Thanks Mark for all the info and interesting data.
As you said in the real world results can be different so a couple of experiences...
My deepest coins I ever dug so far were in good soil in Kansas but the site had some issues.
At the edge of a big park that always had horrendous EMI problems constantly and every time i hunted this area.
More thrumming, pulsing problems than any site I have ever bern to before or since.
Large DD, sense at 80, thresh at -1, DE speed, 4H tones, disc not sure but might have been about 6 but could have been as high as 22-23.
Lots of jumping around but the F70 still stopped over targets to give me indications something was there and those weren't false signals.
I got a pretty jumpy signal that ranged from the 50's to almost 80 over a large area about a foot square and the depth says 7-8".
With all that EMI causing jumping and the large area I usually would have passed this by but those range of numbers somewhat repeated as I ran the coil around the area and the kicker was the tone sounded great, solid and sharp here and there as I moved the coil around.
This got me to dig and I come to find out this was a coin spill that was 3 Indians and an old wheat, so the number range was correct, and most were at least 8" but at least two were deeper closer to 10".
Wish I would have bumped the thresh into the positive at the time but this was early on in my experimentation and didn't think to do that.
I thought this signal was some sort of junk at the time, anyway, how was I to know these were coins?
In that same park more in the middle away from all that EMI I dug my deepest target ever.
This one was in the red on your chart all the way to the corner so if you could set settings to this level I believe you would have found some shocking double digit numbers there.
Same big coil, disc in the low 20's, sense 99 and thresh at +9, 1F tones and in this spot these were relatively quiet.
Mark, I must mention again in areas with EMI the lower tone choices do seem to handle it better than the higher ones...1, 1F and 2F are more stable than multi tones or DP from all my experiences which is why I asked you to test in monotone.
It might not matter in your home doing this testing but in the field it just might.
Using these high settings I easily acquired a few targets deep, mostly tabs at 6-8" and then a small bell like off of a cat or dog collar at about 9"...then I got this one.
Sounded pretty solid, saw numbers go from the mid 20's with a jump or two to 40 but they repeated from all angles and I saw 23-26 numbers repeat more than any others.
When I hit the pinpointer I was shocked to see 13-14" numbers on the screen and they stayed there every time I came at this target from every angle.
I never dig this deep in public parks but this one I went after just to see if anything was actually down there that deep.
We all know that on this platform the audio goes deeper than the screen, it is like the audio is always in all metal but the screen in disc can't match it on the really deep stuff at the very end of the scanning field so it gives up and just goes blank.
I dug several beaver tail tabs at 10" before that usually have a high tone when that deep using the 10" elliptical concentric and a few had screen info but most had that blank screen
This I had never seen before, a target that deep with good audio and screen info so my curiosity was piqued.
I checked the signal with blown out maxed all metal and got the same numbers and good tone so I dug.
This wasn't a coin but a thumb ringer off of an old bicycle bell so a bit bigger but still there was something down there so I was thrilled.
I measured this one...every bit of 15" deep and to have screen info on this thing astounded me.
Checking it out of the ground this was a solid 23-25 signal so the screen info was fairly accurate even that deep.
I believe it was that maxed thresh and sense in disc that enabled me to see it and it easily matched the all metal depth.
Here is a post I wrote up in an F70 log I was putting all my experiences in 3 years ago and I will just copy and repost it here and it goes along quite well with your testing results although I never went past 0 on the thresh.
Wish I would have now because positive numbers could have been good data to gather but I was going by what sounded good to me as a diggable signal at the time.
This pertains to a real world target using low sense and playing with the thresh on a measured 5" dime I came across.
I mention the weird sound as thresh was pushed higher...that modulation that you seem to like but I don't because I prefer a more solid sounding tone which doesn't matter because as long as any settings work for us those are the correct ones.
On this one SL speed did matter.
Starting settings were bid DD coil, DE, 4 disc, -3 thresh, 4H tones and sense on 30 which fools that big DD coil into thinking it is a scalpel-like sniper coil.
I wanted to get an idea on how deep low sense could get me when using sense at low levels when hunting in trashy areas.
I titled this post...."19"...
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A Jr. College right near my house.
Been here a million times, took a ton of clad when I first came here but not a whole lot left, 3 gold rings from different areas so far too.
Just wanted to see if I cold still find clad I left behind in the past.
All settings were where I left them from the last hunt.
Disc was lowered to 4 because I still want to find the tiniest chains, everything else was left alone except thresh was lowered to -3, DE, sense at 30, 4H tones, notch always at 1.
Zip, zip, zip, found some coins pretty easily, a few pieces of trash, avoided most other trash that was jumpy and so on...a nice short but productive hunt.
These settings are excellent for shallow coin and jewelry hunting, I will probably keep them around but still not sure on the depth they will go.
Now I will get to that 19 thing.
Near the end of this hunt I came across a dime signal.
Solid 78, no jumpy numbers at all, solid tone and numbers from every direction, the depth reading said 5" deep and there was no trash or other signal near it.
This was the one.
I knew it was a dime with every fiber of my being, hoped for a silver ring but 99.9999% sure I had a dime under my coil.
I stopped and played with this awhile with every setting I could think of to figure out a little more about depth on low settings.
The sense was still on 30, I started lowering down the sense while swinging in short passes over this thing.
When I got down to about 23 it started breaking up a bit, at about 21 it became a signal I would not dig anymore.
Also something weird happened when I got to about 24 or 25 while it was still a solid signal I would dig, the high tone in 4H changed and became weird sounding.
Very weird sounding.
Still solid, still repeated, but it was not full sounding at all like half of the tonal qualities just went away.
Hard to explain but I didn't like it.
At that point I started adjusting the thresh and moved it from -3 to -2.
The tone got a bit louder but still sounded weird.
Then I went to 20 on the sense and I lost the signal completely.
It was gone.
I moved the thresh up one notch to -1 and it came back again, solid and repeating but still weird sounding.
Thresh back to -2 gone, up to -1 back...I did this several times.
No breaking up or iffy signal at any time during this, it was just like a wall went up at -2 and went down where I got a signal again at -1.
Strange.
I moved it up one more notch to 0 and it was a bit louder and I left it there.
Then I switched from DE to SL at this point and the signal came back, sounded clear and full, and everything was all right with the world again.
The 78 number stayed solid and stable throughout all of this except when the tone went away completely and then the number did too.
One more thing to do.
I lowered the sense one more number to 19 and the signal was still there in all its glory, one more move down to 18 and it was totally gone again.
Ok, lets take stock of what we have at this point.
Thresh on 0, 4H, SL, Sense at 19, Disc on 4, dead quiet, no falsing or extra noise at all and by scraping the coil on the ground I was picking up a for sure dig me dime at a supposedly 5".
Impressive!
Now these are the kind of things I need to know to give me confidence in hunting at really quiet settings at or even below the factory start up 60 and still feel I can find deeper coins at 7-8" or maybe a bit more if I had to.
Not sure I will ever do this but it is nice to know I could if needed.
At that point I picked up the coil 1" off the ground, swung and the signal was gone.
If this thing really was at 5" this was the limit in my ground at these settings.
I turned the sense back up to 30 and I could raise the coil another 2 inches or so and still get the signal solid.
That would be 7" on 30 sense.
I turned up the sense to 40 and I could raise the coil 2 more inches and still get that solid signal every time I passed the coil over it.
9" on 40 sense.
Up to 50 on the sense, two more inches on the coil upwards, 11" on 50 sense with 6" air and 5" in the ground and that was all I needed to know.
Talk about confidence building!
All that was left now was to dig the coin.
I opened a hole, dug down slowly, got to the coin which of course was a dime and I took out a small plastic 8" ruler I get free from my bank and stuck it in the hole and put it right where the dime was laying.
looking sideways across the top of the hole at the very edge of the grass where I was scraping my coil I saw the number 5 on the ruler.
Alrighty then...this is data that I can use to my advantage!
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So in the real world higher thresh can help in not only unmasking good targets around iron and trash but in the area of depth under all kinds of circumstances.
It is not only there to mitigate chatter or to locate tiny targets but also for depth.
A million ways to set this thing up...I am trying my best to try every one I can think of and put it down somewhere until I can't lift my detector anymore.
I still got the 10" but I didn't gain anything.