The Characteristics of Net Volume and Port Area

[Sencheezy 689]

My question is in regards to enclosures. Mostly the relationship between net volume and port area.
From the little research I've done.

 

• High port area combined with small volume net will yield a very narrow bandwith but with most SPL.
• But, if you increase net volume, combined with high port area, you will increase SPL while sustaining a wide bandwith.

So what I am thinking is. As an example. If I only had 1000watts to a 3000watt subwoofer, 180cuin would be too much port area because I do not have adequate power to displace as much air as I would if I had 5000 watts. Is this way of thinking correct?

Like, hard to convey what I'm thinking via typing. But, I guess what I'm saying is that, If I have too little port, with too much power, than I'm "choking" the air displacement. And in contrary, if I have too much port area, and not enough power, than I have a leaky enclosure.

 

Thoughts?

[edouble101 314]

None of that is correct. The driver being used determines port and enclosure characteristics. 

[OuTLaWeD 110]

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

[Sencheezy 689]

None of that is correct. The driver being used determines port and enclosure characteristics. 

 

Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

[Sencheezy 689]

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 

Can you give an example of what you're saying?

[nadcicle 77]

I do believe that the port size does serve a direct correlation with the xmax along with box size. In my personal tests I've found that a smaller box/smaller port will yield more travel than a larger enclosure/larger port. The problem with this is that going larger net/smaller port tends to drop tuning (if you keep port wall the same common size) and doesn't let the suspension travel as far due to having a much larger enclosure to reverberate through.  You put a high xmax sub in a tiny box/tiny port and watch that thing leap out the box. All of this is simply in terms of xmax travel and nothing to do with tuning so much btw. Hell, in most peoples eyes what I've done with my Sp4 would be considered blasphemy in terms of the tiny port/tiny enclosure, but I'd be willing to let them build me another enclosure if they thought they could do better with my space constraints.

 

Perfect example of how to tune in real life. Put both hands over your mouth like you're beatboxing. Make your hands smaller and larger and bring your voice as low as you can to as high as you can between making your hands smaller and larger and see where you find the most sound comes out. It's reasons like this people sound like a superstar in an enclosed shower and William Hung on the mic.

Edited August 4, 2013 by nadcicle

[shizzzon 461]

Well, from my experience, the reason your score isn't higher is because your box is too large and your tuning is too low.

 

You need to measure your cabin gain, with the current setup installed, without the port interfering with reading first.

 

Then you can see how frequencies react in your vehicle.

 

then you know what to aim for as which frequency is the most efficient(resonance of your vehicle).

 

Higher frequencies do not do well in large enclosures or at least any of the ones i've ever messed with or witnessed.

[ramteid 17]

From what i understand, a larger port can be more effecient. It never hurts to build a new enclosure and see what happens.

[Quentin Jarrell 671]

LDC7 page 70     Top picture 4 port.  Bottom picture 6 inch port.  Obvious that there is NO change in bandwith.  Only the slightest bit of ripple change at higher power levels due to FS change caused by non linearity.  ALL ports are non linear, no way to get around this.  (One reason why I post large signal T/S with my drivers)

 

 

 

[OuTLaWeD 110]

None of that is correct. The driver being used determines port and enclosure characteristics. 

 

Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

  

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 

Can you give an example of what you're saying?

Don't need to, your on the right track having a larger enclosure is more efficient and also opening up the port will help release more pressure from the enclosure helping you get Max excursion easier. You do have to be careful with how much you do open the port with your enclosure being as large as it is though so you don't run into mechanical issues. At 180in. Sq I think you'll be just fine and should net you some great gains.

[Sencheezy 689]

 

None of that is correct. The driver being used determines port and enclosure characteristics. 

 

Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

  

> 

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 

Can you give an example of what you're saying?

Don't need to, your on the right track having a larger enclosure is more efficient and also opening up the port will help release more pressure from the enclosure helping you get Max excursion easier. You do have to be careful with how much you do open the port with your enclosure being as large as it is though so you don't run into mechanical issues. At 180in. Sq I think you'll be just fine and should net you some great gains.

 

 

Sweet, thank you for your input.

[Sencheezy 689]

LDC7 page 70     Top picture 4 port.  Bottom picture 6 inch port.  Obvious that there is NO change in bandwith.  Only the slightest bit of ripple change at higher power levels due to FS change caused by non linearity.  ALL ports are non linear, no way to get around this.  (One reason why I post large signal T/S with my drivers)

 

 

 

 

 

I need to study these images for a bit.

[Shogen 325]

basically, you need Quentin to help you holding hands... wish I could have the understanding some of these guys have... as well as the wallets... :'(  lol

[Quentin Jarrell 671]

 

None of that is correct. The driver being used determines port and enclosure characteristics. 

 

Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

  

> 

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 

Can you give an example of what you're saying?

Don't need to, your on the right track having a larger enclosure is more efficient and also opening up the port will help release more pressure from the enclosure helping you get Max excursion easier. You do have to be careful with how much you do open the port with your enclosure being as large as it is though so you don't run into mechanical issues. At 180in. Sq I think you'll be just fine and should net you some great gains.

 

 

 

No, larger ports do not allow the driver to hit xmax easier.  Top pic 2'' port.  Bottom pic 6'' port.  The top lines in both graphs are group delays and the bottom lines are excursion at each power lever.  Very clear no noticeable difference in xmax.  Again only slight ripple shift due to FS change.   Come on guys this book is only like 30 bucks shipped to your door.

 

 

 

 

 

[Quentin Jarrell 671]

pics are backwards.  Top is 6 inch port bottom 2 inch port

[OuTLaWeD 110]

 

None of that is correct. The driver being used determines port and enclosure characteristics. 

 Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

  

> 

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 Can you give an example of what you're saying?

Don't need to, your on the right track having a larger enclosure is more efficient and also opening up the port will help release more pressure from the enclosure helping you get Max excursion easier. You do have to be careful with how much you do open the port with your enclosure being as large as it is though so you don't run into mechanical issues. At 180in. Sq I think you'll be just fine and should net you some great gains. 

  No, larger ports do not allow the driver to hit xmax easier.  Top pic 2'' port.  Bottom pic 6'' port.  The top lines in both graphs are group delays and the bottom lines are excursion at each power lever.  Very clear no noticeable difference in xmax.  Again only slight ripple shift due to FS change.   Come on guys this book is only like 30 bucks shipped to your door.     

I understand what your saying, but science doesn't agree. Make an enclosure with a stupid large port and watch what the subwoofer does, then make the exact same enclosure and make the port area really small and again watch the subwoofer. They will react differently in the same enclosure with same tuning, but having a port opening on opposite ends of the spectrum

[nadcicle 77]

 

 

 

None of that is correct. The driver being used determines port and enclosure characteristics. 

 Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

  

> 

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 Can you give an example of what you're saying?ockquote>Don't need to, your on the right track having a larger enclosure is more efficient and also opening up the port will help release more pressure from the enclosure helping you get Max excursion easier. You do have to be careful with how much you do open the port with your enclosure being as large as it is though so you don't run into mechanical issues. At 180in. Sq I think you'll be just fine and should net you some great gains. 

  No, larger ports do not allow the driver to hit xmax easier.  Top pic 2'' port.  Bottom pic 6'' port.  The top lines in both graphs are group delays and the bottom lines are excursion at each power lever.  Very clear no noticeable difference in xmax.  Again only slight ripple shift due to FS change.   Come on guys this book is only like 30 bucks shipped to your door.     

I understand what your saying, but science doesn't agree. Make an enclosure with a stupid large port and watch what the subwoofer does, then make the exact same enclosure and make the port area really small and again watch the subwoofer. They will react differently in the same enclosure with same tuning, but having a port opening on opposite ends of the spectrum

 

 

I'm assuming you are saying the one with the small port will move more cause I believe that's what I'm gathering from what's being said.

[Quentin Jarrell 671]

No, at the same tuning it will not behave differently.  Below tuning yes it will unload easier as shown above.  The pictures above are the same enclosure volume, different port areas, tuned to the same tuning with increase in power.  All while measured on a Klippel analyzer.  The out come can not be disputed it is actually real world testing via a calibrated analyzer.  Arguing hte fact is akin to arguing that apples dont fall from trees.

[OuTLaWeD 110]

 

 

 

None of that is correct. The driver being used determines port and enclosure characteristics. 

 Most of the information above was in taken from my SSA Evil. Which has a high xmax value. I have a low score in my current setup, which is 8.3 net with only 130cuin of port tuned at 33hz. I am completely flat from 30hz to 50hz. After 50hz it begins to slightly lose output, but anything below 30hz I have a really big dip in output. I ask these questions becuase almost every program I've used, suggests that I use at least 180cuin of port. Which is far more than what I have. And I believe that the programs are correct because right now I don't believe I am reaching max xmax. Which is crazy because of how much power I am applying (5500 watts). So, this all ties in because, as stated above, my theory is that I have too little port area combined with the power I am utilizing. I am "assuming", that thet too little port area combined with high power is causing me to "choke" the air that is being displaced. Or in other terms, I have too much water pressure to get through the water hose.

  

>

> 

i hear what your saying. i had this arguement last year with somebody. by making your port area on the small side you WILL have more bandwidth than with more port area because of the compression that's happening.

 Can you give an example of what you're saying?ockquote>

Don't need to, your on the right track having a larger enclosure is more efficient and also opening up the port will help release more pressure from the enclosure helping you get Max excursion easier. You do have to be careful with how much you do open the port with your enclosure being as large as it is though so you don't run into mechanical issues. At 180in. Sq I think you'll be just fine and should net you some great gains. >

  No, larger ports do not allow the driver to hit xmax easier.  Top pic 2'' port.  Bottom pic 6'' port.  The top lines in both graphs are group delays and the bottom lines are excursion at each power lever.  Very clear no noticeable difference in xmax.  Again only slight ripple shift due to FS change.   Come on guys this book is only like 30 bucks shipped to your door.     

I understand what your saying, but science doesn't agree. Make an enclosure with a stupid large port and watch what the subwoofer does, then make the exact same enclosure and make the port area really small and again watch the subwoofer. They will react differently in the same enclosure with same tuning, but having a port opening on opposite ends of the spectrum

 

 

I'm assuming you are saying the one with the small port will move more cause I believe that's what I'm gathering from what's being said.

subwoofer in enclosure with small port will be less likely to "unload"

[Quentin Jarrell 671]

^ agreed as shown in graphs

[OuTLaWeD 110]

Having a larger port opening will allow air to escape from the enclosure easier and reduse the holding "vacuum" on the subwoofers cone. Having a smaller port opening will restrict the flow of air out of the enclosure and keep "vacuum" on the cone so the cone can't move as freely even above tuning.

Edited August 4, 2013 by ChILL

[Sencheezy 689]

Having a larger port opening will allow air to escape from the enclosure easier and reduse the holding "vacuum" on the subwoofers cone. Having a smaller port opening will restrict the flow of air out of the enclosure and keep "vacuum" on the cone so the cone can't move as freely even above tuning.

 

 

This is exactly my theory.

[frogcase2002 393]

I have built enclosures the same volume and tuning but different port areas and seems like they move more with a lot more port area. with same tuning. That's just what I have seen

[OuTLaWeD 110]

I have built enclosures the same volume and tuning but different port areas and seems like they move more with a lot more port area. with same tuning. That's just what I have seen

I've seen the same with my own eyes and enclosures I've built.

[nadcicle 77]

Having a larger port opening will allow air to escape from the enclosure easier and reduse the holding "vacuum" on the subwoofers cone. Having a smaller port opening will restrict the flow of air out of the enclosure and keep "vacuum" on the cone so the cone can't move as freely even above tuning.

 

Ok, this is exactly what I was saying too. So we do all seem to agree with each other then. I am going to call a holy crap session as this is a first here on SSA. We usually have at least 1 guy that comes in just to disagree with everything that's said on here because his cousins friends dad build a box for his kicker solo baric and it didn't do what we said it was going to do.