There's a lot more bass in a 6.5" driver than most of you think

I work in a high end store, but do not care to pay the cost for anything we sell, even at half retail.  So I built speakers using components from Parts Express, including their pre-fab crossovers.  I used the 4 ohm Reference Series 7" aluminum cone woofer, and their 1 cu. ft. cabinet (since discontinued) with a vented alignment with an f3 of 39 Hz.  With room gain, I'm measuring into the mid-30s and it sounds it...very solid not muddy at all.  I settled on Morel's integrated "Twee-Mid" and made the system bi-ampable.  With zero engineering, but a lot of experience in audio, I came up with something I feel closely conveys the sound I hear at Boston Symphony Hall when I play live recordings of concerts I actually attended and heard performed live.  To me that's the gold standard.
I took my home-brew speakers in to the store and compared them to a variety of contenders...they held up rather well.  They did not perform up to my personal favorite, the Focal Sopra No.1, but they cost me one third of what those would...at half price!
I write this to support the OP's claim that satisfying bass can be obtained with relatively small woofers.  But also to remind that a reasonable cabinet volume is needed...mini monitors mine ain't...and that room size is a factor...mine is only 2000 cu. ft. (plus openings to other spaces).

With room gain, I'm measuring into the mid-30s and it sounds it...very solid not muddy at all.

@Crustycoot

That's what I'm talking about. Smaller speakers can integrate a lot better into a room, and leave you more satisfied with less effort.  The combination of better matching the room gain, plus not disturbing the dragons in the depths (room modes) is a big big win for a lot of consumers.

There are a lot of ways of getting great, deeper bass in a room, but they don't come easy and they don't come cheap.


Best,
E

BTW, anyone notice how damn smooth that bass response is??


Ty GIK acoustics and a semi-open room. :)

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. 

long term, ive never been happy with 6 inch woofers. even if the bass at first is quite decent. tit has nothing to do with extension either. real bass need to move air

no replacement for displacement.