Re: Issue with Alpine CDA-9807 & BA FX-5
No 5.25 speaker will be able to play bass frequencies very low, so i'd say set your crossover, should have one in the hu, to cut off everything below atleast 50, 80 would probably be better assuming you have subs. If you don't have a crossover in your hu, get some bass blockers. The other things is if they are amped, you may have the gains up too high.
Alpine CDA-7995, A/D/S 3 Series Comps, ED 8A, SoundStream Reference 604, 98 Civic Sedan