# Midbass & midrange polyfill help on infinity crescendo cs-3009



## Briandumm2955 (Sep 4, 2017)

Hey everyone, new here. I have a pair of infinity crescendo cs-3009's. I am wondering about the poly fill in each sealed enclosure, they are 4 way speakers, so the midbass & midrange are in their own "tube" shaped enclosure. The midbass tube enclosure is 13" deep & is 6" in diameter, the mid-range tube enclosure is 5" deep & 4" in diameter. How much poly fill should go in there? Do I calculate the volume of the enclosure & decide how much then or do I measure volume and how much poly fill decreases the volume. If anyone can help I can take more pictures. also the area behind the woofers had nothing... just bare wood. Echoes bad, did these come from factory like that or should they most definitely have foam on the walls?


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## ajinfla (May 10, 2009)

Did someone remove the fill from each chamber or are you assuming they all need it?
The mid cavities should have some, but the woofers, not necessarily so.

Btw, please do not post same question over multiple forums, thanks.


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## Briandumm2955 (Sep 4, 2017)

OK, sorry if I remember correctly I wasn't sure which forum would of been the best one to get an accurate answer. So I have polyfill for them, I know some does go in there. I was just wondering how I calculate the correct amount.


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## ajinfla (May 10, 2009)

There is no calculation for this. Best approach is to measure the individual mid/woofer impedances as stuffing is added to each. In lieu of this, simply adding stuffing to each and listen. Mid chamber should not be overstuffed. A "modest" amount should do. Woofer chamber, depending on upper crossover frequency, may need very little at all. Here there is less danger of overstuffing.


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## Briandumm2955 (Sep 4, 2017)

OK, yeah I don't have equipment to test but I've been told that using 1 pound per cubic foot is a good start. Harman kardon the now owners of infinity were no help. So I'll just fiddle with amounts. I wish I knew the amount they used when producing the speakers, I'd think that info is floating around somewhere.


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