In reply to:
I have the volume on the sub currently set to 9'o clock as the manual states to start,...
This could be part of the problem. The manual actually says "VOLUME: Set this
midway to the 9 o’clock position for initial setup." You could possibly have the 500 volume set too hot. The off position of the volume knob is around 4 o'clock. So, "midway" between 4 o'clock and 9 o'clock, would be halfway between 6 and 7 o'clock. I found that was still too hot. I ended up with the volume knob set about half way between 5 and 6 o'clock. At this setting I could match the rest of my speaker's SPL with my receiver's sub setting at 0 dB.
However, the fact that you could reduce or eliminate the port noise by holding the port could mean the port itself is loose. If you feel that's the case, by all means, give Axiom a call and discuss the problem with them.
