Chase Goldman

Wishing for a speedy recovery for Joe. As you can see, water hunting at any level from diving on wrecks to swinging ankle deep in the surf and everything in between has an element of risk, regardless of your experience and Joe is one of the most experienced water detectorists I know and he doesn't appear to be someone who is cavalier about safety. Once Joe has recovered and able, I hope he shares the experience online so that we can learn about the circumstances and lessons here. These things can sneak up on you, and the unexpected can happen quickly, and you can be in trouble before you recognize you are in trouble. I read a story of a fatality in the same region just the day after Joe's incident regarding a boater who was ultimately found by the same rescue crew involved in Joe's incident. Be careful out there folks. Very thankful that Joe will be able to ultimately tell the tale, himself.

Depending on condition anywhere from $250 to as high as $500 for the mint DFX/300 seems like the going price. They are relatively rare to find now (compared to say older First Texas machines) and with White's demise (despite being sold to Garrett), Whites die hards seem to be snapping them up as backups or for parts etc. So you should have success getting whatever you ask in that range. Here are some more recent threads on the subject, including Steve H. and Jeff M. discussing recent used DFX purchases. HTH

Whose list, pray tell?

I just noticed that they Trademarked the coil names "GPX 11" and "GPX 17". I get it that "Commander" and "GPX" and "GPX 6000" are separately trademarked, but GPX 11???. Why??? Do they really think it's that catchy? I guess it differentiates them from there Commander cousins (except that there is no equivalent Commander form factor for the GPX 17" elliptical). From Steve's box image capture:

Even though your question appears as a “general” coil question, since this is a GPX thread, I will answer your question in the context of a GPX PI detector. We are talking primarily the GPX 4500/4800/5000 models. We haven't seen iron rejection advertised as a feature on the GPX 6000 and although it appears the GPX 6000 can utilize DD coils based on the menu settings, we haven't yet seen any DD coils announced or pictured that are compatible with the GPX 6000. PI detectors typically use a single Monoloop winding that acts as both the transmit and receive coil. Pulsed Induction as the name implies, uses pulses instead of a continuous wave like the more common VLF induction balance (IB) detectors to transmit the magnetic field into the ground. A brief pulse is transmitted and then the delayed receive signal is analyzed before a new pulse is transmitted into the ground. The process is so fast that the rapidly repeated pulse/receive cycles appear to be continuous to the user. DD coils on a PI enable the use of separate transmit (left “D”) and receive (right “D”) coils to be used analogous to the IB detectors. The DD enables use of the iron rejection feature on the GPX 4500/4800/5000 model detectors released before the GPX 6000 (GPX iron rejection cannot be used with monoloop coils). But because of the pulsed nature of the transmit signal, the coil can also be re-wired on the fly (on GPX detectors) using a switch to make the DD emulate a Mono coil by making use of both “D’s” to comprise a “bigger” receive coil that can enhance sensitivity (at the expense of iron rejection accuracy) or wire the two “D’s” in opposite polarity to enable EMI noise cancellation (also at the expense of iron rejection accuracy and overall target sensitivity). So in effect I have heard of using two receive coils (as described above) but not two transmit coils. I don’t think there would be any advantage to doing it that I could see. Using two transmit coils would seem to be inefficient from a power usage standpoint due to the resistive power losses in the copper and the whole point of the transmit pulse is to pump as much power as possible into the ground to maximize penetration depth, while the objective of the receive coil is to maximize sensitivity and that is actually enhanced by more copper.

Per Steve’s GPX 6000 info page, the controls and settings support a menu option for: Double-D Modes - EMI Cancel (Default) / Conductive Ground Cancel So I suspect ML will offer DD coils as well, perhaps having different form factors from the Mono coils offered in this particular bundle.

I’m rarely messing with settings even on a GPX 4800/5000. You set it up for the desired target and soil type and go, only adjusting the operating channel as necessary to avoid interference that you may subsequently encounter. Flip a toggle for a new timing if necessary.

Don’t know anyone who actually has one but we discussed it at length in this thread.

With the Mono coils provided as standard equipment and no mention of iron reject, I suspect iron reject is not an included feature and possibly also not compatible with legacy GPX coils (ML or 3rd party). If that is the case, it won’t be very popular with the relic hunter crowd other than the fact that it does appear to be lighter, weatherproof, and no cables flopping about. If it had/has iron reject and legacy GPX DD coil compatibility - no brainer for me, there would be a used GPX 4800 up on the classifieds board tomorrow. But without it, would have to wait for a highly discounted, lightly used “oops why did I buy this?” unit. But Simon, it has a built-in loudspeaker!

EL NINO who posted just before you did thinks there is still room for improvement in the scenario you mentioned by using a higher top -end frequency. I guess we'll see. Unfortunately, it looks like we won't see anything from Minelab along these lines until 2022.

You've mentioned this several times, Chuck. Mostly, this has been addressed primarily by improved responsiveness also know as recovery speed, taking advantage of improvements in processing power. The Equinox does a pretty good job also with target "spills" (multiple targets "in the hole") by alerting to multiple target IDs and using coil control to "zero in" on the desirable target. Signal processing advances and disc/target ID improvements a la FBS2 might be able to help here - so there might be some ability to wring more out of IB tech through improved filters (a la iron bias), audio, and possibly graphics. But what about targets that are masked vertically? Then there is not much one can do about that. You can't necessarily see through an iron "wall" by improved signal processing. In that case, you have basically reached the limit of the induction balance principle and have to use something else. OTOH - if you can detect the masking target in the first place, your best bet is to just recover it and clear it out of the way. In this case the detector did at least reveal the presence offending target in the first place. Nevertheless, I personally am amazed at what the manufacturers have wrung out of the frankly "crude" induction balance principle to bring it to today's level of sophistication for treasure hunting. Besides masking, if there are ways to improve IB ultimate Target ID depth in mineralized soils, that would also be a good thing.

The DP thread that points to that discussion in the Dankowski forum is here. Don't know if Minelab is really interested in that "new technology", but it was actually Tom Dankowski's reach for the moon idea. It's nice to dream but not something that is likely to be able to be accomplished using the induction balance principle alone. Lunk explains one method for doing it here. We've really just about hit the top of the curve of what you can do with induction balance (more commonly called VLF detectors as differentiated from the Pulse Induction principle). Perhaps you can continue to tweak signal processing and bring in some of the target ID and discrimination sophistication of the FBS2 detectors. But once everyone starts releasing their own flavor of simultaneous multifrequency (first Garrett, next Nokta (?)) then there really isn't that much more that can accomplished with the technology short of bringing in some sort of hybrid technology device that incorporates induction balance and say...ground penetrating radar. In other words, something that can sense target density would really not look anything like an Equinox or any other VLF detector because the technology required would be radically different.

Apples and oranges - Bluetooth 5 has higher data transmission rates which just means it crams more audio information in the data stream resulting in better audio fidelity (not really something that makes a huge difference on the relatively narrow bandwidth associated with detector audio versus listening to high fidelity music) but that does not have anything to do with latency (other than the processing time associated with the higher data compression needed which tends to INCREASE latency/delay). But I totally agree with you that having a multitude of audio options/choices like they provided on Equinox is a good thing.

Every BT headphone does not support Low Latency BT transmission - it has to be supported on both ends - the detector transmitter and the phones themselves. APTX LL the low latency bluetooth standard transmission protocol Minelab has adopted for incorporation into its Equinox and Vanquish detector BT transmitters - is kind of a fading standard. Hasn't really caught on with the general marketplace and manufacturers of BT headphones seem to not be willing to play to licensing fees to incorporate the chipset and firmware in to their products as a result, unfortunately. APTX LL would at least be better than yet another non-cross compatible proprietary wireless/Wi Stream variant. They now have at least 4 proprietary Wi Stream variants, none of which have interchangeable hardware (WM08 for Equinox, WM10 for the CTX 3030, WM 12 for the GPZ 7000, and the Pro Sonic standalone unit - totally ridiculous.) See above. Bose does not support any sort of low latency BT standard protocol, definitely not APTX LL. Low latency is pretty much a necessity for detecting with wireless audio otherwise your coil swing does not sync up with where your coil is when you hear the target audio. It is pretty noticeable with non-low latency bluetooth headphones and pretty annoying. I definitely sympathize. There are BT headphones that I have that would be much preferable to those that I am forced to use that comply with the BT APTX LL standard. I've pretty much switched over to proprietary wireless audio solutions for everything but the Equinox because they allow me to use headphones with optimized audio characteristics for my hearing and comfort.

I guess my point was not so much whether the GMT should/could be used for coin shooting, of course it will snag some coins under ideal conditions. But whether any further investment should be put into the GMT by buying a new coil to do so (Ron's question). That is throwing good money after bad IMO. The stock Twin D 6 x 10 should be fine for coin shooting with no money put of pocket, I don't really think another coil will do much better for the amount of money you would have to lay out. If Ron is keen to spend money, however, it would be better spent on a general purpose detector and coil IMO.

This is an important point. One I forgot to make in my previous response. You apparently are doing well with whatever settings you are using so don’t mess with success by over tweaking things. If my recommended iron bias setting doesn’t help (with falsing) or makes things worse, dial back to your previous settings.

My advice would be to get a more versatile and affordable detector. Namely, an Equinox 800 and possibly the 6inch coil for max micro target sensitivity. If there is small gold near the surface, you will find it and that would clue you into whether it makes sense to drop serious coin on a PI. If you don’t find any natural gold, at least you have an excellent coin, relic, and beach machine too. That 10 acre site might not give up nuggets but it could give up relics or coins, perhaps even of the gold variety. GL

Problem is when you've been implying it is imminent for multiple years, you kind of lose credibility. They've been saying that about the Deus companion app for years also. It's always just few months away. A few months later, its still a few months away. That's how XP has done things since they announced version 4 SW is imminent 1.5 years before it was actually delivered. I've been seeing photos of their 2-box coil since 2015. Bottom line, I'll believe the XP rumors when I actually see some hardware and not just whispers or even glossy marketing brochures.

Ron - Welcome to the forum. Do you have the stock 6x10 on there now? Whites makes an 8 x 14 coil, if you can get your hands on one, that will eek out some additional depth. But it can set you back about $175 to $250. Also, with the GMT operating at 48 kHz, it is really not going to give you much high conductive coin depth (general purpose coin detectors usually run at 4 to 14 kHz). The problem with high frequency is that it does not penetrate as far into the ground as lower frequency machines and a bigger coil will only marginally help depth at that frequency. You can get a lot of detector for $250 to $350 today. I would recommend instead considering a general purpose detector such as the Nokta Simplex+ or Minelab Vanquish in the $300 ballpark if you want to do coin detecting rather than investing in a new, expensive coil for a gold machine that is only going to give you poor to mediocre depth on coin shooting. The GMT is a great gold detector, one of the best in its hey day and can still get the job done on nuggets But it is optimized for gold, micro jewelry, and meteorites, while coin shooting (unless you are talking gold coins) is not really in its wheel house. Right tool for the job. HTH

Advice: Don’t overthink it. If you are not having issues with noise or detection, leave it be. Don’ts: Don’t wrap it so loose that it flops around, don’t wrap it such that it constrains your ability to position the coil at the desired angle with respect to the shaft to keep it parallel with your desired swing plain and to lie it flat for transport. You want to minimize strain at the coil cable to coil interface or at any place else along the coil cable that could cause wire breakage due to repetitive flexing at stress points. Otherwise, other than certain special cases with certain coils and detectors, a properly shielded coil cable should not care from an electromagnetic standpoint where you start the shaft wrap.

Park 2 is no better or worse than any other mode in hot soils. All the modes become limited in depth in hot soils. Theoretically, lower frequencies penetrate further overall but I have really not found any mode on Equinox that is preferred in hot dirt. so I set my mode based on my target objective - which is typically relics, so I am usually hunting in Field 2 because it is higher weighted in frequency and better suited to mid-conductive relic targets like brass. lead, and the occasional gold coin or nickel. But I have also found plenty of old silver in Field 2 as well. Park1 theoretically hits silver better (than Park 2) because it is weighted towards lower frequencies, but the fact is that since all the modes are multifrequency, they can all theoretically hit targets across the conductivity spectrum. The deepest mode from a silver perspective should be 4 khz single frequency but it comes with a lot of other baggage like EMI susceptibility and the iron bias feature is disabled in single frequency. I would stick with Park 1 for silver slaying or 2-tone Field 1. Regarding Iron Bias - I prefer F2. I usually just run it at the default of 6. It can help reduce falsing, and tests by users have shown little risk of inadvertent masking of non-ferrous targets even at higher settings, so give it a shot if you are really having falsing issues. HTH

It's an advantage only to increased dry or wet sand swing coverage. You will not gain any appreciable depth as it is only 1" wider than the diameter of the 11" stock. You might lose some sensitivity on micro targets, but I have still been impressed with its ability to pick up tiny targets. Using it in the water just increases coil drag compared to the 11" so it is somewhat counterproductive. I've used both the 15x12 and 6 inch round coils and except for vary rare detecting situations where the other two coils might be advantageous, find the 11" is the sweet spot.

Excellent info. Thanks, Dew!

Somewhat surprising - the machine setups matter and no clue on how this guy 's machines were set up, his proficiency, and ground coverage strategy or discipline. If he switched around on all those detectors during a single visit, sounds like a classic skunk desperation death spiral move (been there, done that). When your confidence is shot, believe me, every detector you grab for is probably going to disappoint. Not necessarily a reflection on the machines' capabilities in that case. But if your buddies were indeed not picking up the signals on your targets before they were dug, that is saying something, again, as long as those detectors were properly set up. I assume your buddies are experienced and know how to set up their machines properly, those machines are relatively complex, especially in regards to disc, and you can easily set them up in a manner that would degrade their performance if you are not proficient. Barring that unlikely situation, silver depth in the absence of high junk and mineralization is not something you would expect an eTrac or CTX to struggle with, especially if the Equinox is doing just fine. Nevertheless, great saves and congrats on the finds and the bragging rights over your buddies' misfortune.

4 is probably as low as I would personally go because I usually hunt with no disc to avoid disc clipped non-ferrous tones. Much lower and sweep speed becomes an issue as you cannot slow it down enough to overcome ground feedback (even with a sat GB). Probably a non-issue in "0" soil conditions such as at the beach, but then again, you don't really gain a raw depth advantage by lowering recovery speed, just a better ability to hear blip iffy tones associated with lower modulated micro or edge-on targets at depth. I really mostly just stick with the recovery speed defaults for any given mode as a decent starting point, and find I rarely have to (or want to) tweak it in the field as most of my sites are heavily mineralized. If I do, it's at most a one click tweak from the default.