Contrary, Lpf filter will only send signals at the hz you set it to, and lower. No higher frequencies will play at set hz.
if possible with headunit, set sub to 80 hz lpf or natural.. then set sub amp to the same..
just do it!
then you should deaden your doors, and use sheetmetal to cover any open cavities in your doors, as well. This will emulate a sealed enclosure and yield better clarity and response from your mid speakers.. btw, tell use what you are running for amps, and speakers..
You shouldn't run LPFs on the HU and amp simultaneously...just one or the other. Pick whichever one you're more comfortable with.
---------- Post added at 04:02 PM ---------- Previous post was at 04:02 PM ----------
So either set the LPF on the HU and put FULL on the amp or vice versa