sonotube insulation advice.. - AVS Forum
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post #1 of 10 Old 12-29-2012, 03:35 PM - Thread Starter
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i have loosely placed 3.5 inch R13 insulation inside my sonotube...which can be seen below...this seems a bit excessive...keep in mind this is only 14" diameter sonotube...

will i be okay with the R13 or should i look into egg crate foam...

i believe there is a difference between open cell and closed cell...i believe closed cell will take away from the internal volume of the enclosure...i imagine i do not want this...can someone tell me which of the two is best and how do i know whether i am buying open or closed cell...



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post #2 of 10 Old 12-29-2012, 04:53 PM
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There's nothing wrong with using the R-13 as shown. I'd leave it as is.
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post #3 of 10 Old 12-29-2012, 05:03 PM
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Is this going to be a ported enclosure? I have found that overstuffing a ported enclsoure even if the material is kept away from the ports can lower output around tuning by a few dB's.

If sealed what you show is fine.
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post #4 of 10 Old 12-29-2012, 05:09 PM
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Can you pull apart into like half that?

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post #5 of 10 Old 12-29-2012, 06:07 PM
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If ported, consider using something other than fiberglass, so you aren't blowing glass fibers into your room.

-Max
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post #6 of 10 Old 12-29-2012, 06:46 PM
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Quote:
Originally Posted by maxcooper View Post

If ported, consider using something other than fiberglass, so you aren't blowing glass fibers into your room.
-Max
+1. There are a number of issues with home insulation fiberglass, and that's why professional designers don't recommend it. Rigid type 700 fiberglass works quite well, but not in sonotubes. I'd go with foam, as it is easily glued in. Polyester batting is OK too. A tube doesn't need a lot, two inches is plenty, as the round shape minimizes internal reflections anyway.

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post #7 of 10 Old 12-29-2012, 07:01 PM
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Quote:
Originally Posted by cnp112 View Post

i have loosely placed 3.5 inch R13 insulation inside my sonotube...which can be seen below...this seems a bit excessive...keep in mind this is only 14" diameter sonotube...
will i be okay with the R13 or should i look into egg crate foam...
i believe there is a difference between open cell and closed cell...i believe closed cell will take away from the internal volume of the enclosure...i imagine i do not want this...can someone tell me which of the two is best and how do i know whether i am buying open or closed cell...



Michael Hurd and Neo Dan did a bunch of comparisons with and without the insulation. Give them a shout and they can offer some advice.

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post #8 of 10 Old 12-30-2012, 08:51 AM - Thread Starter
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nice...thanks guys...i didnt expect such a turnout...

the sub will be ported....and i understand that there is a possibilty of fiberglass being blown out of the port...but i have also read that it will not be a problem...if it is...i will have to build a nylon port cover....

i would like to stay with the R13 only because i already have it on hand...i liked the suggestion of pulling apart the R13 to like 2 inches of material as opposed to the 3.5 inches...quick question though...i have read that R13 is mainly used to dampen the upper harmonics...will this also have a noticeable effect on its ability to dampen those harmonics...

thanks robert...i will have to reach out to hurd & dan...
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post #9 of 10 Old 12-30-2012, 12:01 PM
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You will have loose fibers that will become airborne, and blow out of the port, as well as falling on the back of the driver, and getting sucked into the voice coil gap. I would suggest using something other than fiberglass. If it was a sealed sonotube, and there was a way to prevent it from entering the gap, or sagging down / covering the vent on the back of the magnet, sure.

I did a bunch of measurements a few years back to see why an untreated sonotube sounded so 'ugly' when I fired the first one up. Turns out that the end to end dimension was long enough to create a big spike in the frequency response that rang way out to 300 msec after the initial signal.

Two polyfill pillows placed around the port slightly away from the endcap opposite the driver is enough to completely get rid of that nasty spike. It did however come with a slight penalty in efficiency above tuning, with a slight gain below tuning. Pillows are nice because the material is contained in the cover, they are non-shedding and easy to work with.

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post #10 of 10 Old 12-31-2012, 07:55 AM - Thread Starter
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thanks michael...just wanted to summarize where i will end up in regards to the insulation...

i will test the following once the rest of the build is completed...may be a while..still need to order the amp...

i will be stuffing a couple pillows around the port...which will be on the opposite end of the driver...but not completely against the endcap...this will leave a small air gap between the stuffing and the endcap...

i have copied the link to the original post by michael...for those who may care...

http://www.avsforum.com/t/1141956/vented-boxes-and-absorption
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