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Found 129 results

  1. Hi, Regarding the VLF detectors.Can someone answer for me what constitutes a VLF with good discrimination?.I feel to discriminate that speed is a factor as well.Otherwise no matter how good,if a target is next to iron it will read off a good hit. The Deus has fast reactivity,so is this now a good discriminator.Between ferrous and non ferrous?. How does this compare to say the Nokta Impact for speed discrimination. Thanks in advance Ash
  2. The more I learn (by reading and experience) the more I realize that unmasking is the holy grail future of induction balance (IB) detectors. Dankowski has been emphasizing the issue for years (as your link to a 2000 article shows Dankowski - Beneath The Mask). The sites I hunt are visciously peppered with iron, small and large. That goes for old homesites here in the Midwest and out West, at old abondoned mines, placer sites, and ghost towns. As bad as littering is today, at least we have trash barrels, recycling, refuse collection, and advertising pleas to keep the world a beautiful place. I get the impression that back in the 19th century the thought didn't even occur to them. People can still cherry pick (using strict discrimination) to avoid the trash. If all you're after is recent drops (clad, zinc, and maybe a few pieces of silver jewelry) then go for it. I want old stuff and, as you note, that means dealing with lots of trash. But even careful hunting today is hampered severely by masking. As Tom D.'s report shows, not only don't you hear the good target, sometimes you don't even here the bad ones! How do you know there might be good target being masked if your detector responds as if there is no metal at all within its search field?! It's my impression that masking is just as big of a problem for nugget hunters. Does it just get less attention because most nugget hunting is done with pulse induction (PI) and zero volt transmission (ZVT) technology, which (AFAIK) doesn't offer much discrimination anyway. If you're really going to dig-it-all, including iron, then eventually you're going to find just about every piece of detectable metal within range.
  3. The following information is from an apparent leak from a First Texas distributor meeting? The link is posted at http://www.detectorprospector.com/forum/topic/555-new-fisher-pulse-induction-multi-frequency-detectors/?p=10571 as part of the thread about upcoming Fisher products that have been circulating for a couple years. These leaks seem to jive with previous statements by Tom Mallory of First Texas. The main one of interest to the people on this forum would be a new CZX model aimed at gold prospecting. Here is the text from the posted screen shot: CZX - Fisher and Teknetics This machine is ground breaking technologyTurn on and go2 frequency - 9:1 ratioNo need to ground balance or adjust the detector to the environmentIt automatically senses the ground and makes changes accordingly.First detector birthed from this platform is a gold unit priced around $1000, but deeper than current VLF, this detector will also see through red dirt, and highly mineralized soil.From this platform other machines will develop. We intend to develop the CZX and MOSCA platforms to offer more machines in the $1000 to $2000 range than have ever been available.Target release 2016We have senior engineer Dave Johnson on this projectThe "Mosca" platform referred to is further described and apparently is aimed more at being a general purpose non-prospecting detector (coins, jewelry, relics). Again, here is the text from the posted screen shot: "Mosca" Fisher and Teknetics Waterproof up to 10' (3 meters)Wireless headphones - Waterproof loop and connectors for headphones2 frequency - 7:1 ratioHobby/Treasure Market - Great for Saltwater, Relic, CoinAuto Ground TrackingSingle Pod DesignLCD Pad, control buttons, 2 AA batteriesArm Pad in rearRetail target - $1200 - $2000Target release 2016We have dedicated engineers on this project OK, so a gold unit around $1000 that goes deeper than current VLF designs. I also have high hopes that knowing the proclivities of the engineer, Dave Johnson, that it will be relatively light and ergonomic. Dave also prefers simple and the design statements reflect that. We seriously need something that brings gold detector weights and prices back to earth and so hopefully this will be it. I have stated over and over again I would be very happy with ATX equivalent performance in a less expensive lightweight package. Garrett so far seems disinclined to make that unit but they have a year at least before it may be a moot point. The CZX would have to obsolete the White's TDI as it is aimed squarely at or below the same price point and unless it beats TDI performance would be dead on arrival. We will not have long to wait - 2016 is coming fast!
  4. http://md-hunter.com/new-xp-q-mond-machine-novelty-2018-look-at-that/ Is this for real, why not go with the smart phone?????????
  5. Editors Note: this thread split from http://www.detectorprospector.com/forum/topic/4335-the-reg-wilson-gold-album/ Nice stuff again... I'm having cardiac palpitations seeing all this gold....lol I wonder if you could tell us how your sled was rigged up. That looks nice for some open ground. Keep it coming....
  6. Whats a good detector to try out for diving 20 to 30 feet in rivers in swim holes etc....... Maybe something I could pick up used? I was thinking maybe an Excaliber II or Garrett Infinium?
  7. Hello, Does the coal or carbon block the EM signals? For example if the metal object buried and covered by shield of carbon or coal. Does the metal detector able to penetrate this type of materials.
  8. The whole depth with VLF detectors thing in my opinion has been nothing but a red herring for decades. I have read a thousand posts from people wanting VLF detectors with "more depth". Yet VLF detectors maxed out for usable depth by at least 1990 if not before. I have not used any VLF metal detector since 1990 that got more depth on coins than my Compass Gold Scanner Pro. The only real improvement we have seen and are still seeing is in the ability to find and correctly identify items that are masked by the ground itself or adjacent undesirable targets. There are an amazing number of targets in the ground at depths achievable by any decent detector made in the last 25 years, but that are being missed because they are improperly identified and ignored or just completely masked and invisible. This is an area where the Minelab BBS and FBS detectors have excelled. They do not go deeper. They simply get more accurate discrimination at depths exceeding what most detectors achieve. Machines like the DEUS and a lot of other Euro machines are excelling not for the depth they get, but this ability to acquire and accurately identify targets at shallower depths that are missed by other detectors. If we had a detector that could simply see through everything and accurately identify coins to 10" the ground would light up with countless missed finds. I get a chuckle out of all the deep coins I see people talk about on the forums when the best detectors made can't accurately identify a dime past 5-6 inches in my soil. Anything deeper just gets called ferrous. There is huge room for improvement in metal detectors still not by getting more depth, but by simply finding shallower targets that have been missed by other detectors made up until now. How To Make Yourself Crazy! U.S. Versus Euro Style Detectors
  9. I think I could show more interest in any of Garrett detectors but in my opinion they try to put too much info in such a small area. They could take a lesson from White's and let it pop up on the screen on what you detected. This looks like what Minelab is doing the same as White's with a big and better display so all has no trouble to see. I don't see myself buying anything from Garrett until they do. White's has some for the same reason I wouldn't buy either. The young will buy the small screen but with a large one the younger and older will buy. So detector companies you want your sales to go up then come out with a larger display. Chuck
  10. I was wondering about this new machine to hit the market and do believe other manufactures are also releasing soon, the same or very similar type of technology.I dont belive it s new.Can we obtain a list of the main players who will be releasing something similar so i may do a comparison.I think Fisher has one but dont think the At Max coming soon is the same.I m asking this as im not 100% tech savy but dont believe Minelab is the first here or by any means the best.In saying that ,this machine looks very sweet indeed.Also last point.In regard to reactivity speed ,where does the AT Max come in.Thanks in advance. Ash
  11. So Steve or somebody explain to me, putting aside higher frequency is more sensitive to tiny objects like gold nuggets. I realize that. Does higher or lower frequencies go deeper? is there any difference for general coin or relic hunting? Would one or the other pick up or let me hear better a deeper fainter signal?
  12. The latest issue of the ICMJ is out, and I have an article in it titled Selectable Frequency vs Multi Frequency Detectors. Those of you with a digital subscription can read it online. The ICMJ has a policy against mentioning brand names in articles so I wanted to post this as a supplement to the article. Most metal detectors run at a single frequency. Low frequencies, that is single digit frequencies under 10 kHz, react well to high conductive targets, like coins, or large items, even if those items are of low conductivity. If you look at this typical metal detector target scale below you will note that non-ferrous items read higher not just based on conductivity but size also. Low frequencies also do not "light up" the ground or hot rocks as much as higher frequencies. Many do not even offer ground balance controls. Low frequency machines under 10 khz therefore tend to be aimed at the coin detecting market. There are too many models to list but most people have heard of the 6.5 khz Garrett Ace 250 as a perfect example. High frequencies 30 khz and over have extreme sensitivity to low conductive and small items, but also struggle more with ground penetration and hot rocks. Their extreme sensitivity to tiny trash items like aluminum bits do not make them very practical for any detecting except gold prospecting. Machines 30 khz and higher tend to be dedicated prospecting machines. Examples would be the 48 khz White's GMT, 71 kHz Fisher Gold Bug 2, and soon to be 45 khz Minelab Gold Monster 1000. In 2002 White's introduced the White's MXT at 14 kHz, and it is a perfect example of how detectors running in the "teens" make excellent "do-it-all" detectors. Since then everyone and their brother has jumped on that bandwagon, and there are too many machines running from 10 kHz - 20 khz to mention. Prospectors in particular would recognize the 19 khz Fisher Gold Bug Pro, but few know it is also sold in slightly different versions as the Teknetics G2, Fisher F19, and Teknetics G2+, all 19 kHz detectors sold to the general coin and relic market. Garrett has the 15 kHz AT Pro and 18 khz AT Gold to name a couple more hot selling detectors. Well if low frequencies are good for coins and high frequencies good for gold, why not make machines that can do both? Or both at once? Selectable frequency refers to machines that can select from one of several possible frequencies, but analyze the signal from only one frequency at a time. These may also be referred to as switchable frequency detectors. Multiple or multi frequency detectors analyze the signal from two or more frequencies at once. Multiple frequency detectors usually have a fundamental frequency they run best at, and then other "harmonic" or secondary frequencies they also use, but the power (amplitude) fades with distance from the primary frequency. From page 9 of Minelab's Metal Detecting Terminology: You can find more information on harmonic frequencies at http://www.ni.com/white-paper/3359/en/ and here also. Coils normally must be wound specifically to make use of any given frequency or set of harmonic frequencies. A coil will usually work best at the given fundamental frequency making it difficult to get the best possible performance at all frequencies using one coil. The Minelab X-Terra series specifically requires a coil change to achieve a frequency change for this very reason. People who own them know 3 kHz coils weigh more than 18.75 kHz coils. Why? Because heavier windings are used at 3 khz for optimum performance at that frequency. Here is what is probably an incomplete list of selectable frequency detectors and year of release: 1989 Minelab Eureka Ace Dual 8 kHz 19.5 kHz 1993 Minelab XT 17000 6.4 kHz 32 kHz 1994 Compass X-200 6 kHz 14 khz 1997 Minelab XT 18000 6.4 kHz 20 kHz 60 kHz 1999 Minelab Golden Hawk 6.4 kHz 20 kHz 60 kHz 2002 Minelab Eureka Gold 6.4 kHz 20 kHz 60 kHz 2005 Minelab X-TERRA 50 7.5 kHz 18.75 kHz 2006 Minelab X-TERRA 70 3 kHz 7.5 kHz 18.75 kHz 2009 Minelab X-TERRA 305 7.5 kHz 18.75 kHz 2009 Minelab X-TERRA 505 3 kHz 7.5 kHz 18.75 kHz 2009 Minelab X-TERRA 705 3 kHz 7.5 kHz 18.75 kHz 2009 XP DEUS 4 kHz 8 kHz 12 kHz 18 kHz 2016 Rutus Alter 71 Variable 4 - 18 kHz 2017 Nokta Impact 5 kHz 14 kHz 20 kHz Multiple frequency or multi frequency machines have become very confusing, as a lot of marketing material has focused on the number of frequencies transmitted. What really matters is what frequencies a detector receives, and how the information is compared and processed for results. Some commentary here. Many people look at the marketing material and assume that a machine processing multiple frequencies is somehow working across the board to deliver the best possible results at all frequencies. However, the two issues outlined above do apply. The machines are employing harmonic frequencies, and so cannot compete with a machine optimized at a single frequency as opposed to one of the distant harmonics running at less amplitude. Second, making one coil run perfectly at all frequencies is extremely difficult, again giving the dedicated machine an edge. I highly recommend people not go down the technical rabbit hole but instead focus on what the machines do, on how they act. Two things are very apparent. First, the big market for a long time was coin detectors, and the goal always was to identify coins as deep as possible while ignoring trash as well as possible. Processing two or more frequencies simultaneously gives the detector engineer more information to work with. All the focus was on developing great coin detectors and guess what, the multi frequency machines for all intents and purposes act just like very good lower frequency coin detecting machines. Good ground rejection, and great discrimination on coins for as deep as it can be achieved. The multi frequency machines don't really go deeper than single frequency coin detectors, they just do a better job delivering clean discrimination results to depth. Here is a list of introductory models of multi frequency detectors and year of introduction. I am not listing all the derivative models to reduce clutter. I will post that later. 1991 Fisher CZ-6 5 & 15 kHz 1991 Minelab Sovereign BBS 1999 Minelab Explorer S/XS FBS 2001 White's DFX 3 kHz & 15 kHz (Simulates single frequency by ignoring half the dual frequency signal) 2012 Minelab CTX 3030 FBS2 Second, single frequency detectors have a ground balance problem. They can ground balance to mineralized soil, OR they can ground balance to salt water. Multi frequency machines can reduce signals from both mineralized beaches and salt water simultaneously, making them ideal for saltwater use. 1993 Minelab Excalibur BBS (Sovereign in waterproof housing) 1995 Fisher CZ-20 5 & 15 kHz (CZ-6 in waterproof housing) 2001 White's Beach Hunter ID 3 & 15 kHz (DFX in waterproof housing) There is a third class of machine that can run either as selectable frequency OR multi frequency detectors. Quite rare at this time. 2009 White's Spectra Vision 2.5 Khz or 7.5 kHz or 22.5 kHz or all three at once Note added 9/20/17 - Minelab has announced the Equinox Series. Equinox 600 5 kHz or 10 kHz or 15 kHz plus multi frequency options Equinox 800 5 kHz or 10 kHz or 15 kHz or 20 kHz or 40 kHz plus multi frequency options In my opinion multi frequency has delivered well on its promise. The Minelab BBS and FBS machines are renowned for their ability to discriminate trash and detect coins due to their sophisticated processing. Again, focus on what they do. Not even Minelab in their marketing tells anyone these are prospecting detectors. Second, the Fisher CZ-20/21 and various Minelab Excalibur models are without a doubt the most popular and successful non-PI saltwater beach detectors made. I have a DFX and I think it is a fantastic jewelry machine in particular. A good coin machine but lacks a bit of punch. The Vision/V3i upped the ante but while amazing on paper suffers from interface overload. The Minelab units are simple by comparison and a lesson on how people in general just want the detector to get the job done. Feature overload is not a plus. However, I think White's has the right idea. The ability to run either separate frequencies or multiple frequencies at once is very compelling. I just think nobody has really done it right yet in a properly configured package. The V3i has the ingredients, but needs to be stuffed in something like an MX Sport with a simplified interface and improved ground balance system. It really never did beat the MXT in some ways and many people when "upgrading" to the V3i end up going back to the MXT. Selectable frequency has yet to really deliver on its promise in my opinion. So far it has been difficult to produce a selectable frequency machine that truly performs at all frequencies on par with a dedicated single frequency machine. The Minelab Eureka Gold at 60 kHz just never gets mentioned in the same breath as the White's Goldmasters/GMT or Fisher Gold Bug 2. Also, most selectable frequency machines in the past have been very feature limited prospecting machines, restricting their overall market appeal. I personally think we have seen enough variations of single frequency detectors. I do not believe much can be done to exceed the performance of the dedicated single frequency VLF type machines we currently have. What can obviously be done is a better job of packaging machines that deliver true punch at different frequencies, or multi frequency machines that bring across the board performance closer to what is expected of PI detectors. I do think we are seeing this happen now. The new Nokta Impact and the new DEUS V4 update are expanding the available options in selectable frequency in more usable packages. The Minelab GPZ and other hybrid platforms blur the line between what is traditionally considered PI and VLF and simply need the addition of discrimination to go to the next level. There is still a lot of potential to deliver machines that might reduce the number of machines many of us feel compelled to own by delivering more across the board performance in a single machine that would now take several detectors. Exciting days ahead. For those who want to try and get their head around selectable frequency and multi frequency technology, Minelab and White's have a gold mine of information in a few of their references. Dig into the following for some great explanations and diagrams. Minelab - Metal Detector Basics and Theory Minelab - Understanding Your X-Terra White's - Spectra V3i Owners Guide White's - V3i Advanced Users Guide Better yet are the last three parts of the DFX instructional video by White's featuring engineer Mark Rowan explaining frequency and multi frequency methods:
  13. I always have one question in mind which is the best frequency for silver and gold jwellary or treassure hord at the same time i know 7 to 15 khz is for silver relics tressure 15khz to upper is for gold suppose if i find a cannal full of silver and gold jwellary which frequency is best suited for it
  14. Metal Detector Robot

    Looks funny but there is not far between this video and a decent beach detector at least. Just need the digger scoop arm on the back. Kind of like turning a Roomba loose on the beach!
  15. I often see posts on various forums where people use high GB phase numbers as examples of hot, mineralized ground. I thought that GB phase numbers are only indicative of the TYPE of ground(rock,soil,clay,salt). Rock, soil, and clay can actually be pretty benign or very mineralized. Isn't the determining factor for hot ground that affects metal detectors the amount of Fe3 in the soil? A phase reading of 89 may be mild soil if the amount of IRON in the soil is low. Conversely a phase reading of 65 may be very hot ground if the ground consists of clays with high iron content. Some VLF detectors now have Fe3 meters on them and the higher the reading is on that meter the more the ground will affect your detection depth and the accuracy of the VDI number(if supplied). It seems like many people are confused by this. I think it is important info that can affect your coil selection(size and type), the amount of discrimination you may choose to use, and the mode(all-metal or discriminate) that we run in. We need somebody that knows their stuff to give us a definitive answer!
  16. Steve, your a great source for unbiased information. I trust your opinion greatly. Don't fret over what just happened. Many many people view you as a great resource. As you know I have been metal detecting for 30 years. I still consider myself a newbie. However, it is with the same old machine. Back when I purchased my machine we were told it will detect everything, it's a do all machine. I new of prospecting machines, but never knew the difference or seen the demand until I came to this forum. So if you have time, please answer these question. I am going to throw these out as I don't really know how to ask the correct question. What if the difference in a gold machine vs a regular machine? What makes them stand out? I know there is a frequency difference, but what make them stand on when looking for gold? Are they just not tuned for gold?
  17. QED Review

    So far there has been no real “direct” reviews of the QED, in effect just innuendo clouded by politics, which is not helpful. With the help of a friend I've just finished some testing of the QED and want to share our impressions here in the hopes of getting the ball rolling for some quality discussions (but maybe this is being too optimistic?) We hope and believe our tests were rigorously objective, the QED was used for general gold hunting and also comprehensively tested on buried real gold pieces of various sizes in a variety of soils, considerable care was taken to ensure no placebo/bias.* We deliberately tested on only frequently detected but historically very productive public fields, not private property in which it can be relatively easy to find gold using any technology due to only ever seeing a few detectorists. First and foremost, important details of the QED's method of operation that are different to other detectors which needs to be clearly understood: Unlike Minelab detectors, the QED has a “dead zone” that can be varied using the Volume control. The threshold is set using the Bias control and has 2 different audio threshold settings, an upper and a lower value. When the Bias is turned down in number below the threshold lower value, OR, turned up in number above the upper threshold value, the “Threshold” audio increases as per usual. Suppose for example, the lower audio threshold bias value of the Bias control happens to be 50 and the upper threshold bias number happens to be 60. Then if the Bias is turned down below 50 OR turned up above 60, the audio “threshold” level increases as per usual. For these threshold examples, 50 and 60, small gold (fast time constant targets) “in effect” produce signals less than 55 (half way between 50 and 60), and larger gold “in effect” produce signals more than 55. If the Bias is set at the lower threshold limit, 50 for example, then the detection of small gold will give the usual INCREASE in audio level response, and larger gold will give a BELOW threshold level response, OR If Bias is set at the higher threshold limit, 60 for example, then the detection of larger gold will give the usual INCREASE in audio level response, and smaller gold will give a BELOW audio threshold level response. Similarly with ground noise; some ground noise will in effect produce signals below 55, so that if the Bias is set at 50, this ground noise will give an increase in audio sound, but if the Bias is set at 60, this ground noise will give a below threshold audio response. Conversely, if the ground noise is in effect above 55, then if the Bias is set at 50, this ground noise will give a below threshold audio, but if Bias is set at 60, this ground noise will give an increase in audio level. Signals in effect BETWEEN 50 and 60 are in the “dead-zone,” for which the audio is below threshold. Signals in effect below 50 OR above 60 give an increase in audio. So if threshold is set at the lower threshold of 50, then faint signals from small gold will give an above threshold audio, and large targets a below threshold audio. Whereas its the opposite for the upper threshold of 60, faint signals from large gold will give an above threshold audio, and small targets below threshold audio. So for shallow small gold select the lower threshold limit, for big deeper gold select the upper threshold limit. Bigger target signals will produce above threshold signals regardless of whether they are small or larger targets. However the Volume control controls the dead-zone width; the gap between the upper and lower threshold Bias settings, that is, the dead zone gap is increased by turning the Volume down, or decreased by turning the Volume up. In fact the QED can be set to operate with NO dead-zone (like the usual Minelab PI audio). To do this: a. Vary the Bias between the upper and lower threshold. Note the gap. b. Increase volume a bit. c. Re-do a. and note the decrease in the gap. d. Continue to repeat a, b, c until there is no gap. (This will allow some feel for true ground noise etc.) However the QED audio has a very low level signal EVEN if below threshold, This below threshold faint audio signal is just the pitch signal only, and detects all signals, ground noise, target signals, whether long time constant or short, and EMI. But this below threshold pitch sensitivity is not as acute as the audio set at threshold per point 2 below, and it is very soft. Yet even further, if a target or ground noise (or EMI) does drive the audio below threshold, the nature of the audio is that it has the usual “re-bound” response once the coil has moved over and past the target or ground noise. I refer to the lower pitch audio following the initial target higher pitch audio (“high-low”) or the opposite; the higher pitch audio following the initial target lower pitch audio (“low-high”) effect known from Minelab PI's. So for moderately weak target signals that cause the audio to dip below threshold once the coil moves beyond the target and the audio then rebounds above threshold. To recap; for these targets, as the coil passes over the target the audio goes first below threshold THEN above the threshold. However for the fainter of these target signals (the important signals one listens for in thrashed ground), this rebound signal is hard to discern compared to the same signal that would occur if the Bias had been set at the alternative threshold setting for which the audio signal then would have given an initial increase in threshold as the coil passes over it and then a below threshold rebound. Therefore, it is important to understand that you EITHER need to set the Bias to chase the faint small targets in shallow ground (Bias at the lower number setting), but lose out a bit on the faint large target signals OR set the Bias to chase the faint larger targets in deeper ground (Bias at the higher number threshold setting) but lose out a bit on the smaller targets. The QED has a “motion” audio response; meaning the coil has to be moved to hear a signal. It can be operated both quickly, and also, remarkably slowly. If the coil is moved “remarkably” slowly it is possible to hear the average audio detect a very faint target above the audio “background random chatter”, considerably more readily than if the coil was moved at a typical realistic operational speed. When depth testing and when you know where the target is, beware that you do not slow down the coil swing to an artificial unnatural swing speed to enable the detection of a deep target at its known location.* Important recommendations: 1. It's very important to get the threshold (Bias) spot on for optimal results, If the threshold level is too high, then faint signals get drowned out, but if the audio threshold level is too low then only the residual very faint pitch signal remains, but this faint pitch only signal is less sensitive to target signals than the audio set optimally as per point 2 immediately following. 2. The threshold must be set so that it is just audible; in effect just immediately below the “real” audio threshold signal, so that what you are hearing is just between only the pitch signal and actual above threshold audio. 3. Note that the effective principal threshold control (Bias) is temperature dependent and requires reasonably frequent adjustment over time as the ambient temperature changes to get best results. Therefore there is NO actual specific optimal Bias number setting, rather it entirely depends on temperature. It can be as high as 70 in very hot conditions 4. Once 2. and 3. are optimally achieved, you will find that the GB setting has to be spot on for best results. If you find that it is not critical, you really need to re-address points 2. and 3. 5. The QED does produce ground noise that sounds on occasion like a target. If you aren't digging some ground noise you do not have it set up properly, especially in variable soils. With ANY detector (automatic GB or Manual) altering the GB setting slightly to eliminate a faint “deep target-like signal” will result in eliminating the faint signal whether it is ground noise OR in fact a deep real metal target. 6. You need to listen to the soft “subliminal” threshold of the QED very carefully, quality headphones are a must. 7. “Gain” acts as a sensitivity control as you would expect. I suggest that the QED is best used as a specialist very fine (Small) gold detector. It produced a reasonably clear but quiet response to the extreme small gold (of the order of 0.1 g), we managed to find 5 tiny pieces in well-worked ground in all totaling 1 gram, although the SDC would have picked 5 of the 5, but not so well in one location due to power line noise (This could be remedied somewhat by lowering the Gain of the SDC and using minimal threshold). However, we purposely went over exactly the same ground with the SDC with the SDC set at a lower threshold and 3 on the gain, and then found 3 more pieces of gold; we are 100% sure we had already passed the QED exactly over the target locations so we put this down to QED ground noise masking targets. The QED struggles compared to the SDC in the more mineralised soils, however the QED does seem superior to the ATX. To get the most out of the QED, use a small coil such as an 8” Commander mono, and set the Mode as low as possible so long as the ground signals do not become too intrusive. Usually 1 or 2 is OK for Minelab coils, but some other coils may produce too much ground noise at this setting so you may need to increase the Mode to 3 or above dependent on the ground. Further, we got some very thin aluminium foil and very gradually trimmed it down until the SDC could no longer detect it. This represents particularly fast time constant targets (“extremely” small gold), and found that the QED did still detect it, but only within several mm of the coil surface, not further. But this does mean that the QED will detect extremely small shallow pieces that the SDC will not. Alternatively we suggest the QED is also a suitable lightweight low-cost patch hunter when used with a large coil with the Mode turned up so that there is less ground noise. For the sake of completion, to answer questions posed of the QED depth for an Australian 5 cent piece compared to the Zed both using the same sized coils. We measured this carefully and we are not prepared to give exact figures to avoid any trivial arguments, other than to say that the QED detected between 60% to 2/3rd of the depth of the Z. The QED susceptibility to EMI in areas remote from mains compared to the 5k on EMI noisy days? In one word: “Good. The QED susceptibility to mains in urban areas compared to the SDC or Zed? In two words: “Typically Bad.” The QED’s main strength is its cost, light weight, ergonomics, and simplicity of use, and yes it IS definitely simple to use, but a bit “fiddly.” It has no “magic settings” once you understand exactly how it operates as described above. Going back to the SDC really highlighted the difference a light weight detector can have on general comfort and enjoyment of detecting, and our experiences with the QED underscored Minelab's poor ergonomics. In our opinion the QED fits a market where people are looking for a cheap detector capable of finding small gold in thrashed areas, and are wanting more coil choices without the specialised "one size fits all" approach of the SDC. Good value for money. Its main weakness is its underlying ground noise, which although having the advantage of being “hidden” in the dead zone, nevertheless limits depth compared to lower ground noise capable detectors, for targets other than the very fast time constant targets. In summary it works relatively best in the less mineralised soils for small gold. Beyond the scope of the above suggested prospecting (very small gold & patch hunting mainly in relatively unmineralised soils), I choose not to comment further, other than we will not be using the QED for purposes other than secondary activities, and still intend to use other well-known detectors for primary prospecting activities because of their other advantages. No doubt others with QED's will disagree with us. We welcome this, and would be happy to be proved wrong. Ultimately, time tells the truth by substantial gold finds or lack thereof in well-worked ground. *Note: because of the subtle audio, it is easy to imagine you are “hearing” a target above the general background ground noise when you know where it is. We endeavoured to avoid this tendency.
  18. On his forum at http://www.dankowskidetectors.com/discussions/read.php?2,121626 This gives a very rare, in fact as far as I know, never before seen inside look at the prototyping process and field test reporting. Thomas Dankowski is a true "engineer nerd" (I say that as a compliment) and so goes to extreme lengths and detail beyond what would normally be seen. His extremely lengthy and copious notes also provide many insights about what to possibly expect from the new Nokta Impact. Keep in mind things changed from the early reports to the final product so things Tom talks about early on change at later dates. Quoting from his thread out of context could cause a lot of misperceptions to arise. The thread well illustrates something I have observed for some time. When it comes to max depth, standard single frequency induction balance detecting technology is tapped out. Look at the struggle to obtain not another inch but even just another 0.1 inch of depth. The main advantages have come as of late in recovery speed and the ability to separate closely spaced targets. Max depth however is at a standstill. Tom's testing just confirms what I have been seeing for years. It is near impossible to discern more than hair splitting differences for max depth between most top of the line VLF detectors these days. And now a Report on the Nokta Impact from Keith Southern And a Report From Ziggy Report from Lawrenzo - Low-Boy/LCPM Report from tnsharpshooter Report from goodmore Report from Sven1
  19. Steve, Every since you posted that you lose depth when you ground balance, It is in the back of my mind........ "Ground balancing is a filter and not all that different that the way the discrimination system works. The ground signal or salt signal (or both) are identified and then tuned out. The ground effect is still there, but the detector subtracts it from the overall signal. The key word there is "subtracts". Ground balance methods work by subtracting part of the signal, and all subtractive methods create depth losses of some sort the closer any detected item gets to the "hole" created by subtracting the ground or salt signal. Signals are not perfect but spread over a small range, and so eliminating any signal usually means taking out a small range of signals. " I have always tried to keep my detectors ground balanced while using them.... Now I wonder if I should? Can you put my mind at ease......
  20. I got my first metal detector in 1986. It was a White's Coin Master 6000 DI Pro. I bought it because I live near the beach and a friend of mine had a friend who was selling them. I didn't know much about detectors and I used it on the beach in the dry sand only for about 3 years before life happened and I put it away. I didn't get another detector until 2010 and it was a ML 5000. Now that I had it I had to start learning about the desert and more about metal detectors. One of the first things that I 'noticed' about a detector is that you don't have to be directly over a target to hear it. You get a sense for a target by coming close. You get a bigger sense for an aluminum can than you do a quarter for instance. I've searched and searched over the years for a way to describe this near to target sense which is much greater in the 5000 (PI) and the 7000 (ZVT) than with the Coin Master (VLF). Today I was reading an email from Kellyco who is the company that services most Minelabs in the United States. They also sell most other detectors and give advice to their customers. The email that I received led me to a reprint of an article: How Metal Detectors Work Reprinted with permission from Modern Metal Detectors. The full article is here: https://www.kellycodetectors.com/catalog/how-metal-detectors-work#more In that article it uses the term Fringe Area Detection and that gave definition to what I had been trying to describe for years. I had tried to say a coil is like a Nerf ball with many targets off the search area and you are drawn to a target like a moth to a flame. As it turns out this is just 'fringe area detection' which lets us push our detectors to much greater finds. I think you will see how many times we have discussed this part of metal detecting without using this term. The fringe area on my 7000 is larger than the illustration shown. Here is what the article says about fringe area detection: Fringe Area Detection Fringe area detection is a phenomenon of detection, the understanding of which will result in your being able to discover metal targets to the maximum depth capability of any instrument. The detection pattern for a coin may extend, say, one foot below the search coil. The detection pattern for a small jar of coins may extend, perhaps, two feet below the search coil as illustrated in the drawing on the facing page. Within the area of the detection pattern, an unmistakable detector signal is produced. This illustration shows the location and approximate proportional size of the fringe detection area in which faint target signals from around the outer edges of a normal detection pattern can be heard. What about outside the detection pattern? Does detection take place? Yes, but the signals are too weak to be discerned by the operator except in the fringe area around the outer edges of the detection pattern as shown in the drawing above. A good set of headphones is a must, if you desire to hear fringe area signals. The next more important thing, is training in the art of discerning the faint whispers of sound that occur in the fringe area. Skill in fringe area detection can be developed with practice, training, concentration and faith in your ability. Develop fringe area detection ability to a fine art and you are on your way to some great discoveries that many detector operators will miss. The ability to hear fringe area signals results in greatly improved metal detection efficiency and success. Mitchel
  21. If somebody has offered you at option: 1. to reduce the weight of your favourite detector by half 2. to increase its depth by 10% What would you choose?
  22. No, I'm not talking about politics and being a Moveon.org trainer. I'm talking about resistivity detecting. Electrical resistivity tomography From Wikipedia, the free encyclopedia Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI) is a geophysical technique for imaging sub-surface structures from electrical resistivity measurements made at the surface, or by electrodes in one or more boreholes. If the electrodes are suspended in the boreholes, deeper sections can be investigated. It is closely related to the medical imaging technique electrical impedance tomography (EIT), and mathematically is the same inverse problem. In contrast to medical EIT however ERT is essentially a direct current method. A related geophysical method, induced polarization, measures the transient response. The technique evolved from techniques of electrical prospecting that predate digital computers, where layers or anomalies were sought rather than images. Early work on the mathematical problem in the 1930s assumed a layered medium (see for example Langer, Slichter). Andrey Nikolayevich Tikhonov who is best known for his work on regularization of inverse problems also worked on this problem. He explains in detail how to solve the ERT problem in a simple case of 2-layered medium. During the 1940s he collaborated with geophysicists and without the aid of computers they discovered large deposits of copper. As a result, they were awarded a State Prize of Soviet Union. Andrey Nikolayevich Tikhonov, the "father of ERT" When adequate computers became widely available the inverse problem of ERT could be solved numerically, and the work of Loke and Barker at Birmingham University was among the first such solution, and their approach is still widely used. With the advancement in the field of Electrical Resistivity Tomography (ERT) from 1D to 2D and now-a- days 3D, ERT has explored many fields. The applications of ERT include fault investigation, ground water table investigation, soil moisture content determination and many others. In industrial process imaging ERT can be used in a similar fashion to medical EIT, to image the distribution of conductivity in mixing vessels and pipes. In this context it is usually called Electrical Resistance Tomography, emphasising the quantity that is measured rather than imaged. https://en.wikipedia.org/wiki/Electrical_resistivity_tomography Here is one unit being offered by Kellyco. https://www.kellycodetectors.com/blog/find-gold-resistivity?utm_source=email&utm_medium=BlogBUTTON&utm_content=BlogGoldResistivity&utm_campaign=MSTRBlogGoldResistivity20170624&utm_term=Lead_SuperBowlGiveaway2016 Mitchel
  23. As a rule do the lower vlf frequencies punch deeper than the higher ones, say 4.8 verses 14khz? But what is the trade off? Are some frequencies better for silver coins? How does iron enter into this? Need to understand how this all fits together! Thanks for any and all answers.
  24. A lot of detectors let you notch out (silence) a target identification (TID) band but are there any that let you choose which tone (audio frequency) to assign to a band?
  25. I do what I can to foster competition that develops alternatives to the all too common single frequency 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 prospecting machine like the Gold Bug Pro, GMT, AT Gold, X-Terra 705, etc. These machines all sell for around $700 and weigh 2.5 - 3.9 lbs. 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. To clarify what I am talking about here, I should say that for many people a $700 single frequency 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 single frequency 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 and ATX and the White's TDI models. These detectors are used not just for prospecting but also by relic hunters, beach detectorists, and others who face challenges regarding ground mineralization and single frequency 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 single frequency 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 prospecting. 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 to Australia for one month, and needed a GBPI detector, considering machines past and present, what would I take 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 to Australia, 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 over 4 lbs and sells for over $2000 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 Minelab's and with a stronger battery system might rate 4 to 6 on my comparative scale. 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 $1089. The White's TDI SL takes the crown. 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.