Getting a air vibration in the lower register on my soprano sax - below G. Model Super 80 Action Series II

You might also have a reed problem. Check your positioning of your reed on the mouthpiece table. You should have very little tip showing when you squeeze the end of the reed against the end of the mouthpiece. Make sure your ligature is tightened. Check for a leaky pad on the G# key. It might not have enough spring tension or the adjustment screw on the forked F key might not be holding the G# key closed when playing lower notes. Also check your low C# key for leaks. The spring on it may be weak. You can make a leak light fairly easily to check if you want. Google it. Leaks in the lower register can be caused by leaky keys in the upper register. Also check your upper Bb key.

This can be caused by a poor seal on one of the valve pad seals. You should be able to find which one(s) by simple opening or closing valves to see which changes or stops it.

The pad will just have a crack in it and isn't sealing properly. If you have a instrument or music store that sells instruments they may have a instore tech or will know of one. You might even be able to find one through a local school if they have a band and so on. I have no idea of your location so can't suggest more than that. The repair is cheap and quick and is just replacing the pad with a new one.