Do we really need anything more than 8" woofer and 1" tweeter for medium size room?

Ok,  to push the discussion a little further... In reality,  you can design an 8 inch 2 way to be somewhere around 3db down at 35 hz and still go out to 2k to blend with a tweeter. Of course,  every 8 cannot do this... Way back, I had a peerless woofer that had enough excursion that when adding enough mass, it could go comfortably down to the mid 20's in a sealed box,  but it would loose its mid performance.  We did use it occasionally as a sub, never developed or used it in big numbers.  So,  you can definitely, get an 8 inch woofer to go down. The big deal that has already been discussed is that as the driver gets larger, it can move a substantial amount of air.  I have hear 15 inch 2 ways that I could live with, but didn't go down any lower than a decent 8, yet the difference in impact of the air moving along with the added sensitivity was a great experience. 

Tim,

My statement re distortion at 85db wasn't loaded, I cited the source - htshack.com.  Go look for yourself.

However, I neglected to specify one condition and should clarify a second.  

I was focused on low bass, but didn't mention the frequency at which a purpose built 8" subwoofer distorts "horribly".  So, go check distortion at let's say, 55 hz ( or lower). I'll choose 55 hz because it's typically close to the fundamental of a kick drum (no pipe organ needed to demonstrate the shortcomings of an 8" driver).  As you go lower in frequency, distortion increases dramatically.

I will note that the tests are "quasi anechoic, measured at one meter".  Some could argue that this will produce results closer to a large room than a medium sized room.  I could make a case either way, but I'll leave that to everyone here to decide on their own.

Hi Marty, I don't mind going to take a look at whatever that you would like me to read. For this discussion, it isn't necessary.  You quoted that Most 8 inch woofers distort Horribly at 85 db output... Well, with most 8 inch woofers that is less than 1 watt of power. Again, I am saying that an 8 inch woofer with a reasonably stiff cone, proper spider tension, good surround and proper xmax will not distort horribly at 55 hz playing at 85 db.  Just tested too many..... I'm not saying that you didn't read that or that some woofers won't distort horribly at 85 db.... Just not most... at least certainly not any woofer that we would consider using in the Audiophile world.  I hope that this makes sense,  Tim

X2 tim 

I have a pair of 6-1/2" 2-ways that fully energize a room, have excellent power response (uniform frequency response curve throughout the room), are linear to 29 Hz and audible to 26 Hz.

However, they’re no mini-monitors. They’re bipolars, with 6-1/2" woofers facing both front and back, and 1" titanium dome tweeters also facing front and back. The cabinets are 50" tall by 16’ wide by 8" deep and weigh 85 lbs. each. They are the late lamented Mirage M5si's, a product from around 1995. I bought mine on closeout in Oct. (Halloween, actually) 1996.

They have that transparency and purity of a 6-1/2" 2-way minimonitor with the fullness and power of the 85-lb. floorstanders that they are. They just manage to do it in a 2-way configuration. They’re so good at what they do, I’m a bit surprised that they didn’t become the new standard for simple yet effective floorstanders.