I just returned from a Caribbean dive trip with my brand new Oceanic Delta 4.2 and FDX10. The reg started honking on the first dive at around 35 feet deep. I looked online and found others complaining of this problem with the FDX10 and Delta 2nd stage also. The more I read, the more it seemed an annoyance more than anything. One a second dive it started honking at 50 feet and again seemed like an annoyance as we did not dive deeper than 50 feet. On a third dive it started honking again at 25-30 feet this time, but worked fine. As I descended to 70 feet the honking became very loud and it started vibrating that the noise or vibration became extremely painful to my inner ear. I found that it became very hard to draw air from the Delta 2nd stage and so I quickly moved to my octo which started free flowing as I grabbed it. As I pulled out the Delta 4.2 and inadvertently turned it upright, it started free flowing also. Luckily a friend quickly swam over and provided me with his octo. I stopped the free flow by turning the reg and octo to point the mouth piece down. As we ascended back up to 35 feet I moved back to my octo (and Alpha 8 octo) which worked and after a while I tried the Delta 4.2 which now worked without honking. I did not dive again during the trip as I felt I had defective equipment and was pressing my luck. I just wanted to chime in on the honking problem as I feel it is more than just an annoyance and feel it is dangerous and is probably a defect. I have also just lost my faith in Oceanic after my move up to the Delta 4.2 after using the GT3 without incidence for many dives. I know I am not perfect, so please do not blast me. I am just making a point about the honking problem and looking to save someone else from a potentially deadly situation.