Normally, I have the disc set to below iron and or lower. You will be amazed at how good the signals are and you are hunting with limited disc at best. The iron in MOST cases will sound broken, and to verify when you get the signal, move the coil rapidly over the sound. If it breaks up you have a pretty good idea that it is iron. If it doesn't break up, then you have a good signal. The good signal will sound "clear", in ways a higher, truer, tone. The bad signal will sound broken or clipped. If your disc is set higher than iron at some sites you will miss some thin gold. So keep that in mind. If you are hunting a trashy area then by all means increase your disc settings. Finally, if the ground conditions are too much and there are signals everywhere and you are looking only for quarters or dimes, take either and wave the coin over the coil and then adjust your disc to where you still read the coin as you increase the disc. Then when you have found that point on the machine, lower the disc down by a small nitch and then start detecting. I once did this in EXTREME mineralized ground and found a 1852 half dime, 1858 dime, and a breast plate. All in the same area's where others had dug before- they couldn't read the ground because the ground was too mineralized and with another brand machine, I just disc'd the machine to 10 and started sweeping the coil. I also found a few one cent pieces this way too.