advantages of 8" vs 6" speaker

[dasdoing]

the ideal is not to have a crossover in the mids/voice-range. combining a subwoofer with a 5" or even 4" 2-way would be optimal. would be, because those all don't seam to have the required SPL. to solve this problem one has to go 3-way. I wish some company would produce a 2-way targeting subwoofer systems. there is probably no demand for this

 

[Helicopter]

Oh yeah. I had to bring out my pocket book
I believe the Joseph Perspectives use SEAS most expensive mid drivers. (FWIW).

I was just reading about someone who replaced big JBL L220's, which use a 14 inch woofer with a 15 inch passive radiator, with the Joseph Perspective speakers and the owner still managed to be blown away by the bass of the Perspectives and their lil' 5.5" drivers.

Still, all my intuitions expect more powerful bass from bigger drivers.

Yeah, it's an 'all other things being equal' type of thing.

the ideal is not to have a crossover in the mids/voice-range. combining a subwoofer with a 5" or even 4" 2-way would be optimal. would be, because those all don't seam to have the required SPL. to solve this problem one has to go 3-way. I wish some company would produce a 2-way targeting subwoofer systems. there is probably no demand for this

I am a big proponent of the 5" midrange 2-way + sub combo. They seem to measure a bit better than the 6" 2-ways, and get low enough to pair with a sub seamlessly. I am thinking of the Revels specifically since Amir has measured both driver sizes.

 

[More Dynamics Please]

It's been correctly noted here that smaller mid-woofers can be crossed over higher which helps relieve the tweeter from having to reproduce some lower frequencies. Ironically however in the case of the two examples mentioned by the OP -- Kali LP-8/LP-6 and JBL 308P/306P the 8" models are crossed over higher than the 6" ones:

1,500 Hz = LP-6
1,800 Hz = LP-8
1,425 Hz = 306P
1,800 Hz = 308P

 

[AnalogSteph]

It's been correctly noted here that smaller mid-woofers can be crossed over higher which helps relieve the tweeter from having to reproduce some lower frequencies. Ironically however in the case of the two examples mentioned by the OP -- Kali LP-8/LP-6 and JBL 308P/306P the 8" models are crossed over higher than the 6" ones:

I presume the rationale in this case would be that the tweeter has roughly the same level handling capabilities but the 6" woofer won't go as loud, so crossover can be pushed lower. Some extra level may also have explicitly been sacrificed in the interest of better nearfield driver integration.

EDIT: Funnily enough, in the JBLs distortion in the crossover region is still lower in the 6" model even so:

Distortion has been classically high in this series and the 306P carries the family signature:

Here is the JBL 308P MKII in comparison:

We see more of distortion between 1 and 2 kHz in the larger 308P than in 306P. The larger woofer seems unhappier in the higher range than the smaller one in 306P. Or there are sample variations.

 

[dfuller]

I presume the rationale in this case would be that the tweeter has roughly the same level handling capabilities but the 6" woofer won't go as loud, so crossover can be pushed lower. Some extra level may also have explicitly been sacrificed in the interest of better nearfield driver integration.

EDIT: Funnily enough, in the JBLs distortion in the crossover region is still lower in the 6" model even so:

That's because the woofers and the cabinet are the weak points in the 300s, the tweeter is generally just fine at intended listening levels.