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Registered: 23/05/12
Posts: 134
I could try and make an analogy of my own regarding sensitivity but I would have a hard job explaining it better than it was explained by John Lynne (AKA the Norfolk Wolf) God bless his memory.  I'm doing the following bit from memory, it's not verbatim.  If you want to see what he actually wrote then buy his book "Advanced Detecting: How to Improve Your Metal Detecting Technique and Finds Rate!"

Sensitivity is often the most misunderstood control on a metal detector, it is not about making the machine as sensitive to the smallest metal object in the ground, it is about making the machine as sensitive as possible to changes in the ground under your coil without overloading the machine and making it unstable.  if you're detecting in a highly mineralised area and your sensitivity is too high then your finds rate will decrease, the machine will not be able to "see" the difference between high mineralisation and and a good signal.  Likewise, if you have it set too low then you're not going to get the best out of your machine.  John Lynne's anaology is spot on:

Imagine that you are in a dark room, completely dark.  In the middle of the room is a 100w lightbulb.  That lghtbulb is going to be very easy to see.  This is like a low mineralisation field with good, shallow signals.  Any machine and any user will find those signals.

Now, open the curtains and bathe the room in light and that 100w lightbulb is harder to see.  the difference between ambient light and the lightbulb isn't so great.  That's like having a good signal in a mineralised field.  You'll still hear the signal but it's going to take a bit more listening.  So how can you make it easier?  Turn the senitivity down!  It's like being in that room and putting on a pair of sunglasses, the 100w lightbulb become easier to see when you block out some of the ambient light.  Remember, the sensitivity does not make the machine more sensitive to smaller metal items, the sensitivity makes the machine more sensitive to the difference in the make up of the ground under your coil.  by turning down the sensitivity your making it easier for the machine to measure the difference between background mineralisation and the good stuff.

Don't be afraid of lowering the sensitivity, what you want is to be using the machine properly set up.  Ground balance affects sensitivity, gain affects the machines ability to ground balance and sensitivity being run too high can affect both of these controls.  This is why a few people will not get on with the Blisstool, they won't have the patience to learn how these controls interact and affect each other.  The end aim is to have the threshold as stable as is possible, the threshold set as finely as possible and running the sensitivity as high as you can whilst maintaining the stability of the machine for the field your're on.

it's no dark art, it just takes a little bit of patience and understanding.  that will only come with experience.

Registered: 23/06/12
Posts: 4
That is the perfect anaology.  and makes so much sense. thanks!!

Registered: 27/03/12
Posts: 212
Originally Posted by hutch1313
That is the perfect anaology.  and makes so much sense. thanks!!

As above, cheers Sheddy


US Moderator
Registered: 18/05/12
Posts: 483
Thanks for the post. It helped a lot.

US Moderator
Registered: 04/05/12
Posts: 451
sheddy, I printed your post so I can read it many times,  and i will be putting it into practice, thank you bro 

Registered: 01/05/12
Posts: 108
Hi Sheddy you are 100% right. I am still waiting for my machine to arrive but I know exactly what your talking about. I put this into practice on most of my hunts letting the machine dictate the amount of sens I should be using and it is a fine line but when you get it into your head that often less is more then you get the rewards finding the small goodies in amongst  the high mineralization,high iron contaminated ground. Everyone needs to put this into practice before their machines come and see for themselves.

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