GPZ 7000 Audio Smoothing

[Steve Herschbach]

The Minelab GPZ 7000 audio Smoothing function was directly derived from the Stabilizer control used on the GPX series. From JP at http://www.detectorprospector.com/forum/topic/715-gold-i-found-in-victoria-with-the-gpz/?p=6424
 
"On the subject of Audio Smoothing: Off on the GPZ = 20 on the GPX 5000, Low equals 15 and High equals 10."
 
JP at the link referenced obviously prefers Smoothing to be left off. Some people are experimenting with higher audio smoothing settings combined with either hotter Gold Mode settings or higher Sensitivity settings or both. I think this is a good thing so do not go thinking it is "wrong". There is no right or wrong per se, it is all about what works for each prospector and their personal tolerance for noise or the lack thereof. Experimentation is good.
 
I thought it would be informative to copy what the GPZ manual (page 66) has to say about the Stabilizer control. Warning: the GPX Stabilizer control is backwards. The highest setting if 20 is the off position. Lower numbers increase smoothing. So the GPZ at off is same as GPX at 20 (off). Note that the GPZ High setting is the same as the GPX default setting of 10. The default for the GPZ 7000 is Low Smoothing which is the equivalent of a setting of 15 on the GPX.
 
One final note. RX Gain as referred to on the GPX is the same as the Sensitivity control on the GPX.
 
From the GPX manual:
 

Quote

The Stabilizer function controls the point at which faint variations in the Threshold begin to be heard. These faint variations can either be ambient noise or faint target signals. As you increase the Stabilizer control faint signals will become louder but the noise level will also increase. This may potentially hide a desirable target signal. The Stabilizer allows you to mask faint variations, to provide a perfectly stable Threshold, improving your ability to identify faint target signals.

The Stabilizer is best left in the Factory Preset position until the soil conditions are determined. Once the Rx Gain level has been set for the local conditions, and other audio settings have been selected, the Stabilizer can then be used to fine tune the Threshold stability.

To find the optimal position of the Stabilizer ensure the coil is being swept across the ground. One number below the point at which the Threshold begins to chatter is generally the best setting.

The effect of the Stabilizer could be seen as having a similar effect to that of the Rx Gain control. However, the Stabilizer affects the audio processing only and does not change the Receive (Rx) signal, so it should be used as a final stage fine tune.

After making any adjustment to the Stabilizer, if the ground conditions change or you wish to change coils, you may need to reset the Rx Gain. Before doing so, return the Stabilizer to the Factory Preset setting. This will ensure you select the most appropriate Rx Gain level to suit the conditions and then you can fine tune the Stabilizer.

Note: Regardless of which Audio Type is selected, the optimal setting of the Stabilizer is one number below the point where the Threshold begins to chatter.
 
Tip: By turning the stabilizer control close to minimum (<3) the threshold will be very stable, but you will lose a lot of sensitivity to smaller targets. This can be a desirable feature in certain scenarios, such as looking for large nuggets in a high-trash area, or using the GPX Series to search for coins or treasure. We recommend the best order for setting these controls are:

1 Select an appropriate Search Mode.
2 Select the desired Audio Type.
3 Adjust Rx Gain until the threshold starts to break up.
4 Adjust Stabilizer to smooth out the threshold.

 I guess I should say that my preferences tend to follow JPs - I run with audio Smoothing off under nearly all circumstances. But I wanted to make this post to create a thread on the subject as it is very clear people are having success with other ways of thinking and again, I like out of box thinking. Lunks settings at http://www.detectorprospector.com/forum/topic/830-lunks-zed-settings/ are at the other end of the spectrum. I also liked Jason's observation on the subject at http://www.detectorprospector.com/forum/topic/827-minelab-video-gpz-7000-ground-type/?p=8276

[jasong]

On 4/6/2015 at 9:35 AM, Steve Herschbach said:

There is no right or wrong per se, it is all about what works for each prospector and their personal tolerance for noise or the lack thereof. 

Very true. On that subject, I've heard that the users having the hardest time adapting to the Z are the ones who are really used to GPX's. I was definitely one of these people, I really didn't feel like the Z was speaking my language the first few days until I tamed the audio. I was stuck at keeping it off for maximum depth at first. This may be exactly what the guy detecting next to me prefers though. I think it depends how a person had their GPX set up, some ran it much closer to how the Z is set up by default, some ran it on either of the 2 edges of that spectrum.

If a new user came up to me with the same concerns I had the first few days of using the machine, the first setting I'd advise them to adjust would be the Smoothing. Either up or down depending how they were used to running their GPX. Threshold would be a close second. As you become more used to the machine it seems like it becomes easier to listen for spots where you should be kicking the Smoothing up or down depending on the conditions.

[Jonathan Porter]

On 4/6/2015 at 9:35 AM, Steve Herschbach said:

The Minelab GPZ 7000 audio Smoothing function was directly derived from the Stabilizer control used on the GPX series. From JP at http://www.detectorprospector.com/forum/topic/715-gold-i-found-in-victoria-with-the-gpz/?p=6424

"On the subject of Audio Smoothing: Off on the GPZ = 20 on the GPX 5000, Low equals 15 and High equals 10."

JP at the link referenced obviously prefers Smoothing to be left off.

My public comments always come from what I feel are a basis of solid field experience, in the case of Audio Smoothing it has come from many hours of discussions with Bruce Candy and Minelab's PD team, if Bruce tells me a way to get maximum performance out of his technologies then I'm all ears because in this particular case it was Bruce.

JP

PS Upon reflection, a tip for people reading the methods described when using Audio Smoothing as a ground controlling tool.

Audio Smoothing is a filter and as such will filter out a certain amount of ground signal as well as a lot of the target signal especially the deep faint targets, hence if you can tame the ground signal somewhat in ground that is not too mineralised then you can continue detecting in a Normal Ground type mode instead of reverting to Difficult.

Difficult Ground Type removes ground signal and at the same time also removes target signal responses as well, so in less aggressive ground types, such as is in the US, using the Audio Smoothing as a ground signal filter when using Normal Gold Type mode makes sense, however keep in mind the operator needs to get the Volume levels correct to save on retraining their ears to the volume level differences between OFF and High, because although it sounds great going higher on the Smoothing it will be painful coming back again!!

[Lunk]

PS Upon reflection, a tip for people reading the methods described when using Audio Smoothing as a ground controlling tool.

Audio Smoothing is a filter and as such will filter out a certain amount of ground signal as well as a lot of the target signal especially the deep faint targets, hence if you can tame the ground signal somewhat in ground that is not too mineralised then you can continue detecting in a Normal Ground type mode instead of reverting to Difficult.

Difficult Ground Type removes ground signal and at the same time also removes target signal responses as well, so in less aggressive ground types, such as is in the US, using the Audio Smoothing as a ground signal filter when using Normal Gold Type mode makes sense, however keep in mind the operator needs to get the Volume levels correct to save on retraining their ears to the volume level differences between OFF and High, because although it sounds great going higher on the Smoothing it will be painful coming back again!!

I totally agree with JP on his Audio Smoothing tip, and I've been experimenting lately on additional ways of avoiding the necessity of switching from Normal to Difficult Ground Type; when in Normal and the ground becomes too noisy for High Yield Gold Mode even at low sensitivity, changing to General often solves the problem and the sensitivity can be increased a couple points to compensate for the slight loss in sensitivity to small gold. If the ground is still too bad, switching the Gold Mode yet again to Extra Deep and increasing the sensitivity appears to still have a noticeable amount of performance over the Difficult Ground Type, and has been able to eliminate extremely variable ground noise.

[DDancer]

Not emi related but it does answer a question in another post as well as tie two view points together.

Thanks JP.

*points that way : http://www.detectorprospector.com/forum/topic/827-minelab-video-gpz-7000-ground-type/?p=8270 *

[mn90403]

The subject is serious.  If you can't hear targets then you can't get nuggets.  Hi, low, on, off, a little of this and not so much of that ... is this machine more art than science?

[Steve Herschbach]

The GPZ has oodles of power in the stock settings and it is only the never ending quest for the perfect setting played out online that is making it seem difficult. Frankly, in my opinion too many new users are overdriving the machine too quickly. I ran mine at near default settings to make most of my finds and have not strayed very far from them even yet. If you perform the Quick Start you are basically good to go. The default settings are:

 

Gold Mode - High Yield

Ground Type - Difficult

Ground Balance Mode - Auto

Audio Smoothing - Low

Sensitivity - 9

 

To show you how conservative I am so far the only real adjustments I have made are to generally run with Audio Smoothing Off. I will try Ground Type Normal if the ground appears mild enough to handle it, and go back to Difficult if the machine gets unstable. And I generally run Sensitivity between 9 and 12, with 12 being my most common setting.

You can make the GPZ as simple or as difficult as you want it to be. I prefer simple. A lot of thought went into the default settings and in my opinion they are far closer to where you want to be than most people seem to think. Just my opinion.

[LuckyLundy]

You can't run this machine wrong! There are many setting members have posted, what they have found color with. I don't have a dialed in setting and have a small note pad full of settings that have added gold to my poke from NorCal to Northern Nevada. The GPZ, is like a Corvette! You can run it hard and fast or at normal cruise speed. I like both speeds depending if hunting old patches or new ground. Until the next hunt,

Rick

[Norvic]

My GPZ is more like a Toyota, nothing fancy just gets the job done. Oh what a feeling.   I`ll get some more speed out of it once it trains me.

[Sourdough Scott]

A new video from JP on Audio Smoothing.