Subs: Can I make a ported design sound better if I stuff the air duct with cotton? (1 Viewer)

[Javier_Huerta]

Hi all!
I recently discovered how much air noise my Definitive Technology ProSub 100s generate. They sound AWFUL. Bass is loose, uncontrolled and they tend to bottom out and make terrible noise (I have two of them).
I have been thinking about stuffing their port with compressed cotton, so that the cone sees a "sealed" enclosure. I understand I'll lose some efficiency, but I hope to have a better damped and fuller sounding system. Should I do it? And if it works, would you recommend closing the air ducts of my BP8bs too? I don't worry too much about efficiency, since I also have a 15 in. sealed PF-15TL (Definitive) that will handle the LFE.
Thanks for your help!

 

[NickSo]

First of all, when 'stuffing', its not stuffing to plug the port, you're stuffing the inside of your sub enclosure. This 'fool' the driver into thinking you have a bigger box than you actually do. Some people have had huge improvements with stuffing.

Go and find some Polyester Stuffing, or Polyfill, then just open up the sub and stuff it up.

If you're thinking of PLUGGING the port (sealing the enclosure), try sticking a tennis ball in there, or a balled-up sock. I dont think cotton will do the trick to keep air from escaping.

 

[Tom Brennan]

Javier---Plugging the port won't effect overall efficiency but it will drive the rolloff frequency higher, the speaker won't go as low. The new sealed alignment, being helter-skelter, could as easily be underdamped and even boomier than before as optimally damped. There could be a danger of overexcursion of the driver with resultant higher distortion or damage too. I doubt this will work well, you can try it, it might sound better to you but it's a band-aid. If you knew the T/S specs of the driver you could possibly design a new sealed enclosure but it's likely that the drivers won't work well in any sealed box.

 

[Patrick Sun]

Nerf footballs and basketballs are useful for stuffing ports.

 

[Chris Tsutsui]

lol, I could just see someone carefully packing cotton balls in their port and firing up the sub.

jk, I know you wouldn't use cotton balls. But your options should be to either plug the port, or fill up the cabinet with an even amount of polyfill. Polyester can burn (seen burnt polyfill) so try not to let it touch the hot driver, and definitly don't block the venting porst if the driver has one.

There is no in between so your attempts to slowing down the port air movement for tuning will likely be unsuccessful.

 

[Javier_Huerta]

Heh... cotton balls in the port? That would be so fun... I could also try styrofoam peanuts
I wasn't thinking about stuffing the entire inside of the subwoofer, actually. I was just thinking about closing the port with some cotton. It's not a circular port, either - it's a rectangle, similar to the one on Velodyne subs. That's the reason I wanted to stuff it with cotton.
I already tried doing so yesterday. The sub lost a lot of power on the lower octaves, but in the bright side, the "chuffing" (or what is the term for the noise air makes when exiting the port?) is inaudible now. Bass is a bit more controlled now, although less prominent. And the speaker doesn't sound as if it was going to blow any minute anymore. When coupled with the PF-15, though, the entire system is more dynamic, yet less musical. It seems playing around with two types of powered subs and a tower speaker doesn't do wonders for sonic properties. I think my BP-6b's with a Velodyne sub sound *a lot* better.
I think I need to find out yet another way to integrate 2 kinds of subs in one setup. Any ideas?
Thanks for your input!

 

[Bhagi Katbamna]

No, but if you have Bose speakers, you might try stuffing cotton balls in your ears.

 

[Javier_Huerta]

Bose?
Well, yes, I do have a *complete* Bose setup. And no, I can't get rid of it. It's installed in my car as "premium" equipment. Get rid of the stereo and the car computer goes crazy. So I'm stuck with it.
The speakers I'm talking about are Definitive Technologies, though.