Just finished WO #4 with 12" eminence woofers.I've put small amounts of polyfill in some of my previous WO's.I've stuffed this one pretty heavy with fill.
Correct me if I'm wrong,the fill tricks the woofer into thinking it has a bigger compression chamber.
So if it sounds a bit muddy will removing some fill correct this. ???

Gex you are a dilligent one,alway there.
Yes loosley packed would have been a better description.The other WO's I've made I just stapled a 2" layer around the chamber and had good results.I thought I'd try a little more fill to see the affect.
Again correct me if I'm wrong,a larger compression chamber will allow a speaker to go deeper but can lossen up the bass.Inversly a smaller chamber,less low end but tighter bass.

In the compression chamber? we are talking about the chamber with the throat exit in it right?  if so the fiberfill should help absorb some of the distortion in the higher frequencies a sub produces, and it should lower your response, meaning better low end.

In the sealed chamber it will trick the sub into thinking it is in a larger chamber that it actually is, which is beneficial when the chamber is between 75 and 100% its needed size.(depends on how much fiberfill goes in.)  If the sealed chamber was correctly sized or a bit large and the fiberfill was added, it could muddy your bass by creating a larger chamber.

If it is in the actuall compression chamber, well that would trick the sub into thinking it had a larger compression area which could result in worse response, in the form of slower and lower bass.  

I think...

Wouldn't lining the compression chamber with fiberfill slow down the air flow and make the compression chamber seem longer than it really is?  That should lower the tuning just like it would in a transmission line enclosure.   That's something I've been meaning to experiment with.

packed tight eh?
I will have to verify that and maybe change my answer.
so no it's not my final answer.
I use packing specifically for what jj calls harmonics and harshness.
I use it stapled and glued to the walls depending on the enclosure.
I have not seen a big differance in packing in a sealed enclosure to "trick" into thinking its bigger. But evidently I was misinformed on how it was to be used.


good point Big Air on the TL's I guess it really depends on where you are using it and how. the TL is loosely packed is it not. and fiberfill would not be used as a lining. a flat matt of whatever would be used. Differant use and results.

turbulence can slow air flow down and have a positive effect on desired sound can it not? what happens when you blow air through  a batch of fibre fill? a uniform vortex?

Just tossing stuff around to get some answers

Gex

[quote author=jj420  link=1129433749/0#9 date=1130422193]"lining" (attaching a layer uniformly to the walls) slows down airspeeds, this makes a nicer sound

"Stuffing" (filling a cavity with light fiberfill) dissipates pressure more efficiently than just air, and you need between 2 and 3lbs per cubic foot to make a difference.  above 3lbs per cube though, diminishing returns, theres not too much more to be had.

lining deals with resonances, standing waves, airspeed etc

stuffing deals with only one thing, dissipation of the backwave.  the purpose of a box is to contain the backwave off the cone, in order to do that, you need a certain volume of air to dampen it.  air with thousands of tiny light fibers to move mixed in dampens energy a lot faster and more efficiently, creating the illusion of a bigger box.

so, stuff your chambers, and line your throats (i know, i know, that sounds bad, get your mind out of the gutter) [/quote]

That's not always the case.  Stuffing will change the tuning of any enclosure whether it's sealed, vented, a horn or transmission line. Transmission lines enclosures are very sensitive to any kind of stuffing.  It's because of the air speed that you spoke of.  If you have an enclosure that is perfectly tuned, you will throw it off by adding stuffing and make it sound worse.  I'm pretty sure that if you add stuffing to the compression chamber and/or the throat of a WO, you will lower the tuning substantially.  Not that there's anything wrong with that.  It's just going to sound different and probably lose a little output.  Depends on your drivers and environment.  

Depending on the kind of sound you're after and your drivers, I would think that you would get the best results by stuffing the sealed chamber.  The reason is that  by stuffing the sealed chamber you should be able to make it slightly smaller and maximize the compression chamber.  A larger compression chamber and throat area should increase output.  There's a lot more to consider though, room/vehicle size and treatments, drivers, etc... I use Bass Box Pro to model my enclosures.  It takes amount of stuffing into account.  That way you should be able to model it almost perfectly for your drivers.  Have fun.