I like TTF too and I'd use it all the time.... but I'm fearful that I'd be missing deeper (good) targets. It seems, as some suggest, that if you do this experiment:
"Drop a dime on clean ground and place your etrac in manual 25 sensitivity multi tone conductive mode. Put your headphones on and start sweeping the dime and continue to sweep progressively raising your coil over the dime. You should hear the high (dig me) tone to around the 9-10 inch mark approximately. Repeat again but this time instead of concentrating on your headphone tone watch your screen and pay particular attention to the ferrous numbers as you sweep while raising the coil. Now go into the 2-tone ferrous mode. Again with headphones on, start sweeping the dime and continue to sweep progressively raising the coil distance. You should hear the ferrous tone start changing at around 5-6 or so inches. Some sweeps at 5-6 inches will be the higher ferrous tone, others will be the ferrous grunt (no dig) tone. Granted this is not even an ideal airtest, but it does shed light on changes that begin to take place as distance between target and coil increase. Even sweeping the dime at moderate distances with the perimeter of the coil will drive ferrous numbers up. Remember in 2-tone ferrous audio the etrac must process a signal and report a 17 ferrous or lower to get the higher tone (possible dig me signal). Now add a little iron, nails, mineralized soil, and depth and who knows what ferrous value would be processed and reported , hence a good (digme) tone or grunt (walk) tone. I believe a deep recovery say 9 inches plus on a dime, for instance, would be more luck than anything else using 2-tone ferrous. IMO effective useable depth is greater in conductive tone mode than using 2-tone ferrous audio mode."
tnsharpshooter
You'll see that Multi-Tone Conductive is the best, overall mode to use... except, maybe in, heavily iron infested sites.
