bigsausagepizza Posted September 17, 2014 Report Share Posted September 17, 2014 Polk has been using this technology for a long time, it is supposed to allow you to dramatically shrink the length and diameter of your ports without introducing port noise. Last week polk had a cool page on it at their "polk university" site, but that is now unavailable. Here's the thread from Home Theater Shack where I found this: http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/16591-power-port-calculations.html There is a link on the page to download a spreadsheet with all the calculations. It seems like a legitimate design for getting low tuning with reasonably sized ports. Here's the diagrams from the spreadsheet: I'm thinking about using this to build a small home theater sub with tuning in the 15-20hz region. 2008 Subaru WRX STI K&N Typhoon Intake Invidia Polished Stainless 3" turbo back with cat Cobb Accessport Dyno tune from Kaizen Tuning 320awhp 330ft-lb awtq MTX 421D Sub amp American Bass SQ900 Highs/Mids amp Sundown Audio SD-2 10 D4 JL Audio XR653-CS 3-way Components 3sixty.2 Second Skin Damplifier Pro Custom fiberglass wheel well enclosure Transmission Line quasi-floor enclosure http://www.stevemeadedesigns.com/board/forum/13-member-rides-builds-show-off-your-whip-show-off-your-system/ Bill Fitzmaurice TLAH line-array hifi towers 9 Goldwood 4" mids (each) 12 Goldwood 1/2" tweeters (each) NAD 1020 Preamp MiniDSP 2x4 Balanced processor Thorens TD166mkII Turntable Hafler DH-200 Amplifier http://www.stevemeadedesigns.com/board/topic/192638-line-array-hifi-tower-build/ https://www.facebook.com/HolyMountainGlass Link to comment Share on other sites More sharing options...
philrab Posted September 17, 2014 Report Share Posted September 17, 2014 So, it's a traditional flare port with an insert/airguide? On the doublesided port, how exactly would you affix the center guide? Just seams like it's hanging in the air. 2015 Toyota Tacoma Build Thread 2007 Mazda 3; 5000K HID's, Kenwood Excelon KDC-X997, Infinity Reference 6.5 comps in front and coaxials in the rear doors, JL 320.4 four channel, Rab Designs built ported enclosure with an SA12, Kenwood monoblock, Redline Leater shift boot/e-brake boot/center console cover, JBR short shifter/shifter bushings/rear motor mount. Build Thread 1996 Mazda Miata: Kenwood Excelon HU, Alpine speaker in the doors, Clearwater (miata specific) headrest speakers. 1994 Mazda Protege: Kenwood Excelon HU, Infinity Reference 2 ways all around, 2x RF Punch 10's in ported boxes. Link to comment Share on other sites More sharing options...
TRON Posted September 17, 2014 Report Share Posted September 17, 2014 All that port does is allow you to increase the port opening size without changing the tuning. I don't really see what you would gain with that other than less port noise. I also don't think you'll get lower response just becasue of the port. You want low, build a horn or quarter wave. At the end of the day, it's still just a ported enclosure. Avalanche Alpine Type S comps Alpine Type S 10'' Alpine MPR-F300 Alpine MRX-M50 Mechamn 270 XS Power d3400s Link to comment Share on other sites More sharing options...
bigsausagepizza Posted September 17, 2014 Author Report Share Posted September 17, 2014 All that port does is allow you to increase the port opening size without changing the tuning. I don't really see what you would gain with that other than less port noise. I also don't think you'll get lower response just becasue of the port. You want low, build a horn or quarter wave. At the end of the day, it's still just a ported enclosure. Have you checked out the spreadsheet? It seems to be the actual spreadsheet polk uses ("Confidential Property of Polk Audio, Inc"), and they put this into some of their highest end speakers. If you play with the spreadsheet it shows you can use dramatically shorter and smaller ports and achieve the same tuning. For example, if I plug in a standard 3" diameter 40" long port, it says I can use a 2" diameter port, 11" long, with 8" disks on each end ( w/ 3" diameter flow guide cones and 1/2" roundover on the port tube). If this is correct (Polk has patents on it and use it in their high end equipment, so I want to trust them), using a ~12" long port seems pretty great compared to using a 40" port. Here's a build that used this design, he was able to use a 36.5" long port instead of a 62.5" long port, and the tuning came in exactly as predicted (11hz!!!, those HT guys are nuts). http://www.hometheatershack.com/forums/home-audio-subwoofers/10524-custom-re-xxx-subwoofer-build.html 2008 Subaru WRX STI K&N Typhoon Intake Invidia Polished Stainless 3" turbo back with cat Cobb Accessport Dyno tune from Kaizen Tuning 320awhp 330ft-lb awtq MTX 421D Sub amp American Bass SQ900 Highs/Mids amp Sundown Audio SD-2 10 D4 JL Audio XR653-CS 3-way Components 3sixty.2 Second Skin Damplifier Pro Custom fiberglass wheel well enclosure Transmission Line quasi-floor enclosure http://www.stevemeadedesigns.com/board/forum/13-member-rides-builds-show-off-your-whip-show-off-your-system/ Bill Fitzmaurice TLAH line-array hifi towers 9 Goldwood 4" mids (each) 12 Goldwood 1/2" tweeters (each) NAD 1020 Preamp MiniDSP 2x4 Balanced processor Thorens TD166mkII Turntable Hafler DH-200 Amplifier http://www.stevemeadedesigns.com/board/topic/192638-line-array-hifi-tower-build/ https://www.facebook.com/HolyMountainGlass Link to comment Share on other sites More sharing options...
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