# So, I stuffed my vented box with polyfill...



## Danometal (Nov 16, 2009)

Hello. 

Last year, after cooking a DD sub, I modified my 4.2 cubes @ 36 hz DD box to 4 cubes @ 31 hz by adding a piece of MDF inside the port to reduce the port area, as well as a small L-turn, to drop it to 31 hz. 

I ran a RE Audio SE/x 15 D4 in that, but I wasn't impressed with the SQ, as it had an ugly peak at 45 hz, and didn't drop low all that well. And so it's been sitting in my bedroom for months waiting on me to unload it on craigslist or something. I've been running the RE in 2.6 cubes sealed and stuffed since then.

Well, today I decided to run to Walmart and grab some polyfill and see if that could affect my old 31 hz box before I took pics and posted it on craigslist for sale. It was a shot in the dark. Local shop advised me not to do it, but they also swear 31 hz is far too low to tune...

Color me impressed. 

No more ugly peak. Hits lows much better. Much better SQ for sure. I think it dropped the tuned frequency to about 29 hz, maybe 28. In essence, it has the same great SQ as the sealed box, but more output at the expense of trunk space.

Alls you gotta do is toss some screen material over the inside port opening.

So, if you were ever ill-advised to avoid stuffing polyfill in a vented box, DO IT!! 

Peace.


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## m R g S r (Oct 1, 2009)

wait walmart sells polyfill??


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## Danometal (Nov 16, 2009)

Yep, and it's cheap. Just don't get the other brand they have. It doesn't work the same. It gets too dense with a quickness.


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## matthewo (Jan 31, 2008)

Or just get poly batting that's used in cushions. Line the inside walls of the ported box. You don't have to worry about it flying out or covering the port with a screen


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## Danometal (Nov 16, 2009)

matthewo said:


> Or just get poly batting that's used in cushions. Line the inside walls of the ported box. You don't have to worry about it flying out or covering the port with a screen


I thought of that, but I wanted a drastic effect, that is, if I was going to be convinced that I should keep the box. It seems to me that just lining some walls might cause a more nominal effect than what I've experienced by fully stuffing.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

DO NOT put screen over your port... 

You MAY chance the tuning of the port..

The air velocity in and around the port is far greater than you might think, applying screen to the port could restrict air at different frequencies and velocities... (don't mess with a good thing now..lol)

You would be better off stapling or baffling away the polly fill from the mouth of the port..


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## Danometal (Nov 16, 2009)

Aaron'z 2.5RS/WRX said:


> DO NOT put screen over your port...
> 
> You MAY chance the tuning of the port..
> 
> ...


I hear you, but I was hoping the tuning would change. I wanted to smooth out the tuning spike. 

With that said, I attached the screening over some braces with large circular cutouts in them about 3 inches or so from the inner port opening, so the poly ended a little before the actual port opening. That may not have affected anything. I'm not sure.

I lost a tad bit of efficiency, but there's still more output than in my sealed box (which is also highly recommended for this sub if space is a concern. Great sub)


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## mosconiac (Nov 12, 2009)

It's very common to throw a few cheap walmart pillows (synthetic filled) in home theater subs. Those boxes tend to be HUGE ported enclosures and throwing whole pillows in there is a great solution (no loose fiberfill floating around to get pumped out the port or stuck in the suspension of the sub).

In fact, that's how we filled a JL 15W sub box for a friends car recently.


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## [email protected] (Jun 12, 2008)

Would putting poly in a ported enclosure affect the tuning of the box? I would think it does.


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## Danometal (Nov 16, 2009)

BeatsDownLow said:


> Would putting poly in a ported enclosure affect the tuning of the box? I would think it does.


I was hoping it would affect the tuning. I didn't like how my RE sub performed with a 31 hz tune. This was just an attempt to salvage a box I was intent on unloading, but I was pleasantly surprised that it dropped the tuning as theorized. It will definitely meet my need until I get around to building a true 27 hz box. I'll probably just line the walls with batting when I build the new one, but it will probably be sometime this summer before I feel like doing it.


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## sqshoestring (Jun 19, 2007)

I've done it and it seemed to do the same as a sealed, you have to near fill the box for it to work well, keep the port clear, it takes the higher bass out it seemed to me. Kicker did it factory in their truck boxes and they filled them right to the port. They used stuff heavier than the walmart poly. The walmart stuff used to be 1.97 for a bag not quite as big as a bed pillow, or so. I tried batting walls a couple times and it never worked for me.


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## Danometal (Nov 16, 2009)

sqshoestring said:


> I've done it and it seemed to do the same as a sealed, you have to near fill the box for it to work well, keep the port clear, it takes the higher bass out it seemed to me. Kicker did it factory in their truck boxes and they filled them right to the port. They used stuff heavier than the walmart poly. The walmart stuff used to be 1.97 for a bag not quite as big as a bed pillow, or so. I tried batting walls a couple times and it never worked for me.


Yea, it's filled just like my sealed box was. I went with 4 lbs for 4 cubes net volume after port and woofer displacement. My biggest concern was impeding airflow with the window screen material over the inside port opening, but it seems to resonate fine. I thought about some harware cloth/chicken wire, but I grabbed screen instead, thinking it would be easier to deal with. 

Nonetheless, I managed to squeeze some nice SQ out of a box I once hated with a passion. That box costed me around $85 for wood, wood glue, spray glue, screws, silicon, carpet, and spray paint for the port, so I hated the idea of just throwing that money and time away without dropping just a few more dollars to experiment.


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## sqshoestring (Jun 19, 2007)

Thats great you could make it work, even if you use it in something else. I did it with a 1cf bought box I had, ended up inverting the 10 in it and stuffing it, tuned to 27 trying to get it low. But never tried it in a car only the house. I think it would work on my HT, especially since I never put a sub on it, lol. A friend supposed to have an amp for me if he ever brings it, some pro rack amp I guess. But I've tested a lot of amps on this 10 and it goes pretty low for a single 10, it vibrates stuff in the house no problem.


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## Danometal (Nov 16, 2009)

sqshoestring said:


> Thats great you could make it work, even if you use it in something else. I did it with a 1cf bought box I had, ended up inverting the 10 in it and stuffing it, tuned to 27 trying to get it low. But never tried it in a car only the house. I think it would work on my HT, especially since I never put a sub on it, lol. A friend supposed to have an amp for me if he ever brings it, some pro rack amp I guess. But I've tested a lot of amps on this 10 and it goes pretty low for a single 10, it vibrates stuff in the house no problem.


Ported with poly would probably work even better in the house. My problem was trunk space. If I build a new box, I MIGHT be able to squeeze out 4.7 net cubes, maybe 5 if I used less port area than I really want to. But, 4 cubes + port = no trunk space already. This is just my back and forth to work car anyway. We have another car for family travels and such (and it has a 15 inch Kicker sub in a sealed box. lol) I like bass...

In essence, filling a ported box appears to be an option with a too smallish box...


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## mitchyz250f (May 14, 2005)

I just modeled four subs on UniBox, DIYMA12R, Adire tempest, JBL 1200Gt1, JBL 1500GTi. In every case the filled box had a higher tuning. Not saying at all that it doesn’t sound better, it probably does. But the tuning went up.


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## Danometal (Nov 16, 2009)

mitchyz250f said:


> I just modeled four subs on UniBox, DIYMA12R, Adire tempest, JBL 1200Gt1, JBL 1500GTi. In every case the filled box had a higher tuning. Not saying at all that it doesn’t sound better, it probably does. But the tuning went up.


Thanks for checking that out on UniBox, but it doesn't audibly sound like the tuning went up. It had too high tuning before, and wouldn't hit the lows properly, but now it does. I haven't measured anything whatsoever, but by ear, my results sound consistent with the following article:

Sub Box Polyester Fiberfill


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## sqshoestring (Jun 19, 2007)

From what I read the fill makes the air in the box 'heavier' and thus vibrate at a slower rate. Since a ported essentially acts like a sealed until it gets to tuning, seems like most of the time it would have the same results as sealed. At tuning seems like it would not change much since if the stuffing makes the box smaller in volume it should also dampen the air inside to compensate. It could restrict and give a little less output from the vent....via reducing the energy in the box I guess. To my ears it seems to reduce upper bass more than increase in lower bass....you just hear a deeper response better because it is what is left.

I like bass and trunk space too, my pyle 15s IB are fantastic, I'm sure a set of AEs would be better if I needed them but so far I can't complain at all.


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## Danometal (Nov 16, 2009)

The high notes sound louder to my ears than in traditional sealed. Also, I played a track this morning that once made the cone pretty still as the port took over (without stuffing), but now I'm getting excursion like it hasn't dropped far enough yet, so it would seem it indeed has tuned itself lower (unless stuffing a vented box circumvents that phenomenon of a standard vented alignment) 

The port still puts off a decent amout of air on that note, so I guess the stuffing and the screen are breathing adequately enough for music.

This is strange; it's like a sealed/vented hybrid, with better SQ than I had in either traditional sealed or vented, (and about 1.5 - 2 dbs gain over sealed I'm guessing) at the expense of some of the efficiency gained by having a port. 

Is this how high end home towers are?


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