I used winISD pro to model a Dayton quatro 15"in a br and came up with this ; 7.3 cu. ft. with a 4"x8.4'' port. I'm not sure if this is right, because of others i've seen use a much longer port&smaller box,(winISD says -3 db@20 hz). Is this right or wrong? If it's wrong what was my mistake?
Your box is well designed. You could go down to 6.5 cu. ft with a 10 inch long 4" diameter port, this will be a bit closer to room gain in a standard room.
If you go smaller, the port need to be longer, that's why you saw that.
