GPX 4500 Settings

Since the 4500 has come out, one of the biggest problems has been - what settings do I use? Do I use deep, sensitive extra or sensitive smooth and what should I use - either deep settings or shallow settings.

Whilst I was at Laanecoorie, we had the benefit of the experience of John Gladdis, who used to manufacture the Coiltec coils and has been a professional prospector. He set up all our 4500's on the Sunday on a field trip and said it was set and forget. One thing I was surprised at was the big difference it made to my detector and the large response from targets.

Reading what Nightjar had written on a mono coils discussion, they were almost the same. I copied Nightjars discussion and here is the result. I will put John Gladdis's differences in the second column

'Nightjar
I have heard but never seen it proven that using the larger Mono's ie: 20" some sensitivity is lost re: small gold.
However I usually swing a 20" NF/SL Mono in Mono mode and have consistently found gold down to 0.1g in depths ranging from surface to 50mm depth. Yes it is a fact that the 20" can detect deeper however in my opinion the jury is still out on the debate that the larger monos miss the tiddlers.
The only reason to swing the 8" or 11" Mono's is because of mineralisation or delving in creeks or very rocky ground. Needless to say you can get closer to the ground with the smaller coils on restricted ground.
My favoured settings with GPX-4500 on majority of ground are. (of course there are ground condition exceptions requiring totally different set up)

Front panel:
Search mode- Deep - same
Timings- Enhance - same
Ground balance- Fixed - Tracking (Your preference)
Coil/rx- Mono - DD (The switch only transfers DD coils to Mono)


Digital Readout:
Back light- Off - 3
Volume Limit- 19 - 17
Ground Balance Type- General - same
Special- Sensitive Extra - same
Manual Tune- Range between 90 & 100, usually 95 - 96 (10 above is someone else is close, 10 below if EMI occurs)
Deep- Motion slow - same
RX gain- 7 (This can vary depending on atmospheric conditions) - same
Audio- Normal - Deep
Audio tone- 50 - 32
Stabiliser- 6 (This varies with RX gain) - 8
Signal- 19 - Same
Target volume- 12 - 16
Reponse- Normal - same
Tracking- Medium - Slow
Iron reject- Off - 2

When ground balaning, switch from Enhance to normal, do your ground balance then switch back to Enhance and you are on your way. **note** There are instances where ground and or atmospherics don't allow this method and you have to balance in Enhance. (Rarely though)

I use double external speakers, one positioned on each shoulder and wear a wide brimmed hat. Only the severest windy conditions hamper hearing.

Nightjar

I used these setting the during the week and was very happy with them until it was cloudy and windy then EMI played havoc. Jim did'nt really tell me about this and I almost threw my detector away because of the noise.

So talking to a friend, he said that many of the settings were similar to amplifiers so turning down the gain and manual tune made it so much quieter. It just goes to show, that listening and learning can improve what you already think you know and the experience gained by others is very much appreciated.

Jeff

Jeff, was either John Gladdis or Nightjar using headphones or a speaker, I assume going by the very high Volume Limit numbers it was headphones? Just another point, if Enhance is selected on the front end cap then it is irrelevant what is selected in the Special section of the menu as it is disabled.

As an aside, normally there is not a big difference in sensitivity on shallow targets (loudness of a small target response) when going from say a 20" Mono to say 14" (targets larger than say 0.5 gram), yet with the Enhance timings there is a HUGE difference. This year the coil that really hit the mark for me in the highly mineralised shallow areas of WA was a 17" elliptical Mono, the ellipticals really do hit the nail on the head for outright sensitivity on small gold thanks to the narrow design but with excellent coverage thanks to the tip to toe dimensions. Because the winding is actually quite small there are more wraps to achieve the right resistance hence better sensitivity (similar to smaller coils) but they have the same coverage of their larger counterparts. Stepping up to a 16" round for instance reduced the loudness of the almost boundless at times number of small sub gram nuggets I was digging every day (over 40 at times) but still gave me the coverage to keep the ground exposed to the coil for the best chance of hitting at patch.

As a last comment, it is physically impossible to affect or change the Ground Balance of one timing by Ground Balancing in another, I have read about the "so-called" secret GB method of adjusting in Normal then flicking to Enhance. However there is possibly some merit in using the Specific GB with Enhance if the ground is causing a swamping effect.

JP

Hi Jonathan

Yes speakers were being used as you picked up.

You mentioned

"if Enhance is selected on the front end cap then it is irrelevant what is selected in the Special section of the menu as it is disabled"

however although Enhance is selected, if you change the special settings from Sensitive Extra to Sensitive Smooth, you can actually hear the difference, so are you correct in what you have said.

Another point however is the coils. There had been sooooooooooo much discussion on coils that maybe the type of coil is the one that brings out the sensitivity to small gold. It is probably one of the reasons why the 14 x 9 Goldstalker and 11" Commander mono are so good as all round coils.

Jeff

Jefgold wrote:Hi Jonathan

Yes speakers were being used as you picked up.

You mentioned

"if Enhance is selected on the front end cap then it is irrelevant what is selected in the Special section of the menu as it is disabled"

however although Enhance is selected, if you change the special settings from Sensitive Extra to Sensitive Smooth, you can actually hear the difference, so are you correct in what you have said.

Another point however is the coils. There had been sooooooooooo much discussion on coils that maybe the type of coil is the one that brings out the sensitivity to small gold. It is probably one of the reasons why the 14 x 9 Goldstalker and 11" Commander mono are so good as all round coils.

Jeff

I would say John Gladdis and others using those high Volume Limit settings would be suffering from a lot of speaker oscillation problems.

If Enhance is selected then it is impossible to select another timing simultaneously, if you listen carefully when a change is made in Special even though Enhance is selected on the Timings switch on the front end cap there is a "plonk" type response from the menu select function but there is no loading up sound of the timings being implemented. Have a listen when Special is selected and you make changes under the Special menu option (say going from Smooth to Sens Xtra as an example), you should hear a nulling of the threshold hum (threshold smoothes out momentarily till the timings is loaded then it goes back to the slight threshold chatter).

Yes size has a very large impact on sensitivity to smaller gold sizes with the Enhance timings, far greater impact than if you were using say Normal or Sens Xtra unless you went really small, but there is also a converse law at play as well with a nearly corresponding reduction in outright depth on larger targets as well although it is not as apparent as a lot of the larger gold has already been removed due to the larger signal to noise ratio of larger nuggets hence them being already removed.

JP

Thanks Jonathan, as this below really helps to clear things up for me to explain the reality of the sensitivity of coil sizes and also round, elliptical respose on small gold. For shallow ground the 17" elliptical Mono is the go-to coil for the added coverage. The best balance of all worlds, an all-round coil giving the best balance(give and take) on all nugget sizes and depths would be the 11" or 12" round monos BUT they fail on poor ground coverage. SO a person would step up to a 16" round but loose a little sensitivity(reduced the loudness) on small gold to get the added coverage. Do you ever use the 24"x12" for the great coverage(but yes they get less depth than a round)?

As an aside, normally there is not a big difference in sensitivity on shallow targets (loudness of a small target response) when going from say a 20" Mono to say 14" (targets larger than say 0.5 gram), yet with the Enhance timings there is a HUGE difference. This year the coil that really hit the mark for me in the highly mineralised shallow areas of WA was a 17" elliptical Mono, the ellipticals really do hit the nail on the head for outright sensitivity on small gold thanks to the narrow design but with excellent coverage thanks to the tip to toe dimensions. Because the winding is actually quite small there are more wraps to achieve the right resistance hence better sensitivity (similar to smaller coils) but they have the same coverage of their larger counterparts. Stepping up to a 16" round for instance reduced the loudness of the almost boundless at times number of small sub gram nuggets I was digging every day (over 40 at times) but still gave me the coverage to keep the ground exposed to the coil for the best chance of hitting at patch.


And thanks Jeff for this too!:

Another point however is the coils. There had been sooooooooooo much discussion on coils that maybe the type of coil is the one that brings out the sensitivity to small gold. It is probably one of the reasons why the 14 x 9 Goldstalker and 11" Commander mono are so good as all round coils.

I have a GP 3000 so I do not understand all the talk about timings. But I might in the future if I buy a new model GPX 5000 and I hope it is in a more compact and lighterweight housing about the size of an E-Trac!

Thanks Jeff/ Jonathon,
Well this thread certainly clears up where I and maybe others have been going wrong. Am surprised John Gladdis wasn't aware that the 4 Special timings could not be selected while in Enhance?
Enhance is a timing on its own and Special for the 4 other timings. Maybe next time I'll read the manual more closely.

Will certainly be reducing the volume Jonathon because you are right my twin external speakers do oscillate on surface targets.
A recent trip proved the 11" ML round mono was dynamite on shallow and not so shallow gold ranging from less than 0.1g to multiple grams. On one small area known for extreme hotrocks and previously chained using 2000, 2100 & 3000 another 12 nuggets were found, mostly 100mm+ deep.

Question: My understanding is if you have "Deep" selected on front panel it is not advisable to select "Audio Deep" on the menu?

Question: A very noticable difference is experienced if detecting in Enhance then switching to Normal, do another balance then flick back to Enhance. Why isn't it feasable to balance in this way yet results appear to be better suited to current ground?

Cheers
Peter

Question for JP

"...As an aside, normally there is not a big difference in sensitivity on shallow targets (loudness of a small target response) when going from say a 20" Mono to say 14" (targets larger than say 0.5 gram), yet with the Enhance timings there is a HUGE difference"...

JP would that be the same when running in Smooth timings on a 4000?

Thanks in advance

Hi Nightjar;

I have heard this myself

“Question: My understanding is if you have
"Deep" selected on front panel it is not advisable to select
"Audio Deep" on the menu?”

My understanding is that the “Deep” switch
on the front panel has no other function than to set the ‘Menu’ functions to
values appropriate for searching for deep targets.
The “Deep” switch does not switch in any special processes/settings which are
not available from the rear panel Menu.

An example being. If you set up a custom setting e.g. Test A
and copied the menu settings for deep (as listed on P48 of the manual under Deep), Test A
would perform the same function as the “Deep” switch on the front panel.

Selecting
“Deep” on the front panel and changing the Audio tone (menu) to Normal would make the
signal more stable but you would lose the advantage of the deep search.





Scrat

raymondj wrote:Question for JP

"...As an aside, normally there is not a big difference in sensitivity on shallow targets (loudness of a small target response) when going from say a 20" Mono to say 14" (targets larger than say 0.5 gram), yet with the Enhance timings there is a HUGE difference"...

JP would that be the same when running in Smooth timings on a 4000?

Thanks in advance

Very much so with a 4000 and Smooth mode, Smooth is no where near as sensitive as Enhance is.

“Question: My understanding is if you have
"Deep" selected on front panel it is not advisable to select
"Audio Deep" on the menu?

Deep Search Mode is just a suggestion by Minelab to help in the search for deep gold of which one of the FPs in the audio section is the Deep Audio option, once you make changes to the Deep Search Mode then Deep is no longer the Deep Search mode suggested by Minelab (which is OK BTW, just trying to make the distinction between the suggested Deep Search Mode option and the Deep audio filter which really does assist on deep large targets).

If you select mono & do a balance, its balanced in that mode, but will not be balanced if you select dd, you have changed from one timing to another yu'll have to balance again....which is the same as your question

This is not quite correct, DD, Mono and Cancel modes are not timing changes but receive (RX) methods, going from one to the other does affect the GB however so the detector should be re-balanced each time. Enhance, Normal, Special/Sens Xtra, Smooth and Salt Coarse are all timings which when the detector is balanced in any of them will keep that information stored in memory which can be re-called when the timing is re-selected assuming the given area has the same Ground Balance as when it was set (otherwise it will be out as the stored GB information is stored in a Fixed GB state). Balancing in one should/would not affect the others as they are all individual.

Ground balancing in Enhance timings using the Specific GB method described in the owners manual can help in areas that have massive ground effect (highly mineralised surface concentrations that swamp the coil).

Hope this helps,

JP

Gday JP, Nightjar, All
I run in Enhance but sometimes this "hot" ground over here means it's SS or nothing. It's a bugger SS loses so much depth as it would be perfect to run if it had the Enhance functions performance. Running in Enhance I'll often just flick the switch over to SS and re GB just to check hotrock, only takes a sec and I don't do it for anything faint. Then switch back and re GB. Works ok.
Have encountered the coil swamping you talk about JP on many occasions and hadn't thought about the Specific GB but will definitely give it a shot next week.
Running the NF 14x9 Advan mono and it is extremely quiet with noticeably less emi on the 4500. Great depth and sensitivity as well and also has good coverage and weight.
I was watching/listening to a couple of guys out bush a few weeks ago running a 3000 and a 3500 with mono's and the noises being produced by their machines was unbelievable. Made me realise just how quiet the 4500 runs.
cheers
Brett