Box questions

[mjlorenzo 10+ year member]

I'm thinking about replacing the sealed box I currently have with a larger one. I think the box I have is roughly .75cu ft and the sub is rated for 1.25cu ft. The result is pretty bad, the bass is muddy and it won't hit lows nearly as hard as higher frequencies.

1. When considering the volume of the box, should I estimate the volume of the driver and subtract it from the volume of the box empty? aka, hypothetically if the driver's volume was .25cu ft and I wanted 1.25cu ft internal volume would I be looking for a 1.5cu ft box?

2. How effective would polyfilling the current box be? If possible I'd obviously like to use the smaller box cuz it frees up trunk space and I don't have to get another box shipped to me but if the results aren't going to be as good as just getting a larger box I'd rather do that. If polyfilling would be effective, any recommendations on material, brand, amount, etc..?

Click to read more...

 

[altoncustomtech 10+ year member]

I'm thinking about replacing the sealed box I currently have with a larger one. I think the box I have is roughly .75cu ft and the sub is rated for 1.25cu ft. The result is pretty bad, the bass is muddy and it won't hit lows nearly as hard as higher frequencies.
1. When considering the volume of the box, should I estimate the volume of the driver and subtract it from the volume of the box empty? aka, hypothetically if the driver's volume was .25cu ft and I wanted 1.25cu ft internal volume would I be looking for a 1.5cu ft box?

2. How effective would polyfilling the current box be? If possible I'd obviously like to use the smaller box cuz it frees up trunk space and I don't have to get another box shipped to me but if the results aren't going to be as good as just getting a larger box I'd rather do that. If polyfilling would be effective, any recommendations on material, brand, amount, etc..?

Question number one is correct... You do indeed have to adjust for the volume being used by the driver...

Question number two you are correct it will help... You need about 1lb. of polylfill for each cuft of box space... you can use something simple like pillow polyfill from walmart or there's stuff out there like "Acousa-stuf" from parts express made for it.... honestly I don't think you'll notice a difference between the products, I had a friend use loose house insulation like you'd find in an attic with fine results....

Obviously the best way to go is to build yourself a new enclosure, but if you like the one you got try the polyfill, its cheap and easy enough to do...

 

[mjlorenzo 10+ year member]

I just examined the box I currently have and it's possible it's more like 1cu ft internal volume which makes me think my problem is possibly not totally the box. I'll try throwin some polyfil in and hope for the best but could it possibly be just shitty components?

Here's the setup:

Profile AP600 2ch amp (bridged to 300W RMS @ 4ohms)

Q-Logic enclosure

Infinity Reference 1250w

some cheap Radioshack wiring kit for amps

The amp was only $110 and the sub was $60. I figured even a budget build would be acceptable but maybe not. Anything stick out as particularly bad there?

 

[altoncustomtech 10+ year member]

Profile is not the best stuff around by any means but my first few amps were Profiles and I never had any issues with them... It really is all decent stuff for a first system... I know how hard it is getting decent stuff when you're first starting out... another problem you may have with your box is air leaking around where the woofer mounts... Q-logic used to use some funky plastic mounting rings that I always used to question as to their ability to properly seal... do they still use those? you might try sealing the mating surfaces up with a little bit of silicone...

what kind of car is it in? where is the sub located and where do you have it facing? Sometimes the orientation is as much a problem as anything else...

 

[mjlorenzo 10+ year member]

It's in a 2002 Civic sedan, rear facing in the center of the trunk. I'm gonna start with the polyfil but I think I'll also use sound insulator on the trunk and rear deck. From what I'm reading around the web tho it sounds like the symptoms of an overly small box match what I'm experiencing so hopefully the polyfil helps a lot. It's also a brand new sub so I'm assuming it will perform better once it's broken in.

As for the seal around the sub itself, I'll check it out tho I'm pretty sure it was a tight seal.