Advice on using polyfil in ported enclosures?

[truckramrod 10+ year member]

Heres the situation: I built an enclosure in my friends car and the subs sound fine without polyfil and wired to the amp @ 4 ohms, but today I pulled the subs out and rewired them to run the amp at 1 ohm. and I added about 30 oz (approx 1.8lbs of loose polyfil with a mesh over the port opening) per side of the enclosure, and now the bass doesn't seem to be as deep and there doesn't seem to be a lot of air movement in the port as compared to the same setup with no polyfil.

I don't understand what the problem is, I've read that 1.25 lbs/ft3 worked well in a 1.4 ft3 box, however as box volume increase then the effect decreases.

So basically with 1.8lbs in 2.5 ft3 per side that would calculate out to about .75 lb per ft.

With that The inside of the box was pretty well stuffed with fibers, so should I still have and open path through the polyfil to the port opening.

Im just irritated and disappointed to go from maybe 125 watts a sub in the ported enclosure built to the lower size of the woofers specs, to almost 3 times more power per sub as well as what should be a somewhat larger, more efficient and slightly lower tuned enclsoure.

It sounds silly but I havent done much testing with the setup as it keeps popping the 60 A agu main fuses, we will be upgrading to an anl fuse holder with a 100 or 125 A fuse tomorrow.

BTW the subs are Phoenix Gold Xenon 12d4s powered by a Soundstream PIC1.900d in a 5 cube box firing forward through the folded down seats in an 03 Mustaing.

So any advice, suggestions, questions, similiar experiences ETC... would be very appreciated.

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[Lil Poot 5,000+ posts]

i learned this early on, working on cars. **** with one thing at a time, and observe the results so you can put it back if you dont like it. in other words, take out the poly, see how it sounds. its not like thats some huge chore.

 

[truckramrod 10+ year member]

Originally the enclosure didn't have any polyfil in it and the subs were wired to 4 ohms on the mono amp.

It sounded good and had good output, now the subs are putting a 1 ohm load on the amp and the box has polyfil in it and it doesn't sound as good nor does it sound any louder.

It seems like the polyfil is blocking the port as there isn't much airflow in the port, which if that is the case then how do other people put polyfil in the boxes with good results.

The reason i don't just want to keep removing the woofers and reinstalling them is they are firing forward in a ported trunk enclosure I built into my friends 03 mustang. I have to use a right angle drill bit attachment and it takes about 10 minutes to remove 1 sub.

So in anybody has any ideas or opinions on what I should, then I'd like to hear them.

 

[DFW40 10+ year member]

Are you sure you wired the subs correctly and got the polarity on all coils correct? Adding polifill will change the sound a bit but I doubt it would do what you are describing. Do you have a voltmeter to test the imp or "ohms" from the amp.

 

[azbass 5,000+ posts]

poly fill and ported enclosures = devil.

 

[xclusiv3 10+ year member]

i recently found out my box had polyfil in it...ported box....and when i had posted pics of it on here everyone said to take it out

that polyfil shouldnt be in ported enclosures

heres my thread from a couple days ago when everyone said get it out

http://www.caraudio.com/forum/showthread.php?t=194644&page=4

 

[Lightninghoof 10+ year member]

There are many many home audio cabinets that use fiberfill effectively in their ported designs. You just have to account for the change in tuning frequency as a result of increasing the enclosure's effective net volume.

Check out this article to give you an idea:

http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic&f=11&t=076651#000000

 

[CBFryman2 5,000+ posts]

I persoanlly say stay away from it. Only dampen ported enclosures to get rid of internal standing waves.

 

[jimmyjames1700 10+ year member]

There are many many home audio cabinets that use fiberfill effectively in their ported designs. You just have to account for the change in tuning frequency as a result of increasing the enclosure's effective net volume.
Check out this article to give you an idea:

http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic&f=11&t=076651#000000

Good post. A little fill is a good thing in a ported box because of the above mentioned reasons. To the original poster, I would maybe take about half of the fill out of each chamber of the enclosure. Otherwise you most likely have more going on here than just to much polyfill.

What kind of amp and subs is your friend using here? Is the amp rated for 1 ohm stereo or bridged? Are the coils hooked up correctly? Have you verified you final load with a ohmeter? Much more can be going on here.