size of the driver

05-01-12: Drew_eckhardt
04-29-12: Johnnyb53
>04-29-12: Tamule1
>real bass comes from moving a large surface area gently -not a small surface violently . 6.5" is not a woofer size IMO

"Violent" isn't a problem until you reach the linear or physical limits which geometry dictates you do when using such small drivers.

>And you base this opinion on what?

I draw upon personal experience with speakers including transmission lines built with similarly small drivers...

Drew, it's pretty obvious I was responding to Tamule1 and not saying anything concerning your previous statements. I question his setting a size definition on woofers that essentially excludes 90% of them. A driver doesn't have to function well as a subwoofer in order to be a competent woofer.

Your enthusiasm for larger drivers is already well known. You play down the disadvantages of the flex and weight of a larger diaphragm, the cost and bulk of a larger magnet structure, the dispersion enhancement of a waveguide (I've yet to see a waveguide on a 12" driver to turn it into a midrange) while pointing out the disadvantages of longer excursion, small radiating area, etc. of smaller diameter bass drivers. It's really a matter of picking your poison.

If cost, size, and weight are not important factors, fine. Knock yourself out and put in 12" and 15" drivers. If WAF, floorspace, and bass speed at affordable prices is important (and it's intuitive that this package is an easier sell to both sexes), then the narrow column anchored by multiple 6.5" woofers rules. And that's why they dominate the sweet spot (not the highest end) in high performance loudspeakers.

I tend to look at it from the perspective of basi physics.

Size matters in order to pressurize air more effectively.

Larger rooms and lower frequencies at higher volumes require more air be pressurized to maintain a smooth frequency response. Larger drivers have the advantage.

The dilemma is that larger drivers will tend to have more mass. More mass means more inertia. Inertia is the enemy of transient response. Transients are an important part of real music. Therefore larger drivers are at a disadvantage when it comes to transient response.

A lot of what works best comes down to a matter of scale ie how much speaker is needed to deliver the desired scale of performance in the target roo m.

All you have to do is go to Parts Express or Madisound websites and look up the specs on various drivers of different sizes and types, including "pro". Some have detailed frequency response and impedance graphs. You can go further by plugging some of those T/S numbers into a speaker box calculator.

For example, plain and simple...
http://www.bcae1.com/spboxad2.htm

Some of you might be in for a shock. The evidence speaks for itself but interpretation varies.

I tend to look at it from the perspective of basi physics.

Size matters in order to pressurize air more effectively.

Larger rooms and lower frequencies at higher volumes require more air be pressurized to maintain a smooth frequency response. Larger drivers have the advantage.

The dilemma is that larger drivers will tend to have more mass. More mass means more inertia. Inertia is the enemy of transient response. Transients are an important part of real music. Therefore larger drivers are at a disadvantage when it comes to transient response.

A lot of what works best comes down to a matter of scale ie how much speaker is needed to deliver the desired scale of performance in the target roo m.