high threshold

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high threshold

Post  bbrook on Thu Dec 03, 2015 2:32 pm

Hi , I have just got a gpx 4500 and I'm wondering about the threshold level .
After using a gp3000 I am used to the threshold control being at about 12 or 1 o’clock , however the 4500 is inaudible till about 4 o’clock and since the knob only goes up to 5 and a bit ,there's not much leeway

I have the right battery , if that makes a difference ( could it be the inbuilt amp in the battery? )
I’ve tested it with several coils , external speaker or head phones .The detector seems to work ok , except for the high threshold setting , so , is this an issue ( Just running on factory pre-set for the moment )

I sent an email to minelab who replied very promptly with "The threshold control is a Variable control for each individual to set to suit their own personal preferences, so there is not a specific point to set it to. Otherwise we would not need a variable control."
Fair enough ,but since the point at which the threshold is a steady hum is nearly flat out I think there is something not right .They did say I could send it in but just in case I'm the problem , any clues ?

thanks , Brett
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Re: high threshold

Post  Guest on Thu Dec 03, 2015 4:20 pm

G'day Brett,

Have you gone into the back control panel and check where the volume settings are set at. There is 2 volume settings in the 4500/5000 and set them to the FP settings and you should be able to see if that improves the threshold level. We normally have our threshold set at around the 1-o'clock area on the 4500/5000. Hope this helps with your problem, but if the volume levels don't help then I would be sending your machine back to Minelab.

Cheers.

Mike.

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Re: high threshold

Post  bbrook on Fri Dec 04, 2015 8:43 am

Hi Mike ,thanks for the reply , yes, had it all on F.P . Had a fiddle last night and tried cranking the target vol flat out but it only helped a little ; with the threshold humming in at a bit past 3 oclock , so I guess its due for a holiday to minelab
thanks , Brett
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Re: high threshold

Post  davsgold on Fri Dec 04, 2015 2:20 pm

bbrook wrote:

I sent an email to minelab who replied very promptly with  "The threshold control is a Variable control for each individual to set to suit their own personal preferences, so there is not a specific point to set it to. Otherwise we would not need a variable control."
Fair enough ,but since the point at which the threshold is a steady hum is nearly flat out I think there is something not right .They did say I could send it in but just in case I'm the problem , any clues ?  

 thanks , Brett

As are most of the other controls (variable) but they all work better if they are working properly, I have seen other detectors same model that did this and they sent them back to minelab to be fixed, they came back with proper adjustment on the threshold. Most likely replaced the trim pot, can't remember.

It's true the threshold just needs to be heard at a nice steady hum not to loud and not to soft, but in my opinion if the trim pot is a bit faulty and needs the be way higher than about half way then there is not much lee way left for further adjustment on the up side.

It won't necessarily affect the detectors performance it is just plain annoying when you are nearly out of adjustment.

cheers dave
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Re: high threshold

Post  kiwijw on Sun Dec 06, 2015 3:06 pm

Hi there Brett, I run my 4500 threshold at about 1 o'clock too, so maybe you should send it off for a holiday. Wont do any harm to have Minelab give it a health check, probably a bloody good thing to do. You will be in for a bit of a learning curve going from the 3000 to a 4500 but once you have a bit of time under your belt with the 4500 you will love it.

Good luck out there

JW V08
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Re: high threshold

Post  bbrook on Mon Dec 07, 2015 8:44 am

thanks Dave and kiwi ,I think a check-up is in order .I had a first swing last weekend and it seemed to go alright ,got a couple of lead slugs , but detecting is such a mind game that you need to trust your machine is 100 % .

I'm not sure on Minelab's turnaround time so I will probably send it off after new-year , I would like to get some swinging in over Christmas

Thanks , Brett
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Re: high threshold

Post  Nightjar on Mon Dec 07, 2015 9:58 am

Brett,
Just set it to suit your hearing and forget it. Who cares if it is 1 o'clock, 2 o'clock what ever. As Minelab have told you it is variable.
We only use the B&Z threshold knob, almost forget where the threshold knob on the 45 is situated. Smile
Have met prospectors out on the field who swear by running the gain flat out and threshold zero. Tried it once but after using the 45 with a faint background threshold for years it seemed very strange running silent. Had to swing the pick past the coil every now and then to see if the machine was still working.
By all means send it in for a check up, wouldn't do any harm, just dent your wallet.


Last edited by Nightjar on Mon Dec 07, 2015 11:12 am; edited 1 time in total (Reason for editing : extra)
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