Newbie needs some help interpreting GPX tones

I'm borrowing a friend's GPX-4000 to use at a site that has produced a number of very early coins, and am trying to go as deep as I can. I've already dug 2 silver sixpences with this machine at the incredible depths of 18" and 22". But my question is in regard to why the machine responds to targets with either the hi-lo or lo-hi tones. Right now I'm using the inverted response setting, so the coins are coming in as a faint hi-lo tone. But fairly small and deep iron is also responding the same. I know this question does not have a simple answer, but what is the general relationship between target size, conductivity and depth with how the detector responds (hi-lo or lo-hi)? Even though I can afford to dig every signal at this site since its almost trash and iron free, I'd like to take the GPX elsewhere and be able to at least partially determine what to dig or not dig by properly interpreting the tones. I'd also like to hear some suggested settings to see if they match up well with what I'm currently using at the coin site. I'm using the 11" mono coil, and have all the settings hot due the clean and low mineralized ground, and the 4000 is still rather quiet and stable. Appreciate any help you can provide. Thanks

hi
i have alays thought that the hi-low and low - high tones were caused by size x depth

for e.g.... if the deepest you could get get a coin (the size of a dime) was 10 inches then=
if you went over that dime at 3 inches then you would get a high - low signal
but if you went over that same dime at 10 inches you would get a low - high signal

or

if the deepest you could get a can was 3 ft then
if you went over that can at one ft you would get a high - low signal
but if you went over it at 3 ft it would give a low - high signal

this is in normal signal..if in inverted it would be... low - high for shallow and high - low deep

i think when you get a deep target for it's size the machine use a differant channel for the signal

some may correct me if i'm wrong or explain it better but i hope this helps
cheers fencejumper

fencejumper has got it there off what happens hi-lo ect. if it go lo-hi it could be the depth off the target or the size off it. you should dig anythig that it picks up, i'm not sure on coins as i have only found 2 a 3 pence from the 1860s and a shilling 1856. i'll post my settengs up tomorrow for you as i have 2 lots, one for deep seaching and one for normal seaching.
cheers
stoppsy

I have found that that deep targets dont always have "drop" signals... where the signal dips below normal audible detecting sounds. I think that may be the case with the older sd's etc but the sound i have been more accomodated to is more like a faint WOOO_HOOO....mellow sound. Much the same as going over a small nugget with a larger coil??
The old sd 2000,2100,2200,2200D, etc really picked up on those tones i think... hence so many people trusting in those models for deep gold...it is well documented
Fencejumper is on the ball..... size of target and depth are the factors..i would like to just add that some models let you know it deep than other models.... would love to hear some opinions on this...good topic

Hi Bill,

Here is the thing:

Thats a gold detecting machine. Sure, it will find coins and what-not better than anything else, but it also has world's poorest tone descrimination. It is build to find gold nuggets and thats the hardest thing to hear. So by comparison, anything else sounds BIG.

Best advise, IMHO, is to forget about tonality of sound, and just dig every target.

But here is the actual answer you probably wanted

the "high-low" and "low-high" sounds are a combination of conductivity, target size, shape, depth, soil conditions, coil size and machine settings. And maybe something fancy like "signal decay rate" (i think i made that one up).

Because there are so many factors, there is no way to accuraetly judge ANYTHING from sound alone. So a nugget on the suface will sound like an iron hammer at 1 foot. A 1mm shred of iron on the surface will sound like a 1 gram nugget at 6 inch, an these kind of comparisons are endless and pointless.

There is however, a couple of "rules of thumb":

1. Generaly, soft low-high sound means "good target at depth" (not iron), or "tiny target near the surface" (any metal). If you can kick it away with top soil, its the second kind. Otherwise - dig!

2. A good big target at shallow depth can sound loud and high-low. Like a bad target. So you can not ignore them.


Now, about the "inverted" response on GPX machines. Thats for better hearing of deeeep nuggets. Deep targets, especially of non-iron metals give a pecular sound - like a "warble in the treshold". So this inverted signal is menat to bring that up and make it sound "normal" like the targets you are used to. I think

Anyway, if you have good soil to work with you can crank that GPX up so bad you will find targets at 3 foot+. Hell, people do that here in Australia, and our soils are really bad for detecting.

Cheers!

P.S. Go really slow. Really. Like 3 seconds per swing.