.... If you have two drivers of a relative same size, and you are trying to listen to both at let's say 95db, they will have the same speed of acceleration. F=MA but that is within a window, and that window is shaped by other driver properties too.
If you change the acceleration you either A. changed the SPL if it's within the window, or B. changed the frequency because the window changed. You're talking about not changing the window now, but that is not what you previously were saying where you're claiming the Fostex actually moves faster all together. Both drivers of a similar size (Fostex is actually a little smaller, but relatively there isn't much difference) so the actual speed capability is a comparison of frequency at SPL. The MA has way higher output at 18-20khz even at the EXACT same input power. The MA is literally faster in every sense a driver can be than another of a relative same size.
Also you don't make "bigger waves" you make higher differential between low and high pressure. The waves sizes are based on frequency (length), and directionality ("width") of that frequency (directionarlity is a relationship to cone size and baffle size (for our other readers).
You should look into BL curves, and how those work... there's a lot to be said about how much you truly get out of a wide bander that is highly sensitive when you break it down to the different types of VC to magnet structures. And there's something to be said for efficiency with that. Modern drivers like the MA's often have a very flat BL curve for a huge swath of their usable range. If the BL curve look like a skinny mountain you have to through a good amount of power to try and get anything outside of the limited range. Generally the suspension on high sensitivity stuff limits this (limits xmax, you could say) to try and compress instead of distort like mad by lobbing watts at a total failure of damping. I hope that sounds like a type of driver we've been talking about...
To get 95 dB out of the Mark Audio driver would take nearly 100watts (most of their models are 85 dB and only one is 87) and the Fostex less than two. Which one is likely to suffer thermal compression at that SPL?? You know which one...can the Mark speaker even take 100watts for more than a few ms??
You don’t make sense, SPL for a given input wattage encompasses all factors that got you there, electrical and mechanical.
Don’t parse words, it is pretty clear that by “bigger” I meant higher amplitude.
Let’s put in a watt, for an equal input at let’s say 1khz, the acceleration of the Fostex is clearly higher to get the 8db higher SPL. At 20khz the response absolute of the Fostex even though it is lower than its midband is still 84db(look at datasheet). So nearly the same. Again has less to do with the motor and more about cone design.
So both oscillate with about the same force at 20khz but below that the Fostex motor generates higher acceleration factors. It’s like letting the air out of the balloon slowly or popping it. Which one compressed the air around it more and is thus much louder?
Another example: Compression drivers are much more “explosive “ than a standard soft dome tweeter...both can get to 20khz and probably the soft dome has even a bit more extension but it would melt trying to do what my drivers do with a single watt. They simply cannot accelerate sufficiently to generate the force needed to make such high SPL...even if you put them in a horn (gains them a few dB).
As I don’t have the BL curve data for these drivers (if you have I would like to see it) the rest of your post is speculative if you don’t know it for both drivers.
What I can say from experience is that my Decware modified Fostex Fe206E drivers are very responsive at low input levels until fairly high levels where they start to shout a bit, likely due to breakup. Even in a non-horn enclosure they hardly move at SPL that results in furious pumping from low sensitivity drivers. This is only possible with a high acceleration to compress the air. Same with the Supravox I have but they are also loaded in a TQWT, so that loading helps reduce excursions. HDTs get down flat to 40hz in my room without backhorn loading (complex reflex design).
Again, sonically I have no reason to doubt the Mark based speakers are good...
I also know simple designs with low sensitivity drivers can work fine with 20-30 watts. I demonstrated this last year in one of my rooms at the Swiss High End driving a pair of Boenicke W5se (83db) with the Aries Cerat Genus (25watts). The W5 uses a 3inch Tang Band full range driver augmented with a side firing woofer and rear ambience tweeter. Not an exaggeration to say jaws dropped...but in a small hotel room and not TOO loud...but loud enough.
