Want to get some opinions. Will you get a 15" or 18" sub? Let's go with the Xcon.

And, why you would choose one over the other?

not enough info,

 

 choosing a sub and its size has ALOT more to do with then you have listed.

 

 how many cubes do you have to work with,  what are your goals, what environment will it be in

Exactly^^^ also it's better to have a smaller sub in the best box than the bigger sub in a shitty box.

It will be one of either sub, in a Yukon (a good size box. Maybe 6 cu ft or 7 cu ft). Amp power of planet audio 1200 watts. i will then upgrade to a crescendo 3500 watt amp. Let's go with a ported enclosure.

Also, the goal would be to have a sub that hits the Low notes, high output, while maintaining sound quality. From what I've gathered, the xcon is a mixture of both.

Also, the goal would be to have a sub that hits the Low notes, high output, while maintaining sound quality. From what I've gathered, the xcon is a mixture of both.

if you have the space and those are your primary goals go with more cone area (The 18)

Looks like the 18 will do the job better since you have enough space.

I know this is a naive question, but what's the advantage of the 18 over the 15? I know for one the 18 emits more air space, which is more bass output to the ear. Lower notes and more thump. Are those the primary reasons?

*excuse the rookie*

Yes the cone will move more air. The bigger the cone area the potential for a louder setup increases.

How come you are only comparing the 15 and 18? Do you plan to upgrade later and add another sub? What's your budget? If I were you I would get 2 15s or maybe 2 18s(if you want to give up that much room).

Why did you pick the 3500? For one Xcon I would do the 2000. For 2 I would do the 3500.

Yeah, I'm doing one 18 first then sometime next year ill upgrade to the new amp and the second 18. I'm going to use the amp I have right now to power the 18, which is a planet Audio BB 1250.1 amp. I know it's the power that 18 needs, but I'll run with it until summer of 2014. I have the budget for this setup, but it'll take a year to complete. That's the best way I'll be able to get all this stuff. Other members here recommended the crescendo 3500 for two xcons.

Yes so get a dual 1 ohm Xcon and run it at 2 ohms.