Ran my V3i with a new to me 4.5x7 Detech coil through several tests on the nailboard. Had no issue going 8x8 and about 6-7x8 on the second location....just needed to adjust the filters to 12.5 Hertz and speed up the swing for best results.
As anyone who has run the test knows, the nails drag down most targets, with smaller targets getting a bigger bias. Dollars, halves and quarters could be touching the nail in position 2 and still pass fairly easily.
Once you moved to penny/dime/$2.5 gold/half dime, you have to sometimes be willing to dig negative VDI's on a whites machine. The half dime seemed to ring up fine but was almost always in negative territory, but once I start accepting below -20, i begin to bring some nails into the mix depending upon orientation and head size. So, that -20 to -29 range poses a challenge if you want to knock out nails, but accept a small silver coin - at least given this specific orientation of nails. Think the key here is to stop around -20 and bank on less than perfect hits in all direction....or one risks spending time on too many nails. Small gold also behaves similarly.
None of this was very surprising to me, but i think back to the noise we constantly hear when in a ghost town, and how easy it is to get tone deaf after a short while and skip over the jumpy and iffy signals. I'm sure there is little doubt that we pass over countless good targets simply out of willful neglect.
Playing with all metal gain also made a difference in results when using pro mode - hearing all metal in one ear and discrimination audio in the other. I supposed by definition, the machine is trying to make sense of what its reading in both motion and non-motion modes. Now, why exactly it provides a better result when turning all metal sensitivity fairly low and discrimination up....well, i have some more studying to do. Seems if they acted independent from one another, it shouldn't make any difference....so are they actually giving me an independent result?
Things that make you go hmmmm.
Zincoln