Auto vs. manual sensitivity question

[robertj298]

Was finally able to get out for a bit today and was playing around with my etrac. I usually run auto +3 sensitivity and the etrac runs pretty stable on that. I tried a little test. Where my etrac was running 20+3 on auto if I would switch it to 23 manual it wasn't near as stable as the auto setting even though the settings match up pretty closely. Any reason why this is so?

 

[Prep1957]

In auto you were running at 20,in manual you were running at 23 you want to run as high as you can.It was more unstable because you were running hotter.Beware of anything Auto on any detector.Auto is personal setting of the Manufacture to run a detector smoothly not better or deeper.

 

[robertj298]

In auto you were running at 20,in manual you were running at 23 you want to run as high as you can.It was more unstable because you were running hotter.Beware of anything Auto on any detector.Auto is personal setting of the Manufacture to run a detector smoothly not better or deeper.

So when my auto settings show I'm running 20 that is with the +3 already added? I guess I just assumed when I'm running auto +3 if the machine shows 20 I'm actually running 23.

 

[Prep1957]

In auto running 20 +3 you are running somewhere between 20 and 23 maybe,who knows?.I am impressed that you picked up on the difference so quick most Etrac users do not.I should tell you each detector is different they come from a factory that strict quality controls are set so each product comes out the same,that is almost impossible to do Minelab does an out standing job trying to do this.Having said that do not get hung up any number on your Etrac it is best attempt to give you an accurate guideline.Your ear told you that it was not the same between auto 23 and manual 23 trust your skills.It is just a number ,you are hunting to find the best treasure, getting the best performance from your detector.I have friends that cannot hunt because there machine readings are not as accurate for the money they paid for them it bothers them so bad it affects there, hunt they will be looking for the next great high dollar detector.Then they are mad because lesser machines are beating his machine at hunts.Etrac is the best there is for now for average over the counter detector.

 

[Goes4ever]

I run in auto +3 98% of the time, RARELY am I ever on a site clean enough for me to run manual, way too much chatter. I have a couple sites where I can run manual 30 and it runs quiet as a church mose, and other sites where I cannot even go 20 manual without it chirping like crazy.

But don't worry if your at 23, your getting pretty deep, you won't miss much

 

[LabradorBob]

I always run manual, most of the time looking for silver,the only time i use auto is to check to see what kind of ground i am running in.
auto will tell you how bad the soil is.
Then right back to manual i go.

LabradorBob

 

[robertj298]

I always run manual, most of the time looking for silver,the only time i use auto is to check to see what kind of ground i am running in.
auto will tell you how bad the soil is.
Then right back to manual i go.

LabradorBob

So is mineralization what causes the changes in sensitivity or are there other factors such as trash in the ground or electrical interference?

 

[LabradorBob]

yes the mineralization is the main factor relating to the sensitivity.
trash can be a factor too if very dense. electrical interference will cause a lot of interference and noise.

 

[moonshine]

So when my auto settings show I'm running 20 that is with the +3 already added?

Yes.

I guess I just assumed when I'm running auto +3 if the machine shows 20 I'm actually running 23.

No.

Whatever number is shown, thats what youre running.

One other thing, auto "XX" is not equal to manual "XX" (any number). Reread pages 54 and 55 in the instruction manual.

 

[Agseeker]

I think the point of robertj298's original question has not been answered; ie. why is the detector less stable at Manual 23 than Auto 20+3? If you read pages 54-56 in the manual you will find that the E-trac has three internal signal channels (high, medium, and low). In Auto Sensitivity the number on the right is the average of the three channels while the number on the left shows the highest level of the three channels. In Auto Sensitivity, the detector operates each channel at its optimal sensitivity simultaneously. In Manual Sensitivity the number on the right is the suggested sensitivity (an average of the three channels, the same as when running in Auto Sensitivity). The number on the left is the actual number you have selected. Here's the real difference: In Manual Sensitivity all three channels are set at the number you have selected. This is the real reason the detector was less stable in Manual than Auto. You only have one channel operating at its optimal sensitivity. The other two channels are running "hotter" than the optimal levels for those channels. Page 55 in the manual states "The important difference between Auto and Manual is that all of the channels are set to the same level in Manual and if set too high may cause unstable Target IDs."

I'm going to make an assumption here (and we all know what that means). Since the E-trac is operating three channels simultaneously in Auto Sensitivity then when Auto +3 is selected the detector is not running at +3 of the right or left number, but +3 in each of the channels individually (since the right number is an average of the three channels and the left number is the highest of the three channels). Even if the right and left numbers do increase by +3 on the display then that is still only showing the highest sensitivity on the left and the average sensitivity on the right which as moonshine states is not necessarily equal to the same left hand number in Manual Sensitivity.

Any Minelab engineers want to weigh in on this discussion and tell us how this really works?

 

[LabradorBob]

When using Auto Sensitivity the E-Trac will show your sensitivity selection as well as the

 

[utahshovelhead]

I might add a little bit here: In really good areas with known old deep coins I will (after hunting in auto) try to successively up the Manual sens to levels that tend to be unstable to see if i can "force" a bit more out of the depth i am getting. It is not fun and takes alot of concentration and effort and has paid off but so rarely that I do not do this very often and I'm not fully convinced that I would not of found the coins with just good concentration everthiing else running good in auto.
I'm sure many of us our trying to find ways to max the sens with more stability and would love to hear some expamples from any of you.

 

[Agseeker]

I conducted an air test last evening to see for myself the difference between auto +3 and manual. This was done inside my house with the detector in a horizontal position on two wooden chairs. I used a silver "war" nickel, a silver dime, and a silver quarter. I made the measurements with a plastic metric ruler and converted the metric reading to inches. The bottom of the coil was perpendicular to the floor. All setting remained the same other than the sensitivity. The 11" coil is the stock coil and the 4.5x7" is a DD EQ Pro Excelerator coil.

11" coil Auto +3 Manual Manual Manual The signal was becoming unstable at setting 19, worse at 22, and much worse at 25. It's interesting that the depth didn't increase once the stability worsened.
(reading 19) 19 22 25

nickel 4.2" 7.1" 7.9" 7.9"
dime 5.4" 7.1" 8.3" 8.3"
quarter 5.8" 7.9" 9.2" 9.2"


4.5x7" coil

nickel 3.3" 5.0" 6.7" 6.7" The signal was unstable at sensitivity level 25
dime 4.2" 5.4" 6.7" 7.1"
quarter 5.0" 6.2" 7.1" 7.9"

It's pretty obvious (on this test at least) that 19 in Auto +3 does not equal 19 in Manual. I would imagine that coins in the field would react differently. The test also demonstrates the expected loss of depth with a smaller coil. It would be interesting to see the results other folks get from a similar air test.

 

[robertj298]

I conducted an air test last evening to see for myself the difference between auto +3 and manual. This was done inside my house with the detector in a horizontal position on two wooden chairs. I used a silver "war" nickel, a silver dime, and a silver quarter. I made the measurements with a plastic metric ruler and converted the metric reading to inches. The bottom of the coil was perpendicular to the floor. All setting remained the same other than the sensitivity. The 11" coil is the stock coil and the 4.5x7" is a DD EQ Pro Excelerator coil.

11" coil Auto +3 Manual Manual Manual The signal was becoming unstable at setting 19, worse at 22, and much worse at 25. It's interesting that the depth didn't increase once the stability worsened.
(reading 19) 19 22 25

nickel 4.2" 7.1" 7.9" 7.9"
dime 5.4" 7.1" 8.3" 8.3"
quarter 5.8" 7.9" 9.2" 9.2"


4.5x7" coil

nickel 3.3" 5.0" 6.7" 6.7" The signal was unstable at sensitivity level 25


dime 4.2" 5.4" 6.7" 7.1"
quarter 5.0" 6.2" 7.1" 7.9"

It's pretty obvious (on this test at least) that 19 in Auto +3 does not equal 19 in Manual. I would imagine that coins in the field would react differently. The test also demonstrates the expected loss of depth with a smaller coil. It would be interesting to see the results other folks get from a similar air test.

I did a similar test using my 6" excelerator coil with an indian head.. dime and quarter using your settings with an open screen

dime 5.5" 7" 7.75" 8.5"

indian head 5.5" 7" 7.75" 8.5"

Quarter 6.5" 8" 8.5" 9.5"

 

[robertj298]

What I'm trying to understand is, with the new 6" accelerator coil I can't pick up a silver quarter I buried 6" deep a couple months ago no matter how I set it

 

[Agseeker]

robertj298

When you are attempting to find the 6" deep silver quarter I assume you are in Auto +3? Can you pick it up with the 11" coil in Auto +3 or with the 6" or 11" coil in Manual?

 

[utahshovelhead]

seems like somthing is not right you should be getting that to hit. do youhave access to another e trac to test with?

 

[robertj298]

The 11" will pick it up in auto +3. I can run the 6" coil all the way to manual 29 and it won't pick it up, even with an open screen.

 

[Goes4ever]

something is not right at all, I have coins in my test garden at 7.5" and I can pick them up with a sensitivity of 18 while using my 6x8 coil

 

[Big Boys Hobbies]

Lots of good answers here. When in manual the E-Trac runs all the channels at same level. In Auto the machine decides which channels to run where for most stability. The # shown is an average.