The 7000 and settings

Late in the afternoon yesterday I went back to the Coiltek testbed because every since I put the 19" on I have been struggling with settings I feel comfortable with.  Where ever I have it set I feel like I should have it set somewhere else, I feel like I`m just not getting the best out of the coil.     It was a very hot day yesterday and I`m guessing the ground was probably pretty warm, which may have effected the results.  There are 5 targets out there ranging from a 3 grammer at 9" down to a 5 ouncer at 22".
Running the settings I used to run with the 14, High Yield. Difficult ground, gain around 12 volume 6, the ONLY target I could here was the 3 grammer at 9".   Regardless of how slow or fast I swept the coil I could not hear any of the other targets.
I`ve been playing around with Normal ground since maybe a couple of weeks before I got the 19 and the big problem with Normal and the 14" is you get every damn hotrock about the place, but I have discovered with the 19" you don`t get the hotrocks.  So without cranking the settings because I want to find settings I can use in the real world, I discovered yesterday, running Normal Ground, a gain of 1 and target volume of 1 and High Yield I could hear all the targets except one and switching from high yield to General I could hear ALL the targets.  The three deepest gave off that nice little electronic warbley signal I like.
I`m thinking I`m never going to run the gain much above five, but I am rapidly losing all faith in "difficult"
Dave

phoenix wrote:Late in the afternoon yesterday I went back to the Coiltek testbed because every since I put the 19" on I have been struggling with settings I feel comfortable with.  Where ever I have it set I feel like I should have it set somewhere else, I feel like I`m just not getting the best out of the coil.     It was a very hot day yesterday and I`m guessing the ground was probably pretty warm, which may have effected the results.  There are 5 targets out there ranging from a 3 grammer at 9" down to a 5 ouncer at 22".
Running the settings I used to run with 14, High Yield. Difficult ground, gain around 12 volume 6, the ONLY target I could here was the 3 grammer at 9".   Regardles of how slow or fast I swept the coil I could not hear any of the other targets.
I`ve been playing around with Normal ground since maybe a couple of weeks before I got the 19 and the big problem with Normal and the 14" is you get every damn hotrock about the place, but I have discovered with the 19" you don`t get the hotrocks.  So without cranking the settings because I want to find settings I can use in the real world, I discovered yesterday, running a gain of 1 and target volume of 1 and High Yield I coild hear all the targets except one and switching from high yield to General I could hear ALL the targets.  The three deepest gave off that nice little electronic warbley signal I like.
I`m thinking I`m never going to run the gain much above five, but I am rapidly losing all faith in "difficult"
Dave

What this says to me Dave is the ground at the test bed can handle Normal Ground Type modes on the GPZ albeit with a reduction in sensitivity and Volume. There will be some ground types were the ground signal is just too great no matter how much you back everything off, which brings us full circle to a time when the GPX 4500 came to the fore and so much gold came out of variable ground using Enhance.

For a target to be heard it has to be greater than the sum of noise created when detecting, so ground signal, salt signal, EMI, Saturation, physical scrubbing of the coil, poor coil control all add to the threshold which then needs to be listened through to identify a target. The trick is to discover the correct ratio of where ground signal in Normal is not greater than the reduction in depth by selecting Difficult. I can assure you the loss of depth you are seeing with Difficult in the ground you are working is just as severe in other ground types where Normal struggles.

JP

Thanks for that JP. I had to re read that about 5 times to get everything you were saying and I certainly take your point about losing targets in the ground noise. Lately what I have been doing is, before I dig anything I am switching between settings to see where I get the best response. It`s still early days with this coil and I do quite like using it so I`m not going to take it off yet
cheers Dave

JP, would it be fair to say that:

Increasing the sensitivity from 19 to 20 using difficult ground type....... equates to the same sensitivity increment rise as going from Difficult Sensitivity 20 to Normal Sensitivity 1.

I hope that question makes sense.

JG.

Jay Gold wrote:JP, would it be fair to say that:

Increasing the sensitivity from 19 to 20 using difficult ground type....... equates to the same sensitivity increment rise as going from Difficult Sensitivity 20 to Normal Sensitivity 1.

I hope question that makes sense.

JG.

No because the Timings are so different from each other. Normal will continue to make ground noise regardless of the Sensitivity setting, just that your damping or negating said noise by reducing the sensitivity. You can also achieve a similar result by implementing some Audio Smoothing, this will filter out some of the ground signal too. Audio Volume also plays a part in this process, cutting back on the global Volume as well as the Target Volume has a pretty big impact, after all target signals are measured in dB 's.

Difficult removes ground signals regardless of the sensitivity setting, in fact it inherently has more Gain than Normal does to increase the target response relative to ground signal. This is why going from Normal to Difficult the threshold sounds initially a bit gritty or jittery until you get your ear in, what your hearing is the higher amount of Gain associated with the timing (regardless of sensivity setting).

The larger coil removes a lot of ground signal, especially the near to coil ground signals purely because it has less windings than a small coil so is less sensitive up close, this is advantageous to bring deeper target responses to the fore and is the main reason why there is a depth improvedment on nuggets from 2 grams and up, these signals at depth have potentially been previously lost in ground signal and saturation signal with the GPZ 14 coil.

Hope this helps
JP

OK great, thanks for clarifying.

JG

Jonathan Porter wrote: I can assure you the loss of depth you are seeing with Difficult in the ground you are working is just as severe in other ground types where Normal struggles.
JP

JP I have been thinking about that last sentence and I realise what you are saying is correct.  Thinking back on it now I realize that detecting between the targets on that test bed there is no ground noise so even though I couldn`t hear most of them in difficult, had there been ground noise with normal I probably wouldn`t have heard the targets anyway because the target response wouldn`t have been greater than the ground noise.
And when I do air tests comparing difficult to normal I`m getting better results in normal because the coil is maybe 18"-2 ft in the air and NOT being affected by ground noise
That makes me feel better about "difficult"  
cheers

Some good news has been filtering through, via the lads of the good old USA. The new 19 inch coils, are quite near to being delivered & soon to be put to the test there.
I can't wait to hear how they're all going to be achieving & maybe even surpassing, that magical, average, depth advantage of 30%, on nuggets found in the ground, ranging from 2 gram to 60 gram,(by the 19 inch coil) over that of the ever reliable 14x13
Only a matter of time now, before we see, the so called "magical handfuls" of missed multi-gramers (by the 14x13), now being found & brought to light, by the ever conquering, Almighty, GPZ 19 inch coil, hey?      
Patience Dave. All shall soon be revealed.

Cheers Kon.

Hey Kon you could always sell your coil then buy a QED and strap on a 19 Evo for that extra depth l hear the QED out does the ZED and 4500 and near matches the 5000 so still plenty of options for the deep ones lol

JP wrote (in part) ...
Audio Volume also plays a part in this process, cutting back on the global Volume as well as the Target Volume has a pretty big impact, after all target signals are measured in dB 's.
... which makes little sense to someone with an understanding of audio measurements etc. Are you trying to sound "techo" here JP ? It aint working for me !
Cheers

Yep there's always options for the deep ones G.B, but you & I both know (and this is without even trying one) that we'd both be very surprised, if the QED can even match the performance capabilities of the 4500 not alone the 7000. $2000 Australian is what you pay for & $2000 worth, is what you get in performance.
Like I'v said, only a matter of time before we hear the flooding reports of gold coming in from USA prospector/detectorists, which were missed by the 14x13 & found by the All Powerful, Almighty, 19 inch Super Du-pa, D coil.
But don't worry, have faith, for the Almighty 19 inch coil, was built on faith & faith alone. We're bound to hit that rusted out sardine can or part shovel,  at 5 feet deep.
What amazes me even more, is that its been a month since the new 19 inch coils introduction/release, of which hundreds of 19s have been sold in Australia alone so far, for very little good feedback/reports, on any of our Australian Gold Detecting/Prospecting forums. The 19 inch coil, must be that good, that few are willing to talk about their exclusive, massive, lucrative finds, going over their old gold producing areas.

Cheers Kon.

Geez Kon l was hoping you and l could team up with the QED and clean out the goldfields oh well looks like it's back to lumping the 19 around better than lifting weights at a gym. lol

PS good old USA and neighbours might surprise in some of their milder grounds

Yep G.B I'm looking more like a blue swimmer crab by each passing day, constantly lugging that 19 inch coil around. Popeye, eat your heart out.
Yep, I'm hoping the Americans do far better gold wise, swinging the 19 inch coil, than what I'v been able to achieve in the last month.
Running the, GPZ 7000 & 19 inch coil in Normal/General, might be better over US soil, than over our variably changing, mineralized Victorian soil conditions. Too bad we'll never get to use the advantages of running the 7000 in Normal/General whilst keeping our sanity intact.  

Cheers Kon.

Auger wrote:JP wrote (in part) ...
Audio Volume also plays a part in this process, cutting back on the global Volume as well as the Target Volume has a pretty big impact, after all target signals are measured in dB 's.
... which makes little sense to someone with an understanding of audio measurements etc. Are you trying to sound "techo" here JP ? It aint working for me !
Cheers

Not at all. Everything on a metal detector is audio related, therefore a signal response needs to be louder than anything else to be identified. However if your max volume is at X dB, but ground signal is nearly reaching that X level then target signals need to fit into that tight range to be recognised or in a lot of cases are lost because of the overall volume of the audio is to loud. Cutting back on the Volume Limit (Global Volume) and Target Volume helps make the ground signal max volume less intrusive thereby allowing faint signals to be heard.

Not trying to be techo just its very hard to put into words what I mean that everyone can understand sometimes, especially when everything you say gets so scrutinised.

JP

Jonathan Porter wrote:

Auger wrote:JP wrote (in part) ...
Audio Volume also plays a part in this process, cutting back on the global Volume as well as the Target Volume has a pretty big impact, after all target signals are measured in dB 's.
... which makes little sense to someone with an understanding of audio measurements etc. Are you trying to sound "techo" here JP ? It aint working for me !
Cheers

Not at all.  Everything on a metal detector is audio related, therefore a signal response needs to be louder than anything else to be identified. However if your max volume is at X dB, but ground signal is nearly reaching that X level then target signals need to fit into that tight range to be recognised or in a lot of cases are lost because of the overall volume of the audio is to loud. Cutting back on the Volume Limit (Global Volume) and Target Volume helps make the ground signal max volume less intrusive thereby allowing faint signals to be heard.

Not trying to be techo just its very hard to put into words what I mean that everyone can understand sometimes, especially when everything you say gets so scrutinised.

JP

Dont worry JP i understand exactly what you mean.

To simplify perhaps we can re phrase it this way-
if we crank up the sensitivity, we are applying extra amplification to targets, ground response and emi resulting in lots of "noise" in the threshold. if we crank the volume up we are also adding more volume to targets, ground and emi resulting in more noise. if the noise from the ground and emi is greater than the noise from a target, we are likely to not hear a target in amongst the other noise. (especialy deep targets which will rarely be strong/loud signals)
if you run a lower sensitivity (and or volume) we will cut out a lot of the response from the ground and emi, thus allowing targets to be clearly heard. they may not be loud, but they will be clearly audible as there is much less noise for our ears to deal with.

does this clarify?
cheers,
cory

JP
People should have no great problem following what you say about vol-limit/target-vol etc. Thats pretty much what my 5000 handbook gives on p52/3 I guess. While I have no clue about a 7000 I get very annoyed when people with no great electronics/audio background stray outside their field of expertise simply because they are renowned in one or more other fields. That can lead to MISinformation which is worse than no information at all. Dropping in the dBs reference is spurious at best and you should do some serious reading before going there.
Cheers

Auger wrote:JP
People should have no great problem following what you say about vol-limit/target-vol etc.  Thats pretty much what my 5000 handbook gives on p52/3 I guess.  While I have no clue about a 7000 I get very annoyed when people with no great electronics/audio background stray outside their field of expertise simply because they are renowned in one or more other fields.  That can lead to MISinformation which is worse than no information at all.  Dropping in the dBs reference is spurious at best and you should do some serious reading before going there.  
Cheers

 

I can assure you Auger, dBs are used/referenced a lot in the development of metal detectors.

JP

Jonathan Porter wrote:

Auger wrote:JP wrote (in part) ...
Audio Volume also plays a part in this process, cutting back on the global Volume as well as the Target Volume has a pretty big impact, after all target signals are measured in dB 's.
... which makes little sense to someone with an understanding of auDont worry JP i understand exactly what you mean.

To simplify perhaps we can re phrase it this way-
if we crank up the sensitivity, we are applying extra amplification to targets, ground response and emi resulting in lots of "noise" in the threshold. if we crank the volume up we are also adding more volume to targets, ground and emi resulting in more noise. if the noise from the ground and emi is greater than the noise from a target, we are likely to not hear a target in amongst the other noise. (especialy deep targets which will rarely be strong/loud signals)
if you run a lower sensitivity (and or volume) we will cut out a lot of the response from the ground and emi, thus allowing targets to be clearly heard. they may not be loud, but they will be clearly audible as there is much less noise for our ears to deal with.
dio measurements etc. Are you trying to sound "techo" here JP ? It aint working for me !
Cheers

Not at all.  Everything on a metal detector is audio related, therefore a signal response needs to be louder than anything else to be identified. However if your max volume is at X dB, but ground signal is nearly reaching that X level then target signals need to fit into that tight range to be recognised or in a lot of cases are lost because of the overall volume of the audio is to loud. Cutting back on the Volume Limit (Global Volume) and Target Volume helps make the ground signal max volume less intrusive thereby allowing faint signals to be heard.

Not trying to be techo just its very hard to put into words what I mean that everyone can understand sometimes, especially when everything you say gets so scrutinised.

JP

   Thanks JP & Corydale ,so i'm assuming JP ( ,not sure of corydale ,) that this is one of the major reasons as to why you appear to love using an external audio booster ? ?

Just for those scratching their head.................

dB in itself is a meaningless value.

To have any meaning it needs to have a reference point.....like dBm or Dbi or it could even be dB14c (decibels as compared to a 14" coil as the reference point)

In the case of a metal detector a much more meaningful measurement would be a Signal to Noise reference, where the signal is the target sound compared to the Background threshhold.....so it could be called dBt or similar.....

dB in audio is very complex, and there are many references , but all are a way of describing Ratio........ the way you describe one thing against the other.

I have a Noise/sound level meter.
When I point it at a screaming baby and it reads 186 db;     What is is the db reading a ratio of?
I once had a copper point his noise level meter at my motor bike exhaust coz he thought it sounded too loud from where he heard it. What was the db reading in ratio to?

I can be a number of things, but most measure sound pressure levels dB SPL at a given distance in reference to silence and are logarithmic , so the number climbs up on itself as it gets higher ..........186db sounds a very high number though, thats similar to jet engine noise

Adrian - dBA come to mind (A weighted for environmental sounds etc) - you need to read the instruction manual again - sounds like the baby would make your ears bleed etc ? Cheers

I think I tried both A & C weighting and A gave the highest reading.
Yeah if that kid had screamed right in my ear ole I reckon my drums would have punctured. 

GB has a video on Youtube comparing settings with the 19" coil at a test site.

https://www.youtube.com/watch?v=Os4ZbhBpB9E