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Old 07-15-2017, 10:26 AM
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ToddB64 ToddB64 is offline
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Default Threshold Setting...Negative vs. Positive

Hi !

In BottleCapKing's post #21 located here > Detectors and Gear > All About Detectors >Thread by Dsparil Titled: Gain on Forum page #3, BCK says "When you increase sensitivity, you are lowering that threshold. When you decrease Sensitivity, you are raising the threshold."

Now, with reference to the attached image, which I copied and pasted from Digger27's post #22 in the same thread mentioned above, looking at this image it seems obvious that when you increase Sensitivity thus lowering the Threshold (depicted as a horizontal bar in the image), you are exposing more audible signals.

So, having said the above I come to my question, which is "when you lower the Threshold are you creating a Positive or a Negative threshold setting ?"

I've seen those terms used before, but was never sure how to apply them to threshold.

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Old 07-15-2017, 10:53 AM
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On the Fishers negative numbers raise the threshold audible limit and cuts out targets...-9 is the lowest we can go.
Positive numbers lowers the threshold so adds targets, up to +9.

I guess you can consider negative thresh = less targets....Positive thresh = more targets.

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  #3  
Old 07-15-2017, 03:40 PM
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Default Threshold Setting...Negative vs. Positive

Originally Posted by DIGGER27 View post
On the Fishers negative numbers raise the threshold audible limit and cuts out targets...-9 is the highest we can go.
Positive numbers lowers the threshold so adds targets, up to +9.

I guess you can consider negative thresh = less targets....Positive thresh = more targets.
Digger27 !

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Old 07-17-2017, 08:25 AM
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Originally Posted by DIGGER27 View post

I guess you can consider negative thresh = less targets....Positive thresh = more targets.
This is my experience with the F70 as well...Since I Park/Sportfield/Beach/ and Totlot, for clad and jewelry, I want the 'good' targets to ring true and clear and not hear so much junk backscatter, so I begin a hunt with a -3 thresh and figure it out based upon what the dirt/location is saying....

Trying to hear the depth and target profile...finding the optimum settings for a particular site and learning what they are telling us takes a bit of time behind the coil...Ya cant get close to Totlot poles running too hot, and you cant sweep a beach to maximum effect by running too soft...especially when you are zipping along and highflying the coil...

I guess if you are a relic hunter out in a beanfield, you want to hear 'more' targets..If you are a cladder working a park, you want to hear less targets...Actually you want to hear all GOOD targets comfortably, and this is where adjusting thresh can assist......

Disc, Sens, Thresh, Tones....find what you are comfortable with and YOU understand the best and work them for a while...It all starts making sense what they all do in conjunction with each other and the ambient conditions/location...One you got this, you can then focus on speedy pinpointing and retrieval methods and other ancillary skills to maximize your time afield...

It certainly is a study, put into practice, and luckily we have people here that like to study and practice!

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  #5  
Old 07-17-2017, 09:01 AM
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Very well put Mud-puppy !

Thanks,
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Old 07-17-2017, 11:43 AM
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Default Threshold Setting...Negative vs. Positive

Hi !

I just had the following thought process regarding the interplay between Sensitivity, Threshold and Discrimination, which brought me to a conclusion.

I'm not trying to steal wind from anyone's sails, just thought offering some well-known aspects in different words might help someone.

Since raising the Sensitivity lowers the Threshold, exposing more signals to the processor circuitry, depending on if and where the Discrimination was set, some of these signals will be nulled out (no audio or visual report.).

Therefore, tagging onto the previous advice of Digger27, my suggestion, particularly with the Compadre, would be to hunt in All Metal for maximum depth and signals, then after getting a signal thumb the dial UP/DOWN, analyzing the tones as a target "comes in" full and then decide whether or not to dig.

Of course, the safest way would be to dig everything in the beginning of your hunt so as not to miss any good targets, until boredom and/or fatigue set in and then forego digging some of the iffy targets with the thought of reevaluating those at the beginning of a future hunt when you are fresh.

I hope this helps to correlate these aspects of metal detecting for someone.

Good Hunting !

ToddB64

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Last edited by ToddB64; 07-17-2017 at 11:59 AM. Reason: adding text
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  #7  
Old 07-17-2017, 07:10 PM
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Good thread guys. Todd I think you're right about the AM theory and checking each one. At the VERY fringe of my IDXPros ability, most targets sound like iron. I do have it modified and it's kinda hot so that might be why. I do have a Compadre but haven't toyed with it much,as I'm a deep silver hunter. But I'll get around to the Compadre at some point...sure is lighter than anything else in my closet!

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Old 07-17-2017, 09:26 PM
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Default Threshold Setting...Negative vs. Positive

Originally Posted by IDXMonster View post
Good thread guys. Todd I think you're right about the AM theory and checking each one. At the VERY fringe of my IDXPros ability, most targets sound like iron. I do have it modified and it's kinda hot so that might be why. I do have a Compadre but haven't toyed with it much,as I'm a deep silver hunter. But I'll get around to the Compadre at some point...sure is lighter than anything else in my closet!
IDX....Thanks for replying to this thread !

I imagine you've read up on the little "C". It's the Tot Lot King for coins and Jewelry at modest 5"- 6" depths, maybe a little more, very sensitive and treasure near the big iron must to it's double-beep.

ToddB64

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Old 07-17-2017, 11:42 PM
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I know one thing from the couple times of screwing around with it for a bit...it's fast! Like....ludicrously fast! Thanks Todd,I'm sure it'll be a lot of fun to go ring hunting with,as that's actually why I bought it. I'll have a head start coming from the single tone Whites, just have to tune my melon to the quality of the signal again.
I'll be sure to follow along...

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Old 08-04-2017, 05:31 PM
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It would be helpful on the graph at the top of this post if the negative and positive threshold setting values were written along the y axis. if we say the threshold horizontal line on the graph is given a 0 value (0 setting on the detector) , and increasing positive threshold adds more targets , the y axis should be given increasingly positive values the further the axis goes BELOW the shown line. That way, the blue areas (audible signals) should get larger.

Or am I wrong? Can someone who knows this stuff fix the graph? I think it would help novices understand thresholds better.

This is a bit confusing, as a standard y axis in most math graphs shows increasing positive values ABOVE the y axis.
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