Hope you dont think Im picking on you here Buck, most of what you've said in this thread is correct. I just felt I should point out a couple thing you said that needed clarifying imo.
Hope Im making sense here, Ive had a few beers at this point.
That's crystal clear to me.
I like for my subs to make 30 cycles and below :)
i have nothing to add to this thread but I will say it got very interesting reading between audio and buck lol. I like threads like this.
I don't feel picked on, I don't know everything.
i agree with you quick, easy and to the point. thanks.
One point that someone touched on that was not emphasized enough....THERE'S NO REPLACEMENT FOR DISPLACEMENT.
This applies mostly to SPL applications, not SQ.
Displacement can be in the form of cone area x excursion. Displacement can simply be a 21" woofer with a 10mm xmax, or a 8" woofer with 20mm of xmax. If you don't have a lot of cone area, excursion is your friend. Subs like the SA-8, RLI-8, possibly the new Alpine 8" all have a high amount of excursion, thus displacing a lot more air compared to a lower 8".
Cone area can be a good band aid for displacement (if there is a lack of excursion). Lots of cheap 12" subs in a wall, for instance.
SQ: Generally a speaker with a lower Fs, lower moving mass, and well designed/linear motor will sound "better". A sub with a stiffer suspension, higher Fs, and higher moving mass will generally not sound very good, but may be awesome for SPL. This requires having high amounts of power and strong motor force to overcome the suspension stiffness, while not being very accurate/SQ.
Want to instantly win any SPL comp? Line the vehicle with as much cone area and power as it can handle. POP ;)
A stiff suspension does not mean distortion will automatically be higher. In fact, a stiffer suspension means once the cone direction is suppose to reverse, the suspension is applying more force to stop its current motion, and reverse it back towards its center position (helps 'cone control', doesnt hurt it). In other words, a stiffer suspension provides more cone damping.
Excursion is only a direct replacement for cone area if the sub displays linear BL throughout its excursion range. For a sub with a standard non Bl optimized motor design, you are generally better off with more cone area than with more excursion.
DD has a PA version of the 2500 series. It is an 18". It has a higher Fs than the 10" standard version. (just a stir stick for generalizations above)