dynamat in a ported box

has anyone ever put dynamat extreme inside a ported box instead of using polyfill?? I've thought of only putting a certain sized dynamat extreme on the inside directly opposite of the sub to eliminate backwave. I've wondered if the Dynasorb works for subs since they're mostly for door speakers.

Report this post to a moderator

 RE: dynamat in a ported box

quote:

---

Originally posted on 02-05-2007 by gameguru1360
has anyone ever put dynamat extreme inside a ported box instead of using polyfill?? I've thought of only putting a certain sized dynamat extreme on the inside directly opposite of the sub to eliminate backwave. I've wondered if the Dynasorb works for subs since they're mostly for door speakers.

---

Report this post to a moderator

 

did you put the dynamat on the sides or on the back wall opposite of the sub's magnet?? I would think that putting it on the back wall would take care of the backwave air coming from the sub.

Report this post to a moderator

 

dynamat will not do what polyfill will, but..it will dampen the enclosure the same way it dampens your sheetmetal on your car. Kinda like making 3/4" mdf sound like 1". Kinda.

Report this post to a moderator

 

I thought putting polyfill in a ported enclosure wasn't recommended?? I have read that it's best to use the rolled polyfill and secure it using a particular adhesive instead of the curly polyfill. I was only going to put dynamat extreme on the back wall opposite of the sub or getting the Dynaxorb to cut down on the backwave opposite of the sub.

Report this post to a moderator

 RE:

quote:

---

Originally posted on 02-09-2007 by hornedfrog2000
I think dynamat in your box would only kill the waves, and make your subs sound quieter...?

---

Report this post to a moderator

 RE:

quote:

---

Originally posted on 02-08-2007 by 91SR20DE
dynamat will not do what polyfill will, but..it will dampen the enclosure the same way it dampens your sheetmetal on your car. Kinda like making 3/4" mdf sound like 1". Kinda.

---

Report this post to a moderator

 

well I put dynamat extreme on the back wall opposite of the sub. Then I put a thin cushion of rollable pollyfill inside and used a spray adhesive so that it wouldn't shift and block the port area. So far it didn't resonate when I had nothing inside. I have scene pre-built single and dual ported boxes such as ones by Kicker and they had the rollable polyfill near the port.

Report this post to a moderator

 Polyfill

Sorry for reviving an old thread.. But like so many replies in this forum.. The information given previously is mostly inaccurate. A WELL designed and Accurately Designed vented enclosure should not have any fill of any kind...changing the internal and/or perceived volume of the enclosure WILL affect it's tuning! If you are worried about the resonant vibrations of the box....add another layer of wood to the baffle and back wall --since they are the largest surface areas. Polyfill should only be used in a sealed box to make up for deficiency in volume. As a LAST Resort! If you DO use it, the "formula" is: 1 to 1.5 lbs of Polyfill per cubic foot volume of the enclosure. It is NOT an exact art, but the benefit is about 25-30% increase in perceived volume. But How does Polyfill work?? The energy of the pressure from the subwoofer is literally consumed, if you will, or converted to heat, in the density of the Polyfill. Remember, using it in a box that is too small will of course give you a little deeper bass, but there is always a trade off. By putting Polyfill in the enclosure you will be giving up some of the subs power handling capability. With this being said, you do NOT want to use a flat sheet of fibrous material or insulation, or any other such material that is densely packed/compressed. I know you have seen in the past (circa 1970-ish +) people using the old Pink Home insulation in home stereo speaker cabinets. It basically does the same task, but must me "Pulled" or stretched in order for the sound waves (ie: pressure) to permeate and hence be converted to heat. Otherwise, you could be making the box appear smaller to the sub instead of your intended enlargement. And of course we are back to dealing with, at worst, losing cubic volume which is exactly the opposite of what we want to do...or not taking full advantage of the Polyfill we do take the time to put in there. SOOoooooo..... If you are going to add Polyfill to the box, make sure it is the loose, or bagged, filler--usually found at fabric stores and used for pillow stuffing. Stay away from the flat, and densely packed material that is usually used for quilting, etc. When installing the correct weight of Polyfill, be sure to "pull it apart" and avoid any dense areas, which would be inefficient in this whole process. If you fear movement of the filler material, you can do what I do and spray the inside of the enclosure (sides and back) with a spray glue. The Polyfill will hold to that and not separate. But, it is, after all, a sealed enclosure and this material really cant go anywhere anyways. And if your concern is it getting up against the sub and causing problems? It is likely NOT going to happen. I opened up an old box I had been using (while re-building my current set-up, and the poly was right where I had left it, but slightly "pushed" or compressed to the back of the box.

Report this post to a moderator

 

so the flat polyfill doesn't have the same properties as the weave kind??

Report this post to a moderator

 RE:

quote:

---

Originally posted on 02-12-2007 by gameguru1360
well I put dynamat extreme on the back wall opposite of the sub. Then I put a thin cushion of rollable pollyfill inside and used a spray adhesive so that it wouldn't shift and block the port area. So far it didn't resonate when I had nothing inside. I have scene pre-built single and dual ported boxes such as ones by Kicker and they had the rollable polyfill near the port.

---

Report this post to a moderator

 

oh well, I've only put dynamat on the MDF of both chambers and put that rolled up polyfill in the corners of both chambers in front of the MDF's.  I can probably remove them if the subs sound too muddy!

Report this post to a moderator

 RE:

quote:

---

Originally posted on 12-05-2007 by gameguru1360

so the flat polyfill doesn't have the same properties as the weave kind??

---

Report this post to a moderator

 RE:

quote:

---

Originally posted on 12-05-2007 by gameguru1360

so the flat polyfill doesn't have the same properties as the weave kind??

---

Report this post to a moderator

 

well, in a sealed box that is smaller than the subs recommendations, the polyfill tricks the sub into thinking its in a bigger enclosure, and yes I have been told as well not to put polyfill in a ported enclosure, but I have seen high end home speakers with polyfill in them, so I can't give you a definate answer, but I can't see putting dynamat in the enclosure would help in anyway.

Report this post to a moderator