Just sold my month old gamma.I really liked how the id locked on at depth,a really deep and accurate detector.But the high tone for coins was weak and volume was low, manual also stated this. I have some hearing loss but I can hear my old f4 fine the high tones on all my detectors are sharp and clear.My question is. All all tecknetic machines like this ? How about the other f series. Really want to up grade but need some more info .