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Blue Collar Audiophile
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So let's switch gears here. What about polyfil in ported boxes? I've seen it used and seen it suggested by ID in the smaller ported designs.
 

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I'd rather have a properly sized/designed ported/sealed box rather than relying on polyfill anyday. It comes into play when you are very tight on space other than that, there is no replacement for displacement.
 

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I'd rather have a properly sized/designed ported/sealed box rather than relying on polyfill anyday. It comes into play when you are very tight on space other than that, there is no replacement for displacement.
I did a lot of research about 3 years ago when I installed my subs (only had .65 cuft per sub). This is the conclusion that I reached as well. Adding polyfill will lower the Fb in a sealed enclosure.
 

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Here's an idea, if you want to know what polyfill does to sound, wrap your head in it while listening to music; or stick some cotton in your ears. It does something to cancel out some sound. Stops resonance (ringing?) inside subwoofer boxes. It affects the sound of your subwoofer, plain and simple. It's dirt cheap, and if you don't like it, remove it.

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Here's an idea, if you want to know what polyfill does to sound, wrap your head in it while listening to music; or stick some cotton in your ears. It does something to cancel out some sound. Stops resonance (ringing?) inside subwoofer boxes. It affects the sound of your subwoofer, plain and simple. It's dirt cheap, and if you don't like it, remove it.

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Pretty poor way to put it. It does not cancel out anything. It just makes the enclosure seem larger to the driver.

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I always thought of it this way, the rear wave in an enlcosure will have a reflection of the surfaces in the enclosure. Poly, will dampen the reflection and "assist" the rear waves collision when they return to the back of the cone.

I could be wrong here, but the poly should act as a dispersion material that will spread out the wave rather than have the wave bounce out in a cone shape and reflect directly back to the rear of the cone?

I suspect that this effect causes the soud wave to act on the entire ( or more of ) the interior surface of the enclosure. Thus utilizing more of the enclosure geometry????
 

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Pretty poor way to put it. It does not cancel out anything. It just makes the enclosure seem larger to the driver.

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That was meant to be a SIMPLE explanation. Sometimes people on forums get too involved in scientific explanations and lose their perspective. The bottom line is polyfill is dirt cheap, so it doesn't hurt anything to try it, just a few minutes. of labor.
By the way, HOW does it make the enclosure seem larger to the driver? Does it convince it, or is there hypnosis or something else involved?

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That was meant to be a SIMPLE explanation. Sometimes people on forums get too involved in scientific explanations and lose their perspective. The bottom line is polyfill is dirt cheap, so it doesn't hurt anything to try it, just a few minutes. of labor.
By the way, HOW does it make the enclosure seem larger to the driver? Does it convince it, or is there hypnosis or something else involved?

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simple and wrong arent the same. also, the answer is in this very thread... you didnt bother reading it, did you?
 

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simple and wrong arent the same. also, the answer is in this very thread... you didnt bother reading it, did you?
You must be a liberal, you can't identify sarcasm when it smacks you in the face.
The scientific explanation for why polyfill works is long and unnecessary, involving multiple pathways and lengths of pathways causing soundwaves to cancel each other out thereby reducing internal resonances.
See, totally unnecessary.
Polyfill works, try it, if you don't like it, remove it.

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simple and wrong arent the same. also, the answer is in this very thread... you didnt bother reading it, did you?
And please, wrap your head in polyfill and tell me I'm wrong. I'd like to see a pic of that, too.

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simple and wrong arent the same. also, the answer is in this very thread... you didnt bother reading it, did you?
Oh, and I did read the erroneous explanations involving thermodynamics and stating that polyfill doesn't work in subwoofer boxes. The effect of polyfill has nothing to do with thermodynamics, that was the whole reason for my original comment.

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That was meant to be a SIMPLE explanation. Sometimes people on forums get too involved in scientific explanations and lose their perspective.
...
Not usually.

It is usually more common to have magic and hand waving, and accusations of over thinking things.
 

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Ok so I might be the only fool who wrapped a pillow around my head, it was then, while listening to the home theatre I realized why this is not a very accurate representation of what polyfill does.
 

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Ok so I might be the only fool who wrapped a pillow around my head, it was then, while listening to the home theatre I realized why this is not a very accurate representation of what polyfill does.
I am doing the Winnie the poo with a head full of cotton, and a T shirt.
 

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Yeah, I realized that this could only work if the sound came from inside my ear.
I wonder if this would work with pants... add polyfill to make them seem bigger, and they would fit again.

I can see a cartoon with "do these make my b... lol big?", and the answer of, "you need a pound and a half of polyfill."
 

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I wonder if this would work with pants... add polyfill to make them seem bigger, and they would fit again.

I can see a cartoon with "do these make my b... lol big?", and the answer of, "you need a pound and a half of polyfill."
Not sure if they woulf "fit" again but my fat Arse could use some dampening! My rear wave creates a resonance at about 1.7 Hz, 3.7 if I am late for dinner!
 

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Really nobody figured it out??? Its on the internet do a search or better yet here:

compression increases temperature and decomperssion lowers it.

As the air in the enclosre compresses and decompersses it temporarily rises and falls in temperature.

Increasing temperature increases pressure.

Polyfill has a super high surface area and being a fiber can also retain some amount of kenetic energy within itself.

The polyfill helps to regulate the temperature as it changes, absorbing heat in the higher pressure air and emitting heat in the lower pressure air.

Since this means the higher pressure air will be a slightly lower temperature, this also lowers the peak pressure that the air reaches.

Lower pressures against the sides of the box and the air within make the system react like a slightly bigger box with no polyfill.
 

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this thread has me so confused...when the hell did polyfill become a conversation about heat dissipation?

Everytime I hear people talk about polyfill its seems like BS for a lot of reasons. But in the more sane conclusions its to breakup the soundwave coming from the back of the cone from echoing or reverberating off the cone causing efficiency loss and cone breakup/intelligibility issues.

food for thought...anechoic chambers, least the ones I have seen are not stuffed floor to ceiling with polyfill. In fact I've never seen polyfill used in a anechoic chamber. But then again material science has come a long way...what we used in the past for speakers may not be needed anymore because we surpased it with stiffer enclosure design, better foams and other things that solve the issues polyfill was once used for.
 
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