There seems to be some confusion in a couple of post of bass vs sub bass, as Erik posted, he is 100 percent accurate.
Looking at specifically a 6 1/2.
There is a problem on moving air for real impact in larger rooms.... Of course Erik qualified Apartment dwellers or some home theater use.
To get a 6 1/2 to truly go down (and you can), it requires some mass to get the fs down, which kills sensitivity, it then requires some good excursion limits and decent size coil to get some power handling..... Its a real balancing act to create a 6 1/2 that does it all as far as just a sub bass perspective.
Of course multiple drivers move more air, several 6 1/2's could make a very good sub.... I used multiple 4 inch at one time just to make a point.... I had several 4 inch in series/parallel configuration that would get into the mid 20's.
In general, a good 6 will get you into the mid 30's and do a very good job for bass through midrange until your room just gets too big and needs more cone area to move more air.
Looking at specifically a 6 1/2.
There is a problem on moving air for real impact in larger rooms.... Of course Erik qualified Apartment dwellers or some home theater use.
To get a 6 1/2 to truly go down (and you can), it requires some mass to get the fs down, which kills sensitivity, it then requires some good excursion limits and decent size coil to get some power handling..... Its a real balancing act to create a 6 1/2 that does it all as far as just a sub bass perspective.
Of course multiple drivers move more air, several 6 1/2's could make a very good sub.... I used multiple 4 inch at one time just to make a point.... I had several 4 inch in series/parallel configuration that would get into the mid 20's.
In general, a good 6 will get you into the mid 30's and do a very good job for bass through midrange until your room just gets too big and needs more cone area to move more air.