Dutchman4

Nice chunk.

I followed up and did some more sensitivity testing a few days ago to characterize my GPX6 post "audio fix" performance. I went through all the settings again while using my #8 bird shot test target buried at 1 inch in mineralized soil. I also brought my Gold Bug Pro-5inch round coil and my SDC2300 along for comparison. The GB-Pro ground balanced at 88 with one to two ferrous bars showing to confirm the soil mineralization. The GB and the SDC both detected the target with a descent audible tone, but of the two machines, the SDC had the quietest signal response on default gain of 2 with some improvement with gain of 4. On the same target, the GPX6 still had a good audible signal response in all gain settings with a slight but noticeable better response on the higher gain settings. Threshold was very stable with manual gain settings of 1-6 using both the internal speaker and oem BT headphones. Threshold got progressively more unstable (warbly) with manual gain settings of 7-10. Whilst going through all the settings I did make two observations. 1. The threshold was noticeably more stable in Auto1 gain setting vs Manual-10. Even manual gain settings of 7,8,9 appeared to have a more unstable threshold than Auto1. 2. When using "Silent" threshold mode it is really silent now in the lower manual gain settings. Before the repair I remember this mode wasn't all that silent with a few peeps now and then. This might be the best indication so far that the "audio fix" has improved overall threshold stability of the machine. I rarely, if ever use the silent threshold mode but I find this an interesting observation. So in summary the sensitivity of my GPX6 is as good or better than my GB-Pro, on small shallow targets, and significantly better than my SDC with oem wired headphones. Not saying that the SDC wont detect small targets, because it will, but the GPX6 responds significantly better. I have found some tiny nuggets and also the usual small lead bird shot with my GPX6 and I still believe that it has the performance of a PI with the sensitivity of a VLF.

I was debating on selling my SDC2300, since I don't use it and it has become a backup machine to my 6000. Now with this price drop on a new one it will be tough to get a fair price on a used one, even a gently used one with few hours like mine. I might just have to keep it in the event that I start detecting in rivers or creeks.

Does that indicate it might be flat wound?

That is why it is called "Jumping Cholla". I carry a heavy hair comb with me as part of my desert gear so I can use it to pull cholla out of my body especially if it is in an area like the back side where it is hard to get to.

That is a tough question to definitively answer due to so many variables in the field that could impact before and after repair comparisons. Only time will tell when more and more reports come in from users in the field with repaired machines. I do share your placebo effect concern but I need to spend more time in the field with my machine to evaluate this. If I had a schematic showing the two components that were replaced and their location in the circuit path, when the speaker is enabled and not enabled, then that would help to understand the potential for overall threshold stability improvement. Other posts about this topic seem to indicate that two unshielded "Inductors" were replaced with shielded inductors. If these two inductors are always part of the circuit regardless of speaker being used or not then it could explain an overall threshold stability improvement and reduced EMI sensitivity. Most inductors contain a small coil of wire that can essentially act like a micro antenna. Any electromagnetic field could induce an unwanted voltage in the coil part of the inductor and introduce EMI. The source of that unwanted field could be the speaker, the transmit part of the detectors coil or over the air EMI. If the inductor is shielded then that unwanted energy is shorted/shunted to the ground plane and wont reach the coil inside the inductor, thereby reducing EMI sensitivity. This is just my possible explanation of how their could be an overall performance improvement to the detector but I need to spend much more time in the field under actual conditions to support this.

Thanks for sharing this important element and a very interesting "read" especially the "auditory" section of the "sensory adaptation" link. It all makes sense that if you have a warbly/noisy threshold then after hearing that for a while your brain tunes it out when in fact that transition/break in the threshold is exactly what you should be listening for. It puts a whole different light on "effective" gain/sensitivity.

I also believe that the whatsit is electronics related but expect it to be gold plated to make it a corrosion resistant type of contact or conductor.

Just thought that I would share my experience with what Minelab has called "GPX 6000 Speaker Audio feedback". As Steve pointed out in an earlier post, Minelab has recently documented this problem on their website: https://www.minelab.com/usa/metal-detectors/gpx-6000 then select "Updates" on the bottom of the first page. As most of you know the symptoms of this problem is very erratic threshold audio when using the internal speaker. Like any other speaker, the internal one creates an electro magnetic field, when in use, and it appears that the high gain/sensitivity of the the GPX6000 detects and responds to this very localized EMI and feeds it back. What you end up with is this out of control feedback loop that tends to oscillate and create a very erratic threshold. When the wireless headphones are used instead then a typical more stable threshold is achieved. Like many of you, I pretty much always use blue tooth headphones and have never used the internal speaker when prospecting but I decided that I wanted to have this repaired just so it was completed within the warrantee period. I also didn't use the internal speaker because it was not practical and after it is repaired/updated at least that becomes an option. On the Minelab website there are instructions for sending in your detector to the USA repair center for this "hardware update" if you choose to do. I sent an email to the repair center including the serial number on the bottom of the control box and they replied that my detector was still under warrantee and qualified for this repair/update. I chose to use USPS for shipping and I elected to insure it for $2000 at a total cost of $53 from Southern NV to repair center in PA. To insure or not to insure is a personal choice but one benefit is the the unit has to be signed for by a person at the repair center receiving department. I only sent the detector control box since my 11 inch stock mono coil works normally and the ears are fine with no visible cracks. Inside the shipping box I placed the following printed information: "To Repair Center regarding Repair Ticket #xxxxx: The problem I have with this GPX 6000 detector is the unstable threshold due to audio feedback when the internal speaker is used instead of the wired or wireless head phones. This is a known problem and is detailed on the Minelab website under GPX-6000/Updates and titled "GPX 6000 Speaker Audio. Please perform the "hardware update" that is mentioned in that article, "Minelab have produced a hardware update that removes this effect." I did this because I wanted it to be clear that this is the only thing that I wanted them to repair and not spend any time trying to trouble shoot or replicate other problems that don't exist with my detector. After I sent the unit I received update emails from the repair center regarding progress through their system. The total turn around time from the day I mailed the unit to the day I received it back was 10 days. The repair center pays for the return shipping and it did need to be signed for by me upon receiving it. I recently tested the detector, about 5 miles from my house, in a place with no known nearby EMI sources and also having mineralized ground. My smallest test target is a piece of #8 lead bird shot that weighs around 0.06 grams. In the past, when I have prospecting in various gold fields, I have found many small pieces of lead bird shot at around 1 to 1.5 inches deep. I buried the #8 bird shot test target 1 inch deep in mineralized soil and the audio response was the same using the internal speaker or the wireless head phones. I tried manual sensitivity setting of 1 through 10 and also Auto1 and Auto2 as well as normal and difficult, all settings produced a detectable audio tone response to the #8 bird shot target although the higher gains settings were slightly louder. I personally don't believe that the detector is any less sensitive after the hardware update. I would say it is the same and possibly slightly better but that is hard to quantify for my. The fact that the threshold appears to be more stable might account for a relative improvement in sensitivity vs an actual improvement just because you can hear the target response more clearly over the threshold. I do recommend having this update performed on your machine but in the end it is your decision. Regards, Ceril

Couldn't agree more. When I lived in SoCal there were many outdoor target shooting areas on BLM land that were shut down due to huge amounts of trash left behind including old TV's and appliances that were shot up.

I always fill my holes also and even put my first scrape layer of gravel/rocks back on top so after some weathering you can barely tell there was a dig hole there. I create a GPS waypoint for every nugget I have found and sometimes I go back to detect the same area and I have a hard time finding the original dig hole. The other thing is TRASH. I pick up trash that others leave behind as long as it is not too big. I was also raised with the same etiquette to leave leave a place the same or better than you found it. The beauty of metal detecting is the surgical removal of gold or other targets with low impact.

I answered my own question. My GPX 6K is currently at the USA repair center for the Internal Speaker Audio Feedback problem so I called and spoke to the repair tech regarding any software/firmware updates and he said it is currently up to date because there have been no software/firmware updates to the GPX 6000 since the production release.

It was my understanding that the Minelab fix for the "Internal Speaker Audio Feedback" problem was a "Hardware Upgrade". Is there a "Software Upload" involved also?

So, if the advertised numbers are correct, then it appears that the NF 16 x 10 is 6oz heavier than ML 11. That is pretty good and makes the NF 16 x 10 6oz less than the, not so pleasant to swing, ML 14 DD and almost 8oz lighter than the ML 13 x 17. Be nice if NF can start delivering these.

Does anyone know how the weight of the NF 16 x 10 compares to the stock 11" mono and also how does it affect the balance of the detector? , shaft twist?

I cant say for sure about how the control architecture of metal detectors work but I do know that there is probably not much decision making going on to require any high level or even low level language. In the basic form there will be a known set of inputs to some type of micro-controller and in the end there will be a known set of outputs. A micro-controller is different than a micro-processor in that it only follows a very limited and fixed instruction set and does not really process a lot of variable data like a micro-processor or cpu. The instruction set, or program if you want to call it that, for a micro-controller resides in non-volatile firmware (eprom or pla). This firmware is typically updated and revised if/when needed to implement factory changes or updates. There is probably some device specific language involved to initially program the firmware but again I don't think that would be comparable to a typical computer language.

The fact that the washer can shift into an offset position indicates the ID of the washer is not properly sized to the OD of the screw. Poor choice of washer, engineering should change the manufacturing BOM and also change the material to SS if it is not already.

I have noticed that too a few times that the 6000 gets real quiet and nice to run after the sun goes down.

So can someone "summarize" the GPX6000/Part 2 video results for me regarding when to use the Difficult vs Normal modes? Do I have it right to just run in Difficult mode all the time for best results in all soils or only when working in heavy mineralized soils and hot rocks?

I might be old school, probably because I am old, but for me I like to be in control of the high level intelligence elements. Sure ground balance, ground tracking, EMI elimination are great features to have and enable the detector and the detectorist to focus on the actual signals of interest but I enjoy training my ears and my mind to learn the sounds of a gold target vs trash or ground noise and it is this element of the hobby that gives me excitement, pleasure and joy. Each gold field can produce slightly different target sounds and again part of the challenge/fun is to learn those sounds and develop the skill to predict if a pre-dug target is going to be gold or trash. I still tend to dig most targets anyway but after a few hours of digging trash targets in a particular area I get satisfaction from knowing that I can reach a 90%+ probability of predicting gold vs trash. IMO it is this HUMAN intelligence skill that differentiates great detectorists from average ones. I do enjoy the convenience of technology for every day tasks but I have observed over my lifetime that as technology get smarter the human get dumber. After Velcro came out kids forgot how to tie their shoes. After google maps came out people forgot how to read maps. Even common sense has fallen by the wayside when you read stories of people that are so reliant on technology that they can't even solve simple every day problems. Sure the computing power behind AI learning can achieve things in hours or days that would take the human brain years or decades to learn but I will never underestimate to power of the human mind that is a result of thousands of years of evolution in the REAL world. Do you really want an AI based, all knowing, detector to reduce you down to the mere unintelligent functions of swinging and digging?

I dont own a legend and cant mention specifics. I am only sharing what I know from troubleshooting electronic equipment for 38+ years. Only trying to help you narrow down the areas to focus on based on past experience with other equipment but I cant say that this would apply to your situation. I am only saying if you can easily reproduce the condition that you believe to be a problem/fault then a professional repair person should be able to evaluate and repair if needed.

I will only add that software/firmware generally does not produce different results over time so if you get typical GB values after the software install/update then you should repeatedly get the same results, over time, under the same conditions. This makes me believe that your machine has a hardware problem or a drifting problem that creeps in after power up. If you can reproduce the problem repeatedly then have it professionally repaired.

I agree that the price of gold is manipulated like everything else. Gold should have reached $5K/oz years ago if it was priced correctly to cover the amount of world debt.

For boots I like the offerings from Merrell and have been using their boots for back packing, upland game hunting and nugget hunting going on 20+ years. I'm 62 now but in my 30's I used to backpack all over the southern Sierra in heavy all leather clunky boots and never complained until I tried on a pair of lightweight, breathable Merrell's and never looked back. There is a saying "a pound on the foot is worth 10 in the pack" and I can attest to that. I like to cover a lot of ground and explore new areas when nugget shooting so I prefer light fast boots. I like mid cut boots but some people prefer the extra ankle support and secure feeling they get from high boots. Breathable boots are usually not very water proof and only water resistant at best, even with treatments. I have tried gore-tex lined boots but the problem I have is that they run hot and your feet sweat and then get wet from the inside out. Most Merrell boots have little to no metal in them. The older boots were a bit tougher than recent years but I think that is the case for most everything. I use these for open desert nugget shooting and day hiking but might be too minimalist for most people: https://www.merrell.com/US/en/moab-2-ventilator/27947M.html?dwvar_27947M_color=J06011#cgid=men-footwear-hiking&start=1 I use these for upland game bird hunting and is just a mid cut version of above. Does have metal tab for top lacing. https://www.merrell.com/US/en/moab-2-mid-ventilator/27935M.html?dwvar_27935M_color=J06045#cgid=men-footwear-hiking&start=1 The also offer defense and tactical versions but I have not tried them: https://www.merrell.com/US/en/moab-2-8-inch-defense-zip-comp-toe-boot-wide-width/53627M.html?dwvar_53627M_color=J099371W https://www.patriotoutfitters.com/merrell-moab-2-tactical-waterproof-side-zip-8-quot-boot?PMOPV1=COY&PMOPV2=11&PMOPV3=M&PMSRCE=POPLA&gclid=EAIaIQobChMIgpL2_NK0-AIVEQnnCh0sEQ3EEAQYBSABEgIqJvD_BwE

I'm not an expert in metal detector circuitry but I do have some background in signal processing and electronics and can add some basics. Metal detectors transmit a signal (TX) and then receive (RX) a signal back from a target response. The frequencies and amplitudes of those signals depends on the type of detector. The RX signal is generally very low amplitude so it has to be amplified first before it can be processed. The GAIN of an amplifier determines how much larger the output is vs the input to the amplifier and is generally by factors of 10x, 100x, 1,000x, 10,000x, etc. A good amplifier will not add any distortion to the original signal because any added distortion is undesirable. Once the signal is amplified it can be processed and analyzed. Filters can be applied to remove certain frequency components of the signal and this is another area that the designer has to take care to remove only the undesired components of the signal and leave the desired component intact as much as possible. The remaining signal can then be processed further to extract desired information and finally converted to an audio representation that the human ear can hear and interpret. In the old days all of this was done with analog circuits and it took some brilliant designers to get the best circuits possible. In the 1960's Digital Signal Processing (DSP) started to come along. DSP provides very flexible and powerful signal processing capabilities that would not be practical with analog circuitry. With DSP the same analog RX signal from the target is also first amplified but then it is converted from an analog signal to a digital signal by and Analog to Digital converter (A/D). This conversion process is not perfect and some very small errors can be introduced but this is minimal with a good converter. Once the signal is in the digital domain then DSP can be applied and the designer has many possibilities and algorithms to choose from to extract the desired information from the signal without the limitations of analog circuitry. Then the remaining digital signal has to be converted back to analog with a Digital to Analog converter (D/A) to provide an audio representation that the human ear can hear and interpret. This can all be done with with very compact and light weight microelectronic circuitry vs the heavy and large analog circuitry of the older technology.