Hunting by ear..... Audio tones on the X-TERRA

[Digger]

Here is a link to my blog post on Minelab's Treasure Talk entitled Hunting by ear..... Audio tones on the X-TERRA
It includes some audio clips on how I can differentiate deeply buried iron from coins, using multiple tone mode, zero discrimination. All you need to do to access Minelab's Treasure Talk is to log in (register) with a username and password. For those new to Treasure Talk forum, you can read each post in it's etirety by clcking on the "more" above the words "Posted by".

http://www.minelab.com/usa/treasure-talk/hunting-by-ear-audio-tones-on-the-x-terra

Don't hesitate to ask questions or make comments. Thanks. HH Randy

 

[TURNMASTER]

Very profesional

Jeff

 

[goldseeker4000]

Digger, Got a question. With the audio sound while in AM when you hit a coin will it always be sharp or definate no matter the depth.? Will certain old coins produce low tones at any part of passing coil over it? How about gold rings or silver?

 

[TomB]

I very seldom use the 99 tone on my 70/705. Got stuck on two tones and three tones. Thanks to this post the next time I go swinging I'm going to try this. Thanks Randy. HH TomB

 

[Digger]

If you are using multiple tones, the pitch of the sound will increase proportional to the conductivity of the target. The higher the conductivity number, the higher the pitch of the audio tone. In fact, there is one specific tone "tied" to each notch segment number. For example, a -8 will always produce a tone that is 130Hz and a 48 will produce a tone that is always 950Hz. The other 26 notch segments fall in between, but one separate tone is dedicated to each TID number.

Deeper coins will not produce as "loud" of audio response as shallower coins. But the tone and the "audio report" should be repeatable when swept from the same direction. The lowest TID I've dug on a coin was a 6 on an old US 3-cent nickel. The highest TID was a US silver dollar at 46. The TID or audio pitch will not be the same for a coin laying flat as it will a coin on edge. You can prove that (and learn what to listen for) with simple airtests of different coins at various distances from the coil. I do not believe that air test prove how deep a detector will detect in the dirt. But for audio reports and coil comparisons, air tests can be of benefit.

Silver rings usually produce a tone in the same range as silver coins of a similar size. I've dug gold rings with TID numbers as low as 4 and as high as 36. It all depends on the size of the ring, how worn it has become and the Kt of the gold. The smaller the ring, the lower it will read on the TID. It also depends on whether the band is broken or not. I have one ring that read a 22 when I dug it. It was an old class ring from the early 1900's, and the band had broken. When I passed the ring under the coil while holding the ends of the band together, the TID became a 32. HH Randy

 

[digmeahole]

If you are using multiple tones, the pitch of the sound will increase proportional to the conductivity of the target. The higher the conductivity number, the higher the pitch of the audio tone. In fact, there is one specific tone "tied" to each notch segment number. For example, a -8 will always produce a tone that is 130Hz and a 48 will produce a tone that is always 950Hz. The other 26 notch segments fall in between, but one separate tone is dedicated to each TID number.

Deeper coins will not produce as "loud" of audio response as shallower coins. But the tone and the "audio report" should be repeatable when swept from the same direction. The lowest TID I've dug on a coin was a 6 on an old US 3-cent nickel. The highest TID was a US silver dollar at 46. The TID or audio pitch will not be the same for a coin laying flat as it will a coin on edge. You can prove that (and learn what to listen for) with simple airtests of different coins at various distances from the coil. I do not believe that air test prove how deep a detector will detect in the dirt. But for audio reports and coil comparisons, air tests can be of benefit.

Silver rings usually produce a tone in the same range as silver coins of a similar size. I've dug gold rings with TID numbers as low as 4 and as high as 36. It all depends on the size of the ring, how worn it has become and the Kt of the gold. The smaller the ring, the lower it will read on the TID. It also depends on whether the band is broken or not. I have one ring that read a 22 when I dug it. It was an old class ring from the early 1900's, and the band had broken. When I passed the ring under the coil while holding the ends of the band together, the TID became a 32. HH Randy

Hi Digger! Great article!! I have a question... Why does this only work in AM mode? and also is this a feature that was designed into the machine or a trick that you discovered? I tried it yesterday and it worked!!! Just wish it would work in other modes besides AM ....

 

[Digger]

It isn't the All Metal aspect that makes it "work". It is the multiple tone functionality. Multiple tone mode works with any amount of discrimination. I frequently use a Pattern mode that only rejects notch segment -8 and notch segment +48. I built this Pattern in an effort to hear most of the targets, and still minimize the wrap around effect of deeply buried iron. When rejecting targets, each of the rejected targets cause the detector to blank out the Threshold and produce a null instead of a tone. Personally, I'd rather hear a tone than hear nothing at all. By hearing the tones, and knowing basically what notch each tone represents, I can separate multiple targets and evaluate most of them by their audio tone, without looking at the display. MHO HH Randy

 

[goldseeker4000]

Digger, will any coins, whether flat or on edge produce a negative TID. I unmasked all target ids on positive up to 48. So all neg tid are masked and also 48. Will I loose any coins under any situation by hunting this way?

 

[goldseeker4000]

Digger, I have seen this video for this Eastern European (I assume Russian or Ukrainian) company that has made an after market coil for the x-terra's called the NEL tornado 12x13 DD. do you know anything about this coil. I would be scared that it might permanantly damage the internal workings of my 705. What do you think of this coil and should x-terra users stay away from it? does Minelab have any plans to make a larger deeper seekig coil for the x-terra's for gold hunting.?

 

[Digger]

If your detector is properly set for NC, GB and Sensitivity, and there are no adjacent targets, all US coins will produce a + TID. In that scenerio, flat coins will repeat the TID, regardless of the direction the coil is swept. With coins on edge, the TID provided when sweeping across the greater mass surface will be a higher number than the TID provided by sweeping along the thinner "edge" (smaller surface to generate eddy currents) of the coin. Air testing can duplicate this process fairly accurately. HH Randy

 

[Digger]

There is quite a lengthy discussion about those coils currently ongoing here on the forum. I've seen the videos, know nothing about the company who is making them, know nothing about the coil other than what is shown on the video and am also apprehensive due to compatibility issues. I won't tell anyone what to buy, as far as accessories are concerned. But I will tell you that I am staying away from them for the reasons stated in my recent post to that string. .. http://www.findmall.com/read.php?55,1427229,1437557#msg-1437557

JMHO HH Randy

 

[goldseeker4000]

Digger, one more question. I was told that the frequincy on the x-terra is actually higher than what it actually is. For an example the Hf of 17.5 KHZ (or what ever it is) is closer to being around 60 or 70 KHZ. I was told because ofthe brain in the coil as well as the control box and cutting edge digital technology that they can acheive with the 705 Gold bug II and eureka gold catagory frequencies with a actual lower frq that is part of x-terra class HF. Is this true or bull crap. Can you explain . Also how does the x-terra 705 compete with any of the explorers by Minelab? In regards to sensitivity, depth, and discrimination.

 

[Digger]

Without having the capability of analyzing the frequency output of the coils, I have no way of knowing the exact frequency of the X-TERRA coils. Based on my discussions with Minelab duing the time I Field Tested the X-TERRA's, I would have to "go along" with what they told me....... LF is 3 kHz, MF is 7.5 kHz and HF is 18.75 kHz. The overlap (and comparison) that you refer to might be based on the fact that the Eureka can operate at 6.4 kHz, 20 kHz or 60 kHz. As you can see, two of those Eureka frequencies are closely replicated by the X-TERRA.

As to depth of detection compared to the Explorer series......when properly set-up, the X-TERRA can hold its own on raw depth. I find the HF coils are just as sensitive to small targets as any of the FBS detectors I've owned. As to discrimination.......... the FBS detectors provide simultaneous ferrous and non-ferrous target analysis and display both on the screen. The X-TERRA analyzes both the ferrous and conductive properties, but only displays one or the other. (negative notch number or positive notch number) To me, this doesn't make the FBS detectors capable of finding more good stuff. But it can make a difference in the amount of trash you dig to find it. JMHO HH Randy

 

[goldseeker4000]

Digger, yesterday I was out hunting for coins and I was working an old lot where a house was torn down. I was getting noises every where. I did what you said to ajust the sinsetivity. After noise cancel and ground balanced I went into sen and set it to 15 and raised and lowered the coil whil increasing the sen till it got unstable and chirpy, then backed it down till it was stable then proceeded to search. I was getting noises constantly and I had to really listen for a tone that did not turn into a blend of low tones, which I assume is called rap around. I got some signals that every once in a while when I would sweep over target would get a low tone then go back to higher good tone. I decided to dig and I would dig up a memorial lincoln pennie. I thought this is odd and I will have to be very careful. Why is a good target producing inconsistant low junk tones mixed in with a consistant good target tone. It makes me really unsure of good targets I might be walking over and deciding not to dig now. Also I opened up segments on program 2 that coins can read on as you had on your list, but I am concerned if it is still posible to miss any type of coins, old and deep because of useing program two. the only segments on program two that I have blocked on discrimination is all the neg numbers and 48. I have hunted 4 days now in areas that are old spots dating back at least to the early 40's and some daiting back to 1910 and all I am finding is new coins. What would cause this? Help

 

[Digger]

Sounds to me like the ground is full of ferrous trash. With the ferrous targets set to reject, you don't hear them. All you hear is silence when you pass the coil over them. Depending on your sweep speed (and your choice of coil) those pieces of trash can either skew your coin readings or mask out the coin all together. By the way, what coil are you using?

If you have all the ferrous (negative notches) rejected, the X-TERRA will "blank out" while the coil is passing over them. Setting a detector to reject certain properties does not mean the detector isn't detecting them. It is! The only thing that rejecting notches does for you is that you get a null sound instead of a tone. Personally, I'd rather hear the low tones of ferrous targets and let my ears sort them out. I think nulling leads us to believe that there is not much trash at a site, and we sweep too fast.

My suggestion would be to have lowered the Sensitivity before you do your ground balance. Try this........turn on the detector and put it into the All Metal mode. Set the Sensitivity to about halfway on the scale. Scan the soil to find a spot that is totally free of any metal objects. Hold the coil about a foot off the ground (with the coil flat to the ground as if you are detecting), and perform a Noise Cancel. After setting the Noise Cancel Channel, do your ground balance over that spot that is totally free of any metal. After you've set the proper NC and GB, you can turn up the Sensitivity to a point the detector either chatters when you sweep the coil, or becomes erratic. If you keep it in all metal or reject fewer targets, and use multiple tones, you will be able to tell if the problem you've experienced is due to an abundance of ferrous targets or if there is something else going on. Let us know what you find out. HH Randy

 

[SeniorSeeker]

Thanks Digger! I'll Give It a Go.

 

[goldseeker4000]

Hello Digger, just got back from detecting. yesterday and the last few days I have been searching with the 6" DD HF but today I switched to the 9.5" concentric MF. I would hunt in all metal and if I got a target that I thought was iffy I would switch to Program 2 that I eliminated the neg and 48. I am starting to really like hunting in AM and it is forcing me to sweep slower. I double check every tone that is consistant with Prgm 2 and AM. I have only dug up one old coin in two weeks, a 1947 wheatie. Could just be the ground or perhaps the places I am searching have already been hammered by someone else. I definately know I need to invest in a Garrett propointer. I will dig at the intersection of perpendicular passes and pull out the plug and it will still be there. I end up with a larger hole and come to find out it is off to one side. I am hunting in wet ground. Perhaps the wet ground is causeing a large halo. the chattering I an hearing is in AM but when I hunt in prgm 2 I do get alot of nullingon almost every pass. So I assume I probably am still to high on sensitivity. I did my noise cancel and then ground balance and then set sen., it quieted down from chatter at 26 and that is where I was hunting at. Do you think it is still too high? Which coild will be best for deep coins?

 

[Digger]

I also like the Garrett ProPointer. And it could be the places you've been hunting have been pounded to death. But honestly, I don't think we ever get them all!

One suggestion I might make as to finding the target off to the side of the hole is to be very methodical with your sweeps. Make a mental note of where you think the target should be when making your initial X over the spot. Relate the location to a blade of grass, small pebble or a clod of dirt. Anything that you can see on the surface, directly above where you suspect the target is. Then, rotate around 90 degrees and sweep back and forth over the target. Then, instead of digging where the two "lines" intersect, go back over the area in Pinpoint mode. Listen for the sound to peak. If the location of the target seems to have moved around, it will likely be trash. Most generally for me, it is a bent nail down on the edge of the hole. And, for some reason I've not figure out yet, the darn thing is usually located in the back - left corner of the hole????? If I ever figure out why, I'll let you know!

If your detector is quiet with a Sensitivity of 26, go for it. I like to hunt with as much Sensitivity as I can, without causing too much feedback to the coil. By feedback, I mean chatter when you sweep, false signals as you switch directions on the sweeps or false signals that seem to "go away" when you sweep back over them. When that happens, I will lower the Sensitivity a click or two, and see if the symptoms go away. I think you will find that you can run more Sensitivity when the ground is dry, compared to when that same patch of dirt is wet. An analogy has been made between Sensitivity and headlights. If conditions are clear, you are best served with your high beams on. If it is foggy (ground clutter), you can see farther into the night with the low beams. Same holds true with Sensitivity and "ground clutter". Too much Sensitivity and the signal bounces right back to the receive circuitry. Just as your high beams bounce light back toward you when driving in fog.

Theory is that the larger the coil, the deeper it will detect. And, that is true to a certain degree. But since there aren't any 9-inch DD coils, nor are there any 10.5-inch concentric coils, it's tough to make a fair comparison. It would seem logical that the 10.5-inch DD would hunt deeper than the 9-inch concentrics. However, in my moderately mineralized soil, I get just as good of depth with the 9-inch concentrics as I do the larger DD coils. That is what lead me to come up with my theory regarding ground balance settings. Remember, the higher the mineralization, the lower the ground phase reading will be. And the lower the mineralization, the higher the ground phase number will be. I believe that if your ground phase setting using the stock coil is a ground balance number of 28 or higher, the concentrics will hunt as deep or deeper than the larger DD coils. On the same token, if you have a ground phase reading of less than 28 when properly ground balancing the stock concentric coil, that suggests your ground is more mineralized and you would benefit from using a DD coil. JMHO HH Randy

 

[Beale]

Hey Digger! When I had my 70 I always hunted by tones. I never used AM but 3 tone. I would love to have another 705 and give your method a go, Beale.

 

[goldseeker4000]

I hunted yesterday and I hunted ground that was pretty darn quite and it wasn't to damn noisey and some ground that was so I am sure that there is alot of tiny pieces of metalic garbage most places I hunt. Went out to an old town site near Bigfork, Montana named Holt and this old man gave me and a friend permission to hunt. He said you probably won't find anything as his son has a high end detector and has hit the whole grounds of the town site and pretty much cleaned it out. So we detected and I found a 1905 V nickel between an 1"-2" down. It was bent and lookes like it had been shot with a 22 cal. bullet years ago on its edge. that is my oldest coin to date since 1980.Detector seems to be working fine, just some ground I really have to be really paying attention to sounds. I can't remember all the tids that were on the screen when pinpointing but I do remember that if I held it over the coin before I dug it up that each time I held it over it, it would breifly show a -2 then go to I think around 10 maybe 8 and 12. I wonder if it put up the -2 because the coin was bent. I have come to a conclusion that why I haven't been finding old coins is due to location and probable fact that one of two guys in town have already hit these areas i am working and possibly pulled out the old coins already.