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Steve Herschbach

Switchable Or Selectable Frequency And Frequency Spread

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I am going through one of those periods where I load up a bit on new detectors and let it all sort out. Darwin's Survival Of The Fittest Detectors! This winter a number will not survive and will be looking for new home. This is the only way I have found that works for me. Detectors that serve a good purpose for me get used, others end up sitting. If they sit long enough, they are no longer needed.

I have my nugget detecting fairly well sorted out. The GPZ 7000 gets used 90% of the time. I might pull out a VLF for a really trashy place, or for where the gold is smaller than the GPZ can hit (really small!). I do keep a Garrett ATX around to handle salt ground or oddball hot rocks the GPZ has trouble with but those situations have proven quite rare so far.

So the GPZ is an obvious keeper. The ATX does double duty as my favorite water hunting machine so there is another.

In the land of VLF however it is more complicated. I have this idea that a good selectable frequency detector might really do the trick in replacing two or more other models. The key there however is what I am going to go ahead and call "frequency spread" for lack of a better term.

What do I mean by frequency spread? Simply put, the number of kHz between the lowest and highest frequency the detector can operate at. The lowest frequency is basically the "large item" frequency that more easily handles bad ground, and the high frequency is the "small item" frequency that tends to have more issues with mineralized ground or hot rocks.

The high frequency option is critical for a person like me who nugget hunts. To really be able to replace machines like the 45 kHz Minelab Gold Monster 1000, 48 kHz White's GMT, 56 kHz Makro Gold Racer, or 71 kHz Fisher Gold Bug 2, the highest frequency option of the detector needs to be 30 kHz or higher or as close to that as is possible. Low frequencies in the single digits are great for coin hunting or very large gold nuggets in bad ground. Frequencies in the teens are a great compromise.

Some examples:

Nokta Impact 5 kHz, 14 kHz, and 20 kHz (15 kHz lowest to highest)

XP DEUS Low Frequency Coil 4 kHz, 8 kHz, 12 kHz, and 18 kHz (14 kHz lowest to highest)

Rutus Alter 4.4 kHz to 18 kHz in 0.2 kHz steps (13.6 kHz lowest to highest)

White's V3i 2.5 kHz, 7.5 kHz, 22.5 kHz (20 kHz lowest to highest - bonus - runs in multifrequency mode)

I am still waiting on the XP DEUS High Frequency Elliptical Coil 14 kHz, 30 kHz, and 81 kHz (67 khz lowest to highest). The XP HF 9" round running at 14 kHz, 30 khz, and 59 khz (45 kHz lowest to highest) is currently available.

In theory the White's V3i is a real winner here but I have just never really taken to the V3i as a prospecting detector. I have to be honest and say that so far the Impact floats my boat more in that regard due to its more traditional approach to a detector interface, all metal modes, and ground balancing. The problem with all of them though is they just don't reach high enough to be used both as coin and jewelry machines and yet still be capable of retiring the high frequency nugget detectors. And that is why I am still patiently waiting for that XP Deus V4 high frequency elliptical coil. At 81 kHz (or 59 kHz in 9" round version) the Deus HF coils on paper at least could in theory make the high frequency nugget detectors redundant. I have to admit I still have doubts however. So far dedicated specifically tuned single frequency detectors have always won the day. For a lot of people however, a selectable frequency machine might prove to be "good enough".

The downside with the Deus is that to get the deeper seeking lower frequency large coil option you have to wrap up quite a bit of money into two coils. The 9.5" elliptical is just not going to reach real deep due to its small size. I have the 11" round low frequency coil which can run as low as 4 kHz, so together the two coils make a pretty formidable package. The other machines however can run both much smaller and much larger coils, and at considerably less cost than what DEUS coils cost due to each one being a self contained metal detector. It may be that the XP HF 9" round running at 14 kHz, 30 khz, and 59 khz (45 kHz lowest to highest) is the better compromise option for most people than the 5.5" x 9.5" elliptical.

The Impact does suit me as far as the way it functions and I like the excellent inexpensive coil selection. It is a shame it weighs twice as much as the DEUS, but that may actually be a benefit when it comes to balancing large coils. Overall at the moment I am really liking the Impact - I just wish the frequency had topped out higher. I really wanted more like 5 - 15 - 30 kHz. Going from 14 kHz to 20 kHz is not quite providing the extra "pop" on tiny gold I would like to see.

nokta-impact-with-15-14-dd-coil.jpg

whites-v3i-metal-detector-2017-herschbach.jpg

xp-deus-with-5x9-elliptical-hf-coil.jpg

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Another issue with selectable frequency detectors is whether they compromise on performance (compared to straight-forward single frequency detectors) in order to deliver the option of choosing among 2 or more frequencies.

It may be difficult to decide if they are compromising since comparing a single frequency detector (like the Fisher Gold Bug Pro @19 kHz) with a selectable frequency detector with an option of the same frequency (such as the Minelab X-Terra with 3 kHz, 7.5 kHz, and 18.75 kHz) means comparing two detectors with very different components.  I'm guessing the big issue in compromise would come from the coils used.  Specifically, if it's "one coil fits all (frequencies)" then one wonders how much you give up for this seemingly nice feature.

To put it simply, ignoring cost and convenience, are you better off (in terms of performance) having three separate detectors that cover the ~2.5 kHz to ~20 kHz range or one detector that does all three?

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So far I have always leaned towards specialty machines. However, as the technology improves I am sure we will see more advancement made towards perfecting true multi purpose detectors. In the end all we can do is go use them and decide what works best for each of us. Some people need a dozen detectors, but we are certainly closer to the day where one good detector is all most people need.

I don't see much difficulty in sorting it out however. Regardless of components used they either perform or they do not. The only way I know how to do that is go use them personally.

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I believe manufactures could just have a one vlf machine that does it all but they wouldnt release what they believe to be the latest in technology; Just like all electronics. 

It been already how long since the gpz came out and all these metal detectors coming out that tries to add another into the closet instead of replacing one or two. 

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On 5/30/2017 at 10:24 AM, GB_Amateur said:

To put it simply, ignoring cost and convenience, are you better off (in terms of performance) having three separate detectors that cover the ~2.5 kHz to ~20 kHz range or one detector that does all three?

This thread and your question are going to be put to the test soon. Now we have two new offerings to add to those originally listed:

Nokta Impact 5 kHz, 14 kHz, and 20 kHz (15 kHz lowest to highest)

XP DEUS Low Frequency Coil 4 kHz, 8 kHz, 12 kHz, and 18 kHz (14 kHz lowest to highest)

Rutus Alter 4.4 kHz to 18 kHz in 0.2 kHz steps (13.6 kHz lowest to highest)

White's V3i 2.5 kHz, 7.5 kHz, 22.5 kHz (20 kHz lowest to highest - bonus - runs in multifrequency mode)

XP DEUS High Frequency Round 14 kHz, 30 kHz, and 59 kHz (45 kHz lowest to highest)

XP DEUS High Frequency Elliptical 14 kHz, 30 kHz, and 81 kHz (67 khz lowest to highest)

Plus arriving soon:

Minelab Equinox 600 5 kHz, 10 kHz, and 15 kHz (10 kHz lowest to highest - bonus - runs in multifrequency mode)

Minelab Equinox 800 5 kHz, 10 kHz, 15 kHz, 20 kHz, and 40 kHz (35 kHz lowest to highest - bonus - runs in multifrequency mode)

The two new DEUS high frequency offerings have the widest frequency spread, but unfortunately they start at a pretty high starting point (14 kHz). They achieve very high frequencies by doing this but my own recent tests of machines like the 45 kHz Minelab Gold Monster and 71 kHz Fisher Gold Bug 2 plus my use of the DEUS HF elliptical coil make me question if there is much to be gained by the frequencies over 50 kHz. Ultra high frequencies are really hot on tiny objects but ground penetration also really suffers at the highest frequencies. I am not convinced that giving up the lower frequency options to reach kHz values as high as 81 kHz is worth the trade to all but a very few people. I suspect the vast majority of DEUS HF coil owners will employ the 14 kHz and 30 kHz options far more than the highest frequency option.

minelab-equinox-metal-detector-large-studio-multifrequency-waterproof.jpg

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Steve I can see why you're stoked over the 800's capability of running 20kHz and 40kHZ.

 

Tom

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40 khz is the biggie Tom. There are piles of detectors that run around 19-20 khz and yes, that is a very good frequency for a general purpose nugget detector. Yet for many years people have gone to higher frequency machines like the 48 khz GMT, 71 kHz Gold Bug 2, 60 kHz Eureka Gold, 56 kHz Gold Racer for their small nugget detecting needs. The 45 khz Gold Monster is just the latest in the series of dedicated nugget detectors running at over 40 kHz.

So while topping out around 18 - 22 kHz is good (more than good enough for most people), it has always been just a little short of where I have been hoping to get with a selectable frequency detector as regards both nugget and micro jewelry detecting. The Deus does a good job in that regard but for most people starting with no detector buying a standard Deus and then adding a HF coil option gets to be a real pricy situation at near $2K for a VLF detector with two coils. That will change if XP ever gets around to selling a model that comes with the HF coil as stock, as they have done in Africa (but nowhere else we know of). But then you get locked into 14 kHz on the low end.

It may all very well be moot now as Multi-IQ proves it's stuff over time.

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      1999 Minelab Golden Hawk        6.4 kHz    20 kHz    60 kHz
      2002 Minelab Eureka Gold        6.4 kHz    20 kHz    60 kHz
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      2006 Minelab X-TERRA 70            3 kHz    7.5 kHz    18.75 kHz
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      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
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      Minelab - Understanding Your X-Terra
      White's - Spectra V3i Owners Guide
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    • By Steve Herschbach
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      Nugget hunters and beach hunters get right with the program. If a nugget "patch" is located it will be relentlessly pounded until no metal remains. Beaches survive by being a renewable resource. Good relic locations can and will be subjected to the same attention given to nugget patches. The rule is that as long as you can find a piece of metal hope remains that good items can be found. If not you, somebody else can and will return until no metal remains. I have promoted PI detectors for all uses for this very reason for over 10 years now - see that last few paragraphs at www.losttreasure.com from 2005.
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      Beneath The Mask by Thomas Dankowski
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