You can get it from length of voice coil and length of magnetic gap, (air gap). These measurements are frequently listed.
The formula: Excursion(+ or -) = (voice coil length - magnetic gap length) / 2.
Example: A speaker with a voice coild length of 17 mm has a 6 mm air gap, (magnetic gap). What is the excursion?
Answer: (17mm - 6mm) / 2 = 11mm / 2 = 5.5 mm.
the excursion is 5.5 mm.
Originally Posted by penngray /forum/post/19643472
Maybe a better question for the OP.
What are you trying to solve?
Originally Posted by mcsoul /forum/post/19643623
Kyptonitewhite had it right. Woofer excursion at a given ported box tuning and size. And I think the gap is a tough measurement to find as well.
I'm thinking of porting my dayton HF 15's (maybe [email protected] each), but they sound good right now in a big sealed box and I'd hate to ruin them.
Originally Posted by kryptonitewhite /forum/post/19643696
The more motor force, the more excursion per given power, the less linear BL, the less excursion per watt at higher excursion. A heavily motored sub at a more moderate excursion will have more movement per watt. Once that bigger motored lower Xmax sub passes it's Xmax, it's BL falls off, I think meaning more compression? IDK. However, if the bigger motored sub still has more motor force even after it's Xmax is surpassed, it still may be more efficient that the still linear sub still within it's Xmax.
Then there's compliance, a stiffer suspension at it's ringing frequency may resonate more, but outside it's resonance may offer more resistence? Again, IDK, speculating.
Moving mass...similar to compliance? It's heavier so takes more power at some frequencies, but when resonating, may have more excursion?
I think just about all parameters come into play, all parameters have their effects, and I think its frequency dependant, alignment dependant, etc.
So what is your current alignment ( how big of sealed box, how many subs?) vs this "maybe [email protected] each"
My shot in the dark, going from the same sized sealed box to the same sized ported box is going to have less excursion, more output, more efficiency, until about 5Hz below tuning where a HP filter would be needed and eliminate worry. But is it 2 drivers in a single 18 cubic foot box going to 1 driver per 9 cubes ported?
Originally Posted by mcsoul /forum/post/19643871
I was thinking two 4" ports, which is less than ideal but it lets me put the plate amp on the upper baffle in the sonotube (if I go that route).
Originally Posted by LTD02 /forum/post/19643947
"LTD02, are you able to run dual HF 15" in a 8cuft box and in a 12cuft box? I want to see how different the FR is below 25hz."
sealed or ported? tuned to what frequency?
Originally Posted by LTD02 /forum/post/19643726
mcsoul, it completely depends on the enclosure and the t/s specs.
scott, add to that 1/4 of the gap height for a rough approximation of the 10% distortion point.
"Answer: (17mm - 6mm) / 2 = 11mm / 2 = 5.5 mm.
the excursion is 5.5 mm."
+ 1.5 mm, excursion is 7.0 mm.