Long story short:
Minimum air space enclosure overstuffed with polyfil=crisp, clear, and very punchy bass

Recommended air space enclosure stuffed with correct amount of polyfil= deep, sloppy, one note playing bass

Does this sound correct?



The Long Story:

My 10" shallow sub(Pioneer TS-SW1001S4) requires a minimum of .35 cubic ft....as a result of a miscalculation that's exactly what it got. Also, not knowing better, I stuffed that .35 cubic ft enclosure with 1 lb of polyfil.....stuffed it like like a pillow! I was impressed with the results.....it didn't go super deep.....but it was clear, crisp, and very punchy!

Being the smart fellow that I am, I naturally assumed it would sound even better with the recommended airspace.....so I built a new enclosure for it. I was shooting for .45 cubic ft....but due to another miscalculation, I got .5 cubic ft. Since the maximum was .7 cubic ft, I figured I was ok.

I later read that you should use 1-1.5 lb of polyfil per 1 cubic ft....so I stuffed the box with the roughly estimated appropriate amount.

The end result was deeper, sloppy, muddy, one note sounding bass! Where did I go wrong? Or is that what added air space gives you....deeper, but less crisp bass?

any small air leak will change the sound of the bass.

Every subwoofer is different. But usually the bigger the box the deeper the speaker will play...that is just general though because tuning and loading environment have a lot to do with the sound.

As for sealed...the smaller the enclosure the higher the peak and the sooner the roll off.

Most people go for a QTC of .7 for sealed applications

Polyfill in effect, increases the size of the enclosure. It slows down the sound waves inside the box, basically increasing the size of your enclosure.

There isn't really a rule to how much/little to use, but adding some does often times help.

Also like aznboi3644 said, any leak will ruin the performance of the enclosure. Try to seal it with and adhesive sealant at all the seams to make sure you don't have any leaks.

As long as the box is within the recommended sizes, it should sound pretty good. Also, the airspace of the box DOESN'T include the airspace that is taken up by the sub's magnet, frame, voice coil, inside the box, so you should try to approximate the space that is taking up and add that into the equation.

one thing i try when the bass gets like that , and the air space is close , is ,
change the wiring to the box, , maybe the amp and sub are out of phase, and the reversing of the wiring could clean it up, a bunch,

I'm gonna try to do a smoke test on the enclosure.....I'm thinking if it's leaking anywhere it's around the sub itself.....the only thing between the sub and the enclosure is the autocarpet I used to cover the box.... may cut it back and put some weather strip

cut it back and use a little silicone to seal it,, but not much, just enogh,, or it gets messy ,