Hey I'm currently running a single SDC2.5 15 in a 4.5cuft box tuned to 40hz 132sq inch of port and 750rms I really enjoy it and since I do not listen to a lot of music in the low 30hz range I do not stress it much below 35hz. Just wondering what your opinons are on what I should tune my next box to, I will be adding one more SDC and doubling the box size and power.

 

trial and error is the only way for your own ear to judge.
PErsonally, I would do 38htz for daily.

 

Thanks for the input I may have to try adding to my current port to see how it sounds the lower I go, before I make the new box.

 

Yep, just keep playing with lengths. Might also want to try removing some air space and see if that helps at all.

 

I voted for 38, but I had good results with a pair of very similar subs at 40 ish hz

 

Keep the votes coming it is looking like 36hz 9cuft with a AP3001D at 4 0hms.

 

38ish sounded nice..