Large midwoofers

[QuantumMechanic]

Is there any scientific reason most modern speakers use 4-6.5 in woofers? Aesthetically, I really like speakers with large woofers in the 10-15 in range, like the new tannoy Legacy series. Can anyone comment on the characteristics, pros, cons of large woofers?

 

[bigx5murf]

Pros, low end... Cons have to be crossed over lower, so more suited for 3way use.

 

[NTomokawa]

Are we talking about bookshelf or floor-standing/tower speakers?

 

[QuantumMechanic]

I'm thinking either one, but I'm referring to mid-range drivers that play from around 800-1200 hz and down. I'm curious about the differences between smaller and larger woofers in the frequency range where they are both fairly flat, around 60-1000 hz.

 

[NTomokawa]

Well, larger woofers generally have more bass extension/output, since physics dictates that one needs to move more air to get more bass.

The trade-off is that in general, the larger a driver unit is (a woofer/midwoofer in this case), the heavier it is, which means it has poorer high-frequency response. Since bookshelf speakers are more-or-less size-restricted, woofer calibre usually doesn't go above 8 inches. Floor-standing speakers have less size restrictions, which is where one begins to see 10/12/15 inch woofers.

Of course, given the high-frequency response issue, woofers that large all but require a dedicated midrange driver, which creates a three-way (or more) speaker system. That's where one gets into the whole enclosure and crossover science. Deep magic indeed...