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Why Do Low End Detectors Always Have Low Frequencies?


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Might be a silly question, but I can't find the answer. Seems like all the lower end detectors are always around 5-8 khz. I was always under the impression that the sweet spot for the biggest target range was around 12-18 khz. Are the lower frequencies cheaper to implement, or is there another reason? 

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I don't know the answer to your question other than to say that your observation is very accurate that in the past, most low end detectors maxed out at about 8 kHz. Now we have the 12 kHz full featured Nokta Makro Simplex and the simultaneous multi frequency Minelab Vanquish which have saltwater beach capabilities and are way better than the earlier low end detectors for actual detecting in my opinion.

 

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7 hours ago, phrunt said:

Could it be they're good at handling a range of ground and capable of having a fixed ground balance and still handling a reasonable amount of ground?

That get's my vote, although it's likely more than a single reason.

I recall a thread way back when I started posting here.  A detectorist mentioned that he was having trouble with his higher frequency (don't remember which) detectors when searching for gold in mineralized ground.  To end the day he switched to his Teknetics Omega (~8 kHz operating frequency, but it does have ground balance adjustment).  He said that ran much better and when I said I was surprised, Steve H. stepped in with (paraphrased) "I'm not surprised...." following with the explanation that lower frequencies are less susceptible to ground noise.  At least that's what my memory is telling me 4 years later.

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The largest target market is the 'high-conductor coin-shooting' user, and the 5-8 kHz range suits that.

Beginners don't want fidgety, sparky machines that false-signal on iron too much.

From a technical view, lower freqs pick up less ground signal, so depth is easier to obtain without the troubles of adjustable ground-balance. It's likely to be cheaper to make a lower-freq machine; coils need less precise adjustment, lower-speed analogue parts like amplifiers are slightly cheaper etc.

It is a US-led phenomena, though. I notice UK manufacturer C-Scope have used 13kHz as a good all-round choice on a large number of their machines, including beginners ones.

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The answer is somewhat "all of the above" - see this link regarding the advantages to low frequency operation which is specific to the Deus but applies to detectors in general and sheds light on why entry level detectors lean towards lower frequencies (plus Pimento's chip in regarding the advantages in detecting manufacturing and design):

https://m.facebook.com/XPMetalDetectors/posts/why-use-a-low-frequency-on-your-xp-deus-lets-briefly-talk-about-using-the-xp-deu/1517191478581639/

Here is the text for those not keen on clicking on facebook links...

 

SmartSelect_20200823-090509_Chrome.jpg

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1 hour ago, Chase Goldman said:

...See this link regarding the advantages to low frequency operation which is specific to the Deus but applies to detectors in general....

That's an interesting writeup.  The last two seem contradictory, which just shows how much of thorn in our side iron can be:

"...Lower frequencies will always give you an advantage when identifying large or mis-shaped iron."

"...I like to use higher frequencies if the soil is contaminated with small iron,...."

Yes, I see 'large' vs. 'small', but often you don't get your choice!

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2 hours ago, GB_Amateur said:

That's an interesting writeup.  The last two seem contradictory, which just shows how much of thorn in our side iron can be:

"...Lower frequencies will always give you an advantage when identifying large or mis-shaped iron."

"...I like to use higher frequencies if the soil is contaminated with small iron,...."

Yes, I see 'large' vs. 'small', but often you don't get your choice!

I understand your point, but they actually aren't contradictory and you sort of hit on the reason why.  The fact that Gary differentiates small and large targets is key.  Lower frequencies do help identifying large ferrous targets (also true of non-ferrous targets) that is just the physical nature of the lower frequencies associated with longer wavelengths and how the targets electromagnetically respond to lower frequencies (i.e., physics).  Similarly, higher frequencies and smaller wavelengths enable better resolution of smaller targets (ferrous or non-ferrous) enhancing separation (at the expense of depth).  Also, just physics.  Yes, you are correct in that you often don't have a choice and that is the key to effective detecting - knowing how to balance all the tradeoffs to best fit the situation at hand - depth vs. separation choose  between low vs. high frequency or between high and low recovery speeds; depth vs. noise choose  lower or higher sensitivity or filter out falsing targets.  Use of filters such as discrimination, notches, or iron bias, also come with the potential drawbacks of masking desirable targets.  He defines a classic tradeoff in the summary paragraph - a bed o' nails situation - then go with the higher frequency to improve separation at the expense of depth (on Deus as on Equinox he would also have the ability to tweak recovery speed as well to improve separation but that also comes with a depth penalty).  Peeling that back - the conventional detectorist thinking would be that lesser detectors and detectorists would walk away from that situation out of frustration or inability of their fixed frequency/recovery speed detector to enable separation.  That means that shallow "masked targets" are probably present therefore the trade on depth vs. separation is a good gamble - i.e., go with a high frequency setting (or high recovery) setting.  Those who can master these often subtle tradeoffs under challenging site conditions often are able to consistently make the best recoveries after the "easy" finds have been cherry picked from a site.

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The simple explanation is partly in marketing .... newer models of detectors have started to use higher frequencies ... not only because of their sensitivity to low conductive targets ... but also because of their better separation in iron ...

try changing the 1f frequency to Rutus Alter 71, Equinoxe 800, and Spectra V3., or Aka Signum MFD on a 3F coil ..... and see how to sign the separation..on low-conductivity nickel and highly conductive silver ..

On the other hand, the lower medium frequency of 6.6khz-8hkz provides the so-called Universal Frequency .... and when it is sufficiently powerful, it also has a high sensitivity to small targets .... ,, in addition, it is less demanding on field conditions ...

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3 hours ago, EL NINO77 said:

a 3F coil

I don't understand what you mean by this.  Could you elaborate?

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