dsw422 Posted May 13, 2017 Report Share Posted May 13, 2017 Hey guys. I asked this question in my build log but No one has answered . I need to lower the tuning of my rear chamber (4th order) but am unable to increase volume. I will be using polyfill to hopefully get the desired effect.. only thing is, I don't know how much to add.. 4th order wall build. 2 RE MT 18s , 6.25 sealed, 13.5 ported. Thanks for any help.. P.s. I will be buying the polyfill that comes in the 10lb box at Wal-Mart.. 2014 Ford Focus SE Sedan Factory Sony 10 Speaker Sound System 1994 Ford Bronco Dual head unit (i kno) Sony door speakers Kenwood Rear Speakers Custom Center console in the works. will house an NVX NSW10" https://m.facebook.com/WinnsCustomCarAudio/ Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted May 13, 2017 Report Share Posted May 13, 2017 You can put up to around 1.25 - 1.5 lbs per cubic foot of polyfill in. It will be packed in there pretty tight at that point though. While putting polyfill in the rear chamber will lower your sealed resonance (sealed chambers don't have a "tuning"), it will also lower your efficiency. Its probably going to cost you output. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
Joe X Posted May 13, 2017 Report Share Posted May 13, 2017 Here's a RE XXX 15" enclosure with specs rear: 2 net, front: 4 net @ 49Hz with 100 square inches of port area. Yellow: no damping in either chamber, Orange: "heavy" damping on the rear chamber, no damping on the front chamber: From the figure you would get a very modest gain below tuning, around tuning a softer peak, this maybe worthwhile for daily setup but not for metering. If I remember right MTs are recommended for a very large sealed box, and not recommended in a 4th BP simply because it would be too big to fit in most vehicles, if so, most likely your box would not be large enough. Link to comment Share on other sites More sharing options...
deathcards Posted May 13, 2017 Report Share Posted May 13, 2017 try egg crate foam on the walls of the sealed section it should lower the frequency well but it will also absorb sound waves on the sealed side...wait not sure if this is a good thing or bad since its sealed joe whats your thoughts https://www.amazon.com/Soundproofing-Acoustic-Eggcrate-Studio-Wedges/dp/B01EIHFOTM/ref=sr_1_7?s=musical-instruments&ie=UTF8&qid=1494688615&sr=1-7&keywords=acoustic+foam skar sk2500.1 0 gauge power and ground kunukonceptz alpine HUvxi65 components on BA gt-275new build log -> http://www.stevemeadedesigns.com/board/topic/150642-project-d-kon-deathcards-build-log/#entry2148821 2 x-15 sundowns singer alt, odyssey bat, and maxwell ultra caps Link to comment Share on other sites More sharing options...
ShadeTreeMechanic Posted May 14, 2017 Report Share Posted May 14, 2017 I use egg crate to eliminate reverberation or the hollow sound in a box. I don't know if it would have same effect as a full box of poly fill. Maybe the same as a little bit of poly. Edit: I use the cheap foam mattress pad kind. 91 C350 Centurion conversion ( Four Door One Ton Bronco) 250A Alternator (Second Alternator Coming Soon) G65 AGM Up Front / Two G31 AGM in Back Pioneer 80PRS CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon) Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon) Link to comment Share on other sites More sharing options...
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