GPX4500 - The role of the stabilizer.

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GPX4500 - The role of the stabilizer.

Post  bencld on Wed Apr 01, 2009 7:45 am

Hi all. Had an instance yesterday where I was close to powerlines. To get my machine to quiten down enough to be usable, I had the motion on very slow and the gain down to 3 and the stabalizer on 10. This was still giving me a little greif so it was my impression that increasing the stabalizer may help. It actually made it worse. When I backed it off to 8, the machine improved.

Couple of things.

What is the purpose of this control ?

What effect does adjusting this control have on the depth and sensitivity of the machine ?

12X7 NF mono coil.
Thanks in advance.
Chris.
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Re: GPX4500 - The role of the stabilizer.

Post  Jonathan Porter on Wed Apr 01, 2009 8:20 am

The stabilizer raises or lowers the floor of the threshold to allow more or less information through, higher numbers lowers the floor allowing more info (plus more instability once you go past the FP point) and lower numbers raises the floor allowing less info through. Generally speaking higher Stabilizer numbers works better for smaller shallow gold, lower numbers help quieten or smooth out the threshold when listening for larger deeper gold. I rarely go below 8 on the Stabilizer when using coils larger than 16" and have never felt the need to go above the FP of 10 on the smaller stuff.

If using a Mono coil in the environment you describe then the Quiet Audio filter might have helped rather than having to back off everything else (Gain, Stabilizer, Motion etc) or you can revert to a DD coil and detect in cancel mode.

Hope this helps,

JP

PS For more info all of this is covered in our "SETA Project" DVD
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Re: GPX4500 - The role of the stabilizer.

Post  bencld on Wed Apr 01, 2009 9:25 am

Thanks for the reply JP. I was the 500th customer who won your DVD but we have moved house and it is packed and I can't get on to it to find the answer.

Sorry, but can you elaborate on the Quiet audio for me a little.

thanks
Chris.
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Re: GPX4500 - The role of the stabilizer.

Post  alchemist on Wed Apr 01, 2009 11:50 am

G'day Chris,
If you do a search for QUIET AUDIO on these sites, you'll find a bit there that JP and Montana Bob has posted on this subject. Bob likes using quiet a lot.

http://goldandcoindetecting.invisionzone.com/forums/index.php
http://arizonaoutback.ipbhost.com/index.php?s=4c4d8363e82643c5d1ae74907e34d022&showforum=2

Cheers
Grey.
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Re: GPX4500 - The role of the stabilizer.

Post  Jonathan Porter on Thu Apr 02, 2009 7:20 am

bencld wrote:Thanks for the reply JP................ Sorry, but can you elaborate on the Quiet audio for me a little.
thanks
Chris.

The Quiet audio mode is a filter that is designed to restrict or prevent the upper part of the noise or signal response from coming through, a little like chopping the top of waves and only taking the level bits rather than the rough surface layer. By doing this it removes the confused chattery signal mixed into the threshold and leaves a place where the bulk of a good signal still remains but without the instability. The Quiet audio mode can be used with mono coils when just on the fringe of power lines where the threshold is fluttery but not totally out of control but the Auto Tune can't find a clear spot or on days of bad EMI where sporadic periods of instability makes it difficult to hear a good target in amongst the chatter.

Hope this helps,

JP
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Re: GPX4500 - The role of the stabilizer.

Post  Beer Beeper on Thu Apr 02, 2009 11:55 am

Jonathan Porter wrote:f using a Mono coil in the environment you describe then the Quiet Audio filter might have helped rather than having to back off everything else (Gain, Stabilizer, Motion etc) or you can revert to a DD coil and detect in cancel mode.

Hope this helps, JP


I have no clue about the settings that you guys are talking about, as I have a 3000 but I have a fibreglass NF 20" SL XP DD with the Normal/XP coil switch on the coil, not on the cable.

JP or anyone, for such hard to handle noisy environmental conditions, should I run the coil switch in Normal Mode and the machine in Cancel Mode "OR" the coil switch in XP Mode and the machine in Mono Mode ?? Which one is preferred, very, very briefly in as few words as possible ??

(I suppose XP Mode and Cancel Mode does not work.)

Thank You.

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Re: GPX4500 - The role of the stabilizer.

Post  Jonathan Porter on Thu Apr 02, 2009 12:15 pm

Beer Beeper wrote:


I have no clue about the settings that you guys are talking about, as I have a 3000 but I have a fibreglass NF 20" SL XP DD with the Normal/XP coil switch on the coil, not on the cable.

JP or anyone, for such hard to handle noisy environmental conditions, should I run the coil switch in Normal Mode and the machine in Cancel Mode "OR" the coil switch in XP Mode and the machine in Mono Mode ?? Which one is preferred, very, very briefly in as few words as possible ??

(I suppose XP Mode and Cancel Mode does not work.)

Thank You.

XP mode and Cancel mode not sure about from memory it might not due to the phase change. XP mode and Mono mode in my opinion was a little better or more stable if you like compared to Normal and Cancel plus the added bonus of having the correct high/low response on small targets and Low/High on the large which saves on confusion.

Deep mode on the 3000 has a slower motion filter along with Mono mode so the threshold should seem smoother in either of these modes.

Hope this helps,

JP
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Re: GPX4500 - The role of the stabilizer.

Post  bencld on Thu Apr 02, 2009 12:18 pm

Ta for that JP. If it cuts the top off the "wave", then how does that effect my ability to hear those really faint ones on the outer edge of the machines limit ? Also how does it affect small readings ?

Chris.
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Re: GPX4500 - The role of the stabilizer.

Post  Jonathan Porter on Thu Apr 02, 2009 1:02 pm

bencld wrote:Ta for that JP. If it cuts the top off the "wave", then how does that effect my ability to hear those really faint ones on the outer edge of the machines limit ? Also how does it affect small readings ?

Chris.

Going much below FP (10) will impact most on the small gold, I run on around 8, 7 to my mind is the cut off point then performance starts to suffer on all gold sizes. 8 and above helps the smaller shallower gold, too high above 10 and the threshold becomes too ratty for my liking unless conditions are very benign and stable. Keep in mind it is a good idea to set Gain and Motion first before moving too far off the FP for the Stabilizer. If the detector is sounding ratty then adjust the Gain back towards 8 before backing off Motion too far past Slow or the Stabilizer too far below 10 for small gold or 8 for larger stuff.

Hope this helps,

JP
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Re: GPX4500 - The role of the stabilizer.

Post  alchemist on Fri Apr 03, 2009 9:01 am

Hi Chris,
If you're using headphones don't forget about Target Volume.
In the manual on page 73 it says "The Target Volume can be used as an Audio boost in quiet conditions and can also be used to reduce, or smooth out, ground noise signals in highly mineralised soils. This is a powerful feature and will work in conjunction with the Stabilizer control, giving you the ultimate in fine tuning ability. A bit of experimenting may be required to find the optimum combination in different conditions."

It's well worth taking this into account while experimenting with settings. The ultimate balance on any site is found between Gain, which alters the magnitude (amp) of the signals exiting the receiver. Motion, Audio Type, and Stabilizer are all filters that process the waveforms post receiver stage, and Target Volume which alters the magnitude of the output signals. I would expect that all the filters except perhaps Motion are digital and the front and rear amp stages are likely analogue.
It’s certainly a fun machine to use.
Cheers
Grey
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Re: GPX4500 - The role of the stabilizer.

Post  bencld on Tue Apr 07, 2009 6:53 pm

Thanks all for your replies fellas, appreciated. Grey, yes certainly a fun machine to use. I use twin externals running off a B&Z and would never go back to headphones. I suppose this target volume could be used with externals ?

Chris.
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