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- - - Poly-Fil
RE:
Posted by squeak9798 on 02-09-2006 08:58 AM:
quote:
Originally posted on 02-08-2006 by dyedef1966
I agree with jowens on that. got so caught up in everything else, we forgot to ask. I guess that'll happen in heated debates!
Insofar as my comments about Standing waves in your "Sealed" sub box is concerned, lets see what an expert has to say about it all...www.elitecaraudio.com/home/html/print.php?sid=22 In this article he explains how standing waves are created in a sub box, at ANY frequency, not just those higher than, say 300 or 400hz, and how poly-fil controls them. I also agree with what N2 said about information sources.
we could probably go back and forth forever on it.
Let me just say this. I am old school, trained and tested, tried and true, and in the last 20+ years, I have NEVER built a sub box without damping material inside it. But thats just me!! lol
While I do like audionutz, and he is an extremely knowledgeable person....he is not always 100% correct in everything he states. This would be one of those instances.
It is simply a fact of physics that any enclosure small enough to fit inside a vehicle is too small for standing waves at subbass frequencies to be an issue.
I could go out and find 1,000 links that state the same, by just as "expert" sources, yet I have the feeling you wouldn't care anyways, so I'm not going to waste my time hunting them all down.
Just know that what you are stating is not possible within the realm of physics ;-) And no link is going to change that.
Poly-Fil
Posted by gellin on 02-07-2006 09:13 AM:
i'm planning on building my own box this weekend and i was wondering if this poly-fil stuff is worth buying.i have two kicker 10" L7's solo barics.
http://www.crutchfield.com/S-Sbcvtl4YRMa/cgi-bin/ProdView.asp?g=741&I=027808&id=review
Posted by dyedef1966 on 02-07-2006 09:20 AM:
Poly fill should be installed in EVERY sub box. at least 1" thick on all sides. I wouldn't buy it on there, though. Go to wal-mart or something, and buy a cheap-ass pillow. Exact same shit inside.
Posted by Donsway on 02-07-2006 10:16 AM:
Only time that I have not used it was on the boxes I have now. Powerbass says when going for SPL and box is tuned high (mine 54Hz) no poly fill, but this is only time I have seen this.
Posted by Ryan21 on 02-07-2006 10:29 AM:
If your box is built to spec you shouldn't need poly-fill. It is a good alternative when you box is to small for your drivers.
Posted by dyedef1966 on 02-07-2006 10:54 AM:
I gotta disagree, Ryan. Boxes without poly-fill are said to sound "hollow". Poly-fill helps to absorb standing waves, and unwanted resonances.
I do agree with the fact that overfilling your box can actually "fool" the speaker into thinking it has a bigger internal volume, though, to a certain %. Just my opinion, and everybodys got one.
RE:
Posted by squeak9798 on 02-07-2006 11:47 AM:
quote:
Originally posted on 02-07-2006 by dyedef1966
I gotta disagree, Ryan. Boxes without poly-fill are said to sound "hollow". Poly-fill helps to absorb standing waves, and unwanted resonances.
I do agree with the fact that overfilling your box can actually "fool" the speaker into thinking it has a bigger internal volume, though, to a certain %. Just my opinion, and everybodys got one.
FYI: Standing waves in a subwoofer enclosure are 100% a non-issue. The wavelengths are entirely too long in relation to the enclosure size for standing waves to be a problem. There is no opinion about this...it's an absolute fact. Standing waves are completely irrelevant and a complete non-issue for subbass in any enclosure small enough that it will fit into a vehicle. The enclosure would need to have side-walls tens of feet by tens of feet before standing waves for subbass would ever be an issue.
Likewise, the foam/polyfil/etc would have to be multiple feet thick to actually absorb subbass waves. Sticking 1 or 2 inches of polyfill on a side wall is not going to do anything as far as absorption of soundwaves is concerned. Again, no opinion necessary...this is a fact.
Polyfill is NOT necessary in every enclosure. Absolutely not. If your enclosure is adequately sized, there is no need for it at all.
If you added polyfil and heard a difference in sound, then the difference was likely due to the increased acoustic compliance of the enclosure (as a result of the polyfill) and not because of the factors you mentioned. Essentially, you heard the subwoofer perform as if it were in a slightly larger enclosure, and you preferred that sound more. All that tells you is that you could have built the enclosure slightly larger and arrived at the same results (without using polyfill).
Posted by Ryan21 on 02-07-2006 12:19 PM:
dyedef1966, I am not disagreeing with you, everyone has there own ways and preferences. I would use poly-fill if a box sounded to "boomy" for the users preference. other than that, i probably wouldn't
Posted by Donsway on 02-07-2006 03:58 PM:
The way I see it is that the box is the hardist and most important part of a system to get right. You should try different things, poly fil is cheap put it in try, don't work take it out. I just rebuild the box and try it out, but maybe I can get 1dB out of this design build it try. Each car does it's on thing on sound so you just have to try if you want the most it can give.
Posted by dyedef1966 on 02-07-2006 07:42 PM:
Like I said, My opinion. But Gellin, before you make a decision, search around the net a little more. a had a few extra minutes, so I did a little for you. you might want to check out......www.the12volt.com/caraudio/boxes.asp as well as www.carstereo.com/help/box_build.cfm and last diyaudiocorner.tripod.com/faq On that one, scroll down to find the question "Do I really need acoustic insulation in my subwoofer box"
RE:
Posted by squeak9798 on 02-07-2006 08:42 PM:
quote:
Originally posted on 02-07-2006 by dyedef1966
Like I said, My opinion. But Gellin, before you make a decision, search around the net a little more. a had a few extra minutes, so I did a little for you. you might want to check out......www.the12volt.com/caraudio/boxes.asp as well as www.carstereo.com/help/box_build.cfm and last diyaudiocorner.tripod.com/faq On that one, scroll down to find the question "Do I really need acoustic insulation in my subwoofer box"
Most of the info given in that "Do I really need acoustic insulation in the box" (it does not state in my subwoofer box) applies to full range drivers, but NOT to subwoofers. There is a HUGE distinction to be made there. Though even then it's only partially correct on some of it, even when applied to full range drivers.
Posted by dyedef1966 on 02-08-2006 05:18 AM:
LOL Yet the other 2 sites you didn't mention (one of which you are on right now) are VERY specific when they state that they are speaking of Subwoofer boxes for "Car Audio". One says it is recommended, the other says they advise it, which is what I did. I recommended it. I don't understand...why so argumentative??
Posted by cmeace on 02-08-2006 08:51 AM:
I'm by no means an expert. However, in the 17 years that I have been doing this, Poly-fil in a box is almost a standard. It is personal preference, but all enslosures that I have built and most of the ones I've seen built by others have some in it. I can definitely tell a difference when you play around with how much you choose to use. Donsway has a point, it's a cheap and easy experiment, if you don't like it, simply take it out. Dyedef has referenced you some good articles. It seems to be a consensus.
RE:
Posted by squeak9798 on 02-08-2006 10:05 AM:
quote:
Originally posted on 02-08-2006 by dyedef1966
LOL Yet the other 2 sites you didn't mention (one of which you are on right now) are VERY specific when they state that they are speaking of Subwoofer boxes for "Car Audio". One says it is recommended, the other says they advise it, which is what I did. I recommended it. I don't understand...why so argumentative??
I'm not arguing that it isn't something you can play around with, and I'm not saying it has zero effect.
What I am trying to make you understand is the principles behind why it has an effect on the sound (because it's not for the reasons you have been mentioning), and that it is not a requirement in an enclosure that is adequately sized for your taste. Simply "recommending" someone try playing with it is different than saying it "should be in EVERY enclosure" (which was your exact original statement). It is not a *must*, but it's something you can play around with. And it does not have an effect on sound because of standing waves, etc, like you mentioned earlier.
I didn't mention the other two links because frankly, I didn't visit those links and didn't feel like it...LOL I went to the last one you mentioned because you had a specific section pointed out in it to read (so I didn't have to waste time reading the entire link).
Posted by dyedef1966 on 02-08-2006 11:53 AM:
Maybe you SHOULD read more! lol
RE:
Posted by squeak9798 on 02-08-2006 12:34 PM:
quote:
Originally posted on 02-08-2006 by dyedef1966
Maybe you SHOULD read more! lol
I don't get it.......
Anyways, do you understand my points (my first post in this thread)? Or was it all in vain and you are going to continue preaching the (inaccurate) standing waves/etc reasoning?
Posted by dyedef1966 on 02-08-2006 01:54 PM:
Ok, OK, Ok, you're right, I'm right, its just our opinions, like I said earlier. Lets let this thread die off, and get back to the fun stuff. Ron
Posted by N2Audio on 02-08-2006 02:18 PM:
For standing waves to be an enclosure problem 2 parallel faces would have to be about 11' apart for 100hz, 14' for 80hz, almost 19' for 60 hz. etc
Squeak and I must get our facts from the same places because I agree basically word for word with what he said.
Ron - if you've had good results using poly-fill by all means keep doing it, but there just isn't much real evidence other than subjective that says it makes a measurable improvement.
I looked at 2 of your links - one referenced polyfill "absorbing energy" or something to that effect - well, that energy absorbtion is the proccess that explains why polyfill causes the speaker to act like it's in a bigger box.
If you like using it, great, but there's no reason to go around insisting it needs to be used. Especially if there is room for the box to be built to the specs of the speaker.
RE:
Posted by squeak9798 on 02-08-2006 02:26 PM:
quote:
Originally posted on 02-08-2006 by dyedef1966
Ok, OK, Ok, you're right, I'm right, its just our opinions, like I said earlier. Lets let this thread die off, and get back to the fun stuff. Ron
I'm not arguing for or against polyfill. Like I said before, it's something you can play with, but is not a must have in every enclosure as you made it sound. So there I guess you could say we "generally" agree (though it is NOT an absolute necessity).
However, you were incorrect in your assestment of how and why the polyfill affected the sound in subwoofer enclosures. There is no opinion there. It's simply a fact.
Posted by jowens500 on 02-08-2006 08:08 PM:
the question that everyone has forgot to ask is, are you building a sealed box? if it is not sealed, then it stops there. it heats up the motor structure of the driver, which will break it. i once took a customers woofer out of a box overfilled w/pollyfill that was so hot, it took 3 days to cool off!! oh yea, NOT COVERED UNDER WARRANTY!!
use a good closed cell foam like hushmat. in a ported box it would all fly out of the port, unless you glued it, but not recomended at all. totally defeats the purpose of a ported box. which is to move as much as air as efficently possable