Frequency on gold

[jangles]

I'm confused and maybe some experts can set me straight. I see gold detectors with freqs like 71 khz and some "gold detectors" with freqs like 18khz I understand the lower the freq the deeper it will find a target (if it's large enough) however the higher the freq the better on small gold but not as deep, so how come the sovereign gt with up to 1.5-25khz is getting a bad rap as a gold hunter when units like the fisher gold bug pro run 18khz? Mind you I don't plan on gold hunting I'm just trying to understand the freq on gold as the freaks are all over the place...what gives?
Thanks

 

Amazon Forum Fav 👍

Treasure of Victoria Peak - Grab it through Amazon!

[GarretDiggingAz]

Great post. I got my detector which has 18 kHz. I've been told by others in mining supply stores that I've got a good detector. ATG.
Yet I never see it suggested as a gold hunter. Mostly I see the PI's like the minelab. Then also the Gold Bug 2. Or the tesoros.
I was researching my detectors based on frequency as well. Thinking the lower the better. For depth that is. Then as you stated there is, higher freqs finds smaller gold.
You can drive yourself crazy trying to decide on this. Reality is. All detectors find gold. You've got to be swinging over it to detect it. Depends on size and depth.
I figured that I'd get a detector that can find pickers at 6-8" then from there I'd dig and pan some samples of area.
Hope that helps some.
If you're looking for a detector for gold and want to spend the money on it. Then I'd check out some prospecting clubs in areas that you'd like to hunt. See if you could try or even borrow/rent one of the detectors they are using. To see if you like it. Them go from there.

 

[Steve Herschbach]

This following is in reference to VLF (induction balance) detectors. PI (pulse induction) is a different thing entirely where frequency is rarely discussed except as relates to electrical interference.

Frequency does two things. First, the target itself. Higher frequencies hit harder on small targets. Not gold per se, small targets. Take a common BIC type ball point pen, the type where the entire pen is plastic except for that little ball in the point. No other metal. A good gold detector will pick that ball up. A coin detector, you can write your name on the bottom of the coil and get no signal.

Low frequencies do not detect deeper. That is a broad statement with no meaning. In air tests high frequencies will detect farther, and on small targets a low frequency detector will miss it is obvious the higher frequency detector goes deeper.

The second thing frequency does is change ground response. Low frequencies do not react to ground and hot rocks as much as high frequencies. So that hot Gold Bug 2 also picks up ground and hot rocks better, and this means it gets very poor depth on larger targets in highly mineralized ground. It gets great depth on large targets in the air or in no mineral ground, but add mineral and the depth drops rapidly.

Detectors that work under 10 kHz hit very well on coin size targets and have a low ground response, making them great coin machines, but they have poor small item sensitivity. Detectors over 20 kHz are hot on tiny targets but have more issues with ground and hot rocks. Detectors in the teens are chosen as a best all around solution for do it all detectors. People used to coin detectors find them "noisy" as they tend to chatter on small targets and ground that a coin detector, designed for smoother operation and depth on coin size targets, will ignore.

People always ignore one thing when they go on about the Minelab multi-frequency detectors. They focus on the so-called high frequencies employed. It does not matter. What does matter is those detectors are designed to find silver coins and are tuned and act like lower frequency detectors. Do not let specs blind you to reality. If multi-frequency were good for nugget hunting Minelab would make multi-frequency nugget detectors. They do not, nor does anyone else. The nugget machines run at one frequency to put all the power into one frequency instead of sharing it among multiple frequencies. I am not saying the Minelab units will not find gold - my CTX 3030 is a jewelry killer. But it is not a hot nugget machine.

There is another thing frequency does, and that is deal with electromagnetic interference (EMI). Some frequencies like the 30 and 40 kHz range get avoided due to interference issues.

Finally, the nugget market is saturated and most serious, that is to say "been at it awhile", nugget hunters already have their detectors. The AT Gold does just fine compared to other mid-frequency detectors. The thing is it also does no better than anything else out there for years. So nobody is rushing to replace the detector they have with the AT unless they need a waterproof nugget detector, a rare requirement indeed. Most guys hunt in deserts. People mention what they have and what has been around for years and the AT is a new kid on the block. Bottom line is as a nugget hunter, take away the waterproof, and it is just another good detector along with a half dozen others.

To sum up, the higher the frequency, the better the response on small targets, and the better the air test. But the higher the frequency, the more response to ground and hot rocks. The two work against each other, and a detector has to balance the two parts of the equation. Mid frequencies are basically just the best compromise. Multi-frequency units just think of as lower frequency units and you will be fine.

Steve Herschbach
DetectorProspector.com

 

[jangles]

Thanks for all's help, I guess those GPX's are P.I. units!

 

[nuggetshooter323]

In minerlized ground with a VLF, it's going to be seldom if ever that your going to detect a picker at 6-8". Reality is more like half that or less, but instead of having an expectation of depth, have none. Just channel all your attention through your detector, your technique, and the terrain. You should be concentrating hard enough to actually fatigue yourself just in it of itself. I have to rest every 1 1/2 hours just from keeping my concentration so high. One of the best books I ever read on the correct technique was "Zip, Zip", by Larry Sallee. For GMT and Goldmaster user's it's required reading, but any nugget hunter can benefit from it.

Reality is. All detectors find gold. You've got to be swinging over it to detect it. Depends on size and depth.
I figured that I'd get a detector that can find pickers at 6-8" then from there I'd dig and pan some samples of area.

 

[GarretDiggingAz]

Yeah sorry about saying picker. Not familiar on sizes to terms. Picker for me is like a half size for fingernail. Lol.
I've got more reading to do. Just when you think you've read enough. Read some more.
I find when I'm swinging I'm trying to pick out which of the multiple tones is the target I want. Does get tiring.
My boy covered a 20'x30' area compared to my 10' straight run. After digging up trash (iron mostly) and tabs I had to call it quits for the day. I try to tell him slow and low. Treat it like painting a wall. Have some overlap. He swings and steps. Ughhhhh. Oh well. Practice makes perfect.

 

[Joe Z]

Just channel all your attention through your detector, your technique, and the terrain. You should be concentrating hard enough to actually fatigue yourself just in it of itself. I have to rest every 1 1/2 hours just from keeping my concentration so high. One of the best books I ever read on the correct technique was "Zip, Zip", by Larry Sallee. For GMT and Goldmaster user's it's required reading, but any nugget hunter can benefit from it.

X's 2 on "Zip Zip" 272 pages of detector/ and operator know how. I'm on my third time reading it

 

[Terry Soloman]

This following is in reference to VLF (induction balance) detectors. PI (pulse induction) is a different thing entirely where frequency is rarely discussed except as relates to electrical interference.

Frequency does two things. First, the target itself. Higher frequencies hit harder on small targets. Not gold per se, small targets. Take a common BIC type ball point pen, the type where the entire pen is plastic except for that little ball in the point. No other metal. A good gold detector will pick that ball up. A coin detector, you can write your name on the bottom of the coil and get no signal.

Low frequencies do not detect deeper. That is a broad statement with no meaning. In air tests high frequencies will detect farther, and on small targets a low frequency detector will miss it is obvious the higher frequency detector goes deeper.

The second thing frequency does is change ground response. Low frequencies do not react to ground and hot rocks as much as high frequencies. So that hot Gold Bug 2 also picks up ground and hot rocks better, and this means it gets very poor depth on larger targets in highly mineralized ground. It gets great depth on large targets in the air or in no mineral ground, but add mineral and the depth drops rapidly.

Detectors that work under 10 kHz hit very well on coin size targets and have a low ground response, making them great coin machines, but they have poor small item sensitivity. Detectors over 20 kHz are hot on tiny targets but have more issues with ground and hot rocks. Detectors in the teens are chosen as a best all around solution for do it all detectors. People used to coin detectors find them "noisy" as they tend to chatter on small targets and ground that a coin detector, designed for smoother operation and depth on coin size targets, will ignore.

People always ignore one thing when they go on about the Minelab multi-frequency detectors. They focus on the so-called high frequencies employed. It does not matter. What does matter is those detectors are designed to find silver coins and are tuned and act like lower frequency detectors. Do not let specs blind you to reality. If multi-frequency were good for nugget hunting Minelab would make multi-frequency nugget detectors. They do not, nor does anyone else. The nugget machines run at one frequency to put all the power into one frequency instead of sharing it among multiple frequencies. I am not saying the Minelab units will not find gold - my CTX 3030 is a jewelry killer. But it is not a hot nugget machine.

There is another thing frequency does, and that is deal with electromagnetic interference (EMI). Some frequencies like the 30 and 40 kHz range get avoided due to interference issues.

Finally, the nugget market is saturated and most serious, that is to say "been at it awhile", nugget hunters already have their detectors. The AT Gold does just fine compared to other mid-frequency detectors. The thing is it also does no better than anything else out there for years. So nobody is rushing to replace the detector they have with the AT unless they need a waterproof nugget detector, a rare requirement indeed. Most guys hunt in deserts. People mention what they have and what has been around for years and the AT is a new kid on the block. Bottom line is as a nugget hunter, take away the waterproof, and it is just another good detector along with a half dozen others.

To sum up, the higher the frequency, the better the response on small targets, and the better the air test. But the higher the frequency, the more response to ground and hot rocks. The two work against each other, and a detector has to balance the two parts of the equation. Mid frequencies are basically just the best compromise. Multi-frequency units just think of as lower frequency units and you will be fine.

Steve Herschbach
DetectorProspector.com

I just wanted to bump this post again because it is so darn good!

 

[delnorter]

frequency on gold

Thanks for all the good info. Steve you said among other things in your post:

"the second thing frequency does is change ground response. Low frequencies do not react to ground and hot rocks as much as high frequencies. So that hot Gold Bug 2 also picks up ground and hot rocks better, and this means it gets very poor depth on larger targets in highly mineralized ground. It gets great depth on large targets in the air or in no mineral ground, but add mineral and the depth drops rapidly."

Does this mean the mineralized ground is deflecting the signal before it gets to the desired target or just masking the target signal by overwhelming it with the mineralized / hot rock signal. Make sense?
Thanks
Mike

 

[Ausgoldhunter]

And threads like this are why i love this forum!

 

[ToddB64]

Thanks for all the good info. Steve you said among other things in your post:

"the second thing frequency does is change ground response. Low frequencies do not react to ground and hot rocks as much as high frequencies. So that hot Gold Bug 2 also picks up ground and hot rocks better, and this means it gets very poor depth on larger targets in highly mineralized ground. It gets great depth on large targets in the air or in no mineral ground, but add mineral and the depth drops rapidly."

Does this mean the mineralized ground is deflecting the signal before it gets to the desired target or just masking the target signal by overwhelming it with the mineralized / hot rock signal. Make sense?
Thanks
Mike

delnorter,

I've got your answer ! It appears in one of Clive James Clynick's books, titled "Site Reading" for Gold and Silver, beginning at the bottom of page 20 and completing at the top of page 21.

Due to Copyright laws, I must receive permission from Clive before posting the paragraphs here and I'm sending him an Email today.

Anyone owning a copy of this book can re-read the answer at their convenience if desired and perhaps these folks might recall the explanation Clive got from "B.B. Sailor".

I'll be back to report asap.

ToddB64

 

[nuggetshooter323]

I'll tell you how I understand it, and Steve can correct me if I'm wrong. The harder the ground rejection circuit has to work, the less depth you get. That's why a lot of nugget hunters using a VLF, use a smaller coil in highly minerlized soil. It "see's" less minerlization at one time, so the ground rejection doesn't have to work as hard.

Thanks for all the good info. Steve you said among other things in your post:

"the second thing frequency does is change ground response. Low frequencies do not react to ground and hot rocks as much as high frequencies. So that hot Gold Bug 2 also picks up ground and hot rocks better, and this means it gets very poor depth on larger targets in highly mineralized ground. It gets great depth on large targets in the air or in no mineral ground, but add mineral and the depth drops rapidly."

Does this mean the mineralized ground is deflecting the signal before it gets to the desired target or just masking the target signal by overwhelming it with the mineralized / hot rock signal. Make sense?
Thanks
Mike

 

[Steve Herschbach]

"or just masking the target signal by overwhelming it with the mineralized / hot rock signal."

It is actually simple. Ground balancing is just another discrimination circuit at work. It is also referred to as ground rejection. The detector discriminates out the ground reading. Targets that read the same as the ground are also eliminated. Targets are masked by the ground. The more ground you must discriminate out the more target masking occurs.

Low frequency detectors react less to the ground so there is less need to discriminate out the ground. But they miss tiny gold. So crank up the frequency, now you hit the tiny gold, but the ground gets more reactive. You apply more ground rejection to eliminate the ground signals, but now deeper targets are getting tuned out. Two opposing effects at work.

Salt can be a ground signal on alkali flats or salt water beaches. Tiny gold items read like salt water. You can use low frequency or PI detectors that do not pick up salt water but they miss the tiny gold chains and earrings. You can try an MXT to hit the items, but now you pick up the salt. You can flip on the Salt switch on the MXT to eliminate the salt reading, and now you lose the gold! Two opposing effects at work.

There are many items in the ground that you want to dig that generate a signal that is the same as the ground reading and so are missed by tuning out that ground signal. What makes a Minelab GPX 5000 special are the timings, which are nothing more than a set of ground elimination settings designed to reveal as many targets as possible. Each timing rejects a certain type of ground and also rejects a certain number of good targets. Changing timings will reveal targets that another timing was eliminating.

Detectors work perfectly in the air. They do actually detect the ground. Prior to ground balancing circuits being developed you just lived with no depth due to the ground hiding everything. Ground balance was a game changer, but people would be amazed at what still remains in the ground due to ground balance systems themselves eliminating targets. Add the use and limitations of regular discrimination circuits and the sky is the limit for guys like me. There is no lack of good detecting left to be had out there.

And yes, small coils help eliminate all types of target masking, including ground effects. Putting a large coil on a VLF often results in less effective depth, not more. Counter-intuitive but true. Especially with high frequency units.

 

[Terry Soloman]

Here is part of a lecture on Discrimination and Ground balancing, and PI vs VLF detectors given by Steve Gholson, at the Minelab Technology Training Center in Arizona. Not all of it applies, but some does. I hope you find it helpful:

 

[Lanny in AB]

Steve,

You really are the master at explaining things so that they finally make sense! Both of your posts on here should be required reading for anyone that wants to understand frequency, the effects of ground, coil size, effects of salt, target size, depth capability, etc., etc.

Fantastic job Sir.

All the best,

Lanny

 

[Steve Herschbach]

Thank you Lanny. If it helps people to just think about it another way that is good. The posts all get expanded for use on my website and then will eventually end up in a book in the not too distant future. So it helps me too as a book should answer people's questions, and where better to build the foundation than on a forum!

 

[ToddB64]

Thanks for all the good info. Steve you said among other things in your post:

"the second thing frequency does is change ground response. Low frequencies do not react to ground and hot rocks as much as high frequencies. So that hot Gold Bug 2 also picks up ground and hot rocks better, and this means it gets very poor depth on larger targets in highly mineralized ground. It gets great depth on large targets in the air or in no mineral ground, but add mineral and the depth drops rapidly."

Does this mean the mineralized ground is deflecting the signal before it gets to the desired target or just masking the target signal by overwhelming it with the mineralized / hot rock signal. Make sense?
Thanks
Mike

To Mike and other viewers,

There have been a lot of good, even great replies to this thread and I am certainly NOT trying to "take the wind out of anyone's sails", but when I first read this thread, I remembered reading the following excerpts and wanted to make a contribution here. So I contacted the author and received permission to post text from his book. What follows is in response to the last paragraph in the above quote.

The following information, including and in context with the sub-title, was excerpted from pages 20 and 21 of Clive James Clynick's book titled "Site-Reading" for Gold and Silver , published in 2008.

Since the subject book was published, I assume that advances in detector technology, as well as increased knowledge on the part of many detectorists has made at least some of this information fairly well known already, however, I think it will be interesting reading to most readers and especially those new to the hobby !

"Go Slow & Low !"

ToddB64

Excerpts Begin
Depth: Overcoming the "Signal to Noise" Problem

Many detector manufacturers have a lot to say about the depth of their products and over the years there have been great improvements as to what these machines will do. However, with any VLF detector, the amount of depth you are able to get is limited by what can be called the "signal to noise" problem. Understanding how this works will change the way you tune and operate any machine you hunt with--to good results.

The most important fact to remember when working shorelines is that many beaches have sand that just does not handle a detection signal well. These may be "black" sand or other less obvious ("gray" sand, corral) consistencies. This is also true of many inland sites--legendary "Bama" dirt is a case in point. Pulse induction machines ignore much of this interference and the results can be surprising.

What is interesting when you compare pulse and VLF units is that many of the targets that the VLF units will miss are not deep at all, but instead shallow objects that are completely masked by the ground's signal. More treasure is missed by detectorists for this reason than everything else put together. At many locations what you basically have is ground that will not evenly conduct enough signal (sensitivity) to allow objects to be detected at any distance beneath the surface. Another way to state this is to say that as you introduce enough sensitivity to hear targets--the ground's response comes up as well, overwhelming everything else. You could also say that the signal in total (ground and targets) is too complex to be sorted through effectively by the detector using normal methods.

Wasaga Beach, Ontario is one such location. It's a 27-mile stretch of shoreline that has seen swimming and picnicking activity since the 1890's. I hunted there for a few years before recognizing that a different method was needed. About that time some of the manufacturers began to introduce what can be called "mega-coils". I purchased one and began the project of asking questions of several old-timers as to how to get the best performance from these coils.

One sharp veteran hunter who goes by the online handle of "B.B.Sailor" came through in spades. He told me that because it is really the density and signal of the ground that impairs the depth of a detector, to find really deep targets you had to work in all metal. He explained that what a detector does is not just to punch through the ground to report any metal, but to separate the response of a metal object from the larger signal of the ground and that using all-metal mode made this easier for the detector to do.

In effect, the difference between the ground and these marginal signals was just too subtle to recognize in discriminate. Working in all-metal, he explained, you had a better chance of hearing the deepest, faintest responses the were mixed in with this large ,overwhelming ground signal.

I began to experiment, trying various tuning ranges in all-metal mode. This location has a lot of dense, fine, "black" sand mixed in with the regular hard-packed matrix. In particular, I looked for sensitivity settings that were not too high so as to allow the signal maximum extension as it traveled into this difficult ground and back. I also experimented with threshold tuning to find a range that gave hair trigger responsiveness--even to objects that were 20" or more down !

Excerpts End

 

[delnorter]

Thank you to all, always learning.

ToddB64 it's a good thing you did, getting permission to reprint this information. A very good explanation.

Terry, thanks for the videos, it's always nice to see an explanation as well as hear it.

Steve, you really do explain things well. With you and Nuggetshooter323's input on smaller coils I think I'll get the 6.5" for my GB2. I have a good range of hearing, is there a particular set of headphones you recommend for the GB2?

Mike

 

[Steve Herschbach]

There are many. I currently use DetectorPro Nugget Buster NDTs and Sun Ray Pro Golds.

 

[ToddB64]

"Frequency on gold" by Mike > Steve Herschbach's Post #3

Dear Steve and Viewers,

Copied & pasted below is the second paragraph from the subject post for reference.
My following reply is in regard to the highlighted sentences.

"Frequency does two things. First, the target itself. Higher frequencies hit harder on small targets. Not gold per se, small targets. Take a common BIC type ball point pen, the type where the entire pen is plastic except for that little ball in the point. No other metal. A good gold detector will pick that ball up. A coin detector, you can write your name on the bottom of the coil and get no signal."

Today, I decided to try the suggested experiment with the little ball from a BiC ball-point pen, using my Tesoro Compadre, a VLF discriminator detector, with a 5.75" round solid coil and operating on (1) 9V battery at 12 kHz frequency. Admittedly, this was an air test, so the results are not what I would expect with the ball buried at various distances in the ground, especially well-mineralized ground.

I wanted to do a pure test, so I removed the little ball from the brass retainer at the end of the pen. In case you want to duplicate this experiment with your detector, the procedure I used for removing the ball is listed down below, along with my setup for the experiment and the results.

After removing the ball, I measured it with a micrometer and got readings of .0380 to .0384 (rolling the ball before the second reading.). So I would say the mean diameter is 1/32" (.0312")......that's tiny and simulates gold mesh sizes of 18 to 20 (.0394" to .0331"). Equivalent sizes in millimeters = 1.000 to .841 and in Microns 1000 to 841.

REMOVAL OF BALL FROM BRASS RETAINER:

#1..Heat the brass ball retainer (at the end of the BiC ball-point pen) with candle flame, for a few seconds until hot to the touch. Purpose: To anneal (Soften) the brass and facilitate release of ball.).

#2..Using a pair of heavy-duty sharp scissors (I used the kind with black plastic handles you can often get Free at Harbor Freight stores with a coupon.), I gripped the brass ball retainer deep into the V between the scissor blades, at a point on the retainer just below the ball and squeezed hard while holding the pen tip straight down over a container to capture the ball.

#3..Using soft tissue, I cleaned ink from ball, then placed it on a piece of Scotch tape, to prevent losing.

EXPERIMENT SETUP:

#1..I utilized an all-plastic yard bench and set it on my concrete patio, using the seat of the bench as a table-top surface, which was 16" above the patio and away from all metal objects.

#2..The piece of Scotch tape, with the ball stuck to it and facing up, was placed on the bench seat.

#3..My wife assisted, holding a measuring stick (graduated with our standard inch scale.) vertically, with the one-inch end touching the bench seat a few inches behind the ball.

EXPERIMENT RESULTS:

#1..Turning the Compadre ON I began scanning the coil over the ball, beginning about 3" above the ball, with a medium to fast lateral swing and gradually raising the coil higher. I got a signal from the ball in both directions of the lateral scanning until the coil reached approximately 9", at which stage I could only get a signal from left-to-right, but not right-to-left, as I continued to raise the coil higher. Finally, I lost the signal altogether as the coil reached 19" on the measuring stick......amazing I thought ! Also, from the 9" height to the 19" height, I had to keep the coil scanning speed fast as it approached the ball in order to maintain the signal.

I will be doing some depth tests with unrefined natural gold of 20-22 K (83% to 92% purity), mesh size #6 (Average .132") after weather warms up and the ground dries......my area has had continual rain, snow and cold temps. in recent months. I'll report the results later on.

Happy Hunting Everyone !

ToddB64