I am still using the 10.5 7.5khz DD coil and I found two more 10 inch deep coins today. I have used CZ's for years and I have the after finding hundreds of 8 inch plus coins, I have that deep sounding signal imbedded in my mind. It is unmistakeable. After 25 or 30 hours on the Xterra 70 , this deep signal is becoming common to me. I get this faint high tone that the DD coil picks up on from at least three angles. If anyone has used an Explorer, I get this barely audible high tone and with short, slow sweeps, I start pulling the coil back until the signal drops off. When it drops off, it just in front of the Minelab logo on the front center of the coil. Foolproof! If I can hear it from two or three different angles, it is almost always a coin. Today I found two of these coins and they were both 10 inches deep! Both were wheats from the early 20's. Thanks to Diggers tip of hunting in all metal, I find this detector to act like an Explorer in iron mask 10 to 16. It is busy, but if you can stand the sounds, it is DEEP. Unlike an Explorer, it is like a feather and I can swing it all day. I am finding coins as deep as my CZ 70 and it is real easy to use. I have hunted every day for the last 5 days and I am so confident with this detector that I am leaving my beloved CZ 70 home. My ground balance today was 19 to 21. All metal and sensitivity at 28. What a detector. And to think I almost sold it. R.L.