Those impressive video results of the Fisher Impulse AQ with its 12.5” mono coil on the 10K Gold ring at 17”-18” and 14K Gold ring at 19”-20” as did a 22K Gold ring drove my curiousity to air test two Gold rings using a QED in its Beach Mode-11 operating at its pulse delay of 7.5uS with a NF 12” Advantage mono coil.
For my test, the QED’s settings were Threshold-B at 5 below Null and Factory Default for Threshold-A at 30 and Gain at 1.
(Threshold-A settings range from a 1 up to 90 and the Gain settings range from 1 up to 10}
The results for a clear response on a 3.04-gram 9K 21mm diameter Gold ring was 17” and on a 2.05-gram 18K 19mm diameter Gold ring was 16”.
I have no idea how a QED using its Beach Mode would operate within a Beach environment and my intention is not to compare in anyway the QED to the Fisher Impulse AQ only results using a pulse delay of 7.5uS.
By Steve Herschbach
I do what I can to foster competition that develops alternatives to the all too common VLF detector. There are plenty of options out there, but in my opinion they all weigh too much or cost too much. Usually both. I envision people out there with a popular VLF metal detector for beach, relic, or gold detecting. These machines all sell for around $700 and weigh 2.5 - 3.9 lbs. Perhaps they would like to add a ground balancing PI (GBPI) to what they have. I think that for "normal people" with normal budgets a machine under $2K and under four pounds just makes sense. It would be more than twice what they spent for their VLF, and in this day and age there is no reason why a decent PI should weigh over 4 lbs. I am drawing the hard line at 5 lbs and refuse to ever buy a metal detector again that weighs 5 lbs or over. I am setting under 4 lbs more as an aspirational goal that I think can be achieved, but recognize that battery power and coils are key inhibiting factors in high power PI systems that May make sacrifices in depth necessary to get total weight under 4 lbs. To clarify what I am talking about here, I should say that for many people a $700 VLF detector is a great place to start and in many cases is all a person ever needs. However, there are places where extreme ground mineralization and mineralized rocks (hot rocks) severely impede the performance and use of VLF detectors. Alternative technology to deal with these conditions has been developed, by far the most familiar being the Minelab ground balancing PI (GBPI) detectors. These differ from common PI detectors by having the ability to ground balance. Other brands have offered the Garrett Infinium (discontinued) plus Garrett ATX and the White's TDI models. These detectors are used not just for gold prospecting but also by relic hunters, beach detectorists, and others who face challenges regarding ground mineralization and VLF detectors. Frankly, in my opinion GBPI technology is largely maxed out. The main room for improvement comes now in better ergonomics at lower prices. This challenge therefore limits detectors to those that weigh under 4 pounds with battery included, and which sell brand new with warranty after discounts for under US$2000. Detectors need not be ground balancing PI models, but must offer similar ability to ignore mineralized ground and hot rocks that trouble VLF detectors. I am going to rate detectors as to their relative performance using what I call the "Minelab Rating Scale. Details here.
1. Minelab SD 2000 - crude first version, very poor on small gold, excellent on large deep gold
2. Minelab SD 2100 - vastly refined version of SD 2000
3. Minelab SD 2200 (all versions) - adds crude iron disc, ground tracking
4. Minelab GP Extreme - adds greatly improved sensitivity to small gold, overall performance boost.
5. Minelab GP 3000 - Refined GP Extreme
6. Minelab GP 3500 - Greatly refined GP 3000, last and best of analog models
7. Minelab GPX 4000 - First digital interface, rock solid threshold
8. Minelab GPX 4500 - Refined GPX 4000, solid performer
9. Minelab GPX 4800 - Released at same time as GPX 5000 as watered down version
10. Minelab GPX 5000 - Culmination of the series, current pinnacle of GBPI prospecting machine technology.
All Minelab models leverage an existing base of over 100 coil options from tiny to huge.
I am a very practical person when it comes to detecting. I know all the existing models and options by all brands very well, perhaps better than almost anyone. This is the way I look at it is this. If I personally were to spend a lot of money to go gold prospecting for one month, and needed a GBPI detector, considering machines past and present, what would I get and in what order of choice? Put aside concerns of age, warranty, etc. just assume functioning detectors.
Here is the issue in a nutshell. On the Minelab scale of one to ten as listed above, I would be generous in rating the White's TDI SL as a 2. Same with the Garrett Infinium which I will mention in passing as it is no longer being made. If I was going to spend a month of my time and a lot of money going on a prospecting trip, I would choose a TDI in any version over the SD 2000. I might go with a TDI Pro over a SD 2100 but I would have to think real hard about that, and when push comes to shove I would go SD 2100 were it not for the realities of age I said to ignore. A newer TDI Pro might be a better bet than a very old SD 2100 from a reliability standpoint, but again, this would be a tough choice. The TDI SL not really. In my opinion I would be shooting myself in the foot to go on this hypothetical trip with a TDI SL instead of a SD 2100.
You see the problem now?
The Garrett ATX fares better. I would rate it a 3, roughly analogous to the SD 2200 variants. Still an agonizing choice really and the ATX being new versus SD 2200 being old might again be the tipping point, but from a pure prospecting options perspective the case can be made that the SD 2200 might be the better way to go. The problem for this challenge is the ATX weighs way over 4 lbs and sells for slightly over $2000. The price is close enough really but the 7 lb weight is way off.
That's it folks. That is reality. The best of the best that the competition can offer can only go solidly up against models Minelab has not made in years. I am not saying that to be mean or as some kind of Minelab toadie, that is my pure unvarnished opinion as a guy who is pretty well versed on the subject.
Let's bring it all home. This person with the $700 machine really, really wants that under 4 lb, under $2K GBPI machine, but if they do their homework they discover that truthfully, they would be better off shopping for a used Minelab than what the competition offers new. With the TDI SL rated as a 2 the ATX in a much lighter box at under $2K is a solid win as a 3. A well designed ATX with standard dry land coils would look very enticing as compared to the GP series Minelabs. But Garrett refuses to budge!
White's can certainly do something, anything to improve the TDI SL. A battery that lasts all day would be a good start. In the end they are limited by the basic single channel design of the machine. The SD 2000 dual channel design was literally the answer to and the improvement on the single channel technology used in the TDI, the basics of which predate the SD 2000. Still, White's currently owns the under 4 lb under $2K GBPI category so they have the first out of the starting gate advantage. Anything they do would at the very least just show they have not given up.
The Minelab MPS patent that formed the basis of the SD series has expired. Not sure about DVT, which formed the basis of the GP series. Where is the competition? What the heck is going on here? Much gnashing of teeth and pulling of hair is going on here, that's what!!!
That is my challenge to the manufacturers. Under 4 lbs, under $2K, on the 1-10 scale I am offering, what is the best you can do?
The TDI SL as a 2? Really? Yes, really, that is currently the best of the best in the brand new ground balancing PI, full warranty, under 4 lb, under $2k category. You can pick up a 3.5 lb TDI SL right now brand new for $1049. The White's TDI SL takes the crown.
Note that a challenger has a half pound of weight they can add to the TDI SL and still make the 4 lb mark, and retail can be almost double the $1049 of the TDI SL and still come in at the 2K mark. I therefore do not think my challenge is outright crazy.
Hopefully we will see more competition in this wide open category soon. I have been beating this drum for years to no avail, but I do have reason to believe we are finally going to see more alternatives soon. I hope. Maybe? All I know is I have had it. I sold both my 6.9 lb Garrett ATX and 7.2 lb Minelab GPZ 7000 and am boycotting metal detectors that weigh over 6 lbs from here on out. I don’t care how well they work, I simply refuse to buy such heavy beasts from here on out. In the future I will support and give my dollars to companies that pay attention to and prioritize lightweight, more ergonomic designs.
White's Electronics TSI SL metal detector
I had a guy approach me at the lake today who lost a 14K college class ring size 11. I told him I would spend time looking for it and get it back to him if I happen to recover it. I have a 10K college class ring I found this year(unable to locate owner) but, it's a 10K. On the Simplex, it reads 64-65, the Nox hits at 20-21 I'm wondering how much of a difference the 14K will read. Any help would be appreciated. Thanks.
By ☠ Cipher
What do you make of this description on KellyCo? It seems to suggest the IPTU sensor would work with machines other than the Invenio. Does anyone know if that is true and how that would work?
"One of the biggest issues that people run into when metal detecting is difficulty with accuracy. The IPTU Sensor (Invenio) is going to help increase your accuracy and help you find more items and be sure what they are and where they are better. This is an easy to install sensor and is going to make a world of difference when it comes to your overall success when metal detecting. This sensor works with Invenio detectors and is a great addition to any metal detector."
By Steve Herschbach
The original 1985 Fisher Impulse metal detector
A note on saltwater. On dry land and in freshwater pulse induction (PI) detectors can be run to max limits. Not so in saltwater. There is an inherent limiting factor in saltwater that tends to flatten top end performance on all PI detectors, or even VLF detectors for that matter. The problem is simple - saltwater is conductive and so is visible to electromagnetic devices like metal detectors.
Pulse induction detectors saw their earliest use as beach detectors because of the pulse delay control. Lower pulse delays expose items with a shorter time constant, and this usually means low conductive and/or small items. As the pulse delay increases a PI loses overall sensitivity. Early beach PI detectors all came with a preset, relatively high pulse delay that made saltwater invisible to the detector.
In general somewhere around a pulse delay of 10 uS saltwater becomes visible to a PI detector. The number varies for several reasons, First, salinity varies greatly around the world, everything from salt free fresh water, all the way to the Great Salt Lake, which is water supersaturated with salt. Oceans and bays vary, and especially bays that have large river inflows, and therefore lower salinity levels. Large, shallow, enclosed bays with no rivers may act as evaporation dishes, and have abnormally high salinity levels. Further, this effect is accentuated the deeper you take a detector, and so detectors used for true SCUBA diving must be run at higher delay levels at depth. You can't just pick a number like 10 uS and say that is the magic number for dealing with saltwater. 9 uS may work well, or it may take 12 uS to eliminate feedback from the saltwater in your location.
The coil detects like a globe in all directions, and so it is not just the water under the coil, but all around the coil that is affecting it. This large ball of saltwater is like a giant target. Many hunters riding the edge of sensitivity can tell you a detector can pick up waves as they pass over, making the water deeper.
This long winded explanation is to make people realize that you can't just magically make the detector itself more powerful and get "more depth" or "more sensitivity." The salt range overlaps the tiny gold range, and so if you make a detector able to detect fine gold chains and tiny gold ear rings, it will detect the saltwater. If your set the pulse delay to eliminate the salt signal, you lose the tiny gold items. This is an inherent wall on both PI and VLF small gold performance in saltwater. We have had detectors for decades that can detect tiny gold that people say they want to detect in saltwater, the Fisher Gold Bug 2 for instance. The problem is the Gold Bug 2 will not work in a saltwater environment. The water is just a huge signal to a Gold Bug 2. I have gone round and round with people for the last twenty years trying to explain why you can't detect certain fine gold chains, small ear rings, small platinum, etc. in saltwater. The problem is not the detectors - it is the saltwater.
The same problem exists to some degree on trying to detect larger items. You can make a very powerful detector, but you have to inhibit the detection of saltwater, and this tends to put a ceiling on the maximum attainable performance in saltwater. No matter the machine you use, once you hit the saltwater you can only advance the pulse delay and sensitivity controls to a certain point before the detector starts to protest. The exact settings where this occurs will vary by location. This all assumes "no mineral" sand. Add magnetic soil content to the beach or bottom being hunted, and you have yet another limiting factor to contend with.
Add this all up and do not expect to run the Impulse AQ Limited at a pulse delay of 7 Us and maximum sensitivity in a typical saltwater environment. You will likely have to lower one or the other or both settings to get stable performance, and this requirement tends to be a limiting factor on all PI performance in saltwater. It is this knowledge that keeps me from ever expecting miracles to occur when I try new detectors in saltwater environment. The problem is not the detectors - it is the saltwater.
The original 1985 Fisher Impulse metal detector