GPX vs Earlier Models. Sound only


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As some may know my real professions is Sound Engineering and never detected in my life, but have a huge interest in knowing about it. Would you agree if I say that Sound plays a big role in metal detecting? I believe I have read in this forum in one of Steve Herschbach posts and I quote

“It is not that the GPX goes deeper, it is that you can hear nuggets you would miss with an SD as they could not be discerned as clear signalsâ€

I totally agree with the principle, and have a theory I would like to share with you, which will improve an SD’s performance and I think this is how Minelab’s could have already addressed the issue in their newer models. Bear in mind, I have never detected before but only talking about clearer Sound.

The oldest trick in the book for us sound engineers is to use a Noise Gate. In audio post-processing, noise gating reduces steady noise sources such as rumble from LP records, hiss from audio tape, static from a radio or amplifier, and hum from a power system, without greatly affecting the source sound.

A Noise Gate or gate is an electronic device or software logic that is used to control the volume of an audio signal. In its most simple form, a noise gate allows a signal to pass through only when it is above a set threshold: the gate is 'open'. If the signal falls below the threshold no signal is allowed to pass (or the signal is substantially attenuated): the gate is 'closed'. A noise gate is used when the level of the 'signal' is above the level of the 'noise'. The threshold is set above the level of the 'noise' and so when there is no 'signal' the gate is closed. A noise gate does not remove noise from the signal. When the gate is open both the signal and the noise will pass through, but your ears don’t tell you that.

You’d probably say we all knew that! But that’s not it. In a professional Noise Gate, there are more knobs like Attack, Release, Range, Decay & Gain. These will make a huge difference. Let’s have a quick look at what I think they can do in the detecting world. At the same time I have attached an image of how a Noise Gate looks like. (It’ll be easier to follow if you have it open)

Treshold: Control to set the level at which the gate will open

Detecting world: Finding the sweet spot is crucial. Remember even a 1db change in level can open the gate. Although it actually takes a human ear a 3db change to notice the difference. So now your faint signals aren’t that faint according to how you set the other knobs.

Range: Setting the amount of attenuation when the gate is closed

Detecting world: If you don’t want to totally wipe out the background noise, you can control how much back ground noise you want to hear. Why this is very important? Here is an e.g. Say you set a threshold of -30db, this means anything under that is actually noise, by setting a Range you are asking all the noise under the -30db to go to where you want it to be. So say I tell it to go -3db less in volume. So now you are actually listening to a noise signal which is -33db. What happens is: Say that faint signal comes along with a +1db increase. So now you have 30db noise + 1db signal= -29 db which will cause the gate to open. Your ear couldn’t hear a +1db change before, but now it is actually hearing +4db change. All a human needs is 3db. So with the Range knob you can make it as clear.

Attack: The Attack control sets the time for the gate to change from closed to open, much like a fade-in.

Detecting World: So this means the more attack you set, the slower you have to swing but will be more accurate. The less you Attack, the faster you can swing. This will have a minor effect or sacrifice on how deep or shallow? or how small or large a nugget is? Depends

Release: The Release sets the amount of time for the gate to go from open to fully closed. A fast release abruptly cuts off the sound once it has fallen below the threshold, a slower release smoothly changes from open to closed, much like a slow fade out. If the release time is too short a click can be heard when the gate re-opens.

Hold: The Hold control allows you to define the amount of time the gate will stay open after the signal falls below the threshold.

Detecting world: Your preference really can be used in many ways

Gain: You are not affecting the gate but only increasing the sweet signals. I don’t know if an Enhancer works the same. I have never used one, but if it boosts the whole signal, then that is no use. Just increasing noise.

So I think all Minelab machines would have the same Input Sound as an SD in my opinion, but it all has to do with the manipulation of the sound signal, frequency & time into tricking the ears. This is not all. There are also more additions like Compressors, limiters and Multiband frequency boosters (which could help discriminate if metals do have different sound frequency, I don't know if they do) and that can make it way better.

That’s why I also think the GPX’s turned Digital, cuz it’s much easier to add all these features to their best in 1’s and 0’s. If you wanna do all these features in Analog, you’d need a trolley for batteries. :wacko: but if only a Noise Gate, that can work on a 6- 12v battery seperately.

I don’t know if a laptop causes interference with a SD ( I doubt) but if the theory is right, all I’d need is a tablet pc as my Control Box and get the clearest sound possible. As the Tablet would have all these in Software Logic, even with a touch screen.

P.S Only my opinion regarding sound, not electronics. Im not an Electronic Engineer.

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Kind of like a streoe equalizer, Base, treble, boost. fader, and a background nosie limiter. Like they had on old 8 and 4 track car stereo's? remember 4 tracks? most people can remember 8 track tape players, but before that they had 4 track one's Grubstake

And before stereo, there was a thing called a reverb unit, that made you car radio sound cool.

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AMD thank you for this post, I love to learn knew things and this was a very exceptional post. It is obvious that you really know your business.

While undoubtedly Minelab employs these techniques, I am sure that other detector manufacturers employ them as well so this does not account for Minelabs outstanding performance when compared to other machines.

Minelab's forte' has always been it's ability to track ground mineralization and using their proprietary technology, whether it be multi-period sensing, or SETA, balance that mineralization out, quiet it down, and maintain the sensitivity of the detector to find gold.

Many other brand detectors try to increase depth and ability to find gold by having a knob that increases sensitivity or gain. However a lot of these lower priced units have no ability to filter out the mineralization, so when they increase the gain they also increase the sensitivity to highly mineralized ground, and the noise that accompanies it. The end result is that the mineralization interference cancels out the benefits of increasing the sensitivity in all but the lowest of mineralized conditions.

I don't know all of the technical details of how Minelab accomplishes this, but I know they keep a running track of the fluctuations in mineralization, and automatically keep the detector balanced.

Ground mineralization has always been the bug-a-boo when it comes to metal detecting, and the ground in Australia is so highly mineralized, that Minelab had to develop technology that would deal with that mineralization. Because they managed to accomplish that, and because it is hard to find ground anywhere on earth that is more mineralized than Australia, the Minelab detectors handle just about any ground you can find.

I think you can actually access Minelabs patents online and you would probably be intriqued to learn some of the technology that they are employing. You probably would be in a much better position to explain all the technical jargon to us in more understandable terms, because you gave an absolutely excellent presentation.

Also remember, Minelab is the largest supplier of land mine detectors to NATO, therefore, many of the major technical breakthroughs that Minelab has invented, have been finanaced because of a very healthy R&D budget. Obviously government contracts can be very lucrative. This allows Minelab the financial where with all to research and develop technologies that other companies can only dream about, and these advancements are passed on down to the consumer machines that we own and enjoy.

Doc

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AMD thank you for this post, I love to learn knew things and this was a very exceptional post. It is obvious that you really know your business.

While undoubtedly Minelab employs these techniques, I am sure that other detector manufacturers employ them as well so this does not account for Minelabs outstanding performance when compared to other machines.

Minelab's forte' has always been it's ability to track ground mineralization and using their proprietary technology, whether it be multi-period sensing, or SETA, balance that mineralization out, quiet it down, and maintain the sensitivity of the detector to find gold.

Many other brand detectors try to increase depth and ability to find gold by having a knob that increases sensitivity or gain. However a lot of these lower priced units have no ability to filter out the mineralization, so when they increase the gain they also increase the sensitivity to highly mineralized ground, and the noise that accompanies it. The end result is that the mineralization interference cancels out the benefits of increasing the sensitivity in all but the lowest of mineralized conditions.

I don't know all of the technical details of how Minelab accomplishes this, but I know they keep a running track of the fluctuations in mineralization, and automatically keep the detector balanced.

Ground mineralization has always been the bug-a-boo when it comes to metal detecting, and the ground in Australia is so highly mineralized, that Minelab had to develop technology that would deal with that mineralization. Because they managed to accomplish that, and because it is hard to find ground anywhere on earth that is more mineralized than Australia, the Minelab detectors handle just about any ground you can find.

I think you can actually access Minelabs patents online and you would probably be intriqued to learn some of the technology that they are employing. You probably would be in a much better position to explain all the technical jargon to us in more understandable terms, because you gave an absolutely excellent presentation.

Also remember, Minelab is the largest supplier of land mine detectors to NATO, therefore, many of the major technical breakthroughs that Minelab has invented, have been finanaced because of a very healthy R&D budget. Obviously government contracts can be very lucrative. This allows Minelab the financial where with all to research and develop technologies that other companies can only dream about, and these advancements are passed on down to the consumer machines that we own and enjoy.

Doc

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Grubstake you sure do know your stuff. I still listen to Vinyl and own a 8 track. I love this stuff. nothing warmer sounding.

DOC: Thank you for the compliments. At the same time I do feel you thought I was trying to outsmart Minelab or something? Please dont think so, thats why I tiltled the Topic with Sound Only. Thats because I didn't want to get into any debates about Coil, SETA, Dual Voltage, what goes deeper, what doesn't! As I said im not an Electronics engineer.

I was talking based on the facts of enhancement only to an SD, if the problem was about Sound against the GPX. They are all still minelab machines. I did not say give me a Whites and I will turn it into a GPX. I am not planning to make any noise gates either as I don't even own a machine. Above all its not like I invented the Noise Gate or a Limiter.

All Im saying is if its unwanted noise that caused you not to hear a signal (nothing got to do with deep or anything) then there are many ways to clear that noise. I'm confident in this and more confident that it is not affecting the Source with the right tweaking.

I think you thought I was saying that minelab did nothing but these improvements to their new line. Not at all. My department is Sound.

Hope this clears things. :rolleyes:

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A very interesting post AMD and one I am sure Minelab tech guys would be very familiar with especially now the audio of the GPX series is digital. To be honest I preferred the old analogue audio of the GP range of machines and still to this day feel the digital audio of the GPX detectors are too cut and dried (on off if you like). Obviously the digital world allows one the ability to quickly make changes via software but to my mind it seems to be almost too mechanical compared to the softer more mellow sounds of yesteryear (I also prefer the sound of Vinyl records over digital sounds).

Thanks for the thought provoking post,

Jonathan

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Think of it like this. Someone gives you the latest GPX without any headphones or external speaker and bets you a $1000,000 to find gold for him. Well can you?

So my guess would be that Minelab has a Sound Department wheather internal or external that co-operate. After the technicians and all that Technology you mentioned is finished, patented and ready to be delivered. They would go to the sound guy and ask him to enhance all these frequencies he's recieving into the best clearest sound possible.

All I'm saying is this is what I would do, if I was that Sound guy. So you could consider enhancement and not a new patent. ;)

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A very interesting post AMD and one I am sure Minelab tech guys would be very familiar with especially now the audio of the GPX series is digital. To be honest I preferred the old analogue audio of the GP range of machines and still to this day feel the digital audio of the GPX detectors are too cut and dried (on off if you like). Obviously the digital world allows one the ability to quickly make changes via software but to my mind it seems to be almost too mechanical compared to the softer more mellow sounds of yesteryear (I also prefer the sound of Vinyl records over digital sounds).

Thanks for the thought provoking post,

Jonathan

Thanks Jonathan and very good to hear you like vinyls too. I have mostly every Vinyl you can think of from the 70's upto date and i still order 12" singles. The starting crack itself is music for me.

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DOC you got me excited and did what you asked me to. I tried to read what Minelab technology has for us regarding “Sound onlyâ€. All the other stuff I’ll be lying if I tell you I understood a thing.

Here is what I confirm to you is also being used in their newer GPX’s and definitely not in the SD’s, which also make a huge difference. I was 100% right about the Limiter too. After we insert a noise gate as I explained before and got rid of the unwanted noise. We would obviously want to boost the signal now to listen to those X faint signals. The problem is by just boosting you are increasing the overall volume, which means when your detector hits that clear strong signal nugget, you could probably go deaf :lol: That will cause you to lower the volume down again, which means you can lose those weak signals again. This is where a Limiter comes in.

A Limiter is a form of compression. In simple terms, a compressor is another volume control. Loud sounds over a certain threshold are reduced in level while quiet sounds remain untreated. This is known as downward compression, while the less common upward compression involves making sounds below the threshold louder while the louder passages remain unchanged. In this way it reduces the dynamic range of an audio signal. This may be done for aesthetic reasons, to deal with technical limitations of audio equipment, or to improve audibility of audio in noisy environments.

This way all your weak and strong signals try to meet at a point, where it doesn’t cause you to play with gain or the volume knob anymore and focus on your hunt. All signals will sound sweet.

I hope I’m not boring anyone with all this. I’m just trying to see what the old SD’s missed in technology.

These pics and diagrams will show you better.

Pic 1: A gate with added frequency knobs

Pic 2: Diagram to see how the noise is reduced and your signals gain

Pic 3: How an Analog Limiter looks like

Pic 4: Diagram of the limiter at work

Pic 5: How they meet

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AMD

Boring posts? no...very interesting ideas and explanations.

Besides detecting, I am deeply involved in video editing and as you well know, much of editing

has to do with sound; how to make it clearer and better, etc. Your descriptions of limiters etc.

are spot on in both worlds - detecting and editing.

JP is also heavily into editing, he has to be with the post production being so good on his

detecting DVD's...I am sure he can see the similarities you are pointing out too.

Actually I am sure lots of us can, very clearly set out posts...

Flak

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AMD - like Flak said boring? No way! I am sure I speak for most when I tell you we are absolutely thrilled to have someone like yourself sharing your knowledge.

As for SOUND ONLY. Bruce Candy, who is to Metal Detecting and Minelabs, what Carl Sagan is to the origins of the universe, is an amazing electronics engineer who is actually a physicist.

Bruce is responsible for most if not all of the amazing technical advancements that makes the Minelab machine perform the way it does.

What most people do not know is that Mr. Candy is also the inventor of sound amplifiers marketed under the brand name HALCRO. And what makes Halcro so special? Well thanks to Bruce Candy's brilliance, here is what one of the stereo magazines have to say about Halcro amplifiers.

"Halcro builds gorgeous-looking power amplifers shaped in the form of an "H" that range in price from $10,000 for its dm 33 three-channel amplifer up to $30,000 for a pair of the dm 68 225W monoblocks.

What has raised the eyebrows of the audio community, however, is a bold claim, repeated on the company website, that it is "the only amplifier in the world to challenge a theoretical limit." That limit is the specification for harmonic and IM distortion, which the company claims to have virtually eliminated via its circuitry, whose design is a closely-guarded secret. Halcro says that its dm 68 "produces less than 25 parts per billion harmonic distortion at 1kHz, and the worst result is about 600 parts per billion at 20kHz at full power, a frequency where most amplifiers exhibit very poor behaviour."

So when Bruce Candy finishes doing all of the magic with the innards of the Minelab machines, he doesn't turn anything over to any sound expert, because he is one. Not only is he one, he is doing things with sound that other people say is theoretically impossible.

Jonathan POrter is a very close friend with Bruce Candy, and I am sure JP will confirm that Bruce is beyond brilliant, he is scarey smart.

www.halcro.com

BCOT!

Doc

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G'day DOC, Bruce is more than just a friend he is in a lot of ways my hero, sounds corny I know but thanks to Bruce I have spent the last 17 years of my life pursuing a passion that has also made me a very decent income. Your right about the audio info, Bruce is very much in the know on all things audio which I feel makes his detectors very unique in their own right.

JP

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Flak, Thank you and glad you enjoyed it. Helps knowing you did.

DOC, Thanks again for your warm welcome and atlast someone answered my question in the first post which was "Do you think Sound plays a big role in the detecting world?" You just gave me the best answer why.

It was also great for me to know for the first time who Bruce Candy is, his brilliance, his scarey smartness, Halcro amps, his technical advancements and what the media talks about him. But what has that really got to do with me?

I thank you for the info, but you make it sound like I have something against the guy or Minelab, which is giving people reading these posts the wrong impression. I wish him all the best from all my heart even he comes up with 600 parts per thrillion at 30kHz (which only a super human can hear)

So why do you make it sound like I'm challenging him? heck your making it sound like I want or need a job offer from Minelab, by telling me "he doesn't turn anything to a sound expert, and he does sound that other people say is theoretically impossible" Well good for him, he deserves it and must have worked hard for it. Again I wish him all the best in his future endeavors.

You also make it sound like I want to open a new company for detectors by telling me

" Also remember, Minelab is the largest supplier of land mine detectors to NATO, therefore, many of the major technical breakthroughs that Minelab has invented, have been finanaced because of a very healthy R&D budget. Obviously government contracts can be very lucrative. This allows Minelab the financial where with all to research and develop technologies that other companies can only dream about, and these advancements are passed on down to the consumer machines that we own and enjoy"

And.............Its like your telling Google your dreaming because Bill Gates owns Microsoft. Never underestimate anyone (although I assure you thats not the case here) I just got to know about metal detecting because of the Rush in Sudan my country and was amazed by the Audio, which caused me to research. Hope nothing is wrong with that?

I ask myself, did I offend Bruce? Did i say anything wrong about him or Minelab? Did I cross some certain invisible line?

If anyone here thinks i did? I'd gladly not post anymore. If it makes you all happy, I'll be happy do it. If you find my posts informative, then I'll keep posting.

If you disagree with any of my theory, you'r welcome to bash me with your theory.

Hope this clears things again :)

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JP. You mentioned liking the analog sound a little better than the digital. I may have a hard time putting this into words, but with the SDs I felt that I could discern a slight a slight rise of the threshold signal when a target was far off to the side of the coil which would draw me towards that target. This effect seems to be lessened with the GPXs although once the target is in close proximity to the coil , the digital signal is sharper and clearer. As per AMDs post , could it be that the "gate" doesn't open with this very slight threshold change, with the digital processor dismissing it as unwanted noise, but once the "gate" is opened it opens with a bang making those weak targets stand out clearly? This thread has triggered many thoughts on things that have been lurking in the background of my mind , but have stayed there until now. The technical aspects are way over my head but the picture is coming clearer now. There is also the possibility that by using all the available filters on the GPXs that get rid of EMI , I have tuned out this slight rise of threshold .-----Bob

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Guest Mike C...

Hi AMD as per our emails back and forth I find this subject very important in hearing the fringe signals that others simply don.t hear and if they are knocking it well thats more gold for those who do listen--I've always knew and employ that the TH and the tone play an important part in hearing those faint signals---thats why I can go into pounded areas and still pop nuggets---keep posting I'm all ears :) ---Mike C... :ph34r:

Flak, Thank you and glad you enjoyed it. Helps knowing you did.

DOC, Thanks again for your warm welcome and atlast someone answered my question in the first post which was "Do you think Sound plays a big role in the detecting world?" You just gave me the best answer why.

It was also great for me to know for the first time who Bruce Candy is, his brilliance, his scarey smartness, Halcro amps, his technical advancements and what the media talks about him. But what has that really got to do with me?

I thank you for the info, but you make it sound like I have something against the guy or Minelab, which is giving people reading these posts the wrong impression. I wish him all the best from all my heart even he comes up with 600 parts per thrillion at 30kHz (which only a super human can hear)

So why do you make it sound like I'm challenging him? heck your making it sound like I want or need a job offer from Minelab, by telling me "he doesn't turn anything to a sound expert, and he does sound that other people say is theoretically impossible" Well good for him, he deserves it and must have worked hard for it. Again I wish him all the best in his future endeavors.

You also make it sound like I want to open a new company for detectors by telling me

" Also remember, Minelab is the largest supplier of land mine detectors to NATO, therefore, many of the major technical breakthroughs that Minelab has invented, have been finanaced because of a very healthy R&D budget. Obviously government contracts can be very lucrative. This allows Minelab the financial where with all to research and develop technologies that other companies can only dream about, and these advancements are passed on down to the consumer machines that we own and enjoy"

And.............Its like your telling Google your dreaming because Bill Gates owns Microsoft. Never underestimate anyone (although I assure you thats not the case here) I just got to know about metal detecting because of the Rush in Sudan my country and was amazed by the Audio, which caused me to research. Hope nothing is wrong with that?

I ask myself, did I offend Bruce? Did i say anything wrong about him or Minelab? Did I cross some certain invisible line?

If anyone here thinks i did? I'd gladly not post anymore. If it makes you all happy, I'll be happy do it. If you find my posts informative, then I'll keep posting.

If you disagree with any of my theory, you'r welcome to bash me with your theory.

Hope this clears things again :)

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Hello AMD and all,

First Happy Thanksgiving to all! Secondly, welcome to the forums AMD.

Talking about the metal detectors, I refer the GPX to like an EQ. You have a huge range of control on this metal detectors that you don't on many of the prior units. The Timings,

Audio Settings, Motion Controls, Gain & Target Volume all play a huge role at finding more gold in old spots.

I love the Enhance timing, which is only available on the GPX-4500. This setting alone has found me many ounces of gold I've overlooked in places with high mineralization or a bunch of ironstones. I've found hundreds of smaller gold nuggets I've missed in old spots using a combination of settings along with the Special/Extra timing.

Would love to hear more about the audio stuff you're talking about.

Great to have you here on the forums.

Rob Allison

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You also make it sound like I want to open a new company for detectors by telling me

" Also remember, Minelab is the largest supplier of land mine detectors to NATO, therefore, many of the major technical breakthroughs that Minelab has invented, have been finanaced because of a very healthy R&D budget. Obviously government contracts can be very lucrative. This allows Minelab the financial where with all to research and develop technologies that other companies can only dream about, and these advancements are passed on down to the consumer machines that we own and enjoy"

And.............Its like your telling Google your dreaming because Bill Gates owns Microsoft. Never underestimate anyone (although I assure you thats not the case here) I just got to know about metal detecting because of the Rush in Sudan my country and was amazed by the Audio, which caused me to research. Hope nothing is wrong with that?

I ask myself, did I offend Bruce? Did i say anything wrong about him or Minelab? Did I cross some certain invisible line?

If anyone here thinks i did? I'd gladly not post anymore. If it makes you all happy, I'll be happy do it. If you find my posts informative, then I'll keep posting.

If you disagree with any of my theory, you'r welcome to bash me with your theory.

Hope this clears things again :)

AMD I think DOC was just giving you a little background info on what goes into the Minelab detectors not having a go at your ideas or thoughts on the matter, a lot of Minelab dealers world wide are very passionate people who truly believe in the product because the product is very cutting edge thanks to the inventiveness that Bruce Candy provides to the design, but I can also assure you there are a lot of other very dedicated professional people behind the scenes at Minelab who also help develop these detectors into what they are today, this is something that makes Minelab very strong in the R&D department. Reading your posts and the comments made by others here has been enlightening as the subject of audio is a very important one which is often neglected, you have managed to shed light on a very interesting subject. One of the first lessons I learnt when I got into videography was the viewer can easily accept less than ideal footage so long as the audio is clean and clear.

Montana it is great to see after all these years I have known you your willingness to freely admit you have learnt something new, this is your strength when it comes to detecting and will I feel sure greatly assist you in remaining on the cutting edge of gold metal detection in your country for a long time to come. Even though Minelab have freed up a lot of processes in the GPX series there is still a huge amount going on in the background, having an inkling of an idea of what that is greatly assists in the successful use of their detectors even if the understanding is gut feel only. To my mind the GPX offers a lot of different ways to skin a cat, getting rid of noise is the name of the game but doing it in a way that allows the maximum amount of information through is the priority which is sometimes lost in the pursuit of comfort, finding the holy grail of noise reduction can be as simple or complicated as you want to make it, thankfully the Minelab detectors represent such powerful platforms to work from there is still incredible performance in the basic settings. BTW your are right about the differences between the audio of the digital compared to analogue designs, keep thinking along those lines and I'am sure you'll come to some very interesting conclusions.

JP

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JP. AMDs post did turn on some light bulbs for sure . Now I need to put the info to good use. I'm amazed that a novice detectorist is able to grasp so thoroughly the workings of a detector audio, but I guess electronicly produced sound has anologies throughout the electronic industry. AMD will have no problem running the most complicated detectors. Detecting is all about what we hear after all.----Bob

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Hey DOC, don't think for a minute, that what you have to say doesn't count! It does, and I for one read everything you post, My grand dad told me you can't learn a thing if your the one doing the talking! So I like to listen. Keep posting. Very informative stuff. Grubstake

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Thanks all for your support. I appreciate it. As long as its not boring. Yes even though I have never used a detector, I wan't ya'll to know that it was this forum that helped me understand it, and the many people here who were giving me their best advices to help my people in Sudan at the earlier topic. All were doing their best to help me and that so much includes you DOC

DOC, So don't you think for a second that your information is not helpfull like Grubstake said. I can not lie and tell you I knew any of that info, but honestly I just felt there were some words and sentences that sound more Challenging than info. Especially the two paragraphs I mentioned. My concern was I did not want the reader to misunderstand my post.

I guess that was not your intention and I appologise if I attacked you in any way. I misunderstood and shouldn't have posted that reply.

Don't forget this is not an Audio Forum which makes me the novice here like montana said. So I look up to all of you here and know that your the one's who know better than me in what ever I say and will be learning from you, once I get me a detector (which I'm trying to find at a good price)

I'm in Dubai now for a while and trying to find one before I go back to Sudan, but the prices are just crazy.

Sorry again DOC, looking forward to more advices from you

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AMD. Over the last 6 months I have had the pleasure of meeting several of your countrymen. They were very pleasent, educated gentlemen like yourself. Some were searching for GPX4500s to resell in Sudan , some were trying to obtain 4500s to send to their relatives. I tried to convince them that they could save a lot of money by buying used GP 3000s or 3500s, or even SDs and really not be of much of a dissadvantage . First one on a new spot with any of these fantastic detectors will find the vast majority of the detectable gold. On large nuggets the 4500 has no real depth advantage over any of these. They were convinced for some reason that only the 4500 would do the job. If you are truly interested in finding gold in your country, your priority should be to get out there to the goldfeilds as soon as possible, and not worry about having the most up to date detector. I would say that far more gold was found with the SD2100 than any other model of Minelab and if you couple it with a large aftermarket coil it will probably do better than the 4500 with the stock 11" inch DD coil. Get out there ASAP . The gold is dissappearing fast as it has in all goldrushes in the past . It is a resource which will never be replaced in our lifetimes and once it's gone , it's gone. Good luck . There won't be much left in a year or 2 the way things are going . There will be plenty for the hobbyist for years to come but the chances of becoming rich with a detector dwindle quickly in these situations. Historicly in goldfeilds all over the world the rushes lasted only a few years before the cream was skimmed off the top, and finding the remaining gold became incresingly difficult and expensive.----Bob

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I would say that far more gold was found with the SD2100 than any other model of Minelab and if you couple it with a large aftermarket coil it will probably do better than the 4500 with the stock 11" inch DD coil. Get out there ASAP . The gold is dissappearing fast as it has in all goldrushes in the past . It is a resource which will never be replaced in our lifetimes and once it's gone , it's gone. Good luck . There won't be much left in a year or 2 the way things are going . There will be plenty for the hobbyist for years to come but the chances of becoming rich with a detector dwindle quickly in these situations. Historicly in goldfeilds all over the world the rushes lasted only a few years before the cream was skimmed off the top, and finding the remaining gold became incresingly difficult and expensive.----Bob

Yeah, pick up an SD anywhere possible and get that big coil over a kilo, never a probable, but it sounds like it may be possible out there! (*Some people still claim to this day that they can get better depth on an old SD when it comes to monster nuggets, that will be debated forever, but most agree that you don't lose depth on them, just sensitivity to more of the smaller sized nuggets folks maybe be quicker to ignore in a fast a furious gold rush)

http://cgi.ebay.com/Minelab-SD-2000-GPM-Su...1#ht_2233wt_958

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