GM 5+ signals - how do other detectors behave?

[RossDG]

Well I'm a couple of months into using the GM 5+ and gaining in confidence with it after a bit of a rocky start!
Bearing in mind it is a very different beast to the EuroACE, but has some distinct similarities in terms of the "Iffy" signals.
Perhaps I was hoping for too much (or believed the hype...), but after reading the manual before purchase, and then carrying out some trial runs before going into the field, I was pretty confident that I (listening) and the machine (through it's VDI) could recognise iron, coins, different metals etc. and I have to say that for about 75% of the targets I and the machine get it right.
I now only operate the machine in single tone, 18KHz, Pbox high.

For example lumps of ferrous (such as big nails, screws, and larger items such as horsehoe parts) generally indicate iron, and show -16 on the VDI and have a broken start and end to the audio- so do not get dug.

Flat bits of iron - such as sheet metal fragments laying flat will indicate -17 in one direction, and +85 at 90 degrees sweep, but the hodograph correctly indicates thin ferrous.

Items such as the buckle below (at 7 inches depth) indicate a target ID of around +50 and a nice straight peak on the display.

TECT_1531131577447_rosette buckle_Fig 8_.jpg

Roman nummus come in around +65 from 6 inches depth...

So far so good, BUT, a copper alloy button (size of a 10p) at 4 inches gave a cracking clean signal one way, crackly signal at 90 degrees but no VDI information at all - I almost did not dig it!
Also I sometimes get belting signals from small ferrous, but no VDI info, and also crackly weak signals - but still above the background chatter that do prove to be small ferrous, or other junk, but on occassion broken remains of cartridge cases (corroded and thin).

So, after this long winded diatribe, what I am asking is this - is this typical of detecting pasture land (I know one area is particularly contaminated with junk), do other detectors behave the same or similar (the EuroACE for example will also on occassion have me digging ferrous junk, and certainly does not find as many small items at depth as the GM)?
I am generally very happy with the machine, especially now I have the settings more or less sorted for best recovery/depth compromise, and I know it is all too easy to look at youtube vids and think that a different machine gives far better results, but a little reassurance would be great!

Settings in case anyone else is using one and interested:
18KHz
PBOX high
Threshold - as high as you can get away with - 25 on my pasture permission, down to 21 in really trashy area
Gain 0-1 too unstable at 2
Mono audio
Discrim depth 5 (not the default 8 as this can lead to missing small bronze I have found)
Iron discrim is set just above the iron indicator line on the VDI - could probably go a little higher but still playing.

Final tip - make sure the coil connector is tight and solid otherwise it will chatter like crazy (I mean really tight); and swing slow on pasture - this machine can really pick tiny deep targets out, but patience is needed.

Thanks all

[Koala]

Like the buckle


Doubt there will be much of finds rate increase. But every extra find counts.

[Mud Max]

Interesting feedback, how did you find out that disc depth at 8 misses small bronze?

[Easylife]

It sounds generally on par with most detectors depending on target orientation and closeness to iron which can disguise targets.

[Junior]

""""So, after this long winded diatribe, what I am asking is this - is this typical of detecting pasture land (I know one area is particularly contaminated with junk), do other detectors behave the same or similar (the EuroACE for example will also on occassion have me digging ferrous junk, and certainly does not find as many small items at depth as the GM)?""""

I would say other detectors act the same as yours ....the French stick on some iron come in with hf coil as a 72 vdi....on test bed on good deepish stuff it's showing -- - on screen...the 3? ?? does similar stuff on small or close to iron stuff etc.....do we expect to tooo much out of the detector I prob do !!!!!

"Hype yep I've bought into that on more than 1 occasion... """it's the hammered hover "" yep for me turned into the iron hover....another in seacher "" the land hand been pounded by the club rally but i managed to pull these 20 roman out of an area the size of a tennis court"""" yep got that one tooo....no good on our land....I think each detector has it's strong points and weakness
....One French one I have done It for me when out with a mate we compared a signal which he woz getting big time I wasn't I tryed various preset programs ...nowt...he dug It out and It woz a 6" bit of Ali pipe not far down and I wasn't getting it!!!! Another mate has a large silver Vicky silver coin on a piece of wood just to test his settings on, I know not a proper test but It wouldn't get that either so another detector appeared like his v6.
Some detectors may give u a inch or so deeper due to say fbs but have slow rec speed and null others may have quick recovery speed and get surface ish stuff but struggle on depth, i had 1 that would hit all my test bed but woz so sparky it would b going off left right and centre,there seems there isnt a do all detector yet ???? Hence why people have 2 or 3 detectors ....
....It a matter of getting used to it...and getting in your head it might not b getting everything but I'm happy with what it is getting, which I struggle with hence 18 detectors in 10 yrs ..

[RossDG]

Interesting feedback, how did you find out that disc depth at 8 misses small bronze?

There is a youtube video - testing gm5+ and some other detectors that raised the issue; I ran my own tests and found that the discrim depth setting changed the audio tone on very small bronzes, such that if the VDI is showing -- it is possible to mistake the signal for ferrous as it is a bit scratchy when the target is around 5 inches +/- inch or so. It is subtle, but there is definitely a more solid signal with lower discrim depth. That said having read the excellent responses to my question I perhaps should be digging more iffy signals........

Thanks all for the input, can't wait to get back on it feeling reassured!

[Mud Max]

Interesting feedback, how did you find out that disc depth at 8 misses small bronze?

There is a youtube video - testing gm5+ and some other detectors that raised the issue; I ran my own tests and found that the discrim depth setting changed the audio tone on very small bronzes, such that if the VDI is showing -- it is possible to mistake the signal for ferrous as it is a bit scratchy when the target is around 5 inches +/- inch or so. It is subtle, but there is definitely a more solid signal with lower discrim depth. That said having read the excellent responses to my question I perhaps should be digging more iffy signals........

Thanks all for the input, can't wait to get back on it feeling reassured!

I dug a very iffy signal a couple of nights back, mixed tone, lines flicking through ferrous and mid conductor. Out popped a tiny medieval buckle. As with many machines, the signal was bad due to a mixture of depth and target, wave the object over the coil and it's a lovely signal.

As I understand it, dropping Disc Depth increases the signal quality on deeper targets, giving clearer distinction between deep ferrous and deep non ferrous, or to put it another way, deep good targets won't sound like iron so often. The trade off is less quality on shallow targets.

I think disc depth is the GM version of recovery speed. Here's the buckle.

Tiny buckle.jpg

[Koala]

It sounds generally on par with most detectors depending on target orientation and closeness to iron which can disguise targets.

Thats the thing. The real performance in the ground between most detectors is very similar. The amount of targets that you go over that one detector will miss and another will hit is very small.


So your actual finds rates only increase a very very small amount. Thats not saying its not worth doing as those few extra targets could be a gold stator

[Koala]

Interesting feedback, how did you find out that disc depth at 8 misses small bronze?

First things you loose is small gold and thin lead. Small bonze is fairly high up the scale . Buckles generally give a better and able to go deeper due to there doughnut shape. Fibulas give a poor signal both due to there shape and alloy content. I have yet to find one with a pin but would expect that to be not much passed a small nail.

Its all a compromise. Some people are only interested in silver. Which is fine and means you can crank the discrimination up. Me I like Roman, I like lead tokens. I dig lots of foil, cow tubes but occasionally it pays off.

[Mud Max]

Interesting feedback, how did you find out that disc depth at 8 misses small bronze?

First things you loose is small gold and thin lead. Small bonze is fairly high up the scale . Buckles generally give a better and able to go deeper due to there doughnut shape. Fibulas give a poor signal both due to there shape and alloy content. I have yet to find one with a pin but would expect that to be not much passed a small nail.

Its all a compromise. Some people are only interested in silver. Which is fine and means you can crank the discrimination up. Me I like Roman, I like lead tokens. I dig lots of foil, cow tubes but occasionally it pays off.

So your a low disc depth person too?

[Koala]

Interesting feedback, how did you find out that disc depth at 8 misses small bronze?

First things you loose is small gold and thin lead. Small bonze is fairly high up the scale . Buckles generally give a better and able to go deeper due to there doughnut shape. Fibulas give a poor signal both due to there shape and alloy content. I have yet to find one with a pin but would expect that to be not much passed a small nail.

Its all a compromise. Some people are only interested in silver. Which is fine and means you can crank the discrimination up. Me I like Roman, I like lead tokens. I dig lots of foil, cow tubes but occasionally it pays off.

So your a low disc depth person too?

I dig everything above a nail. Including the foil, cow tubes, pull tabs and ring pulls and so on. Occasionally it pays of

[Oxgirl36]

That last buckle is a very nice medieval one. You’re doing great

[Mud Max]

First things you loose is small gold and thin lead. Small bonze is fairly high up the scale . Buckles generally give a better and able to go deeper due to there doughnut shape. Fibulas give a poor signal both due to there shape and alloy content. I have yet to find one with a pin but would expect that to be not much passed a small nail.

Its all a compromise. Some people are only interested in silver. Which is fine and means you can crank the discrimination up. Me I like Roman, I like lead tokens. I dig lots of foil, cow tubes but occasionally it pays off.

So your a low disc depth person too?

I dig everything above a nail. Including the foil, cow tubes, pull tabs and ring pulls and so on. Occasionally it pays of

But where do you set the Disc Depth Koala?

[Koala]

Each machine I use I take into the field and start off with it too low. Listen to the sound of the target and dig it out. If its a clean signal through the headphones and iron I turn the disc up slightly.


You can't use someone else settings as there is a slight difference between machines and coils. It maybe the same but more likely slightly different.

You also can't wave a nail in front of a coil. When in the ground it will be much lower than in the air.

I am looking for the point where 90% doesn't make a good sound but occationly you dig up odd shaped iron and a few doughnut shaped iron.

Once I have found this point it normally stays the same on most fields. If I go to a new field and I am not digging any iron I lower it a bit and if its too much iron I higher it a bit.


I have never done this but watched a couple of guys bury targets in the field then try different settings and machines to see what gave the best results before they started detecting.

[Mud Max]

Each machine I use I take into the field and start off with it too low. Listen to the sound of the target and dig it out. If its a clean signal through the headphones and iron I turn the disc up slightly.


You can't use someone else settings as there is a slight difference between machines and coils. It maybe the same but more likely slightly different.

You also can't wave a nail in front of a coil. When in the ground it will be much lower than in the air.

I am looking for the point where 90% doesn't make a good sound but occationly you dig up odd shaped iron and a few doughnut shaped iron.

Once I have found this point it normally stays the same on most fields. If I go to a new field and I am not digging any iron I lower it a bit and if its too much iron I higher it a bit.


I have never done this but watched a couple of guys bury targets in the field then try different settings and machines to see what gave the best results before they started detecting.

Koala, the disc depth is not the main discrimination, that is a separate setting on the GM5+

[Koala]

Koala, the disc depth is not the main discrimination, that is a separate setting on the GM5+

you are correct. I was getting confused with the older GM models.


I take it you ment to say recovery speed.

it an odd wording discrimination depth. It very similar to reactivity. Where to get the extra depth at the sacrifice of sweep speed.

[Mud Max]

Koala, the disc depth is not the main discrimination, that is a separate setting on the GM5+

you are correct. I was getting confused with the older GM models.


I take it you ment to say recovery speed.

it an odd wording discrimination depth. It very similar to reactivity. Where to get the extra depth at the sacrifice of sweep speed.

Disc depth is what it's called on the GM5+SE, in the disc options button. Looking at the manual, I can only assume that it's actual function is recovery speed as you suggest. Low amounts better on deeper targets, high amounts better for shallow searches in the trash. mind you, on my early test so far I honestly can't see much difference when I alter it. I think it's very subtle, or maybe I have not tested enough yet.

Standard discrimination is the black bar under the graph, changed with the plus/minus buttons.

[Koala]

Yes that's how I see it.

If you place a none ferrous target just beyond its normal detection depth it will see it as iron. Same on any detector.

It gives you an option to ignore these altogether. By cranking it up to 15. Which is great if you are hunting in a park for fresh droppage.

The lower you crank it the more processing it tries to do to convert those deep none ferrous iron sounds back to a good tone. This require more processing time. If you have already moved onto a new target before its finished it will start processing that one. To get the extra depth you will need to swing slower



I would try a silver coins edge in your ground and try left to right and up and down across the target while lowering the disc depth and slowing the sweep speed. Should give you the optimum sweep speed and setting for depth


Then try the same but at a your normal sweep speed and that should give you your everyday setting.


Thats how I see it working although the manual is very vague.

[RossDG]

Yes that's how I see it.

If you place a none ferrous target just beyond its normal detection depth it will see it as iron. Same on any detector.

It gives you an option to ignore these altogether. By cranking it up to 15. Which is great if you are hunting in a park for fresh droppage.

The lower you crank it the more processing it tries to do to convert those deep none ferrous iron sounds back to a good tone. This require more processing time. If you have already moved onto a new target before its finished it will start processing that one. To get the extra depth you will need to swing slower



I would try a silver coins edge in your ground and try left to right and up and down across the target while lowering the disc depth and slowing the sweep speed. Should give you the optimum sweep speed and setting for depth


Then try the same but at a your normal sweep speed and that should give you your everyday setting.


Thats how I see it working although the manual is very vague.

Excellent stuff Koala, thanks for that. You are quite right, the manual is a little vague, your explanantion clears things up a lot and explains the subtle differences in audio on tiny non ferrous targets at depth.

[Mud Max]

Agreed Koala, it should work the same as it does on other detectors where you can change the reactivity/recovery. And the right swing speed to match will be key. The manual kind of states this, just not how we have heard it before. As Spoc said "It's life Jim, but not as we know it"