Originally Posted by Jim Kiler
If I have bookshelf speakers and a SB-2000 which i love but sometimes i want more bass would buying full tower speakers be an improvement or would it complete too much with the sub?
The tower speakers wouldn't compete with the subwoofer, but I think it's important for you to define what you mean when you say that you want more bass. I looked up your speakers, and I definitely think that you could get better bass with larger speakers. But, even if you have large and capable tower speakers, you would still want to use at least a 60Hz crossover for most content. A lot of people with tower speakers use an 80Hz crossover. The tower speakers are still going to be responsible for all of the upper bass content, and some of the mid-bass content down to a little below the crossover you choose.
With a 60Hz or 80Hz crossover, they can contribute quite a bit to the mid-bass sensation known as chest punch. That sensation occurs when a sudden percussive mid-bass sound, in the range from about 50Hz to 100Hz, occurs. Examples would include the strike of a kick drum or kettle drum, or a bass guitar chord in music; or with gunshots in movies. It does take some SPL to feel that sensation strongly with either subwoofers or with main speakers. That would be one aspect of having more bass.
Another aspect of having more bass would be for the frequencies below about 60Hz or 80Hz. Those frequencies would and should be played by your subwoofers. So, having either a more powerful subwoofer, or multiple subwoofers, would be the best answer for having more low-bass. For frequencies from about 35 or 40Hz up to your crossover to whatever speakers you use, sealed subwoofers work very well. If you want more bass in that range, then moving up to an SB3000, or to dual SB2000's would be a good solution.
If you want more bass below about 35 or 40Hz, then you may want to consider a ported subwoofer. We rarely directly experience the deep bass frequencies with music, although they lend some weight to what we are hearing. But, movies are full of bass special effects at frequencies below 35Hz. Everything from explosions, to earthquakes, to airplanes, to the footfall of a T-Rex, use those deep bass frequencies. And, we may feel them as much as we hear them. The deep bass frequencies are perceived as rumbling or thudding sensations.
Ported subwoofers are particularly strong, compared to sealed subs, below about 35Hz, and they are particularly good at reproducing the deep bass special effects in movies. They also have more low-bass tactile response than sealed subs. If that is what you want, then I would especially recommend trying a PB3000, because it would still be very strong in the mid-bass range and would have a lot more <35Hz bass than what you are getting now. And, it can also be used in sealed mode, if you wanted to compare the difference between ported and sealed.
What may have initially seemed like a simple question has led to a pretty long post.
But, I felt it was necessary to write all of this in order to give you a fair answer to your question.
I really don't think that tower speakers would compete with your subwoofer, but I'm also not sure exactly how much they would do to enhance it either, unless you are looking for more bass above about 80Hz. As noted in the first post, I definitely think that you could benefit from some larger speakers, particularly at a listening distance of about 10' or more.
However, a stronger sealed subwoofer, or dual SB2000's, or a good ported subwoofer (such as a PB3000), would be far more likely to enhance your bass than tower speakers would. Perhaps a compromise might be larger bookshelf speakers, and more subwoofer as well, if you could swing it.
It's just a matter of trying to decide where you want more bass. If you aren't sure where you want more bass, I would either play test tones at different frequencies to get an idea of the range I wanted more of, or I would try a PB3000, as noted. Of course you can also try just turning up the volume on your SB2000 some more, but I assume that you have already tried that. I hope that I have helped to clarify things, rather than just confusing your choices.