The most valueable piece of info I can give you that will save you much trouble is to keep your hands off the adjustments for the Sensitivity that is inside. It is set for the best performance as it arrives and you won't get any extra depth by moving this knob.
As for the signal sounds, all areas produce a different set of variables and you should find a clean piece of sand and lay down different targets and see where they null out after ground balancing and setting the disc. Operate as low as you can and get a funny sound on a bobby pin. Scoop all the rest