How to Improve OE Sub Bass Quality and Eliminate Vibrations

[Gothy666]

So I'm finally doing this modification this Saturday along with the Dynamat. I have ZERO confidence regarding getting the acoustic poly-fill sheets to lay flat and proper. I calculated the square inches (166 sq in.) of the cut sheet diagram and cut the equivalent of cubes that I plan to stuff in the chambers. Do we think this will work?

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[luv2xlr8]

So I'm finally doing this modification this Saturday along with the Dynamat. I have ZERO confidence regarding getting the acoustic poly-fill sheets to lay flat and proper. I calculated the square inches (166 sq in.) of the cut sheet diagram and cut the equivalent of cubes that I plan to stuff in the chambers. Do we think this will work?

Worked for me. I did the same, rough estimate of area and stuffed them in there. Just don't overfill it and you'll be fine.

 

[tadda]

So I'm finally doing this modification this Saturday along with the Dynamat. I have ZERO confidence regarding getting the acoustic poly-fill sheets to lay flat and proper. I calculated the square inches (166 sq in.) of the cut sheet diagram and cut the equivalent of cubes that I plan to stuff in the chambers. Do we think this will work?

Do not stuff or fill up the chambers! Stuffing the chamber will drastically diminish bass response and increase rattle....Your better off doing nothing than stuffing them!

Conversely, padding the sidewalls with thin polyfill sheet is done to eliminate any destructive side wall acoustic reflections which "effectively" increases the volume and in turn improve overall bass response....

 

[Gothy666]

Do not stuff or fill up the chambers! Stuffing the chamber will drastically diminish bass response and increase rattle....Your better off doing nothing than stuffing them!

Conversely, padding the sidewalls with thin polyfill sheet is done to eliminate any destructive side wall acoustic reflections which "effectively" increases the volume and in turn improve overall bass response....

I don't plan to fill to capacity. Far, far from it. But doesn't poly-fill work by simply making vibrations travel slower and thus tricking the woofer into thinking it's in a larger enclosure? Would it work if I just added SOME of the matting in the chambers?

 

[tadda]

I don't plan to fill to capacity. Far, far from it. But doesn't poly-fill work by simply making vibrations travel slower and thus tricking the woofer into thinking it's in a larger enclosure? Would it work if I just added SOME of the matting in the chambers?

In the application I outlined, and as I mentioned earlier, lining the walls is used to reduce destructive wave reflections and woofer dampening effects...

You seem intent on wanting to loosely fill the enclosure, so do it, and see if this works better for you...I will caution you though, that loose fill will have a tendency to move around during deep bass play and may actually create exposed voids within the enclosure and / or may cause the material to plug up the narrow elongated exhaust port holes...During deep bass just place your hand over the exhaust holes and you'll feel how much pressure is released though those holes!

 

[Gothy666]

In the application I outlined, and as I mentioned earlier, lining the walls is used to reduce destructive wave reflections and woofer dampening effects...Not the same as a loose fill application...

You seem intent on wanting to loosely fill the enclosure, so do it, and see if this works better for you...I will caution you though, that loose fill will have a tendency to move around during deep bass play and may actually create exposed voids within the enclosure and / or may cause the material to plug up the narrow elongated exhaust port holes...During deep bass just place your hand over the exhaust holes and you'll feel how much pressure is released though those holes!

Fair enough. I'll try a small sheet of the poly-fill to have lay down on the floor of the enclosure. I do see a lot of people mentioning just loosely packing the enclosure with polyfill, I'm wondering how it worked out for them

 

[tadda]

Fair enough. I'll try a small sheet of the poly-fill to have lay down on the floor of the enclosure. I do see a lot of people mentioning just loosely packing the enclosure with polyfill, I'm wondering how it worked out for them

Yes, over the past few years since I posted this writeup a few have done the loose fill...I'm not saying it won't make a difference, it's just not optimal for the reasons I mentioned earlier....

 

[Nikko]

Finished mine up over the weekend and it sounds great - thanks Tom! I agree with some others that the baffle is a bit of a pain. As many times as I reread the instructions, I just couldn't get in my head how it laid out in the box. I got it in there, but not sure that it's perfect? Sounds great, so I guess it'll do. I think some of us are possibly overthinking this portion as well.

Anyone paint the area where the grills / ports go? On my car it's yellow and you can see it through the grills at the right angles. If it were a bright / crisp yellow like the car I think I would like it, but it's mostly overspray there so it's a faded yellow. I think I may spray it black so you don't see it at all, but I'm not thrilled with spraying the inside of the car TBH.

 

[Bassoonytoon]

Anyone paint the area where the grills / ports go? On my car it's yellow and you can see it through the grills at the right angles. If it were a bright / crisp yellow like the car I think I would like it, but it's mostly overspray there so it's a faded yellow. I think I may spray it black so you don't see it at all, but I'm not thrilled with spraying the inside of the car TBH.

I used soft speaker mesh from an old home theatre speaker I had lying around. 3M double-sided tape holds it in place and it should be mostly acoustically invisible as it came from an old woofer cover. It completely obscures the ugly paint you’re mentioning.

 

[digicidal]

Considering how little visibility there is through the ports, you could probably do the job with a Sharpie or other permanent marker rather than worrying about spraying it (either that or just use a small 1" trim roller to coat the area. Either that or do what Bassoony, tadda, and others have done with cloth, screen, etc.

One note if using grill-cloth like Bassoony... although audibly invisible, many are more than dense enough to cause loss of pressure... which can defeat the purpose of the ports entirely. They're fine in front of transducers with limited extension, but not as good for actual ports where volume and pressure are the key parameters.

 

[luv2xlr8]

Do not stuff or fill up the chambers! Stuffing the chamber will drastically diminish bass response and increase rattle....Your better off doing nothing than stuffing them!

Conversely, padding the sidewalls with thin polyfill sheet is done to eliminate any destructive side wall acoustic reflections which "effectively" increases the volume and in turn improve overall bass response....

So I have read this thread in its entirety, and still I want to clarify: I could only get Poli-fil in my area, so I cut that to the specified dimensions and installed. Tadda, are you saying that nothing is better than just a little something?

 

[tadda]

So I have read this thread in its entirety, and still I want to clarify: I could only get Poli-fil in my area, so I cut that to the specified dimensions and installed. Tadda, are you saying that nothing is better than just a little something?

I'm saying I don't recommend filling the enclosure other than lining the walls...

 

[luv2xlr8]

I'm saying I don't recommend filling the enclosure other than lining the walls...

Understood! The poli is coming out!

 

[Chappers]

I've done the wadding n foam but I've not done the port yet I've not noticed a huge difference yet but I suppose the question is are the ports necessary for it to make a solid improvement as I'm a bit nervous about putting holes in my new car

 

[tadda]

I've done the wadding n foam but I've not done the port yet I've not noticed a huge difference yet but I suppose the question is are the ports necessary for it to make a solid improvement as I'm a bit nervous about putting holes in my new car

Adding ports is roughly 85% of the solution to the problem!

Adding ports to the narrow rear panel relieves the back pressure released against the panel that is causing a majority of rattling and vibration...Also adding the exhaust ports is eliminating destructive back pressure which causes low bass distortions and limiting low bass response...

At the very least remove that narrow rear panel if you want better bass response and reduced rattling and vibration...

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