Sub. with full range speakers ?

I have a pair of Martin Logan Summit Speakers. I am thinking about adding a Sub. The Rel B-1 is the one I feel is the best one in my price range. I like the hook up by way of the amps. and the lower cross over settings.

My Question is is it worth it to add a sub. to the Summit's?

Thanks Russ
I added a DD15 to my wilson WP7 speakers. Nice improvement. Then I added a second hooked up in stereo. Big difference! May work the same for your speakers. I know that some say that the rel is more musical. However, the computerized room correction and control of slope and point of crossover provided by Velodyne is quite important.
Otherwise room placement is even more critical and the need for a second sub required to cancel out conflicting waves.
I use sub for my Vantages wich go down to 35hz. It only helps for really low bass and the lfe track in movies. I have been adjusting the volume down over time and currently have it set at 2.5, not very loud but enough to tell on very low notes and nothing else.

Summits do a great job down in to 24hz so there is really no need for 2 channel. You may get some benefit for movies.
if your spk specs are correct and placement is good i concur with mrmikesmail post. 24 hz is damn low, i assume that figure is the 3db down spec mentioned. a good sub will reinforce this dip which is rare in music, but, the secondary harmonics from deep bass will feel richer. if you have the $ to blow you will obviously get a low boost but if it is really worth it is up to your tastes. is your space that large?
It will ease the load on your main amp which should help with power hungry speakers.
I'd suggest only buying if you can get a full cash return after an in home trial.
In most cases it's a huge improvement. It just adds that bottom end--better foundation and the imaging in all cases I've worked with improved as well. The trick is getting the integration right. Rel in general is a good sub for doing that last bit--below 40 Hz.
I have had subs in my main 2ch systems for the last 35 years. I have had different speakers in my systems over the years and always enjoyed the music more with subs. I prefer 2 sub instead of one.
I feel the subs add more depth, imaging and substance to the music. At the present time I run my main speakers full open and run a second pre out to a crossover to the subs.
It works for me. Good luck.
Joe Nies
just added a b1 to my B&W 801 S3 and the improvement was worth every cent - Soundstage and imaging improved dramatically. Interestingly the benefit seems to be greater when running the b1 from the speaker line via the Neutrik lead rather that from the line input. Great sub and by far the best Hifi sounding one I have heard for the $.
Thanks for all the information everbody.

I've heard pretty much the same improvements when listening to friends systems when adding subs to full range speaker systems. Much better soundstage depth and better imaging. Someday I hope to add one of the Thiel subwoofers to my 7.2s.
Will one Rel B1 sub work with a system. Do you realy need stereo subs. ?
I have been asking myself the same question. Here is what may be worth considering...Space, the final frontier...size of room...the larger the room with open adjacent areas need more cubic air movement by the sub to get the same "coupling" effect than in a smaller enclosed room. If acurrate individual hall signatures or ambience is a priority then two subs may be in your future. Crossover and interaction with both speakers & room vary alot. Some people are more sensitive to "background bass" as produced off in some corner as opposed to "time aligned" which requires either tweeking the signal in the time domain electronically or simply placing the subs in a stereo position closer to the main speakers or even slightly ahead of them...
The Hafler effect also may be worth trying on front firing or other type subs. One sub across the room/hall from the other set for opposite phase. Like a push-me pull-you arrangement.
I have been considering getting a second REL B1 (front firing) and actually using the subs as speaker stands for my main spks. Of course this requires moving the existing out from the corner and making sure the tweeters are correctly aimed to the new elevated listening position...
Enjoy your Music!