X-70's adjustable threshold

[Carolina Phil]

Does the X-70's adjustable threshold provide any depth advantage over the X-50?

 

[Mike Bearden]

before we get the answer on that question unless Andy can provide it from all those in field hours he spent.
When I first started hunting yesterday I was running the threshold volume at factory preset and noticed the break in the threshold in patterns mode when the coil was over a discriminated target. I also noticed a few times where the depth scale was pegged and I only heard the threshold break with no ID or target sound.
I just don't remember if it happened before I went to all metal mode or in patterns, but it happened.
I usually hunt in all metal and can see where the threshold will be valuable in the relic fields but I turned it down to zero while coin shooting yesterday I wasn't in the kind of a site to dig 12" targets.
Mike

 

[Andy Sabisch]

In my usage, I did not find any targets that would alter the threshold and not produce a signal that turned out to be any good - always turned out to be small or deep iron when I took the time to see if I was missing anything.

i think that the big use for the Threshold adjustment will for those hunting in the Prospecting mode where they are looking for faint fluctuations in the threshold for the deep or tiny nuggets and run with a threshold.

If I understand your question, you want to know if hunting with a threshold will give you an edge over the X-50 which runs silent. This is not an Explorer or Sovereign and I have not seen any increase in detection depth by listening for changes in the threshold that would not otherwise have produced a "BEEP". Regarding Mike's comment about being in a Pattern or All-Metal, remember that the All Metal search mode is NOT a true all metal search mode but simply a Pattern with all the notches accepted. It is a subtle but actual difference in how it detects and responds to targets. The Prospecting mode is a true all metal mode as many of you know All-Metal search modes to be (like the Garrett GTI 2500).

Personally I still tend to run the X-70 silent for coins and a slight threshold when relic hunting just to hear the iron nulling out to let me know I may be close to a camp or some other site I may be looking for.

Hope this helps

Andy

 

[Jackpine Savage]

Andy,

With a slight threshold can you tell when you have the sensitivity set too high for ground conditions? ie: faint spurious ground noises ect.

Tom

 

[BarnacleBill]

but here goes.

There are many individuals, including myself, that started with analog machines, and you had to live with a threshold. It was needed because of the discrepancy between how deep the machine could signal a target, & how deep it could identify it. There are many who hold onto that concept like a blankie, fearing they will miss that ultimate deep one without an audible threshold. I am sorry, time has moved on and many machines are now DSP based. One of the driving forces in all electronics is to get signals out of the analog domain and into the digital domain as quickly as possible, so that they can be manipulated. Pay close attention to the word I used, "manipulated".

Perhaps an analogy. Take a turntable and record from days of old(yes I know they're back in vogue with some audiophiles), an analog device from the needle cartridge up through to the loudspeakers. Records were prone to all sorts of damage and wear, so some amplifiers had a rumble and hiss filter that you could switch in. These were very crude filters by today's digital standards, and they removed useful audio information, which decreased the fidelity, but made listening bearable.

Today you can download very cheap software, record those old records onto your computer, and remove all those nasty pops & clicks with a precision that dwarfs what was done previously. You're now in the digital domain, master of you're own little universe, deciding how aggressive you would like the pop/click filtering to be etc. The metal detector designer now has those same tools, but many times more powerful, because they need to do things in real time.

In the coins mode, from the limited time I have spent with the X70 as Andy has stated, there is very little that it can hear, that it will just blank the threshold and not produce an ID tone. Every instance that I checked a blanked tone, meant a rejected target, NOT a target so deep that the Disc routine could not identify it. I stopped using it in coins mode, because I felt it was just redundant, that after switching to AM, only to hear an iron low tones for the umpteenth time. I don't need the detector to tell me the same thing twice, and chew up batteries for the pleasure.

Maybe somebody out there is going to have the threshold blank on a target 18 arrows deep and not ID. But you're going to have to prove it with a video, and a signed note from your mother that it wasn't staged.

Back to "manipulated". Now please don't go out and fuel up the black helicopters, or call the monthly meeting of the star chamber to order. In software, within a DSP or microprocessor, I can create an artificial threshold that has absolutely nothing to do with any signal level within the detector. Thats right a manufactured, digitally constructed, fake threshold that has nothing to do with anything. "Well see I have this friend John and he won't buy any detector that doesn't have a threshold and........". Meanwhile back at the lab, no problemo, we'll just whip up some code, and John'll never know the difference. Please, please, please don't run off and say that Minelab produced a fake threshold on the X70! Or this is the reason another modern detector with threshold is acting the way it is, and I don't like it, since it's not like threshold from the old days, they musta faked it to get me to buy the machine.

I'm only trying to get across how differently signals are processed in this century, as opposed to the last, which was the century of "analog threshold".

All right boys, let loose the hounds!

HH
BarnacleBill

 

[Andy Sabisch]

You are exactly correct.

Many, many years ago when I started with BFO and then early TR and finally VLF units, the threshold was essential to detect deep targets on the fringe of detection depth. Many users never figured that out and as a result those that did made some great finds using that technique.

As BB states, time has moved on and in the motion discriminate mode, you either get a signal or you do not get a signal but when you do, it BEEPS! No faint change in the threshold. So there really is no need to hunt with a threshold in COINS to try to get more depth you will not see.

Now in the Prospecting mode, that is a different story. There you are looking (or should I say listening) for any faint change - the more attuned you are to the changes, the smaller or deeper the target you will be able to detect. I'm sure the dedicated electronic prospectors can add their comments here.

So yes, BB is 100% correct, not just for the X-70 but most detectors currently on the market . . . . . threshold waivers for max depth are for the most part a thing of the past (OK, yes there are exceptions).

Andy Sabisch

 

[Andy Sabisch]

You will be able to hear the ground noise from a sensitivity value to high for the conditions with or without the threshold. Actually, you can get a bit more on the sensitivity with it quiet and not be bothered by the constant waivering threshold tone.

One person's opinion - mine - is when coin hunting, run silent to save battery life, not be annoyed by meaningless chatter and focus on beeps which are the goodies you want to find.

Andy Sabisch

 

[steve herschbach]

Hi Andy,

I figured that was my cue.

It is normally true when nugget detecting that a finely tuned threshold sound can reveal targets based on a tiny waver so small that it might almost seem imaginary.

But while it makes sense to hunt that way if you are right in the gold, it is not really practical for general prospecting, as tiny ground changes or hot rocks will produce the same small wavering signals. I have done quite well with my Fisher Gold Bug 2 in the non-threshold iron id mode as the machine is so hot that extremely tiny nuggets will bang out loud and clear in the iron id mode.

I have yet to really put the X-Terra 70 to the test, but when comparing signals on a small item in the coin mode with those in the prospecting mode it is debatable which mode would be the most advantageous. The prospecting mode is more modulated and so deep items have a very faint signal. A target at the same depth in the coin mode bangs out louder.

I can see the coin mode in 18.75kHz as being a practical nugget hunting mode for general prospecting, especially hunting larger nuggets in tailing piles. The prospecting mode may be better suited for that real serious down and dirty detecting one does when actually in a patch of gold.

It is a shame Minelab decided to remove the target id information while in the prospecting mode. That is something the White's MXT does very well. One can always debate the wisdom of not digging targets while nugget hunting, but I'll always opt for more information over less when given the choice. Putting a big numeric iron mask number on the screen is redundant to what is displayed below via the segments and so serves no real purpose. I'd rather the unit had an expanded iron id range and that the unit display an iron VDI number rather than engage the blanking.

The iron mask blanking appears to hold on way too long, and so it will be best to hunt in prospect all-metal, then toggle to iron mask to check items. But more time needed to check that out yet.

Thanks for all the info you have been putting out on the X-Terra series, Andy. I and lots of others really appreciate what you do!

Steve Herschbach
Steve's Mining Journal

 

[BuckeyeBrad]

but allow me repeat since it's my preference and it lays a tad counter to other opinions in this thread. The threshold is of multi-benefit and importance to me. Let's say I'm hunting with the notches wide open except for the lower couple which is common for me. I don't necessarily want to hear the iron tone with the lowest and smallest of the iron but with the threshold present so it nulls over discriminated targets, I still can tell when and if small iron is present so I can adjust my sweep behavior and analysis accordingly. Same info/audible "input" without listening to and needing to sort through all the iron tones. Important and the best of both worlds to me.

 

[steve herschbach]

Hi BuckeyeBrad,

You are 100% right on. If a person is going to reject any target segments as opposed to using a wide open tone approach, threshold nulling can be very important in relaying that "rejected item" information. Multiple nulls per sweep can tell a person to slow down, or hit it from multiple angles, or that it is time to switch to a small coil.

Some swear accepting all items and sorting by the tones results in less target masking, but I've always questioned whether that is true on digital units. I'm doubtful that an iron tone is masking an item any less than an iron null. On one hand the machine has identified the target as iron and made the appropriate tone, and on the other it has identified it as iron and nulled the tone. The only reason one would mask more than the other would be if the recovery rate is different for some reason when sounds are nulled.

The null in X-Terra 70 coin mode is transient but the iron mask "blanking" in prospect mode really drags. I'm curious what the difference is in the way the two modes reject items. I had hopes that the 20 levels of iron mask would offer a fine degree of iron rejection that would be applicable for more than prospecting but my initial run in with the blanking was kind of scary.

Steve Herschbach
Steve's Mining Journal

 

[Carolina Phil]

n/t

 

[Digger]

Over the years, whether it be a meter-less detector, an analog meter detector or the digital readout, I have come to the conclusion that I can learn just about as much about a target by what the detector don't tell me as by what it is trying to tell me. Depending on the specific detector, that could be a slight negative needle deflection, boucing LCD numbers or just a nulling of the audio tone. These indicators might tell me when I have gotten into a high concentration of nails, trash or even hot ground. With a true threshold tone capability on the X-70, I can avoid over-driving the sensitivity (as I have done on non-threshold based detectors) and set it to a more stable level. Besides that, a very slight hum in the background might overshadow that darn ringing noise I hear all the time! HH Randy

 

[John LA]

n/t

 

[BuckeyeBrad]

n/t

 

[wpaxt]

My feelings exactly. Just let it be quiet until I find something.

Bill