I'd like to get some insight from those with experience with blocking the ports on cabs. I have a cab that is tuned to ~55hz. It is a 2x15 cab and has 4 ports (2 for each driver). I understand that if I block one port for each driver, I will drop the tuning of the box to ~40hz. Can anyone tell me what the effects will be of doing this. I am interested in both the possible technical effects ( ex. changes in response curves/frequescy plots, change in SPL, change in resonant frequency etc), as well as the possible practical effects (ex. it will sound deeper because it has a lower fundamental, it will have lower SPL because of "carrots" ... etc). I'm also interested to know what happens with this cab if I were to block all the ports, effectively making it a sealed cab (although one that was designed as a ported cab). anyone care to help educate me on this topic ?