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GPZ 7000: Threshold Vs Sensitivity Vs Volume Vs Volume Limit (with Discussion On Audio Smoothing, Coil Control, Range Of Motion And Manual Ground Balance)


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Hey All.  I have been researching this last month or so throughout Detector Prospector, Minelab's Knowledge Base and TreasureTalks so that I can take my skills with the GPZ to the next level and I think in order to do that it involves these 4 settings:  Threshold, Sensitivity, Volume and Volume Limit.  A lot of forum members talk about these comparing and contrasting, but none really give you a "How to."  How do you go about adjusting these to reach perfection, to reach that perfect ZVT zen.

Conclusions that I have read are that: it just depends on what you want to hear, or how you hear what is coming out of the detector.  OK, but I think it is more to it than that, and if you don't understand what these controls do how can you really achieve the best results.  

Keeping these setting the same.  Noise Canceled.  Gold Mode: High Yield.  Ground Type: Normal.  Ground Balanced with Semi Auto.  No filters - Audio nor Ground Smoothing.  Lets talk about how we start.

Here is what I have researched and summed up describing these controls.  These are my "interpretations" based on everything I have read and I think I really have a grasp on it now.  This information and dissemination of it came from everyone here, and I mean everyone!  Huge Thank You!

Sensitivity:  aka Gain.  Control of the INPUT "strength" of a "sound wave."  You don't actually control how "sensitive" the coil is.  ZVT is ZVT, that is the tech we are using  In order to understand these controls I think of it like a "sound wave".  What you control is the "sound wave" coming into the machine.  Too much gain and you over modulate the sound wave, cause distortion, and increase the "noise" level.  Too little gain and your "sound wave" is decreased (like making it a flatter line) maybe allowing large "sounds" to come through but in return lowering the "noise" level and small "sounds."  In Sensitivity is where you want to produce the "perfect sound wave" coming into the machine.  You want that sound wave to just barely reach below a distortion level to get the best "sound or tone"  

Threshold:  This is how much of the "noise" level you want to hear.  It kind of acts like a bottom or "noise" filter.  Increase threshold (lower number on GPZ) and you filter out more of the "noise" level as well as small "sounds."  The opposite is to lower threshold (increase number on the GPZ) to filter out less of the "noise" level and hear smaller "sounds."

 

These two setting should play off of each other so that you can achieve the "biggest window" for the ZVT "sound wave" to operate in with the least amount of "noise".  Some people use a 20 sensitivity and a 7 threshold.  Is that the biggest window they could achieve?  Some do a 15 sensitivity and a 27 threshold.  Is that the biggest window they could achieve?  How come you could not do a 1 sensitivity and a 53 threshold?  Nobody has ever commented on that.  Boost it?  Probably not a good idea.  I don't know, never tried.  Food for thought, but I hope you get what I am saying about that.

In my eyes these two controls are where you should start.  Achieve the biggest "window" that ZVT can work with.  If you minimize the window you are not taking advantage of the full technology.  In turn you are probably not finding the smallest pieces you could achieve or  the greatest depth on targets.  Don't limit ZVT, maximize it to its full potential.  Open the window as far as you can for the ground/mineralization you are in.

 

Now on to Volume and Volume Limit

This is where I do not have the best grasp on these controls, even after all the research I am not sure if I am describing these correct.  So many people play off of these and have different explanations.  This is what I "think" they mean.

Volume: aka Audio Boost.  Control of the OUTPUT "loudness" of the Threshold and Sensitivity window that you just created.  We are told that this acts like an audio boost and that increasing this by one is like increasing Sensitivity by 2, etc.  I don't think that is a good way to describe it, at least for me.  What I think Volume is doing is increasing the loudness of the "window."  Than includes the "sound wave" as well as the "noise" associated with it.  If you can not hear the targets you want after adjusting your "window" above, then you need to boost the audio.  Doing this though will increase what you hear in "noise" and  I "think" this is why some describe this as equivalent to increasing Sensitivity but it is not.  The "window" has already been set with your Threshold and Sensitivity, what volume does is change the OUTPUT "loudness" and there by multiplies how big the window is ("sound wave" and "noise").  This allows you to hear hear more, but more of EVERYTHING, in affect increasing overall loudness.  This is why it should be used "conservatively."  Start at 1 and work up until it is where you "like" hearing it.  This is the part that should be subjective to each individual and their hearing.

Volume Limit:  The Big Mystery.  What does this do?  How does it help me?  Some say that this is actually volume.  Some say this is what you should adjust to hear targets better.  Some say it is just there to not blow your ear drums off if your volume is set to high.  My questions are:  Does this affect the "OUPUT" signal or the "INPUT" signal or both?  Why would I want a Volume Limit?  My thoughts on this......  I think that Volume Limit sets the MAXIMUM Volume (Audio Boost) "level" that can be used.  I don't THINK it limits the Sensitivity.  So this is an OUTPUT control.  Therefore if you set the Volume Limit high you would get a higher (louder) incremental step with each number in Volume (Audio Boost).  If you use a lower Volume Limit, you would have lower (less louder) incremental steps in Volume (Audio Boost).  So if you want more precise control of your Volume (Audio Boost) you would set a lower Volume Limit.  The trade off is maximum loudness.  If you need to hear things louder you are going to have to raise your Volume Limit and then adjust your Volume (Audio Boost) accordingly.  My thoughts are that people think this actually raises the volume but in the end if you keep Volume (Audio Boost) at 8 and increase Volume Limit, it will get louder per se because you just raised the the maximum loudness level there by increasing the loudness steps for each Volume (Audio Boost) number.  Make sense?  It does to me, I hope I am right otherwise I am gonna have to relearn this all over again 😉

 

Well now I need feedback from you all.  Am I out in left field on all of this?  Am I spot on?  Or do I just need some minor tweaks? 🤣 

AND if you have the desire to help some, could as many folks as possible make a video of them adjusting these settings to achieve a perfect balance?  These are the videos that are missing on YouTube, etc.  We see tons of people digging up gold but not many at all on "How" they use and set up their machine.  This would be huge to see.  You don't have to make a fancy video, maybe just have someone with their phone over your shoulder while you go through it.  This would be a huge boon for a lot of people, including myself.  Especially us that have to stay in all winter and have to wait to test their own theories. 🤣  So any help in that regard please post!  OR if you already found some vids, please share.  I have tried every search I could to no avail.

Anyways many members on here have said it before.  You need to learn your machine.  Its only one aspect of being an expert detectorist.  I know I am not there yet cause it sure looks like I am still trying to learn my machine.  The rest for me seemed to have come easier, researching locations, reading locations, putting the coil over the gold, etc.  Now I NEED to revisit a bunch of locations where I got the easy gold by just using preprogramed settings that I learned when I just started.  I started detecting at the SDC level.  Turn on and go.  I never had a GPX so comparing to the old never helped me.  I am part of the new school of detectorists and I don't want to be ignorant by having less control.  I want to take control.  Its time to achieve ZVT zen and see what was left behind.  Its time to level up.

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The Volume limit just caps off the loudest part of the signal.

This is so you can set the base volume/treshold/taget signal at a levels that are easy to hear but you can limit the loudness peak of a large/loud response so that you do not blow your ears off every time you detect a 10oz sunbaker😃

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A lil advice mate... read the manual... then read it again... and again... then go detecting and then read it again... then detect some more and read it again!

The manual is your new bible!

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26 minutes ago, Gold Hound said:

every time you detect a 10oz sunbaker😃

Ah, if I had a dollar for every time that has happened I would be broke  😉

 

13 hours ago, afreakofnature said:

Sensitivity:  aka Gain.

Please bear in mind my answers are guesses and how I like to set up a GPZ.  I'm sure JP will have the most relevant answers as he is possibly the only one  on here that really knows what is happening 'under the hood'.   Hopefully he has time to respond.   Steve H - maybe as you were a tester they have told you some of the magic also?   

I always guessed Sensitivity on the Z was a Transmit control. Pumping more power to the coil to light up targets but at the same time lighting up more ground signal and catching more EMI.   

Mostly ran Sensitivity at a point where it starts to get jittery and backed it off 1.  But, on occasion when there were tiny pieces to clean up in an area, I would go full noise at 20 and this would light up the tiniest of pieces.  However, the noise was not something I could handle on a constant basis and I believe you would also be missing the subtler noises in amongst the racket.  

 

13 hours ago, afreakofnature said:

Threshold:

My theory would be putting Threshold much above 27 would be slowly limiting more and more targets as the Threshold went higher.  And my view of Threshold must be the opposite to yours.  I think moving the Threshold higher is taking the numbers higher.  Lowering the Threshold and making it quieter is taking the numbers lower.  Maybe it is due to being in different hemispheres  😄     Taking the Threshold numbers so low that you could no longer hear a Threshold seemed counterintuitive also as I wanted to hear the faint variation in that steady audio 'line'.   The GPX 6000 is going to be interesting with it's couple of no-threshold settings. 

 

13 hours ago, afreakofnature said:

Volume:

I always thought was just that - Volume.  Just like turning your radio up.  Purely increasing the loudness to your liking.   

 

I used a booster (B&Z) and ran Volume on the Z at 1.  I found it worked great.  The mate's Z that I use now simply has the WM12 and I really miss the control a booster provided.   

 

13 hours ago, afreakofnature said:

Volume Limit

The same as Gold Hound described - just a ceiling for any given target.  i.e. - whatever the size or the proximity of the target it simply won't go above 30 decibels or 45 decibels or whatever it is you have it set at.   

 

As I said, this is my simplistic view.  I'm surprised more people haven't responded.  It has been a long day and has taken this long to finally read all of your post and respond.  Great topic though.  I think most of us are only scratching the surface with the positive differences the various Z controls could have.  

 

Cheers, N.E.  

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9 minutes ago, Gold Hound said:

The manual is your new bible!

I agree with that Dale but have also cut and paste most of JP's comments on DP re: the Z and some of Steve's also - there is another whole manual of info there that simply isn't covered in the original.  

Although it is funny that a few things in the manual were pointed out to me by JP but just put in a different way.   Couldn't see the forest for the trees at times  🤦‍♂️

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30 minutes ago, Northeast said:

I agree with that Dale but have also cut and paste most of JP's comments on DP re: the Z and some of Steve's also - there is another whole manual of info there that simply isn't covered in the original.  

Although it is funny that a few things in the manual were pointed out to me by JP but just put in a different way.   Couldn't see the forest for the trees at times  🤦‍♂️

Everything I learnt came from trying all of the settings in the field and reading the manual.

If you want to find more gold you need to have an understanding of what every setting dose. They are described in the manual then you need to apply them for yourself.

There is no substitute for field application and controlled testing when you get a new detector.

I do things a fair bit different to most others as they work for me in my testing.

 

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5 hours ago, Gold Hound said:

A lil advice mate... read the manual... then read it again... and again... then go detecting and then read it again... then detect some more and read it again!

The manual is your new bible!

 

5 hours ago, Northeast said:

I agree with that Dale but have also cut and paste most of JP's comments on DP re: the Z and some of Steve's also - there is another whole manual of info there that simply isn't covered in the original.  

Although it is funny that a few things in the manual were pointed out to me by JP but just put in a different way.   Couldn't see the forest for the trees at times  🤦‍♂️

Yes, I have read the manual.  Over and over. Plus I have also done what Northeast has done and basically inserted a lot of DP, Knowledge Base and TreasureTalk articles based on a couple months of research.  I have used the Z for about 3 years now too.  I plan on posting this "revised" manual in the future for everyone to have.  I am hoping it will be kind of like a wiki that others would want to add to so all the content is in one PDF.  But before I do that I want to have a good "grasp" on how to adjust these controls for ZVT perfection (based on the ground you are in).

Hopefully some videos will roll in. Fingers crossed.

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5 hours ago, Gold Hound said:

The Volume limit just caps off the loudest part of the signal.

This is so you can set the base volume/treshold/taget signal at a levels that are easy to hear but you can limit the loudness peak of a large/loud response so that you do not blow your ears off every time you detect a 10oz sunbaker😃

 

5 hours ago, Northeast said:

The same as Gold Hound described - just a ceiling for any given target.  i.e. - whatever the size or the proximity of the target it simply won't go above 30 decibels or 45 decibels or whatever it is you have it set at.    

more on Volume Limit:  I used to think this too until I read a couple posts by others on here.  They say their experience with Volume Limit is actually more like what volume itself should be.  After researching what a volume limit is it should just set what the maximum volume can be (to protect your hearing), but if this was the case the Volume control would not change how much it goes up incrementally based on that limit.  Therfore, if you cranked up the Volume control everything would just be complete noise or distortion, because in theory the noise loudness would be the same loudness as a target as it could reach the same limit.  Therefore in conclusion, I think it is just a "maximum" loudness level overall setting and not a clipping function of the Volume control.  

Hopefully someone might be able to test this and show in a video 😉.  If not I will be in May when the snow is gone, but the more the better!🙂

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4 hours ago, Gold Hound said:

Everything I learnt came from trying all of the settings in the field and reading the manual.

If you want to find more gold you need to have an understanding of what every setting dose. They are described in the manual then you need to apply them for yourself.

There is no substitute for field application and controlled testing when you get a new detector.

I do things a fair bit different to most others as they work for me in my testing.

 

Yes this is well known and posted many times in the forum.  However, people can also learn from others.  This is what I am trying to promote.  Let's SEE what others doing and lets SEE if the certain theories that have been discussed hold true or not.  

That's my push for some videos.  🤣 I love watching videos of people digging up gold, especially when I can't go out, but how about turning on the camera when you start too so we can watch you set up your detector for the ground you are in.  Let's watch the process.  🙂 

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Northeast, Thanks for the indepth response!  I know that had to take some time cause it took me about 6 hrs to write up my summary from what I had researched and learned.  Here are some of my comments to your replies.

14 hours ago, Northeast said:

I always guessed Sensitivity on the Z was a Transmit control. Pumping more power to the coil to light up targets but at the same time lighting up more ground signal and catching more EMI.   

more on Sensitivity:

I don't think that more "power" is going to the coil.  If that was the case you would have more battery drain.  More power, more energy right?  In other posts people were thinking this should be like volume.  But volume is an OUTPUT control and I think that Sensitivity is an INPUT control.  I think of it like a guitar plugged into an amp.  The amp has a gain and a volume too.  The gain controls what is being sent from the guitar to the amp (INPUT).  The volume controls what goes from the amp to the ear (OUTPUT).  Yes it does sound louder when you adjust the gain, but like a guitar if you just crank the gain all the way up it sounds distorted and noisy.  Bring it down some and you can get the max loudness with the perfect tone.  Same with volume on the amp.  Once you get that perfect tone with gain you can turn up the volume to get the max loudness before you introduce the noise level but that volume increase is subjective to your hearing.

14 hours ago, Northeast said:

And my view of Threshold must be the opposite to yours.  I think moving the Threshold higher is taking the numbers higher.  Lowering the Threshold and making it quieter is taking the numbers lower.  Maybe it is due to being in different hemispheres  😄     

Yes it might be different hemispheres, because this comes straight from the manual made by Aussies 🤣.  I think we all think like you do but I wanted to stay consistent with how the manual describes it.  It is why I put the numbers with it too so we could all be on the same page.

14 hours ago, Northeast said:

I always thought was just that - Volume.  Just like turning your radio up.  Purely increasing the loudness to your liking.  

I used a booster (B&Z) and ran Volume on the Z at 1.  I found it worked great.  The mate's Z that I use now simply has the WM12 and I really miss the control a booster provided.   

 I think we are on the same page here so that is good to see.  I use the WM 12 too.  I should maybe have said that above.  I don't see the need for a booster though when you can boost with the Volume control.  Maybe more analog control instead of incremental steps?  This should be the topic for another thread though.  Also I have not done any research on this yet so everything would be speculation.  Personally I just don't want to wear more gear. 🙂

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  • afreakofnature changed the title to GPZ 7000: Threshold Vs Sensitivity Vs Volume Vs Volume Limit (with Discussion On Audio Smoothing, Coil Control, Range Of Motion And Manual Ground Balance)

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