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Isnt that the Xmax value?
 

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Id guess all of them if you mean what all is factored to determine cone excursion at X amount of power in Y alignment, they all have an effect. BL, efficiency, moving mass, compliance, all of it I would assume.
 

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I couldnt remember the EXACT formula, so I looked it up and found this on diyaudio...

Quote:
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.

These aren't always listed with many drivers so you may need some detailed information on a particular driver to find out but then the xmax would probably listed anyway. Hope that helps.
 

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I'm confused. Cone excursion isn't Xmax.
 

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Maybe a better question for the OP.


What are you trying to solve?
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by penngray /forum/post/19643472


Maybe a better question for the OP.


What are you trying to solve?

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.
 

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Quote:
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.


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?
 

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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.


but then xmech must be known in order to know how much overshoot is possible. many high end drivers have ~50mm xmech. 21lw1400 is a good example of this. 9.5 mm xmax, 52 mm xmech.
 

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Discussion Starter · #10 ·

Quote:
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?

I have 2 Dayton HF 15's sealed in two separate 5.2 cubic foot boxes. I'm considering using two 9 cubic foot enclosures (sonotubes maybe) each ported to 17 hz.


TS parameters if anyone can help:

* VCdia: 2-1/2"

* Le: 1.00 mH

* Impedance: 4 ohms

* Re: 3.3 ohms

* Frequency range: 18 - 800 Hz

* Fs: 18 Hz

* Magnet weight: 150 oz.

* SPL: 90 dB 2.83 V/1m, 87 dB 1W/1m

* Vas: 9.95 cu. ft.

* Qms: 3.10

* Qes: .49

* Qts: .42

* BL 14.67

* MMS 282.6g

* VCD 64mm

* CMS 0.28 mm/N

* Xmax: 14mm

* Dimensions: A: 15-5/16", B: 14-1/8", C: 6-1/8".
 

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All I can say for certain is YOU WILL BE VERY PLEASED!
 

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"All I can say for certain is YOU WILL BE VERY PLEASED!"


it kind of depends on what he is shooting for. if his room has good gain and he wants a little rolloff, the sealed looks good to me. if he wants maximum boost around 18hz, the ported will be best, but must use a big port! 8-10 inches or so.
 

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Don't mean to high jack this thread but I plan on building 4 subs with dual Dayton HF 15"s per sub.


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.
 

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Why don't you build a big rectangular port out of wood instead of two small 4" ports??
 

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Quote:
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).

that is in the realm of reason. at high spl where ports start to chuff, you are usually getting blasted in the face with high spl from your mains, so you probably won't even hear it.
 

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"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?
 

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Quote:
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?

Sorry, sealed.
 

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Quote:
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.

Plate versus coil depth isn't how xmax is calculated any more, being too inaccurate. The standard today is actual excursion at 10% THD, determined by Klippel analysis, which simultaneously measures excursion and distortion. In most cases this gives a bit higher reading than coil minus plate thickness, but not all, under-hung coils being the prime example. By the old standard they have zero xmax.

As for overshoot, a 2:1 xmech to xmax figure is generally considered sufficient. But more isn't a bad idea.
 
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