ground balance till nice hum . there is no trick to this just balance it out by pumping up and down about 1 inch of ground until it levels out. you will find that you balance in 1 area and works great and then move and have to readjust. as you learn the detector you will be able to tell when the ground changes. turning the gain down a little may help depends on the ground but when you do this you lose a little depth. lines of heavy black wont let the machine balance . some hot rocks can be tuned out but then again you lose depth and targets. always go back to the user manual . it doesn t lie.
I have an old whites gm 4b [since 2001 been detecting for 16 years] all manual settings. once I learn it works great. get some dirt from different area and practice ground balancing be sure it contains some black sand. metals will sound real high when and can overload that will scream. heavy black sand will do the same. hot rocks will have different sounds depending on the rock. lead will sound like gold small piece of al. will sound like and small piece of rusty metal , small wire will also sound like gold . my advice is to practice ,practice and practice some until you learn the machine.sometime in certain ground the machine will not balance at all and the only thing to is move on .I have 3 detectors gm 4b ,goldbug 2 and whites tdi sl . I run all 3 at highest settings as the ground will let me . remember the ground will change and you will find you may have to reground balance . hot rocks are a problem they make different sounds so just kick out of the way and detect that spot .I can t say this enough practice practice and more practice until you learn the detector. you have to have confidence in yourself and the detector if you don't have that then you are just out walking . I tell myself when I go detecting , I will find gold and I keep that in my mind as I detect. at the end of the day I not find gold but tomorrow is a new day . when I detect that is all I do .I don't think about anything else .