woofer excursion

[audioholic 5,000+ posts]

Even when playing a burp, at or very near tuning, where excursion is at its minimum... the more the cone moves, the louder the setup will become. For the big time SPL guys, excursion and thermal power handling become a tightrope to walk. They want to acheive full excursion (or as close as possible), very near tuning, without melting the voice coil.

Even a sub with 100mm of xmax would only be able to put that all to use, in a vented SPL setup, if the coil was able to withstand the amazing amount of wattage it would take pumping through it in order to acheive full excursion while play very near tuning.

This is why nobody serious uses an 06 XXX in SPL, you simply cannot push it anywhere near its excursion limits at tuning without melting the coil first. I also believe this is exactly why DD has been so successful, they recognized this situation early on and designed a sub with this in mind (the 9500).

 

[cotjones 10+ year member]

Man you really know how to overreact and blow something way out of proportion.

i'm not over-reacting, you openly insulted me, believe me, i'm NOT over reacting...

but unless you have an actual reason that someones arguement is wrong (which you don't appear to have), don't talk ****... ok? //content.invisioncic.com/y282845/emoticons/thankyou.gif.5451126d09e870f796f50c3a4dd5acd7.gif

 

[cotjones 10+ year member]

This is why nobody serious uses an 06 XXX in SPL, you simply cannot push it anywhere near its excursion limits at tuning without melting the coil first.

X2 thats why i'm doing mine sealed...

 

[audioarsonal 10+ year member]

thanks to the guy's that stuck to the discussion. you really answered my question.

 

[jeremiah 10+ year member]

Even when playing a burp, at or very near tuning, where excursion is at its minimum... the more the cone moves, the louder the setup will become. For the big time SPL guys, excursion and thermal power handling become a tightrope to walk. They want to acheive full excursion (or as close as possible), very near tuning, without melting the voice coil.
Even a sub with 100mm of xmax would only be able to put that all to use, in a vented SPL setup, if the coil was able to withstand the amazing amount of wattage it would take pumping through it in order to acheive full excursion while play very near tuning.

This is why nobody serious uses an 06 XXX in SPL, you simply cannot push it anywhere near its excursion limits at tuning without melting the coil first. I also believe this is exactly why DD has been so successful, they recognized this situation early on and designed a sub with this in mind (the 9500).

? Y is it so hard to get max excursion at box tuning?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[audioholic 5,000+ posts]

? Y is it so hard to get max excursion at box tuning?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

Because the enclosure is minimizing cone excursion at tuning. Have you ever noticed that as the frequency dips lower, the sub in your ported box moves less and less, while output remains relatively constant? That's exactly why. As the frequency being played moves closer and closer to the enclosure's tuning point, cone excursion lessens, but enclosure efficiency increases. So cone excursion goes down, direct output sound from the radiating cone goes down, but output from the port increases more so, resulting in an over all increase in output.

Imagine blowing through a straw. As you blow air through it at different speeds (blowing harder and softer) you will notice a change in resistance to your blowing. This is basically the same effect with a port in an enclosure, but in much simpler terms.

Hope that helps. If not, let me know and I can explain in more scientific ways.

X2 thats why i'm doing mine sealed...

I was not making an arguement against using the new xxx's in ported boxes... honestly I would port it. I was merely arguing against using them in a vented SPL setup.
The new xxx is an efficiency nightmare as it is, at least port the thing. (dejevu... I jsut said this the other day too)

 

[newusername 10+ year member]

I was not making an arguement against using the new xxx's in ported boxes... honestly I would port it. I was merely arguing against using them in a vented SPL setup.

The new xxx is an efficiency nightmare as it is, at least port the thing. (dejevu... I jsut said this the other day too)

I disagree with you here, Chris.

If you're buying an XXX, you're paying a premium price for premium excursion. If using it in any ported enclosure, you're not utilizing the obscene linear excursion it is capable of unless you are putting so much power through the coil that you are causing some thermal damage. You are much better off (in terms of output, specifically) using a sub with high BL^2/Re and Xmax in the 15-25mm range, so long as you are below the excursion limits. Even in a sealed enclosure with a Qtc below ~0.65 (which is pretty low, particularly for a vehicle), you're looking at 3kW to even approach Xmax. In a ported enclosure, it's just not sensible.

As far as efficiency is concerned, the XXX does a fair job of achieving usable efficiency. Though real output is going to be realized with over 2kW, if we are going by the dB/W/m measurement that is typically used in conjunction with efficiency, then the XXX is not that terrible. It would be considerably worse if it were, say, a Split-Gap design.

 

[cotjones 10+ year member]

I disagree with you here, Chris.
If you're buying an XXX, you're paying a premium price for premium excursion. If using it in any ported enclosure, you're not utilizing the obscene linear excursion it is capable of unless you are putting so much power through the coil that you are causing some thermal damage. You are much better off (in terms of output, specifically) using a sub with high BL^2/Re and Xmax in the 15-25mm range, so long as you are below the excursion limits. Even in a sealed enclosure with a Qtc below ~0.65 (which is pretty low, particularly for a vehicle), you're looking at 3kW to even approach Xmax. In a ported enclosure, it's just not sensible.

As far as efficiency is concerned, the XXX does a fair job of achieving usable efficiency. Though real output is going to be realized with over 2kW, if we are going by the dB/W/m measurement that is typically used in conjunction with efficiency, then the XXX is not that terrible. It would be considerably worse if it were, say, a Split-Gap design.

i think i'd have to agree with you, porting it will be advantageous, but with a 3000watt amp i think sealed is the way to go for me... i have heard that i am likely to lose output with ported... esspecially if i'm trying to keep a flat responce... which is top-priority

 

[Jeremiah25 10+ year member]

Excursion is often given too much credit. I saw a perfect example of this 2 years ago. I did a woofer swap in an SPL setup I was working with. Woofer 1 (which was being replaced) was at it's maximum throw capability in the setup. The cones looked like they were going to fly out of the basket during a burp. They were easily achieving 2+ inches of excursion, which cause the woofers to bottom out and crush the coil against the backplate. Woofer 2 (which replaced Woofer 1) was the same size woofer, but a different brand with a much stronger motor. Woofer 2 would barely even move in that SPL setup. I'm talking 0.5 inches of excursion tops, yet woofer 2 was still louder than woofer 1. Why? It obviously had less displacement, but Woofer 2 generated higher amplitude sound waves than Woofer 1, which in this instance was enough to overcome the fact that it had less displacement due to less excursion.

 

[audioholic 5,000+ posts]

If you're buying an XXX, you're paying a premium price for premium excursion. If using it in any ported enclosure, you're not utilizing the obscene linear excursion it is capable of unless you are putting so much power through the coil that you are causing some thermal damage.

My comments were only based upon an SPL rig playing at, or very near tuning. Don't forget, music is transient, it does deviate from tuning, at which time excursion goes up. You dont have to be able to maximize excursion near tuning to be seeing the full potential of the driver in a vented system.
Good seeing you again btw Neil. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

i think i'd have to agree with you, porting it will be advantageous, but with a 3000watt amp i think sealed is the way to go for me... i have heard that i am likely to lose output with ported... esspecially if i'm trying to keep a flat responce... which is top-priority

You heard incorrectly. But yes, for a flat response generally sealed works best. But a vented system, being tunable, can be tailored to reproduce a relatively flat in-car response. Just that most people dont.

 

[terra 5,000+ posts]

people need to back off of cotjones...people who havent even been here long enough to know his posts are talking ****...get a life bit.ches

 

[newusername 10+ year member]

My comments were only based upon an SPL rig playing at, or very near tuning. Don't forget, music is transient, it does deviate from tuning, at which time excursion goes up. You dont have to be able to maximize excursion near tuning to be seeing the full potential of the driver in a vented system.

I agree that music is transient in nature, but keep in mind that excursion drops drastically as the frequency increases. If tuned to, say 20 Hz, it takes almost a full octave for the air mass in the port to be minimized in its effect on the speaker's excursion; by that time, you're at 40 Hz and the excursion that will be induced is disappearing. As someone who had the privilege of using one for a short time frame and almost bought one a few weeks ago, I assure you that there is no ported enclosure where you can achieve anywhere near Xmax with power that won't melt the coil, unless playing below Fb.

Good seeing you again btw Neil. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Good to see you as well. It's always nice to have a cordial discussion with an old mate. That's my britishism for the day, I spose. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[cotjones 10+ year member]

people need to back off of cotjones...people who havent even been here long enough to know his posts are talking ****...get a life bit.ches

//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[cotjones 10+ year member]

You heard incorrectly. But yes, for a flat response generally sealed works best. But a vented system, being tunable, can be tailored to reproduce a relatively flat in-car response. Just that most people dont.

i should've worded that differently... people have told me that "I" am likely to lose volume from a ported, because to make the ported sound loud and good, you have to have a little more skill than i have, esspecially since i'm wanting to do lots of fiberglass

 

[audioarsonal 10+ year member]

so in a ported incloser at the tuning frequency the port makes up for the lesser cone excursion?am i understanding that right?