subwoofer question

In a small room , I would be cautious about introducing any subwoofer into the equation.

First and foremost, first try out any quality sub on a dealer or buddy loaner ... You may be surprised that it is a step back overall with a boominess or a wooley overemphasis simply because of room acoustics in a smaller room and restricted speaker placement alternatives.

Subs for HT are one thing, but adding a sub for quality 2 channel is a difficult alchemy. The good ones are all well north of $1500 w/o prejudice to the acoustic issue above.
It's going to have to be a sealed enclosure rather than a ported one.

Google the reviews,
Vandersteen 2Wq and ATC are two that I would audition ... In that order.
Google the forums for their testimonials.
E.g. The Vandy has three 8" drivers instead of one big one and its external crossover accessory is easier to tailor to the gear and room parameters.

I have a question. I have a pair of Dynaudio 1.4`s and a contour center and am in the market for a sub that is musical. I`m looking for clean tight deep bass. Any suggestions. ? My room is 12x18.

I recommend the SVS Sub Ultra 13. It is a powerful sub, well built, great performance and on the money!
Google it and get all the info. I have two of them and I regulate them with a DS Peaker 8033. Everything in my room shakes, great for movies.

The PSB's are great. Very musical and inexpensive for a smaller one. $300 to $400 depending where you get it. IMO, can't be beat for the money. I've sold a bunch to friends and family.

***DEALER DISCLAIMER***

I agree with Morganmadden. SVS has incredible products for the money and will take anything back within 30 days no questions asked; and even pay for the shipping going back. I did a 7.2 application with two of their sealed subs and the capability of these units are remarkable (to say the least).