Frequency Question

[Jcaldwell1958]

I am somewhat new to metal detecting and was recently told, by a veteran detector, that all machines are multi frequency. I was also told to not buy into the multi frequency hype and that machines advertised as ones, is a marketing ploy. Please help! Is he right?

[Steve Herschbach]

Welcome to the forum! No, that is inaccurate. One simple example is saltwater - multifrequency machines have a clear and indisputable advantage there. Target id accuracy is another area of clear superiority. These are not opinions; there are clear technical reasons why this is so. This article will tell you more about the subject.

Selectable & Multiple Frequency Metal Detectors

That is not to say you can’t do well with single frequency or that single frequency does not excel at some tasks. There is generally a situation in metal detecting where any one methodology can have some advantage.

[Jeff McClendon]

Either you misunderstood the veteran detector user you talked to or they have a bone to pick with a certain type of detector. Most hobby VLF detectors are single frequency. Depending on their quality they may be able to very slightly change frequencies in order to prevent crosstalk with other detectors. Only a few VLF detectors have the ability to selectively change from one detecting frequency to another like the XP Deus, XP ORX and some of the Nokta Makro detectors. A very few detectors also have the ability to operate with simultaneous multiple frequencies. Depending on if your soil has high mineralization conditions or if you detect saltwater beaches, a simultaneous multiple frequency detector may be the only VLF detector that will work well. In very mild to moderately mild dirt you won't see much difference between a good quality single frequency detector and a good quality simultaneous multi frequency detector for shallow to medium depth targets. On the deeper targets (past 6 to 8") the simultaneous multi frequency detector may out perform the single frequency detector as far as identification of the target is concerned.

So, simultaneous multi frequency detectors work very well where many other detectors fail miserably. That is not hype or some kind of marketing ploy, it is a well known fact.

Jeff

[kac]

I think the location your hunt is the single most important part to finding something good followed by knowing your machine and having the right coil for the job.

I hunt more by audio than vdi so if the numbers are a bit dodgy it means very little to me but that is just the way I hunt. Others keep their eyes glued to their screens.

[Jeff McClendon]

24 minutes ago, kac said:

I hunt more by audio than vdi so if the numbers are a bit dodgy it means very little to me but that is just the way I hunt. Others keep their eyes glued to their screens.

I have read this response in your posts before and on many detectors with or without displays that strategy works very well. On some simultaneous multi frequency VLF detectors being hype or not, which is the topic of this thread, visual target IDs are very accurately accompanied by very accurate multiple tone ID capabilities. On the Equinox specifically, I hunt first by tone ID and use the numerical target IDs to support what I hear. I don't know anyone who uses an Equinox (that knows what they are doing) that has their eyes glued to the screen. They don't need to especially in 5 or 50 tones. 

Jeff

[Steve Herschbach]

Yup, what Jeff said. It has nothing to do with the target id information being presented in an audio or visual fashion. It’s is all derived from the same base information, and if one is inaccurate, the other will be also. An aluminum beaver tail that reads like a dime will also sound like a dime, a common occurrence with single frequency in bad ground, but does not happen to me with multi.

[Dances With Doves]

8 minutes ago, Steve Herschbach said:

Yup, what Jeff said. It has nothing to do with the target id information being presented in an audio or visual fashion. It’s is all derived from the same base information, and if one is inaccurate, the other will be also. An aluminum beaver tail that reads like a dime will also sound like a dime, a common occurrence with single frequency in bad ground, but does not happen to me with multi.

  With my xterra 70 many pulltabs  would up  average to coins. In places where  I  didn't mind digging more targets or when the  depth of  up average was where their would be old  nickles or gold rings  I did   not care to much.If the pulltabs and coins were both very deep because of soft ground,that up average thing the  machine did made it tough when you were focused on silver coins or you were cherry picking  .I like the nox Id. It is good enough for me to know it's a coin.

[kac]

My AT Pro with latest firmware and 9x12 concentric audio and vdi match right to the fall off (older firmware numbers would drop off but audio was still there). The MK has very reliable numbers when gain is not maxed out. 80-85 is where the machine should be and gain above that your simply pushing the machine. In Gen Mode that the vdi #'s are just raw unfiltered response.

When I say I hunt by audio first I do that to judge the target size and depth. My last large cent the numbers were all over the place and buddy passed over it with his Nox 800 for the same reason. Turned out there was a tiny bit of iron in the same spot. Coin was only 6" down. Out here hunting for size of an object has helped me more so than the numbers.

[Chase Goldman]

14 hours ago, Jeff McClendon said:

On the Equinox specifically, I hunt first by tone ID and use the numerical target IDs to support what I hear.

That^

14 hours ago, Steve Herschbach said:

It’s is all derived from the same base information, and if one is inaccurate, the other will be also. An aluminum beaver tail that reads like a dime will also sound like a dime, a common occurrence with single frequency in bad ground, but does not happen to me with multi.

The only thing I can add to this is that there are tonal nuances that can provide clues.  Yes if you have junk that gives the same ID as a desired target (Steve's dime/beaver tail example) you will get the base tone ID that corresponds to the visual target ID, but on some detectors, especially those that have audio modulation with depth, whether they are multi F or single F, then if the target is irregularly shaped and not perfectly round, can sometimes hear a distortion or tonal sideband nuances in addition to the fundamental ID tone that tell you maybe that is a corroded zinc, bent tab, or slaw even if you get a rock solid ID.  I have found that the Deus/Orx, especially in pitch mode gives you this nuanced information better than the Nox (but no target ID), similarly on the Nox, sometimes Gold mode can do this too.  I like 50 tones on the Nox because if the target ID is unstable (usually a dead giveaway for junk unless there  are multiple targets in the "hole" or more correctly under the coil - like KAC described with his large cent or a coin spill) you can just hear that right off and decide whether you need to circle the target to lock in the ID, move on, or just dig it out to be sure.  Bottom line, it is both the audio and visual ID information and how the target responds to coil movement and perhaps a shift in modes/frequency (that is why having that single frequency option on a multiF detector is important to me)  that all combine to give you the clues so you can make your best dig decision - I call this interrogating the target.  Regarding the Nox, since it has less tone modulation than other detectors, I find the pinpoint to be a useful tool for "sizing up" the target otherwise, Nox's gold mode pseudo VCO audio is also a useful tool, so I usually keep a gold mode program in my Nox's user profile slot to interrogate an iffy target.  Bottom line, though, these target interrogation techniques and audio clues work regardless of whether the detector is single or multi frequency, but the language varies from detector to detector due to the detector target ID feature implementation differences. 

[Steve Herschbach]

2 hours ago, kac said:

My AT Pro with latest firmware and 9x12 concentric audio and vdi match right to the fall off (older firmware numbers would drop off but audio was still there). The MK has very reliable numbers when gain is not maxed out. 80-85 is where the machine should be and gain above that your simply pushing the machine. In Gen Mode that the vdi #'s are just raw unfiltered response.

When I say I hunt by audio first I do that to judge the target size and depth. My last large cent the numbers were all over the place and buddy passed over it with his Nox 800 for the same reason. Turned out there was a tiny bit of iron in the same spot. Coin was only 6" down. Out here hunting for size of an object has helped me more so than the numbers.

Arguing that you see good results with your single frequency detector does not change the facts of this question. Yes, single frequency does well under many circumstances. Continue to use it all you want, nobody is saying you should not. It works well in your ground - great. Nobody is challenging you and how you detect, so no need for a defense. However, your observations change nothing about the reality of the multifrequency versus single frequency question. It is what it is, actual scientific facts versus anecdotal opinions. If somebody asks the question, I’m sticking with the science, not opinion, when answering the question.

This discussion says nothing about the Equinox being better than other detectors or not. Equinox is not a perfect implementation of multifrequency, just one implementation, and a first version only with room for improvement. Examples of this and that versus the Equinox still do not change the basic facts that properly implemented multifrequency has the advantage. Single frequency, single domain, has less information to work with, period. Single frequency has been developed to the nth degree over decades, every last drop squeezed from what it is capable of. No new single domain, single frequency machine will ever surprise anyone with what it can do. By comparison multifrequency processing is in its infancy with engineers just now beginning to utilize its full capability via high speed processing power and modern battery technology. The first cell phones were a hard sell versus old rotary land lines also. Believe whatever you wish, but multi frequency / multi domain complex processing is the future of metal detecting, single frequency, simple processing the past when it comes to new detector development.