There are two tones associated with manual ground balance. A high tone and a low tone. If, while lowering and raising your coil from about an inch above the ground, (making sure there is nothing metal under the coil) to about 6 inches above the ground, you hear the high pitched tone, you have your detector adjusted with too much negative ground phase. To compensate for that, keep bobbing the coil and press on the - keypad. If you keep bobbing and clicking on the negative key pad, you'll eventually get to where the tone is low pitched. When that happens, you've ground balanced with too much positive ground phase. So back it off by pressing the + keypad until you hear a blending of those two tones. High and low. In most situations, you won't be able to GB to a point where the tone disappears. Just a spot where the two tones blend together. I'm in the process of making a series of videos that will hopefully help folks better understand their X-TERRA. The videos are based on my article (located in FAQFAQ) and I'll post the links to those videos as soon as they are complete. HH Randy