Threshold vs No Threshold
- Thread starter New Kid
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Rudy
Admin
You might want to look here.
http://metaldetectingforum.com/showthread.php?t=15979
http://metaldetectingforum.com/showthread.php?t=15979
Kolby72
Forum Supporter
Well on my V3i for instance if your in coin mode you will be canceling out a ton of trash and iron. With the threshold oni can still here the canceled out stuff as a muffeled tone... Comes in handy near castles where there are coins and iron objects
Just to expand a bit
I am only familiar with All Metal audible threshold machines, so I want to talk a little about how they react. Rudy is correct, you want your threshold set to a constant low hum that is just audible over background noise. Setting it too high will help you miss targets.
In all metal, like when you are looking for gold nuggets with a Tesoro Lobo, or Fisher Goldbug II, you are listening for "Positive Breaks," or a normal "Zip-Zip" signal, and "Negative Breaks," which are silent breaks in the theshold. In Rudy's example, Silent breaks or "nulls" mean Ferrous metal, in my example, they are DEEP targets. I am not sure why a discriminating machine would use an audible threshold. Maybe Rudy has the answer..
I am only familiar with All Metal audible threshold machines, so I want to talk a little about how they react. Rudy is correct, you want your threshold set to a constant low hum that is just audible over background noise. Setting it too high will help you miss targets.
In all metal, like when you are looking for gold nuggets with a Tesoro Lobo, or Fisher Goldbug II, you are listening for "Positive Breaks," or a normal "Zip-Zip" signal, and "Negative Breaks," which are silent breaks in the theshold. In Rudy's example, Silent breaks or "nulls" mean Ferrous metal, in my example, they are DEEP targets. I am not sure why a discriminating machine would use an audible threshold. Maybe Rudy has the answer..
Basically I get information from the threshold. If you read Rudy's link you can find out some good stuff.
With the threshold I can tell if my ground balance is positive or negative.
I can tell by nulling when my detector coil approaches iron
I can tell by crazy buzzing and chirping when the detector is suffering from EMI or some other interference.
I can tell from prolonged silence that the ground is heavily mineralized and to slow down my swing until the threshold returns or lower my sensitivity.
The Sovereigns and Excaliburs have a threshold that retains the tone of your last detected target. If the threshold changes and you miss the beep you still know you passed a target.
To me a steady hum is a happy detector. I know I'm stable and working correctly with a good threshold.
Every once in a while I'll use a detector without a threshold. The AT Pro comes to mind. It bugs me not to have one.
With the threshold I can tell if my ground balance is positive or negative.
I can tell by nulling when my detector coil approaches iron
I can tell by crazy buzzing and chirping when the detector is suffering from EMI or some other interference.
I can tell from prolonged silence that the ground is heavily mineralized and to slow down my swing until the threshold returns or lower my sensitivity.
The Sovereigns and Excaliburs have a threshold that retains the tone of your last detected target. If the threshold changes and you miss the beep you still know you passed a target.
To me a steady hum is a happy detector. I know I'm stable and working correctly with a good threshold.
Every once in a while I'll use a detector without a threshold. The AT Pro comes to mind. It bugs me not to have one.
arsenic
New Member
Awsom post Rudy, thanks for sharing it. It makes me second guess my AT Pro purchase that is scheduled to be delivered any hour now! Lol
Jressman
Elite Member
The threshold on my Minelab Etrac is soothing 
Iron Patch
Elite Member
A null is simply the threshold going quiet when your coil passes over a discriminated target.
There's only two detectors that I own/have owned that I consider having known very well, and they are the GTI 1500 and Minelab Explorer. The Garrett is a good example of a detector that using no threshold is very forgiving, but the Minelab is just the opposite because understanding the null is a big advantage in understanding iron, and of course if you run it silent search there won't be sound to null.
There's only two detectors that I own/have owned that I consider having known very well, and they are the GTI 1500 and Minelab Explorer. The Garrett is a good example of a detector that using no threshold is very forgiving, but the Minelab is just the opposite because understanding the null is a big advantage in understanding iron, and of course if you run it silent search there won't be sound to null.
Rudy
Admin
I am only familiar with All Metal audible threshold machines, so I want to talk a little about how they react. Rudy is correct, you want your threshold set to a constant low hum that is just audible over background noise. Setting it too high will help you miss targets.
In all metal, like when you are looking for gold nuggets with a Tesoro Lobo, or Fisher Goldbug II, you are listening for "Positive Breaks," or a normal "Zip-Zip" signal, and "Negative Breaks," which are silent breaks in the theshold. In Rudy's example, Silent breaks or "nulls" mean Ferrous metal, in my example, they are DEEP targets. I am not sure why a discriminating machine would use an audible threshold. Maybe Rudy has the answer..
Thanks for reminding me Terry. Desirable targets that are very deep, will often have their signals phase shifted into the ferrous range and cause a threshold null. So when the target is deep, don't assume a null in the threshold is due to iron, it could be a good target.
