Originally Posted by nograveconcern
You are going back and forth between 2 different design goals. A 20hz tune means usable frequency response to about 16-17hz. A sealed alignemnt is the way to go if you want to get down to single digits but don't mind, or have the displacement make moot, giving up about 6db of spl around the ported box's tuning. So, do you want 16hz or 6hz?
Too be honest, I would rather focus on higher SPL into the mid to high teens than trying to play clean to 5hz. I was thinking sealed mainly due to the smaller enclosures and WAF factor, and it is still something I am considering, but am mostly leaning towards ported, because as you have mentioned, my room is so large. It is just really helpful to talk all these decisions through with the experts who know more than me, and for that I am very grateful for all your advice and assistance
Going from 4 sealed 15's to 6 is only adding 3 db or so of headroom and only if you run the extra 2 on a second amp. You will need to go to 8 and the iNuke 6k to get back to the 20hz sensitivity of 4 ported 15's and an iNuke 3k.
That's not to say you shouldn't go sealed. 4 dvc's sealed will give you a lot of output. I simply don't think it is realistic to expect this to produce 115-120db at the listening position at 15-20hz in your large basement room.
If you do decide to build sealed a 3-3.5 cu ft enclosure is a good size.
Thanks for your feedback throughout this thread, I did some models and here is a 5 cu ft ported sub tuned at 20hz vs a 3.5 cu ft sealed enclosure using the Dayton driver. I am 99% convinced on going ported now
Yellow line is sealed, grey line is ported. Both are modeled using 440 watts and this is just 1 box
4 boxes should give me what, another 3db or so each across the board? Even more if they are collocated and this is not accounting for room gain?