Don't get all caught up in the TDI, you can tell by the sound if you should even look at the display. I run mine with 4H tones so nickels ring in as a high tone. I had a Tesoro detector and could not get used to the one pitch tone with nuances. I rather have 2 or more tones depending on where I am hunting. In the fields I sometimes use 2 tones especially back east, but around my area I am more comfortable running 4. The F75 isn't as complicated as others might want to make it seem. It goes deep even at a lower sensitivity. I try not to run it too hot so as to reduce the falsing. I disc out 1 thru 14, 4H tone and sensitivity 65-75 in DE mode. If the ground is rutty I change to PF (plowed field) mode to reduce falsing on the ruts since I have a fast swing.. If I am in a trashy area I switch to my 5"DD coil and go into FA (Fast Audio) mode.