straight" PI about as powerful if not more so than most you can buy. It is perhaps the best beach PI you can buy when run with ground balance off.

Thanks Steve That explains a lot of what I was thinking, But I thought I was get it wrong, So Do I Go after a 4800 In order to deep search, is it worth the step up or not?? the 5K might be a little too much over here @ £3999 / $6240.00.

Thanks Again,, John

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Unfortunately I can't help in the relative worth department. One man's waste of money is another man's must have purchase. But I will tell a story. Again, more for the general readership than you in particular John.

I ran a store and sold mining gear for 40 years. When people wanted to buy equipment or upgrade my advice was always the same. Using mining gear it was:

1. Buy a gold pan. Learn to pan gold. if you can pan enough gold to pay for the $9 gold pan....

2. Get a sluice box. Go shovel dirt where your pan tells you there is gold. If you can sluice enough gold to pay for the $80 sluice.....

3. Buy a gold dredge, highbanker, or other powered equipment. If a dredge, get a 4". If you can find enough gold to pay for the 4" dredge....

4. Get a 6" or larger dredge.

The point is it is all about the ability to find gold. If you can't find enough gold with a sluice box to pay for a sluice box, you do not know how to find gold, and spending more on equipment is usually just a waste of money. Gotta walk before you can run.

Same rationale. If you can pay for a GMT with gold found, spending more money on detectors is wise. If not, maybe more research and better areas are needed.

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Spot On, That Makes a lot of sense, I have found the Spot, And I am in the middle of buying an RV as well, so I can stay there  for 2 or 3 weeks at a time and taking one week off then back to it, So I will turn my finds into the 4800 ASAP

 

The GMT is more of an investigative Tool because I am relying on that to find the hot spots In the stretch where I know where it is, So Fingers crossed, I only started this last year and I found enough to pay for half the GMT that I bought this year, So its early days yet, 

 

John

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The TDI SL is a great PI for nugget shooting in nasty mineralized ground and beach prospecting for jewelry in wet salty beach sand. Simply switch out coils and you have a new machine for the task at hand. MXT Pro for multi purpose detecting, coin shooting and nuggets in tailing piles (replaced it with the F75).  For areas known for quartz specimens or I'm digging out crevices in a dry stream bead.....the GMT (or GB2) is  machine of choice. Speaking of dry stream beads; dig out crevices below the water line, classify to 1/4" and dump buckets of material into a couple wide mortar tubs, filling each to about 2" to 3" deep and spread even. Take the GMT w/4x6 shooter coil and go over material at least twice re-shaking between checks. The GMT will find very tiny pieces of coarse gold and most of my finds doing this have come from the minus 1/4" classified tub.  Keep the tubs in a spot that allow the machine to run at high gain and stay balanced. Prospecting in the desert where water is mostly for drinking inspires "creativity" sometimes. I don't know what kind of prospecting you do but I will say you couldn't go wrong owning all 3 of these fine machines.

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The TDI SL is a great PI for nugget shooting in nasty mineralized ground and beach prospecting for jewelry in wet salty beach sand. Simply switch out coils and you have a new machine for the task at hand. MXT Pro for multi purpose detecting, coin shooting and nuggets in tailing piles (replaced it with the F75).  For areas known for quartz specimens or I'm digging out crevices in a dry stream bead.....the GMT (or GB2) is  machine of choice. Speaking of dry stream beads; dig out crevices below the water line, classify to 1/4" and dump buckets of material into a couple wide mortar tubs, filling each to about 2" to 3" deep and spread even. Take the GMT w/4x6 shooter coil and go over material at least twice re-shaking between checks. The GMT will find very tiny pieces of coarse gold and most of my finds doing this have come from the minus 1/4" classified tub.  Keep the tubs in a spot that allow the machine to run at high gain and stay balanced. Prospecting in the desert where water is mostly for drinking inspires "creativity" sometimes. I don't know what kind of prospecting you do but I will say you couldn't go wrong owning all 3 of these fine machines.

Yeah I got the TDI SL and the GMT and The MXT All Pro So I have all Aspects covered I love the MXT But The GMT has my attention at the moment, But I keep Drifting towards the SL and because I like them All it makes it real hard to stay focused on the one machine, Heaven forbid if I take them all out for a walk,

john

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