Polyfill!f

[JimAckley]

About 6 months ago, I put polyfill in my PSW1000 and removed the port cover in the back, and really liked the effect it had. It reduced port noise a great deal and gave it a hair more accuracy. Last night I went ahead and did it to my LSi25s' subwoofer chambers and am liking it even more. They sound a little smoother, and sound like they have less coloration due to any internal resonances. I had all this polyfill sitting around for when I was going to redo the enclosure in my Yukon, but that's gonna go bye bye, so I decided to stuff the 25s.

I'll keep you guys posted as I get more listening time in.

[VR3]

Not to discount anything said above but Polyfill would not reduce internal resonance

[JimAckley]

What exactly does it do then?

[VR3]

It changes the tuning of the enclosure as it makes the speaker believe there is more internal space than there actually is.

[JimAckley]

I thought it had some dampening properties as well. Did I think wrong?

[VR3]

Eh if it does it is very little.

That is what No-Rez, Blackhole 5, Sonic Barrier - etc is for.

[aboroth00]

I wouldn't recommend using more polyfil in a ported enclosure. You're probably noticing less port noise due to the polyfil stuffing inhibiting the movement of air which is essential for a ported design. If you are hearing port noise, you're probably overtaxing the sub which indicates you need a bigger sub.

If you do want to decrease internal resonance you need a dense material lining the cabinet.

[JimAckley]

The port noise on the PSW1000 is primarily created by the PowerPort adapter which is screwed on the end of the port. I didn't mean the polyfill fixed that. Sorry for not clarifying that. Tons of air is still moving through the port.

[Face]

Polyfill in a ported enclosure can help with standing waves.

[aboroth00]

Polyfill in a ported enclosure can help with standing waves.

Yeap that can be true, but not particularly in subwoofers which produce frequencies below 300hz. Standing waves aren't usually a concern in subwoofers due to their lengths.

[aboroth00]

The port noise on the PSW1000 is primarily created by the PowerPort adapter which is screwed on the end of the port. I didn't mean the polyfill fixed that. Sorry for not clarifying that. Tons of air is still moving through the port.

By adding the polyfill you're slowing the movement of air which can reduce port noise. However, by adding the polyfill you're decreasing the volume of the enclosure which affects the Q of the sub. Also removing the port cover can allow more air to pass and reduces port noise, if I'm understanding you correctly.

However, Polk designed the sub for that to be used and by removing it, you can affect how the woofer moves such as causing over-excursion. You could be overdriving the sub and not even know it. Generally I would advise you against with mucking with ported subwoofers as you can cause damage to the sub by altering it. The most I would do is to dampen the enclosure by adding a dense material to the cabinet walls.

[Joe08867]

Actually the polyfill makes the speaker think it is bigger not smaller.

[aboroth00]

Actually the polyfill makes the speaker think it is bigger not smaller.

This is true, the subwoofer thinks its bigger becaues the polyfill causes a spring back action on the woofer. As for affecting port tuning due changes, i'm not quite sure. Maybe some one can chime in on this.

[thesurfer]

Jim, stop modifying everything,, LOL,