Interested in building a Tube/Column sub

[slayer]

Are there any designs on here that are proven winners for low output? This will be the second sub in the room and be used mainly for 40hz and below. I am looking for a design that will extend below 20hz for theater use. I have 2 subs in my room now, 1 in front and 1 in the rear. I will add this one to the mix to either compliment the others or replace one of the others. Any thoughts?

[m-unit]

this thread seems to have a lot of good info about the sonotube design... https://www.htguide.com/forum/showthread.php?t=17629

[SteveCallas]

Mixing different subs - especially one that will go much lower than the other - is not a good idea, as you will always be limited by the weaker sub if you intend to keep things calibrated with a decent FR. Sell your current subs and build one or two badass subs.

[slayer]

I've done it that way for the last year without problems. I agree that two of the same subs would be best but I don't believe it is a must. In my room, the monster sub is in the front of the room in the prime location and is dialed in to my mains with the Velodyne SMS-1. My rear sub is just output out of a second sub out of my Halo C-2 and was tweaked into the system while running the sweeps with the Velodyne SMS-1. I can see an instant response in on my display that helped me add it into the mix without creating problems in the overall frequency response of the system. The way it worked was to have my rear sub set with a different x-over and phase and a very low output. Just enough output to balance the room. The main thing it did was remove dead spots I had before and add a bit more rumble into my couch as it fires right into the back right of it. I tried it several ways before using this method. The Halo let me use it as a dedicated rear sub but the results were not as good as the way I have it now. To each his own I guess. I still plan on getting a Velodyne DD-18 at some point. I love that sub.