GPZ 7000 Threshold Setting Concerns

[PhaseTech]

Some great reminders there JP. The only part that confuses me is where you talk about noise floor. The way I visualise it, when Stabilizer is lowered, you are lowering the Noise Floor (not raising it). This is why it is much harder for very faint signals to burst through the threshold or point of audible target signal. 

When you increase the Stabilizer (higher numbers) you are raising the Noise Floor. So with Smoothing OFF (or stabilizer 20) the noise floor is actually higher than the threshold level, and it's raising the noise floor so high that it actually creates its own threshold. This is why when you switch smoothing Off, you can actually drop the threshold down a few numbers and still hear a constant hum. 

For what it's worth, as I am usually detecting much closer to suburbia than JP, I have a lot of EMI. Combine this with the extra bit of EMI you get in High Yield, and I just can't use Smoothing Off most of the time. When I was detecting out the back of Bendigo, with really hot ground, I was in General, and with the Sensitivity on 6. I was also using the WM12 (instead of my normal headphones), and in this instance Smoothing Off was the go. 

Many times (I have lost count now), I am using my normal settings of HY/Difficult/Sens 7-11/Smoothing Low/Threshold 27 (using headphones) and I get a faint but repeatable signal, and before disturbing the ground I play with settings. I go to High Smoothing and the signal is still there, but now it sounds more like a sharp blip, as the start and tail of the signal are now chopped. When I go to Smoothing Off, the signal is still there, but the increase in all other noises drowns out the target signal - there are just too many signals happening in my headphones for my brain to decipher. Back to Low and all is well. 

So as JP says that being in Normal or Difficult also changes things, but your Sensitivity level, HY or General, Volume settings, headphones or WM12 or speaker/booster combo......ALL will change what your optimum settings will be. 

And if I had one wish for the next GPZ7000 software update, I would like a threshold setting of 26.5 😊

[afreakofnature]

Thanks JP!  Wanna put all that in a video with real world examples and add it to my thread? 😊😊 🙏.  I realize that is probably a ton o work so I’m really not expecting that. 😂

 

 

[Jonathan Porter]

11 hours ago, PhaseTech said:

Some great reminders there JP. The only part that confuses me is where you talk about noise floor. The way I visualise it, when Stabilizer is lowered, you are lowering the Noise Floor (not raising it). This is why it is much harder for very faint signals to burst through the threshold or point of audible target signal. 

When you increase the Stabilizer (higher numbers) you are raising the Noise Floor. So with Smoothing OFF (or stabilizer 20) the noise floor is actually higher than the threshold level, and it's raising the noise floor so high that it actually creates its own threshold. This is why when you switch smoothing Off, you can actually drop the threshold down a few numbers and still hear a constant hum. 

For what it's worth, as I am usually detecting much closer to suburbia than JP, I have a lot of EMI. Combine this with the extra bit of EMI you get in High Yield, and I just can't use Smoothing Off most of the time. When I was detecting out the back of Bendigo, with really hot ground, I was in General, and with the Sensitivity on 6. I was also using the WM12 (instead of my normal headphones), and in this instance Smoothing Off was the go. 

Many times (I have lost count now), I am using my normal settings of HY/Difficult/Sens 7-11/Smoothing Low/Threshold 27 (using headphones) and I get a faint but repeatable signal, and before disturbing the ground I play with settings. I go to High Smoothing and the signal is still there, but now it sounds more like a sharp blip, as the start and tail of the signal are now chopped. When I go to Smoothing Off, the signal is still there, but the increase in all other noises drowns out the target signal - there are just too many signals happening in my headphones for my brain to decipher. Back to Low and all is well. 

So as JP says that being in Normal or Difficult also changes things, but your Sensitivity level, HY or General, Volume settings, headphones or WM12 or speaker/booster combo......ALL will change what your optimum settings will be. 

And if I had one wish for the next GPZ7000 software update, I would like a threshold setting of 26.5 😊

TomAYtoes TomARtoes🥴, Key thing is there is more info at 20 Stabilizer setting on the GPX compared to 1. On The GPZ there is more info at Off than there is at Low or High!! I see your point in essence we are talking about dead zone, however on GPX and GPZ (carry over dross) there is a lot of things happening when you adjust these filters not just ‘dead zone’. Problem is, when trying to describe it that way things get messy really quickly.

If your audio is drowning out the target signal in Off compared to Low then it suggests there is a conflict between threshold and Volume. Any sort of Audio Smoothing filter takes away from a full ‘lead in and tail out’ signal response making the audio train steppy. This is particularly noticeable in Difficult where we want all the target information we can get, in Normal there is a LOT more variation even in quiet ground so some Smoothing won’t hurt rather than going to Difficult.

JP

[Magoo]

Im ran steve's super hot setting all day today. Love them.

Appreciate the time forum member take to put there well written,easy to understand thoughts here..

I ran hy normal 20 sen. No amps, no phones, no speaker just wm on left ear. Threshold as loud as needed to here it..

Volumes as steve suggested 4 for both. Full auto gb.

Smoothing off..Found 3 of the smallest bits of gold likely  0.10g combined..

Smallest buckshot pocket full. And dug my first couple of deep targets. Used 22 slug burried in pipe clay. To do some testing. And happy to say above setting i was using came out on top. Couldnt improve on them..Tried lots of combos.. normal killed. difficult.

Hy, normal, smoothing off killed smoothing on high and low..And i was wrapped at the depth this gpz machine was able to detect this slug..I left it there its my new test hole. Will try friends 5000 combos. X coil nugget finder. What evers avaliable. Because i have it burried at a depth my machine with standard coil with maxed settings can only get...Yes more testing required in hotter ground but good test sample. And gave me lots of confidence in gpz going forward. Was running most of the day in semi mineralize ground. Noisey but as steve said really pops on a target.. Thank guys great learning site..

[Norvic]

My 2 bob on getting more out of the Z, if the ground you work can be done using normal, or you can tolerate a noisy machine even in difficult try manual ground balance, requires you to GB manually which with the GPZ fast track is quick and easy requiring just a couple of up and down pumps with FT button depressed.. Set to whatever settings you are conditioned to use except Volume, keep that at 6 or lower. Get the hang of using manual and you will find the Z performs up a notch or so. Also don`t be afraid of using extra deep at times, it will not leave many signals once your tuned in. 

[Gold Catcher]

I find the treshold volume and volume controls to be the most imapctful GPZ funtions. Together with low smooting (if needed) you can rescue Normal mode for many difficult grounds. Sensitivity in Normal is somewhat less important. I keep it at around 6-7 and that has plenty power. 

 

[Magoo]

14 hours ago, Norvic said:

My 2 bob on getting more out of the Z, if the ground you work can be done using normal, or you can tolerate a noisy machine even in difficult try manual ground balance, requires you to GB manually which with the GPZ fast track is quick and easy requiring just a couple of up and down pumps with FT button depressed.. Set to whatever settings you are conditioned to use except Volume, keep that at 6 or lower. Get the hang of using manual and you will find the Z performs up a notch or so. Also don`t be afraid of using extra deep at times, it will not leave many signals once your tuned in. 

Thanks norvic i read your post on another topic. First few days ran manual gb. Found same type of tiny gold. I was glad to find man or auto didnt make a difference in response on my test target. I was mainly swinging over in auto to make sure it wouldnt lessen the response..So im confident in this type of ground that auto is doing the job..But i take on board what your saying..The biggest shock testing was how much i lot in difficult.. i did try very deep and there was a slight improvement on response but not enough to get to excited about..but normal to difficult big difference. Just hope i can run normal more often than not..I will be over the moon when i can get a mates 5000 over test target and cannot pickup. Will make purchasing 7000 worth it🙂

[Magoo]

11 hours ago, Gold Catcher said:

I find the treshold volume and volume controls to be the most imapctful GPZ funtions. Together with low smooting (if needed) you can rescue Normal mode for many difficult grounds. Sensitivity in Normal is somewhat less important. I keep it at around 6-7 and that has plenty power. 

 

Something to try next test lower sensitivity and see if it hears my test target. Cheers

[Gold Catcher]

2 hours ago, Magoo said:

Something to try next test lower sensitivity and see if it hears my test target. Cheers

JP has written about the settings extensively and I recommend to look into the previous threads on this topic. Some really good info there. My bottom line, everybody runs the GPZ somewhat differently. The general consensus is (with some few exceptions...) that HY/Normal/ Smoothing off/ semi-auto GB gives the biggest bang for the buck, assuming the ground allows it. Some of the main differences come from how you prefer to ID your target. Some crank the sensitivity all the way up and tolerate a very noisy threshold with alot of ground/EMI signals mixed in, some others (like me) prefer to reduce the gain to make the target stand out clearer, but the response might also be fainter. However, gain up or down does not matter that much in Normal as you will always hear your target, it just depends how you want to hear it. Normal offers alot more tolerance to parameter changes than Difficult which filters out alot. Here, you need to make up for it by increasing gain and volume. HY/difficult/smoothing is very much reducing the power of the GPZ, but seems necessary for many Au soils to ID targets. My starting settings are HY/Normal/smoothing off, GB: semi-auto, gain 6, threshold 25, volume 9. Then I adjust from there. Threshold-volume is incredible sensitive and reducing it from the default 27 to 26 or 25 has already a big impact. At sensitivity 6 I usually also never have the problem to do GB with the ferrite. In contrast, at sensitivity 12 or 13 in mineralized/conductive grounds I often can't get the ferrite quiet during GB.

Cheers

GC