I was inquiring on a classified ad that when I modeled this particular sub using T/S parameters I got a much larger box volume of like 2.5 cu ft. for a Qtc of about .82. instead of the sellers recommended .88 cu ft. His reply follows.
Like i posted and PMed, you guys can NOT rely on modelling programs for sealed box woofers in a car! They do NOT account for the car's cabin gain, which changes everything! All those programs do is show you the response charachteristics in an anechoic open-air environment.
Trust me....0.88 cube sealed per driver is the KEY!This has not been my experiance as the relative response of higher vs lower Qtc alignments have been predictable. With the bump in response from typical cabin gain adding the bump from a higher Qtc alignment seems to muddy up the upper bass and makes the transition to the midbass more difficult and requiring lower LP. A big friggin' 'if' is if the T/S parameters are accurate, but a sealed alignment is pretty forgiving for some production variation compared say to ported.
By the way the sub in question is an RF 12 Audiophile w/ Fs=21 hz, Qts=.38, and VAS=9.182 cu ft.
What do y'all think?