Subwoofer for music, how low?

This is a CSS type, the mass is on the outside, BUT the passive is not real sensitive, this type you would add or remove large amount of putty at a time to notice a Q difference.. It will work just fine though. This one is good to 7hz is that low enough? LOL

Regards

Check out the SVS 3000SB , or SVS 3000 micro depending on your needs and room size. They have a great user adjustable interface on the App which you can download for phone or tablet , the have a 45 day return ,they pay for shipping 

and a 5 year transferrable warranty. The app alone is great  I have the 3000SB-sealed box in true music the grand piano can ho down to around 27 hz which btw is below hearing more vibration low frequency ,30 hz is typically the limits of hearing actual musical tones , the sub can do below 20 hz great fior movies and electronic music ,and settings for movies , and music can be stored settings.

Food for thought:  Kick drum fundamental can be around 50 to 90 hertz.  Bass guitar fundamentals are 40 to 400 hertz.  Lowest note on the piano is 27.5 hertz.  A Roland 808 drum machine kick drum (used extensively in rap music) has fundamentals around 60 hertz. There is a lot of energy in the 50 to 80 hertz area in most recorded pop/rock/country/R&B/Folk, etc., music.

Still in experimental stage myself, but so far I am with oldhvymec, a decoupled, dual opposite firing box equivalent to two subs. Yeah, I too thought not much signal in Octave 0. Well, there's PLENTY down there; you control "boom" with SVS decoupling feet and lowering sub gain since a whisper is all you need. Main benefit is opening the mid on the towers. My own remaining problem is how to integrate two ambient subs in a difficult room. I'm trusting MC's advice that the key is not what, but where. Thx to OP for keeping this ball in play.