abdc Posted November 30, 2017 Report Share Posted November 30, 2017 Hey guys, I was about to re-purpose this 1.75cu 31hz slot port box (built for JL W3) for my DC XL12. Despite the differences in these two drivers, recommended box size and tuning are very similar. But WinISD is showing me nasty high port velocity at tuning. This model is showing air velocity close to 50m/s at 2200rms, and doesn't drop below 30m/s until 800rms or less. Am I missing something or do I need to get to building a new enclosure to avoid stupid amounts of port noise? Relatively new to WinISD. Link to comment Share on other sites More sharing options...
abdc Posted November 30, 2017 Author Report Share Posted November 30, 2017 Oh, and port dimensions are as follows: Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted November 30, 2017 Report Share Posted November 30, 2017 Yeah, you really need to build a new box, 2200 watts into a 1.75 cu ft enclosure is a lot. Its going to take a lot of port area. I try to keep port velocity under 22 m/sec if it can, its not always possible, especially with high power density situations like what you have. 30 m/sec is my absolute upper limit, above that and you start losing a lot of output to port compression. Since you already have things plugged into WinISD you should be able to figure out how much port area you will need to bring your port velocity down. Just to get port velocity down to 30 m/sec you are probably going to end up with a very large and very long port. Its going to need to be at least twice as big as what you have now. "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...
abdc Posted November 30, 2017 Author Report Share Posted November 30, 2017 Thanks. I was hoping someone was going to pop up and tell me port velocity is a myth lol. Yes, it is looking like I'm going to need a significantly wider port, which is also going to be considerably longer to keep tuning to 31. Current box is 1.75net 2.35gross. New box will probably have to be over 3cubes gross to keep my same 1.75net with all of that porting. In the meantime, I suppose I'll just play around with this box and see just how bad it huffs air while I plan out a new one. Link to comment Share on other sites More sharing options...
audiofanaticz Posted November 30, 2017 Report Share Posted November 30, 2017 Really the only time you want high port velocity is if your competing in a port wars competition by placing the mic in the port. You always want to keep it lower as stated above, creates a more efficient enclosure that will be louder with the same power compared to a similar box with higher port velocity. Link to comment Share on other sites More sharing options...
notorious97200 Posted November 30, 2017 Report Share Posted November 30, 2017 You'd better build another box. You can Try an higher tuning, like 34Hz, lenghth port should be shorter, and you'll still have enough lows. 1.75 : that seems to be on the small side for such a beefy 12". Maybe 2.5 to really enjoy your beast ! (I remember reading DC subs like small enclosures, so it may be good at 1.75 ...). black BMW X1 2.0 l 192 hp OEM head unit, Amplifiers : Audison AP 8.9 amp with integrated DSP and Ampere Audio 1200. Focal ES 100 K in front doors, and Dayton RS 180 for midbass under the front seats. 2 SSA DEMONS 10" subs, in a 2.6 ft3 ported box. SecondSkin Damplifier on front doors, and Luxury Liner Pro for the cargo area. Link to comment Share on other sites More sharing options...
abdc Posted December 1, 2017 Author Report Share Posted December 1, 2017 OK, so here is the new box I built per WinISD specs. I have not put it together yet, but here is a quick mock up for you to see what it will look like. External dimensions: 17.5 x 15.75 x 32.25 Gross Air Volume: 3.59 cubic feet Net Air Volume: 1.75 cubic feet Tuned to 32hz Max Port Velocity 24m/s at 2200rms at 32hz with DC XL 12 Let me know what you think, almost looks like a T-Line at this point right? Link to comment Share on other sites More sharing options...
ChevyBoy95 Posted December 1, 2017 Report Share Posted December 1, 2017 1 hour ago, abdc said: OK, so here is the new box I built per WinISD specs. I have not put it together yet, but here is a quick mock up for you to see what it will look like. External dimensions: 17.5 x 15.75 x 32.25 Gross Air Volume: 3.59 cubic feet Net Air Volume: 1.75 cubic feet Tuned to 32hz Max Port Velocity 24m/s at 2200rms at 32hz with DC XL 12 Let me know what you think, almost looks like a T-Line at this point right? No, it looks like a small box with a overly long port. Best Score to Date : 160.5 dB Outlaw (47Hz)[4 XM 15's & 2 Taramps Bass 12k's] BL : http://www.stevemeadedesigns.com/board/topic/147800-chevyboy95s-4-15s-7krms-wall-1533-db-on-half-power/YouTube: http://www.youtube.com/hitemwiththeflex/ Link to comment Share on other sites More sharing options...
ChevyBoy95 Posted December 1, 2017 Report Share Posted December 1, 2017 I second what has been said, box in my mind need to be bigger, 2 - 2.25 net, more port area, and I would personally tune to like 35. Should still play down to upper 20's before falling off. Best Score to Date : 160.5 dB Outlaw (47Hz)[4 XM 15's & 2 Taramps Bass 12k's] BL : http://www.stevemeadedesigns.com/board/topic/147800-chevyboy95s-4-15s-7krms-wall-1533-db-on-half-power/YouTube: http://www.youtube.com/hitemwiththeflex/ Link to comment Share on other sites More sharing options...
abdc Posted December 1, 2017 Author Report Share Posted December 1, 2017 I'm no box pro, but I'm not sure I can agree that Net should be bigger. DC advises 1.5 and I took it upon myself to bring it up to 1.75 Net. And as far as bringing tuning up to 35, no problem. Any reason why you would not tune as low as 32? Link to comment Share on other sites More sharing options...
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