How much polyfill?

mazeroth · 29th December 2004, 10:34 PM

Bought 2 bags of polyfill from Jo-Anns for $3.99 each for a 16oz bag. It's in a roll so it should make gluing/stapling it easier. This is going in my line arrays and I'm not sure how much I should start out with for testing. They have 2 compartments with 5 Dayton RS5 drivers in each. Each compartment is 0.8 cubic feet, tuned to 65hz with a 2.875" port. The compartments are 5.5" wide, 11" deep and 27" tall. I'm thinking of a thick layer on the back wall with a thin layer on the sides, top and bottom. What do you guys think?

Thanks!

mazeroth · 29th December 2004, 11:55 PM

I should probably add I'm doing this to kill the internal waves in the cabinet, not to trick the box into thinking it's bigger. Would I be better off using some sort of foam on the side walls, or as I have read in other threads, the roofing material they sell at hardware stores?

Thanks!

nerd of nerds · 30th December 2004, 12:22 AM

well, i'm still a n00b at this but i'd say use some kind of carpet on the inside of the cabinet...

but i'm just a lowly n00b, what do i know

Tim Moorman · 30th December 2004, 07:29 PM

I'd start off with about 6 oz in each compartment spread equally around the box. I leave the back or front temporarily removeable and just clamp back into position with wood clamps/duct tape until both the stuffing density and port tuning sound right.

I adjust both to taste with music and test tones playing. The woofer suspension takes a day or two to loosen up, so don't do anything permanent until then. Pump music or low frequency tones through them all day/night first.

Experiment, too, with sealing the port and leaving the back off.
Won't go as low but you may like sound quality better.

Tim

BillFitzmaurice · 30th December 2004, 09:21 PM

With cabinet dimensions that small a single layer on all internal surfaces will suffice.

mazeroth · 30th December 2004, 09:53 PM

So do you guys think using regular polyfill will do the trick for internal standing waves or should I spring for some 1.5" eggcarton foam?

Thanks!

BillFitzmaurice · 31st December 2004, 02:21 AM

That much foam is only required when the internal dimensions are long enough to support reflections below 500 Hz or so, and your's don't. It might not hurt but probably wouldn't help.

29th December 2004, 10:34 PM	#1
mazeroth diyAudio Member Join Date: Jul 2004 Location: Columbus, OH	How much polyfill? Bought 2 bags of polyfill from Jo-Anns for $3.99 each for a 16oz bag. It's in a roll so it should make gluing/stapling it easier. This is going in my line arrays and I'm not sure how much I should start out with for testing. They have 2 compartments with 5 Dayton RS5 drivers in each. Each compartment is 0.8 cubic feet, tuned to 65hz with a 2.875" port. The compartments are 5.5" wide, 11" deep and 27" tall. I'm thinking of a thick layer on the back wall with a thin layer on the sides, top and bottom. What do you guys think? Thanks!

30th December 2004, 12:22 AM	#3
nerd of nerds diyAudio Member Join Date: Apr 2004 Location: U.S.A.	n00b opinion... well, i'm still a n00b at this but i'd say use some kind of carpet on the inside of the cabinet... but i'm just a lowly n00b, what do i know

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29th December 2004, 11:55 PM	#2
mazeroth diyAudio Member Join Date: Jul 2004 Location: Columbus, OH	I should probably add I'm doing this to kill the internal waves in the cabinet, not to trick the box into thinking it's bigger. Would I be better off using some sort of foam on the side walls, or as I have read in other threads, the roofing material they sell at hardware stores? Thanks!

30th December 2004, 07:29 PM	#4
Tim Moorman diyAudio Member Join Date: Nov 2002 Location: Indiana	I'd start off with about 6 oz in each compartment spread equally around the box. I leave the back or front temporarily removeable and just clamp back into position with wood clamps/duct tape until both the stuffing density and port tuning sound right. I adjust both to taste with music and test tones playing. The woofer suspension takes a day or two to loosen up, so don't do anything permanent until then. Pump music or low frequency tones through them all day/night first. Experiment, too, with sealing the port and leaving the back off. Won't go as low but you may like sound quality better. Tim

30th December 2004, 09:21 PM	#5
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	With cabinet dimensions that small a single layer on all internal surfaces will suffice.

30th December 2004, 09:53 PM	#6
mazeroth diyAudio Member Join Date: Jul 2004 Location: Columbus, OH	So do you guys think using regular polyfill will do the trick for internal standing waves or should I spring for some 1.5" eggcarton foam? Thanks!

31st December 2004, 02:21 AM	#7
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	That much foam is only required when the internal dimensions are long enough to support reflections below 500 Hz or so, and your's don't. It might not hurt but probably wouldn't help.

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