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Old 9th July 2004, 12:17 AM   #1
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Default polyfill adds?

about how much voume does polyfill add? I want to stuff a sealed enclosure enouf to make up for the 2 braces i want to put in.
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Old 9th July 2004, 01:17 AM   #2
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A fully stuffed box equates to about a 20% increase in sealed box volume. I've seen a number of posters here say that their experience is that stuffing is bad. I wouldn't think that a couple of braces would affect your Q enough to worry about for a sealed cab.
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Old 9th July 2004, 02:12 AM   #3
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I have an Adire DPL12 in a 2.4 cubic foot sealed box and just recently stuffed it completely. The results were not good. It lost SPL and slam factor. So, I opened it back up and removed some stuffing and now it is about 1/2 full like it always was before. The SPL and slam came back. When I was testing it, I had no stuffing in it, and it had even more slam. I might go back to that if I feel like opening it back up. So, in my experience, stuffing was bad.
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Old 9th July 2004, 08:10 PM   #4
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Stuffing is bad in a sub, and unnecessary. The wavelengths reproduced in a sub are unaffected by stuffing and do not require attenuation within the box as they are too long compared to the box dimensions for standing waves to develop. The idea of using stuffing to increase apparant box size is a carryover from the pre-T/S days and really does not apply to subs. Stuffing/lining is a must for frequencies from about 300 Hz and up.
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Old 10th July 2004, 02:04 PM   #5
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Yup, I agree with Bill here. If you just stick with the braces you should be fine, as small changes in volume ( c. +-10%) don't really affect response significantly.
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Old 11th July 2004, 06:06 AM   #6
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this isnt for a sub, it is for a 2 way thats sealed and i dont have any acoustic foam for it. So will stuffing be fine?
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Old 11th July 2004, 07:20 AM   #7
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Oops, I misunderstood

Yes, that should be fine, I would start at around 50% fill, then add or subtract until it sounds good.
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Old 11th July 2004, 11:55 AM   #8
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I recently stuffed my 3" satellite (multimedia) speakers with polyfill. With reguards to it change the effective volume, I dont perceive the volume to have changed at all. It just seems like it absorbs harmonic resonances within the enclosure giving a more crisp and defined sound.
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Old 11th July 2004, 08:36 PM   #9
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Quote:
Originally posted by Hadamona
I recently stuffed my 3" satellite (multimedia) speakers with polyfill. With reguards to it change the effective volume, I dont perceive the volume to have changed at all. It just seems like it absorbs harmonic resonances within the enclosure giving a more crisp and defined sound.

That's precisely what you should be hearing; the stuffing prevents reflected waves inside the box from going back to the cone to cause dips and bumps in response.
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Old 12th July 2004, 05:06 PM   #10
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So what is it about stuffing that takes away slam from subs? I can't see what theory would support the subjective comment!

If it's a sealed subwoofer, then it lowers the Q, which should be a good thing! From a fidelity point of view. Perhaps this perceived loss of slam is actually greater accuracy. As I understand, a lower Q will often mean better transient response, by making the box appear bigger.

I can't see why stuffing a sub should be considered a "pre TS parameters thing."

I have heard that stuffing is not a good idea for a vented box. However, if the vent is not blocked and it is partially stuffed, I'm not sure what effect it might have.

I can see the point however, that small changes in box volume aren't that significant for a sealed sub - the response changes very little. It is more a question of transient response I believe.
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