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View Full Version : egg crate in box?



jeremiah
05-21-2007, 02:53 PM
^^ will it work? if so how good

jeremiah
05-21-2007, 03:04 PM
not the egg crate for eggs it's the kind for you bed
will it work better than poly filler?

jeremiah
05-21-2007, 07:27 PM
^^

BassAce
05-21-2007, 07:30 PM
You mean egg crate shaped foam.

I think they are used to clean the muddiness out of mids.

jeremiah
05-21-2007, 07:44 PM
yes egg crate shaped foam will it work in a subwoofer box better than poly filler

azbass
05-21-2007, 07:45 PM
you tell us

bdawson72
05-21-2007, 07:46 PM
yes egg crate shaped foam will it work in a subwoofer box better than poly filler

polyfill

jeremiah
05-21-2007, 08:10 PM
yes polyfill

Wonger
05-21-2007, 08:11 PM
no

jeremiah
05-21-2007, 08:18 PM
O and how much polyfill do I need to make my box seam like it's 4.5cu.ft
my box is 4cu.ft and this what I have http://i200.photobucket.com/albums/aa157/mj-18/052007_15371.jpg

jeremiah
05-21-2007, 08:20 PM
no

do you know or you just saying that

Eugenics
05-21-2007, 08:25 PM
polyfill

polyfiller

azbass
05-21-2007, 08:27 PM
why are you even putting polyfil in a 4cu.ft box anyway?

jeremiah
05-22-2007, 02:01 PM
because I have a mj-18

jeremiah
05-23-2007, 12:22 AM
so how much polyfill do I need to make up for 1/2cu.ft???

CRAZYCORNUTS18
05-23-2007, 12:25 AM
.5 isnt going to be a noticable difference any way so theres no point

oglejust
05-23-2007, 12:30 AM
i believe its 1 lb of polyfil for 1 cubic foot so 1/2 a lb.

jeremiah
05-23-2007, 12:34 AM
so 1/2lb of polyfil will get me my 4.5cu.ft

oglejust
05-23-2007, 12:34 AM
.5 isnt going to be a noticable difference any way so theres no point

^^^^^^^^ x2

jeremiah
05-23-2007, 12:45 AM
Ok??????

Volenti
05-23-2007, 04:05 AM
Don't try and use fill to "make a box larger", because it's robbing peter to pay paul, the damping action of fill will reduce your output far more than the effect of making the box appear larger will increase it.

There are valid applications where fill is very usefull, but using it to make an enclosure appear larger isn't one of them.

Trixter
05-23-2007, 01:05 PM
also, the 1lb to 1cu' is the recommended amount to "smooth" out the waves with out causing any negative reactions. 1lb is not equal to adding 1cu'....if that was the case i'd have my B15 in a .5cu' with 3lbs of polyfilli in it and have plenty of trunk room....lol

oh yeah...the original Q, use the polyfll....the padding is too dense, use the padding for sound deadening and rattles.

jeremiah
05-23-2007, 02:00 PM
OK think you

HondAudio
05-25-2007, 01:23 AM
Ignoring polyfil to make up for airspace, eggcrate foam lining the box will help break up standing waves that would cause distortion.

helotaxi
05-25-2007, 08:32 AM
Ignoring polyfil to make up for airspace, eggcrate foam lining the box will help break up standing waves that would cause distortion.

Standing waves in the box are not a factor at sub bass freqs. A 100 hz sine wave has a wavelength of over 10'.

mrogowski
05-25-2007, 10:48 AM
Don't try and use fill to "make a box larger", because it's robbing peter to pay paul, the damping action of fill will reduce your output far more than the effect of making the box appear larger will increase it.

There are valid applications where fill is very usefull, but using it to make an enclosure appear larger isn't one of them.

Interesting. While there have been tests performed/published on the effects of damping on an enclosure, none of them show this phenomenon you speak of.

Care to share a link?

Best,
Mark

jcbabb
05-25-2007, 10:10 PM
polyfiller

perfect late night humor....:)

jeremiah
05-26-2007, 06:31 PM
hmm

Volenti
05-26-2007, 10:54 PM
Interesting. While there have been tests performed/published on the effects of damping on an enclosure, none of them show this phenomenon you speak of.

Care to share a link?

Best,
Mark

I don't have any links, this stems from my own research, the published fill tests don't show this effect since they don't test for it (why I have no idea) all they do is assume that overall enclosure QTC and FS reduces as you increase enclosure volume (true) and they observe that adding fill reduces QTC and FS (true) and come to the reasonable conclusion that adding fill makes the enclosure appear larger (true).

This is all fine and good untill you look at the output of an unfilled enclosure compared to a filled one, the peak SPL of the filled enclosure will be up to 3db less than the unfilled one (that's like halving your amplifier power), and this is just with sealed enclosures, ported enclosures can be effected far more.

I recalibrated BBP6's damping calculations based on my measured data, and here is an example of why adding fill is counter productive if increased output is your goal.

The white trace is a Type arr 12'' in 1.5cuft tuned to 35hz, let's assume we ****ed up and really wanted 2cuft tuned to 35 instead (red trace) so we add fill to our 1.5cuft to "fool" it into thinking it's a larger enclosure, pretty smart eah? Well mabie not since what we end up with is the green trace, 3db lower at 50hz and 6db lower at 40hz...
http://users.bigpond.net.au/volenti/damping.gif

What it comes down to is the fact that enclosure resonance makes bass, that's the entire point of a ported box, to resonate at a set frequency, fill damps this resonance (reduces it), it's like trying to ring a bell while holding the bell mouth with both hands.

I'm not saying that fill should never be used, I use it all the time in SQ focused setups that sacrifice SPL for SQ, it's just that trying to apply it like a bandaid to street systems where the goal is LOUD but you messed up on the enclosure dimentions is just going to make things quieter, not louder.

jeremiah
05-27-2007, 10:22 AM
hmmm ok think you

jeremiah
05-28-2007, 04:43 PM
are standing waves bad for the sub?

Volenti
05-29-2007, 03:39 AM
No , standing waves just sound bad, they won't cause any damage.

UndercoverPunk
05-29-2007, 03:48 AM
Did someone say bondo?

jeremiah
05-29-2007, 07:26 PM
what?