sub is making a farting noise

[kiteman]

i've got a ppi 900.4 driving an infinity kappa 100.9w @ 450w in a ported box. i have the gain set somewhere in the 70% range, though it's hard to be very precise in percentages since there are no dials on the amp.

in general it sounds good, but if i put some heavy bass rap in there i have a lot of rattles. i've been trying to figure them out but notice the sub itself seems to rattle on low notes, it sounds a bit like a fart. basically something sounds like it is flapping around. i can't figure out what the problem is and the sub is new so i wouldn't think it would be bad (although could see being wrong on this). thanks for any help.

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[adulbrich 5,000+ posts]

Don't feed it beans anymore.....

I'm guessing you've got a prefab box. Usually, those are tuned high and don't have enough port area. Playing below tuning, yeah, your sub is going to unload (flap) and sound like shit

 

[kiteman]

hrmm...yes, it is a prefab box. link below. i also just took a video of my sub playing 50hz 0db test tone, even with the gain all the way at its lowest setting and with the sub nearly out of the trunk, it was making this noise. hopefully that upload will finish soon and i can post it. if it is the box, what can i do? i'm still within the return window of the box and sub, so i can make a change. i'm just trying to keep it all relatively cheap and not too much work (ie i don't want to build my own box). i also only have about 13" of floor to ceiling space in my small trunk, so that is why this particular box worked so well for me from a size perspective.

Amazon.com: Atrend E10Sv B Box Series 10-Inch Single Vented Subwoofer Enclosure: Car Electronics

 

[kiteman]

yeah, it's pretty clearly audible here in the video. thanks for you guys' help.

 

[kiteman]

I figured out what it is, but can't figure out how to fix it. Apparently all that buzzing is coming from where you plug the +/- speaker terminals in, it's the plastic speaker terminal box. I unscrewed it and it's just a solid piece of plastic, so i'm not entirely sure what is causing the buzzing. Maybe air is escaping? Maybe the hole cut out for it is too big and it is bouncing up against the wood when the notes hit? I'm a little confused.

 

[Jeffdachef 5,000+ posts]

I figured out what it is, but can't figure out how to fix it. Apparently all that buzzing is coming from where you plug the +/- speaker terminals in, it's the plastic speaker terminal box. I unscrewed it and it's just a solid piece of plastic, so i'm not entirely sure what is causing the buzzing. Maybe air is escaping? Maybe the hole cut out for it is too big and it is bouncing up against the wood when the notes hit? I'm a little confused.

Use caulk to seal it up. Its air leaks in the sub box from a crappy prefab junk box. Good chance that box will fall apart soon. Cheaping out on the box is one of the worst t

mistakes to make

 

[adulbrich 5,000+ posts]

Yeah, it can be sealed with silicone, but it's still a junk box that's limiting your sub

 

[kiteman]

Use caulk to seal it up. Its air leaks in the sub box from a crappy prefab junk box. Good chance that box will fall apart soon. Cheaping out on the box is one of the worst tmistakes to make

Yeah, it can be sealed with silicone, but it's still a junk box that's limiting your sub

do either of you have recommendations on a better ported box for that subwoofer? as i mentioned earlier, i'm severely limited by size. i truly can't fit anything that has any single dimension higher than about 13".

 

[jRi0T68]

Make one yourself. It'll be cheaper, built better if you apply yourself, and give you a sense of pride when the bass hits. There's even a dedicated subforum for enclosures. Lots of good info there.

 

[kiteman]

Make one yourself. It'll be cheaper, built better if you apply yourself, and give you a sense of pride when the bass hits. There's even a dedicated subforum for enclosures. Lots of good info there.

i don't think my system is nice enough to do that, it's just a pretty basic "hey i added a sub to my car" kind of deal, so i don't want to put a lot of effort into this. i ordered a new terminal cup from amazon, but it seems like this buzzing is coming from the sub too even though i used the weather stripping that came with it along with ensuring all the screws were tightened enough. is there anything else i can do to increase the seal on the sub to the box?

 

[Jeffdachef 5,000+ posts]

do either of you have recommendations on a better ported box for that subwoofer? as i mentioned earlier, i'm severely limited by size. i truly can't fit anything that has any single dimension higher than about 13".

need max length x width as well.

Take the sub out of the box and play it free air to see if it makes any mechanical noise.

 

[Vocaloid]

I think you can still save it. After caulking up the plastic terminals, you can take it farther if you want. If you use a clear sealant, you can make a ring around where the speaker sits then drop it back in. There are many reasons not to do this (damage to surround material from the fumes, permanent ugly sealant all over your speaker basket and box, etc..) but if you seal it, it will fix the air leaking through the seams around the woofer. I usually do a very light ring on the speaker cutout on the box, put the sub in, then do a bathroom tub style ring around the basket to get a nice clean edge all around. Same with any suspect seams on the box itself inside, or running a ring of sealant around the port (inside of the box). Air leaks are bad for sure.

Or you can flip the speaker over (and reverse the positive and negative leads) using the subs gasket to seal the gap too. That also would change the volume inside too though...

But take Jeffdachef's advice too and make sure it's not the speaker.