I need help picking my lowpass frequency on my AMP. I've got an Alpine MRD 500 Digital Mono Amp and 12w6v2 sub in a ported box built to JL spec. I'm still using the factory bose (2001 5th gen.) I took out the stock bose sub and left everything else. What do you suggest? I know most of you are thinking get rid of the bose, but for now I like it.

 

i have my low pass set to around 60 or so. i think 80 hz is a good place to start...and just adjust it until the sub blends in with the rest of the system...ie no frequency gaps.

 

i dont even remember what i finally stopped at i tuned it by ear, but its probably between 60~80

 

Mine is set at 50hz right now.

 

domf3 if i can find the piece of paper on where my sub is tuned at i wrote everything down i will let you know, i have 2 12 jl w6v2 ported built to jl spec as well.

 

DcMaN, if you figure it out lmk. Also, do you have a highpass set on the subs? I've got mine at 25hz, sound about right? 2 12w6v2 must SLAM!Thanks for the responses guys.

 

You need to figure out what the box is tuned to. If it is tuned at ~30 hz, you'd want your ssf set at 30. I'm assuming the box is tuned higher somewhere near 40 hertz, in which case you would need a 40 hz ssf.

 

actually my box is tuned to 25 hz

 

Hmm I would have thought J/L's spec calls for a higher tuning. What is the volume of the enclosure after sub displacement and port length and diameter?

 

25hz is great for HT duty...

 

Mine's tuned at 32.2 hz, according to JL. HT=Home theatre? (noob Q)

 

Yes ht - Home theater

 

I'm with Nismos - there's some math and formulae involved in setting the high-pass / low-pass correctly based on the subs demands and the enclosure's characteristics - and to a certain degree, the abilities of the other speakers in the car... Subs are EXTREMELY inefficient and, in the upper frequency range, anything the sub cant reliably reproduce gets muttled and effectively becomes heat. That said, a lower high-pass is usually a good thing provided you have some mids somewhere in the car that can handle the 50+ stuff.