Sub Low pass filter

dan553

Right now I am working with a 6.5 component system up front dynamated and a polk audio dxi 10'' sub in the back. What should the low pass be for the sub. In a previous thread some people said 50-60 but Ive also heard that people even use 100-120. I like a lot of bass, but Im worried that if i have it at 100-120 the sub will get exhausted from all the stuff that will get sent to it. Also, I have the settings on my received set to 0 for Sub, Low, Mid, and High end boosts. If I want a little more bass out of my front speakers, can I put on the bass boost for my 1 and 2 channels on my amp. Its 6 DB and im wondering if I should rather do that on my amp than my receiver

pentoncm

(1) I would start crossing around 60Hz at the HU. 80Hz at an absolute maximum, I would only use this when 5.25s are up front. Is that sub sealed?

(2) Begin by using a HPF matched to whatever you have your sub LPF set at.

(3) Do not use bass boost at the amp. What frequency is this at? If it is 40Hz then that is lower than the Fs of the woofers and could mess them up.

(4) Your speakers actually are producing a pretty good amount of bass/midbass, you just have too many response peaks in the way so you can't hear it. All that boosting the bass is going to do is create another peak.

(5) 100Hz and above is not bass, it is midbass and only belongs in your front speakers. The lower you cross, the lower it will sound when you turn the sub up which will make it sound as if there is more true bass. Crossing too high will result in one note bass.

dan553

Its sealed but there is a slight problem. The box is 1.36 where the sub says that it deserves a .88 box . I didnt realize it when I bought the box. Yeah I think the LPF is around 80 hz right now so maybe ill just leave it there and see what happens. Thanks for the advice I appreciate it. The bass boost is at 50 Hz according to my amp.

pentoncm

Does the sub sound nice and tight or is it loose and boomy?

The recommended box is .88 but I believe that this is the after displacement amount. Displacement should be around .08 cubic feet or less, so you want to be around .96 to be exactly where polk says to be. You could probably go up to 1-1.1 cu ft, but 1.36 is going to be too big and underdampened. What you can do is, go and get some wood blocks cut (MDF) that will fit in your box. Seal the pieces in the back of the box to decrease the internal volume. Get the blocks so that they will add up to a total of .25 to .35 cu ft.

dan553

Hmmm, the sub sounds pretty good i think. It really all depends on the song. Its actually quite annoying sometimes because i have to turn it up for some songs and down for others and im constantly adjusting all of the equalizer settings. Right now my equalizer is on "xplod" (I have no idea what that does), High is on 2 DB, Mid is on 1 DB, and low is on 6DB, and sub is on 1DB. It sounds pretty good that way. The sub is now lowpassed a lot lower (i think like 60-80), and the extra low end on the equalizer really makes those speakers punch the bass drum.

pentoncm

dan553 wrote: »

Hmmm, the sub sounds pretty good i think. It really all depends on the song. Its actually quite annoying sometimes because i have to turn it up for some songs and down for others and im constantly adjusting all of the equalizer settings. Right now my equalizer is on "xplod" (I have no idea what that does), High is on 2 DB, Mid is on 1 DB, and low is on 6DB, and sub is on 1DB. It sounds pretty good that way. The sub is now lowpassed a lot lower (i think like 60-80), and the extra low end on the equalizer really makes those speakers punch the bass drum.

The reason why it changes so much on each song is because you haven't cut anything out, you are only boosting. It will be extra loud with songs that are playing specific notes in the boosted area. When the bass notes are higher and outside of this region, they will sound weak.