GPX 5000 ?

Would the GPX trump a VLF in mild dry soil for depth.
I understand the advantage in hot ground or salt.
Not that i plan on running out to buy one anytime soon , just thinking.

No. And especially NO... on small and/or low conductors. VLF motion IB units will trump.

Having owned a 4500 and 5000, and most all top of the line VLFs....I respectfully disagree with Tom. The GPX machines use timings to dictate what soil type you are hunting in and what size objects you are looking for. Basically it's like having several detectors in one. The new 4800 & 5000 have the Coin/Relic timing for mild or less ground conditions and it is optimized for medium size objects...coins and larger. My soil is not the worse I've hunted in but its still too mineralized for use of the Coin/Relic timing but I know it air tests well for what that's worth.

Going to in ground VLF vs GPX. In low-mildly mineralized soil I've dug Civil War bullets 18-20 inches without a weak signal...meaning had I gotten over any deeper I would have for sure heard them. A Civil War minie ball will read between a pull tab - zinc cent on an ID meter and is roughly the diameter of a dime and height of a quarter. The shovel I use is a Lesche Pit Diggin shovel...12" shovel head and all aluminum handle and shaft. The shaft has a crook in it, and from shovel tip to that bend/crook is exactly 15". I know of several times I've had it past the bend for single bullets. In the same ground I can take my T2 in all metal, sensitivity at 90 or better, and I can't get a signal at all on bullets beyond 13-14 inches. I can get a whimper on the 13" ones. The T2 is one of the deepest VLFs I've owned but depth wise it can't hold a candle to a GPX on coins and relics in any ground conditions I've hunted in. I've hunted in Tennessee, mid-north Georgia, western part of North Carolina, and northern Virginia.

Now here's the thing. The GPX is like a high octane 3,000 horse power dragster. You can only take it so many places and be effective. They are extremely sensitive to EMI. More so than any machine I've seen. So urban areas of detecting are tough. They are also extremely sensitive to everything metal!! Now the timing selection helps along with some of the other settings....you gotta remember it's a gold prospecting machine and most gold is 1 gram or less. So some timings are optimized for making small pieces of gold stand out. On the 5000, the Fine Gold & Audio Boost modes do this. Great for sub gram gold but if you took it to an old park to coin hunt with, you wouldn't last 10 minutes. But by selecting a timing geared for say, larger nuggets at depth...well now it makes the machine less sensitive to small things and that would be a great timing for coins and relics.

I was trying to optimize my GPX for just coins and running the default gain settings were providing to be too much in audio fatigue in a trashy site. I purposely buried a silver dime at a measured 10" just to see how low I could lower the sensitivity and still get a signal that I would dig on the dime. I lowered it all the way to its lowest...setting of 1. And was hitting the dime decently strong at 10". My camo T2 in boost mode will barely do that at full gain and all metal.

Now my TDI Pro on the other hand...its only area of excelling over a VLF is in bad ground. My T2 will smoke it signal per signal in mild ground. The GPX on the other hand, is in a league of its own. It does equally well in bad soil and good soil. I had to sell my 5000 a few months ago but I am gettin ready to swing for a used 4500 or 4800 if I have to buy new. For raw depth...nothing beats them. Its just certain site conditions, a GPX would hinder more than help. It's why a 3,000 horse power dragster wouldn't do good in 5 o clock rush hour traffic

Daniel,

Your perspective/take is quite interesting and valid. Mineralization/location/conditions do indeed play a large part in performance. Coil size can also change the equation quite a bit. In Florida dirt, the F75 SE in 'bp' (boost process) mode will find very small jewelry items to greater depths/performance than the GPX 5000. I have also found .69-cal musket balls and .58 minie's at 17" with the F75..... and with reasonably correct ID. The GPX with a larger coil will also find these targets; yet, ID is non-existent at these depths. A PI for inland/turf hunting is exceptionally difficult due to ID woe's.... especially at depth.

The GPXs I've had only had the 11" DD coil. I never was able to experiment with the after market coils...most of them started at $300 and already having nearly $5 grand in a machine didn't help me lose grip on the pocket book LOL I actually went the opposite way on the GPX...smaller coils. The GPX really gets better depth with a mono coil but as a relic hunter you lose the iron blanking with mono coils. It only works on DD coils for that. The machine still utilizes the high and low tones for target conductivity which for civil war relics was handy. On large caliber bullets it gives a smooth low tone...this it will do all the way to the extent of its detection ability. The iron null is effective if you set it middle of the road and not wide open...it would null/sputter on nails and small bits of iron down to 12-13 inches. The ones deeper than that would trick you sometimes but seldom do we encounter a nail that deep unless its in a hut site or something. Coin and relic hunters are just catching on to the GPX machines and how crazy deep they are with just an 11" DD coil.

On my camo T2, I just have the two coils that came with it and the 15" DD. I noticed in my particular ground that I didn't gain hardly any depth on coin-bullet sized objects. I gained ground covered on items that size but for objects like belt plates, I gained several more inches with the 15". Coil size for size, I still say the GPX with just normal timings and no tweaking will reach down deeper. I had the 8.5x11" DD CoilTek platypus for mine and vs the same size DD coil on the camo T2 and AT Pro....it was GPX time for me. Now on small jewelry I have no idea. I don't have much jewelry other than my wedding band and its not small. I'm just speaking on the coin/relic side of things.

Do note though that even in my better ground I can't get correct IDs on in ground targets beyond a few inches deep. For example I have been digging this home site and it has rich black dirt....the best we have around here. I was shocked to be getting VDIs on coins in the 5-6 inch range that were IDing 80+. I got a signal reading in the mid to upper 80s showing as a quarter and depth showed 4". Was a mercury dime at 3-4 inches. And in my bad dirt...a 58 caliber minie ball at 6" will ID as iron and occasionally jump into the mid VDI ranges all over the place...from nickel to zinc cent then back to iron most of the time. The deeper ones wont even jump from iron. I have to use all metal to size the target up to determine whether to dig or not and most of the bullets I dig are just 8-10 inches. The GPX can cut through there, give smooth low tones on bullets to about 12" and then deeper bullets give their own kind of low tone...usually requires digging a plug and getting the coil closer to it. If it nulls or sputtered, it is iron...if it got better, you were digging 15+ inches for bullets. Deepest one I dug was a .69 caliber 3 ringer at just over 20" deep. We ran to the truck to grab a tape measure as we could see it in the hole bottom not in loose dirt where it might have just rolled down to the bottom. I thought for sure that I had a belt plate and had started digging carefully with hand digger. No VLF machine I've seen can do that with an 11" coil.

BUT at the same time, I have a few small nuggets...under 1/2 gram. The biggest I have is a .36 gram picker and the GPX would sound off on it at only 1-2 inches Max. My T2 with stock coil will get it nearly 3-4 inches and better with the 5" DD. So I'm just taking a guess that maybe small jewelry would be similar but that's only a guess.

I know where you are coming from Daniel....The Pulse machine's will dig super deep at the cost of disc.....I find when runnig a pulse machine I do dig alot of very deep target's...that the vlf's wont touch ion Disc they will though in all metal threshold based...but there is no disc same as the Pulse unit's...

I believe a VLF machine with an ultra high freq 20-70KHz will see smaller items than a pulse machine also...

the problem with the ultra depth you see with the 5000 is it's seeing object's in a more all metal mode and requires target chasing to some extant even with the 5000 iron disc function...

The pulse delay on a P.I. machine would have to get really fast like below 10 Micro Sec to see what a hyped up VLF machine can see in the small gold category.....

But the advantage of a pulse machine that I have found is it can maintain a super stable smooth threshold in hot ground that a say regular threshold based vlf machine can't obtain.....I can take a 5900 white's and dig 18-20 inch bullet's in semi bad dirt but at the cost of discrimination....the 5000 Pulse does it more easily though in medium to bad dirt...in good dirt a Naultilus 2b with all metal side sens cranked to the edge of stability is mind blowing on the depth achieved .

I know the 5000 pulse is a very powerful machine...and it might in good dirt achieve what a Naughty will on depth but I would not bet the farm it would go deeper....???Or I would not bet the farm the Naughty would go deeper??? coil for coil

I like the stability the Pulse machines offer in bad dirt.Most of my relic hunting is done in all metal anyway..But to be truthful most of the stuff I find with a TDI or Infinium I could find with a 5900 in all metal at the cost of digging it all.Unless the ground is just ultra extreme..the Pulse machine's that have the tonal change ground balance helps alot on actually cutting down on amount of iron dug....

if they can get them to properly disc look out ....


On a side note Pulse machine's love big coil's!Where Vlf's start to loose performance to coin sizes past 15 inch diameter...

Just some rambling's

Keith

Very good reports Daniel and Keith. I concur.

Yes..... a top-end VLF IB unit will far trump the GPX-5000 on very small jewelry. Yet, in hot ground..... the GPX-5000 is almost completely unaffected..... and still retains full depth. Yes.... the DD coil is a requirement for the limited Disc function to operate. The better the dirt mineralization.... the better the performance of the VLF. The more mineralized the dirt....... the PI takes substantial performance gains over a VLF.

Yep I agree fellas. My dirt is on the mid ground between decent and bad. Its bad enough that VLFs can't be ran effectively in disc mode or you lose all the good targets that get thrown down into the iron range. So basically it's all metal mode and sizing up targets. It's trial and error digging.

The bad dirt I've hunted in, still isn't as bad as the Aussies have it. There's is more of a powdered iron...where as ours is red clay. I do prefer the GPX platform over the Infinium and TDI. The TDI would be really awesome if it had some degree of iron blanking similar to the GPX. It still wouldn't be as deep though...I have a 14" mono on my TDI Pro and it will put you in the 15-16 inch range on bullets in red dirt. That's about it. I can't afford a 5000 right now but am looking into a good used 4500. The timings I used for relics are unchanged on the 4500-5000 so I don't need all the enhanced stuff for gold and mono coils.

I too would like to see another PI machine on the market that has the same degree of the GPX on iron or something different that works better. Just as long as its not over priced. But fat chance of that happening. Look at what the DIV relic hunts have done...now you have over 100 people that have bought GPX machines and most just use them 2x a year in Virginia. Laying down $4,500 for that limited use is silly but boy they are on the wagon now and more will join the ranks before the spring hunts. That's a lot of extra income for Minelab to be gettin from a gold machine costing that much.