Originally Posted by tuxedocivic
The biggest downside to downsizing, is mid bass output capability, and lowest frequency of directivity control.
The first part. I've kind of bantered about my thinking on mid bass "slam or punch". Personally, I don't get that. If the system needs more mid bass (100 to 200hz) then eq it. Now, what's the big deal the? Well, mid bass is the most difficult band to produce for the loudspeakers we're interested in (the type that cross to a subwoofer at 80hz) which is probably why there's so much talk about it. The reason its difficult for the speaker is the typical spectal content we see in most playback material, and the baffle step losses really influence this region. Another complexity to add to the situation is that more often than not, the room robs SPL from this region, which I usually blame on the vertical (floor and ceiling) reflections. So we have a demanding source, a demanding room, and a demanding law of physics all at play right in the mid bass. How do we over come that?
1. EQ the speaker the way we like the mid bass to sound and turn down the volume.
2. EQ the speaker the way we like the mid bass to sound and increase the speaker capability.
3. Try to find magic drivers and amplifier combinations to give us great mid bass.
Well, 3 is tongue and cheek on my part. And nobody actually does this in the literal sense. What they do is number 2, and when they find a more capable speaker they praise it's mid bass. And really there's nothing wrong with that.
So what does stepping down from the tempest to the Alchemy do to the mid bass? Reduce the capability to reproduce mid bass - significantly. That is entirely SPL dependent however! IF you listen at -15 dbMV like I do (unless I'm testing stuff) then the 8" should have the guts. The 10" certainly does for me, crossed at 80hz.
Ok, so what about this lower directivity thing. This one is more simple. The larger the speaker diameter, the lower in frequency it "beams". That is, it starts to become directional lower in frequency. For the 12", you might see real world beaming at 500hz whereas the 8" more like 800hz. What this means is there will be a smoothing directivity transition to the 90 degree horn/waveguide, and it'll keep more sound off the walls from say 500 to 800hz. And all the other benefits of directivity that gets talked about.
One last thing. A larger woofer inherently has higher sensitivity and usually better TS parameters for getting bass. All that is driver dependent though. The mid bass capability and directivity are faithful laws of physics you can be sure of just by looking at the speaker.
Hope that helps.