Auto-Sensitivity: Is there really any reason to set it less than 32?

[Erik in NJ]

Like Bryce, I have really gotten to like using Auto-Sens. I started years ago with Manual, but the machine is just so much more stable (I can't stand all of the spurious false chirps in Manual) in Auto and I haven't noticed any loss of depth - I trust Bryce's observations even more so than mine in this area. My question though is if Auto mode selects the highest stable sensitivity level with a ceiling at the number you have it set to, then what do you have to lose by setting to 32? I've never used a manual setting of 32 that I can recall, but if the machine finds a patch of ground where 32 works then why not?

Thanks for any "enlightenment" on this one.

 

[Andy Sabisch]

And that makes a big difference in how it works. If you set the SEMI-AUTO level at say "20", that will be as high as it will go and lower if conditions dictate. Setting at "32" will allow the Explorer to run as hot as conditions allow . . . and if that is a MAX, so much the better.

The E-Trac has a true AUTO sensitivity mode which always tries to drive it to the maximum level the conditions will allow. While this might seem the best way all the time, if you are in a seeded hunt for example, you want to be able to run at a lower level which was a nice feature on the Explorers. That is why Minelab added the +3/-3 offset on the Sensitivity control when running in AUTO on the E-Trac . . . although at times you are forced to go into manual, drop the sensitivity as required and monitor the bars to see if additional changes are needed.

But in answer to your question, for normal hunting looking for deeper targets, "32" is a good point in Semi-Auto on the Explorer. If conditions or targets being sought dictate a lower value, drop the sensitivity and let the detector do its thing.

 

[Erik in NJ]

Hi Andy, Thanks for the reply....yes, I meant to write Semi-Auto, I think you know what I meant since I said it was a ceiling on the max sensitivity that the machine could select. So I guess my question is this: for typical detecting (non-seeded hunt, I don't want to get into semantics here, you know as if I'm out in a park looking for silver coins) is there any reason why you would not use 32 if you preferred to run in Semi-Auto? I've always been curious about this. Thanks.

 

[Andy Sabisch]

That option not being on the E-Trac is a bit of a step back but workable.

If you are in an area where targets are not that deep then dropping the max value will work better on the Explorer

And the reason I made the distinction between AUTO and SEMI-AUTO is that it is a very different circuit in terms of how it functions as seem on the FBS detectors Minelab offers.

 

[sangamon]

i appreciate this conversation. i always run my SE at 24 semi-auto, because i seem to get a lot more falsing on things like rusty nails (and i usually dig 'em, just in case) if i run it any higher. am i just imagining things? i use a SunRay X-8 almost exclusively, but i have a SEF 10x12 arriving tomorrow. i guess i've always thought that maximum sensitivity has its drawbacks, but you're saying that's not the case? thanks

 

[Chris(SoCenWI)]

At least for the XS......

Set it at 1. Now switch between manual and semi. Semi will get a target much deeper; only an inch or so in 1 manual. Many others have done this experiment and there are numerous threads from years past.

I've played with this a lot, and feel as many others do that semi will also drop farther than needed to gain a stable threshold.

Try the test with sense 1. Perhaps this is unique to the XS, but am quite sure others have tried with the newer models and have had the same results. E-trac, don't know.

Chris

 

[Andy Sabisch]

Running at a lower level often produces more . . . . there is an old site near near that has a clay base at 5 inches so nothing is deeper than that but the amount of trash is staggering. Setting the Sensitivity at "18" or less works the best . . . . I am not saying there is one answer for all areas . . . . sometimes it changes at the same site from one area to another

 

[Erik in NJ]

Hmmmm, interesting, I've never seen a thread on this and I've never tried it. I thought the manual described it as a ceiling where the detector can automatically raise and lower the sens but not to exceed the semi-auto value....in mathematical terms x <= n, where n is the semi-auto value. The only thing I can think of is that 1 on the XS is an edge condition, and the behavior that you experience with a sens value of 1 may not apply linearly through 32. I like the smoothness of semi-auto 32, but have seen others drop this value in this mode. Maybe the over compensation of the algorithm is why they added the +/-n on the E-Trac. Regardless the unit is still sending out the same signal strength at any sens value from what I understand - the sens setting only affect the receive circuit.

 

[Rick(ND)]

Andy,

I find this odd you would say that 32 semi auto was a good place to start for deep coin hunting. I feel if it is trash free it probably would work, but if there is trash of any kind I find 32 Semi auto not a good place to start with. Maybe it is just me but I tried 32 semi auto at a place a sidewalk was taken out and it ran so smooth and got no signals. I though down a dime and it would not pick it up unless the coil touched it. In manual it was very unstable so I had to drop the sensitivity in manual 22 until it was stable, now it could get the dime at around 4-5 inches in manual. Switched to semi auto and I felt I lost a little depth and dropped it to 16 where both semei auto and manual was the same. Lower than 16 and semi auto worked better, but over 22 I felt the manual did better. I feel the higher it is set in semi auto the more it will compensate in trashier areas, so I have always found in area with iron or trash it has been better to run manual and get the max depth.
Anyone else notice this and if you dont try a get a null and put a dime on it or very close to it and try semi auto at max and drop it and see if you dont notice the depth will increase as the sensitivity is drop in semi auto, even try manual and see what happens.

 

[Chris(SoCenWI)]

Erik,

There are many older threads on this subject. The manual is definitely wrong as far as the XS goes. Or at least the perception that says the displayed number is a ceiling. Not sure the manual really says this. I've been reading Minelab patents and white papers and have theories on how this works. Not sure I am right. Perhaps we can move geek talk to the Explorer classroom forum.

But try it first. You have an SE and E-Trac?.

Set at 1 and sweep manual. Record the depth. Switch to Semi and keep swinging. Might take a while for algorithm to kick in. I know I can get a few inches on a penny in semi set at 1.

Chris

 

[Erik in NJ]

Thanks Chris, I'll try it when I get a chance, but the E-Trac is full auto, so there's no ceiling and Andy says it's a completely separate algorithm. On the XS & SE we should try it at 1, 15, and 32 to get a more accurate idea of the linearity of what is really happening. Maybe 1 is a special value that's not documented or they are trying to be too smart in the code by saying that you really didn't mean 1, which I personally feel is a bad idea. The algorithm would have been very clean had it worked the way it was documented, or at least "supposed to" have worked. But then again in my career I've seen a lot of God-aweful code put into production by programmers that should have been locked up and I'd bet the Minelab code is no exception based on the quality an intuitiveness of the user interface. Don't get me started!

 

[sangamon]

...i dig enough nails as it is!

but this thread has inspired me to try some tweaks

 

[Hotcz70]

My SE sounds like a pinball machine shorting out

At every site I've ever been to in MO, and IL, and IN....26 semi auto is as high as I personally can go without the falsing and chirping taking over just as you decscribed.

Even in super clean ground my SE just chirps too much for me with any setting higher than manual 26. I'm sure the high gain I run factors into play...but regardless...it gets too hard to discern falsing chirps from deep iffy silver hits.

I have tried semi auto 28 a few times but I get more falsing... and rusty nails start to sound better...hence more of them end up in my pouch

I'm reading all the responses to this post...and copying them for reference. I'm always open for piddling and experimenting.

Posts like this one are what makes us all better hunters

 

[Larry (IL)]

I'm a couple of hours North of Bryce and I have to fall in line with Bryce's observations. I was playing around with the Semi-Auto just last night and I too get better results with S-A at 26 in my ground. When I upped it to 28, my first digable was a rusty nail that looked and sounded good on the Smart screen, IM-30. When switching to manual, I have to go down to 23-24 to get similar results and still a bit noisier and no apparent gain in depth.

 

[NiagracountyNY]

I have been running my SE in manual sens all the time unless the plass has crazy emi(atleast thats what i think happens).I have several sites I use my 18x15 S.E.F on and use 27 to 30 manual .Ive always felt i was losing depth with auto.I have tried a few targets with both and manual always brings the deep ones in sounding more clear.I also use all metal ferrous sounds all the time.Its very noisy,but I can hear the targets over the falsing.I use a headset with volume control to make it easier on the ears.I just ordered the E-Trac ,Gonna be a slight change in how i hunt im sure.This post has been very intresting, Thx everyone.

 

[N2Treasure]

I agree with Bryce's statement and PROVED it on Saturday. I was running Semi-auto 28 and after the deep silver hit, I dug two more identical signals just to find rusted iron nails or such in both holes. That rust sounds GREAT but I think I'll hit that same park next weekend and run Semi 26 and see if I can get some more deepies!


GREAT POST!

Duane

 

[Steve(OR)]

... in my 3 year old test garden (64 dime, 64 quarter, 64 half - all at 8 inches).

Yes, this test garden is not very old (... but that's what you get when you move)... and it's certainly anecdotal, but here's the results anyway (... from this morning (SE; Pro coil; Conductive tones; Gain 10; Deep/Fast Off)):

64 dime:
Semi-Auto(32) == Just threshold - no audible tones
Manual(21) == A few slight 'peeps', correlated with depth meter (hard to tell - real iffy - I'd likely walk away)

64 quarter:
Semi-Auto(32) == Just threshold - no audible tones
Manual(21) == A few slight 'peeps' - better at 90 & 270 degrees, correlated with depth meter (I'd likely dig this one)

64 half:
Semi-Auto(32) == One slight 'peep' that would not repeat - nothing else when circled (I'd likely ignore this one)
Manual(21) == Definite coin tones, correlated with depth meter

These results have improved slightly since I buried these coins - but I have never been able to detect any of these with any Semi-Auto settings. The first year, I could barely detect these with Manual 28 - mainly because the tones where mixed in with the falses. But realistically, these coins are still on the edge of this machine's detection ability. Of course, a silver quarter that's been buried for 50 years at 8 inches should be loud, clear and obvious.

Even so, I think there's still a parallel to be considered here...

SCM

 

[thebeatmachine]

I can usually run 26 manual and not have problems. Being close to AM antennas cause problems that seem like ground problems. It can be stable in the air at 20 but on the ground at 16 or so in a park close to antennas. I don't do Auto because I like to set it myself personally.

 

[Erik in NJ]

Hi Steve,

Interesting results! Can you provide some more sample points on the manual setting (maybe a few more to with semi-auto)? If you have the time it would be interesting to start with a setting of 1 and step up 3 or 4 clicks per trial. Great post - thanks!

I've never planted a test garden, but maybe it's time I do it. I hope you remembered to dig up your old garden before you moved!

 

[thebeatmachine]

The detector has to deal with trash, ground and EMI. So which one is the Semi-Auto responding to? If I am usind a manual setting I can get a good idea of where my problems are coming from. With any detector I find that the verge of instability is where you want the recieve amp to be as long as you are stable enough to clearly hear the signals and not be driven crazy. I double check suspected falsing with the pinpoint mode because it dees not lie.