Subwoofer for music, how low?

Your biggest challenge is not getting your sub low enough but integrating it with the room. 

See:

and

The key to your question was music. Everyone chimed in about "most" music hitting 20hz. Some does. Rel is a coupled sub. In other words your floor is the bottom of the slot on that type of sub. The best way to make that type of sub work is, mass load the box and literally glue it to the floor. You will feel THAT type of sub.

The question is, do you want to feel the sub through your bottom (the whole house) or hear and feel the sub in your seated position? NOT through your BUTT or FEET or the plaster falling off the ceiling or the plates rattling in the kitchen, BUT only at your listening position?

If the sub requires coupling to work, you might want to think if that is the type of "BASS" you want. Some love it. The drunker I get, the more I like it, no doubt about it. The only issue is, I quit drinking 40 years ago..:-)

Regards

@oldhvymec This makes sense.

What sub would you recommend?

T/9x is terrific sub, I have the T/9i Red Gloss, would love to add a second...I use a pair of S/5 SHO in main system...

DEBRA isn’t very expensive. James R. No idea on the shipping. I thought some of the parts were from Parts Express, like the amps. They have pretty good shipping rates too. Flat packs, there are a few sources, some better than others. PE is one.

How much material does it take to make 4 1cf boxes? Under a 4 x 8 sheet of 3/4" Hardwood, Plywood, HDF or MDF. Chip board will work fine for subs.. They don’t have to be pretty.

You can add a Mohawk to your subs.. :-)

Let me hunt up some parts I would and ARE using. 

Regards