I am making a new sub box, and I found space enough for one 12 and a 10, would it be alright, and sound goos if I had a 10 and a 12 hooked out together?

 

Most of the time it's not a perfect situation to have two different size subs. The differences in the way they play will cause a little sound cancellation. But on the other hand the extra output of the second sub would probably out way the cancellation. I've run two 12's and two 10's before and it sound good. The moral of the story.....try to use the same size and make subs to get the whole benefit of the system. Hope I helped some.

Jason

 

One other thing. If the box you have now isn't ported your best bet would be to build a large ported box.

 

You never want to mix different size subs together. A 10", even if its from the same line, will have a different frequency response from the 12" and will make the system sound poor if they were used together.

 

Just to elaborate on what Justin said, not only is the frequency response different, but all of the physical characteristics are different, and with a transducer, physical differences translate into electrical differences. What will happen is that because there's a non identical physical motion between two series-wired drivers, you get what's called a back-fed EMF signal that distorts and changes the electrical signal that's going to the subs from the amps. In a parallel wiring scheme apparently this isn't supposed to be as prevalent (although I'm not sure why - in my eyes it should be just as prevalent in a parallel wired setup), but you still deal with impedance differences which have a profound effect on what amount of electrical energy is sent to what driver at what frequency. What it boils down to is that in addition to the different frequency responses of the subs, now you also have both subs receving non-identical power at any given frequency. This results in a "combing" effect that more or less translats into sh!tty sound.

If you've only got room for 1 12" and 1 10", buy two 10s or 1 12. Spend your money wisely, and you'll wind up with much better sound with just as much or more SPL.