Here is where it gets interesting, I was told not to test for the resident fq. for the vehicle as the frequency changes once the wall is in place and sealed up. I can tell you you though with my last wall setup with 1 XXX-18 my frequency was 46 hz and with that I was able to do 154.1 db. so now with my current setup and port sizing with what I was told to do by an outside source my frequency changed to 40 hz ?????????????? I did numerous testing with termlab to find this out. Even at the 46 hz note of the first wall sources told me the frequency is low for an SPL application. so as you can see my head is spinnin' (LOL) . Out of curiosity did you use a program to give you the info you had given me, if so, are you willing to tell me what program?

 

his res freq will be much higher than this, probally well into the 60hz+ range. I always suggest x-area port per 1ft^3 14"^2 per cube per 18" sub. this wall "to be effective for 2 18s should be 18-20 cubes with between 500-560"^2 of port area.