Well, to start off, this is my first post, not really "Car Stereo/Audio Literal"(However you would want to put it, I just don't know a whole lot about it) as of yet, so don't hate too hard xD. Also, if this is in the wrong place, can a moderator or somebody who can move threads do so?
K, now to the real thread.
I've currently got two 12" kicker subs in the trunk of my mustang, in a dual ported box. I am going to be getting two 15" subwoofers pretty soon. I want to build my own box for the 15" Subs. I seen on youtube a guy who done 2 12's, and 2 15's in the trunk. I read some of the comments, and one of them stood out. It was asking "Why would you use two different size subs? Wouldn't that be alot of wave cancellation?" Or something along those lines. My question is, Would using the subs I have and the new ones together hurt anything? I will pm you a link to the video if you want to see what I'm referring to., as I can't put the URL in this post.
Also, if I were to do this, would I need more smaller (Like the door, or rear deck speakers) speakers? (I have four spare speakers, two 6x9 speakers, and two 6.5's that can be put in the car if need be.)
I believe that is all, if I remember anything else, I'll add it in later.