woofer excursion

[audioarsonal 10+ year member]

ok in therory a woofer with an xmax double of another would move the same amount of air as two of the woofers with the lesser xmax correct?example 12mm compared to 24mm xmax.i am looking for SPL not SQ.am i correct in my thinking??please help!//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

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[Scoobydoo 5,000+ posts]

no

 

[squeak9798 5,000+ posts]

ok in therory a woofer with an xmax double of another would move the same amount of air as two of the woofers with the lesser xmax correct?example 12mm compared to 24mm xmax.i am looking for SPL not SQ.am i correct in my thinking??please help!//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

Yes, you are correct.

Two 12's moving 12mm would have the same displacement as a single 12 moving 24mm...assuming ofcourse that they have the same cone area.

 

[dragnix 5,000+ posts]

wouldn't xmax only matter in a sealed enclosure when it comes to output?

 

[Scoobydoo 5,000+ posts]

a 12" with 24mm xmax would have a much larger surround than a driver with 12mm xmax so the cone area wouldnt be as large

i would say a 12" sub with 26mm xmax would equal two 12" subs with 12mm xmax to adjust for the decrease in area

i'm just here spouting out half cocked theories really

 

[audioarsonal 10+ year member]

so if i replace both subs my db should rise without increasing the number of woofers.

 

[SkatinBassPLaya]

scoobydoo you're wrong. thats why theres such thing as tall narrow surrounds and different surround thicknesses and tensions

 

[audioarsonal 10+ year member]

i was looking at the RE XXX and it has like a 50mm xmax thats ridiculious.any ideas on some good subs for db dragin?

 

[JonJT 10+ year member]

You would need to make new Boxes.

 

[audioarsonal 10+ year member]

new boxes for the specs or to fit the woofer??i confused.of course i would build another box to specs for the replacements but i am talking all things being equal that a sub with higher excursion means more moving air mass which means more DB right?

 

[Immacomputer 10+ year member]

new boxes for the specs or to fit the woofer??i confused.of course i would build another box to specs for the replacements but i am talking all things being equal that a sub with higher excursion means more moving air mass which means more DB right?

Not really. If you're just looking to get loud on a meter, the sub's max linear excursion is not the one and only place to look. At and around tuning, the sub sees a large resistance in the enclosure which limits cone movement. In order to increase output at and around tuning, you need a sub with a ton of motor strength (high BL and low Qes are two specs to look for). If the sub has all the excursion in the world but a weak ass motor, that excursion isn't going to mean jack ****. When you're close to the tuning frequency of the enclosure, your main source of output is from the port itself so you want a sub that can really drive the enclosure to resonate.

tl;dr: If you're looking for a sub to just get loud, look for something with a low Qts, low Qes, high BL, low Mms, high power handling, and stiff suspension. Xmax should not really be a huge concern.

 

[azbass 5,000+ posts]

talls surrounds have flaws in their design too..

 

[cotjones 10+ year member]

Not really. If you're just looking to get loud on a meter, the sub's max linear excursion is not the one and only place to look. At and around tuning, the sub sees a large resistance in the enclosure which limits cone movement. In order to increase output at and around tuning, you need a sub with a ton of motor strength (high BL and low Qes are two specs to look for). If the sub has all the excursion in the world but a weak ass motor, that excursion isn't going to mean jack ****. When you're close to the tuning frequency of the enclosure, your main source of output is from the port itself so you want a sub that can really drive the enclosure to resonate.
tl;dr: If you're looking for a sub to just get loud, look for something with a low Qts, low Qes, high BL, low Mms, high power handling, and stiff suspension. Xmax should not really be a huge concern.

now in this instance you are correct... xmax isn't going to matter much at all because the sub is at it loudest using a lower xmax... but then again it does... lets do a what if here.....

lets take 2 12's, they are identical in almost all of there specs exept woofer #2 has a higher xmax....

they are both in an enclousure tuned close to their resonant frequency but at that frequency they can take enough power to reach full xmax... then sub #2 will be louder... but that doesn't happen very often (because most woofers can't reach full excursion at resonance)...

the only time Xmax shouldn't concern you much at all, is when you are designing a pure competition SPL setup, designed to be burped, not play music...

in any musical setup xmax is a concern... and more of a concern with more diversity of music preference

 

[95bat 10+ year member]

^^ I've never seen so much information given without a shred of evidence to prove it. This is even worse coming from the most laughed-at man on CA.com.

 

[Immacomputer 10+ year member]

Well he didn't really say anything too incorrect.

I think xmax should be replaced with xmech in this case though.