Hi Neilo. I basically use a DD coil (when available) for all my detecting. The reduced ground response allows me to run the detector at such high gain levels that greater depth AND sensitivity (to small targets) can be had over what can be achieved with a concentric coil. The problem with the concentric coil (remember, I'm NOT talking PI detectors) being used over my ground is that often the magnetite will produce an overload signal, regardless of sensitivity setting or brand. This goes beyond plain ol' ground noise. Successful nugget hunting requires a person to be able to distinguish between ground noise and targets.. at least if high gain levels are being used. It's interesting to see just what is left, at a number of sites I like to play around on, by people who run thier detectors too "stable". Yup, they get a nice, quiet machine; they also leave a lot of deep silver and gold in the ground. If a person is willing to listen to a bit of ground noise, the depths that a mere VLF detector will reach can be quite impressive. So far, despite the fact that my X70 has to be sent in for repair, I've been able to detect targets (coin sized) considerably deeper than 8". Yet again, I must state that this is in highly mineralised ground.. not a saltwater beach. On the other hand, if I want scary depth, out comes my PI. Right now it looks like the Pulse Devil will be in production this summer (fingers crossed) and, given what I've read so far, a lot of these depth discussions will become moot.. unless a person is hunting in an area of low mineralisation. One thing that has not been resolved is the minimum target size that it will detect; there may still be a niche available for a VLF.. really small targets. This basically applies to nasty ground. ...Willy.
