My subwoofer isn't supposed to make this noise.

[psych0ticnemes1 5,000+ posts]

this may sound dumb, but it could be your box. One time i thought my sub was bottoming out badly because there was a knocking or thud noise. Turned out to be baffle flexing. Added more support and wouldn't ya know, sound went away.

Take your sub out and free air it... If it doesn't make the sound, then you know your sub isn't bottoming out...

 

[audioholic 5,000+ posts]

If I can, I'll try to record it on the digi camera and post here.
I'm going to be building a new box, and would like to figure out what is causing it so I can avoid it later.

Imagine, if you will, the music is playing, and occasionally you have an extra "thump" sound in there.

Well if the cone is truely bottoming out, the enclosure can be made smaller. The speaker will be harder to bottom out because efficiency is lost (cone motion is lessened), but this also hurts output of course. Ive read alot of threads already today, I dont remember if you said you set your gains apropriately or not. Incorrect gain settings could also be a problem. Basically if the cone is moving too far (bottoming out), you can reduce this by 1) making smaller enclosure so cone motion is less, or 2) reduce power going to the speaker via gain setting, xover or SSF settings, or even just by turningthe volume knob down a bit.

Yeah I know, I have a NON-Fade level control on my headunit that I can turn down which is what I've been doing.
Is there a way to get the same or louder output without making that noise or is there no tuning that will accomplish that?

(Don't mean to thread jack but I really want to know)

Ported box, or sealed?
If sealed, no not really because cone displacement is king. In asealed box, the more the cone moves, the more air is displaced and the louder the system is. Reducing cone motion in a sealed system, even if merely for the speakers safety, will reduce output.

If its a ported box, things get more compliccated. The tuning frequency of your box affects cone motion, frequncy of the material being played affects cone motion, and of course the enclosure size and amplifier power also affect it. If its bottoming out in a ported box, first determine why... is it from playing below tuning and having the sub unload? Or, is it well above tuning in the midbass region where its more likely just too much power to the system. Maybe you got carried away with the enclosure size looking for your flat response? Could be alot of things if its a ported box....

 

[audioholic 5,000+ posts]

this may sound dumb, but it could be your box. One time i thought my sub was bottoming out badly because there was a knocking or thud noise. Turned out to be baffle flexing. Added more support and wouldn't ya know, sound went away.
Take your sub out and free air it... If it doesn't make the sound, then you know your sub isn't bottoming out...

I think I already mentioned checking the enclosure for leaks, but yes checking for wall flex would be another good idea.

 

[ItalynStylion 10+ year member]

Mine is sealed .3 cubic feet for each of my EU700's getting 150RMS each, I think they are hittin the bottom bad and I just need to port those mama-jammas over spring break

 

[bikinpunk 10+ year member]

Ive read alot of threads already today, I dont remember if you said you set your gains apropriately or not. Incorrect gain settings could also be a problem.

Yea, gains were set w/DMM.

 

[<KingKong> 10+ year member]

mine had that but come to find out it was wall flex, just turn it up and feel around your box

 

[ItalynStylion 10+ year member]

My box is .3 cubes......i doubt its flex lol

 

[<KingKong> 10+ year member]

i wasnt talkin to you it was directed toward bikinpunk

 

[synikalt 10+ year member]

Well usually bottoming out a sub sounds more like a rattle than a thud, because you bottom out the voice coil many times a second. Of course, exactly what it sounds like depends on what frequency its bottoming out at (cycles per second), how badly its bottoming out, and the enclosure type/size.
If its a big mystery, remove the sub from the box and play it free-air until it starts making the noise again... but be VERY careful when doing this.

Also, check the box for leaks. Enclosure leaks can sometimes make some pretty weird noises!

I use to have subs that made this rattle noise. one of my rockfords did. and it would come and go no matter what volume i played it at. when i turned it up louder, it would go away...

then one day i was washing my car and i took the box out, it slipped so i kinda body slammed it on its side...to break MY fall of course.

sub became frozen and never worked agian //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

and that was the end of rockford