I'm building a 4th order for a 15" Fi Q. I'm modeling it WinISD but its going weird on the power handling chart, and impedance.
But anyway I've got two models (rear chamber is sealed, front is ported)
#1 2.5 sealed with .8 ported @ 46.2hz. Models flat from 35-63 and f3 is 25hz. Very flat response.
#2 2.75 sealed 1.0 ported @ 45hz. Flat from 39-52 F3=27hz. Has 1.3dB more gain (at peak) than option 1.
Does this seem right for a 15" in a 4th order?
I've never built one before so I'm asking for help.
Also what size port should I use (I know ported is the 10-16 ratio)?
Is a 4" port too small?