The Characteristics of Net Volume and Port Area

[shizzzon 461]

Nope.. everything is false.

My buddies sisters fiances cousin with the crazy eye had me build him 39 enclosures one time for his single 15 and all of them did their best score in 0.85cuft net with 23sqin of port and was still bottoming out above tuning.

Bam. Take that nadcicle.

[Quentin Jarrell 671]

I don't agree, as well as Vance Dickason. It's very clearly written in black and white.

[shizzzon 461]

Bam I got it... black and white.

Everything has changed now.

Its going to have to be retested in color and 3d for it to be valid now, lol.

Seriously, going from 4 to 6in port is not comparable going from 80 to 150sqin of port for example.

I believe others experiences reach the point of no return where the port is so large it almosts acts as if its in IB.

[OuTLaWeD 110]

Bam I got it... black and white.

Everything has changed now.

Its going to have to be retested in color and 3d for it to be valid now, lol.

Seriously, going from 4 to 6in port is not comparable going from 80 to 150sqin of port for example.

I believe others experiences reach the point of no return where the port is so large it almosts acts as if its in IB.

Ding, ding, ding

[nadcicle 77]

Bam I got it... black and white.

Everything has changed now.

Its going to have to be retested in color and 3d for it to be valid now, lol.

Seriously, going from 4 to 6in port is not comparable going from 80 to 150sqin of port for example.

I believe others experiences reach the point of no return where the port is so large it almosts acts as if its in IB.

 

I expect the vid to be uploaded via 12k with 128.1 surround sound by the year 2028 as that is the only thing my bionic eye will play in. Stupid google and their peripherals!

[Quentin Jarrell 671]

It's a 2 inch port compared to a 6 inch port. And a 6 inch port is a LOT of port area for a 10 inch driver with 5mm xmax.

[cobra93 47]

I don't beleive it's possible to have to much port area.

You can have to much enclosure volume, for the amount of power being applied and hit xmech.

Keep in mind a ported box will act as a sealed box until you approach the port tuning.

 

Think of a labyrinth, transmission line or tuned pipe systems.

They still have control over the cone.

 

A larger port, within reason, will have a larger volume of air acting upon the cone and sould provide better cone control.

 

If you don't have enough port you have a leaky sealed box.

[OuTLaWeD 110]

I don't beleive it's possible to have to much port area.

You can have to much enclosure volume, for the amount of power being applied and hit xmech.

Keep in mind a ported box will act as a sealed box until you approach the port tuning.

Think of a labyrinth, transmission line or tuned pipe systems.

They still have control over the cone.

A larger port, within reason, will have a larger volume of air acting upon the cone and sould provide better cone control.

If you don't have enough port you have a leaky sealed box.

You have to look closer at this enclosures though. The length of the line or "port" is what keeps the pressure or "vacuum" on the cone.

Edit: its hard to compare any of those enclosures to a traditional ported enclosure. They are COMPLETELY different in damn near every way.

Edited August 4, 2013 by ChILL

[cobra93 47]

I don't beleive it's possible to have to much port area.

You can have to much enclosure volume, for the amount of power being applied and hit xmech.

Keep in mind a ported box will act as a sealed box until you approach the port tuning.

Think of a labyrinth, transmission line or tuned pipe systems.

They still have control over the cone.

A larger port, within reason, will have a larger volume of air acting upon the cone and sould provide better cone control.

If you don't have enough port you have a leaky sealed box.

You have to look closer at this enclosures though. The length of the line or "port" is what keeps the pressure or "vacuum" on the cone.

Edit: its hard to compare any of those enclosures to a traditional ported enclosure. They are COMPLETELY different in damn near every way.

 

 

OP Question >

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?

 

This was the question posed to us and why my I answered the way I did.

 

 

> To Chill >  I disagree, these are all helmholtz resonators.

The larger the port, the longer it needs to be to maintaint tuning.

And because of this ^^^^^ the mass of the air in the port changes, bigger the port the more mass.

The higher mass in the larger port should have more of an affect on the cone, if anything.

 

If the port is too small it won't act as a port.

Once the port is correct for the system increasing it will not do much, There's no more to gain.

 

I've underlined the last sentence in his OP.

This is exactly backwards.

To small of a port is a leaky sealed enclosure.

A large port will just be efficient.

 

Regarding your response that I underlined. >  It's not the length of the line that acts on the cone, that's more tuning, but the mass in the port that's resonating that's affecting the cone.

 

This is my understanding.

 

Edited August 4, 2013 by cobra93

[OuTLaWeD 110]

That's the reason I went back and edited my last post. A conventional ported enclosure is essentially a chamber with a port. A t-line is the port and the chamber. They are completely different so you can't compare the two.

[Sencheezy 689]

 

I don't beleive it's possible to have to much port area.

You can have to much enclosure volume, for the amount of power being applied and hit xmech.

Keep in mind a ported box will act as a sealed box until you approach the port tuning.

Think of a labyrinth, transmission line or tuned pipe systems.

They still have control over the cone.

A larger port, within reason, will have a larger volume of air acting upon the cone and sould provide better cone control.

If you don't have enough port you have a leaky sealed box.

You have to look closer at this enclosures though. The length of the line or "port" is what keeps the pressure or "vacuum" on the cone.

Edit: its hard to compare any of those enclosures to a traditional ported enclosure. They are COMPLETELY different in damn near every way.

 

 

OP Question >

> 

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?

 

This was the question posed to us and why my I answered the way I did.

 

 

> To Chill >  I disagree, these are all helmholtz resonators.

The larger the port, the longer it needs to be to maintaint tuning.

And because of this ^^^^^ the mass of the air in the port changes, bigger the port the more mass.

The higher mass in the larger port should have more of an affect on the cone, if anything.

 

If the port is too small it won't act as a port.

Once the port is correct for the system increasing it will not do much, There's no more to gain.

 

I've underlined the last sentence in his OP.

This is exactly backwards.

To small of a port is a leaky sealed enclosure.

A large port will just be efficient.

 

Regarding your response that I underlined. >  It's not the length of the line that acts on the cone, that's more tuning, but the mass in the port that's resonating that's affecting the cone.

 

This is my understanding.

 

 

 

wow, well thank you very much for your input. I really appreciate your sight on the matter. 

 

So, overall, the response I'm getting seems to be a battle of real world experience vs laws and physics. Not really sure of which route to take at this point.

[Sencheezy 689]

What I am also noticing, is that, many people will place a driver in any paticular enclosure, some will have great results, and others won't know any better either way. But my misunderstanding of this, is that most will never build again to tell whether or not they are reaching full potential or not. My point to this is, for the people who are using less than optimal enclosure size, enclosure tuning and port area, how can they say that what worked for them, is the better option vs more traditional enclosure designs based upon the works of helmholtz and Small/Thiele?

[swift 501]

I personally think you have too much port area now. Maybe even too much box and port. But this is my opinion. I would have done about 7.5cu with 100sqin of port.

You need to make your mind up if your goal is SPL or something that sounds good. If you want both you need alot more cone area and power. One sub isn't gonna do it all.

[cobra93 47]

 

 

I don't beleive it's possible to have to much port area.

You can have to much enclosure volume, for the amount of power being applied and hit xmech.

Keep in mind a ported box will act as a sealed box until you approach the port tuning.

Think of a labyrinth, transmission line or tuned pipe systems.

They still have control over the cone.

A larger port, within reason, will have a larger volume of air acting upon the cone and sould provide better cone control.

If you don't have enough port you have a leaky sealed box.

You have to look closer at this enclosures though. The length of the line or "port" is what keeps the pressure or "vacuum" on the cone.

Edit: its hard to compare any of those enclosures to a traditional ported enclosure. They are COMPLETELY different in damn near every way.

 

 

OP Question >

> 

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?

 

This was the question posed to us and why my I answered the way I did.

 

 

> To Chill >  I disagree, these are all helmholtz resonators.

The larger the port, the longer it needs to be to maintaint tuning.

And because of this ^^^^^ the mass of the air in the port changes, bigger the port the more mass.

The higher mass in the larger port should have more of an affect on the cone, if anything.

 

If the port is too small it won't act as a port.

Once the port is correct for the system increasing it will not do much, There's no more to gain.

 

I've underlined the last sentence in his OP.

This is exactly backwards.

To small of a port is a leaky sealed enclosure.

A large port will just be efficient.

 

Regarding your response that I underlined. >  It's not the length of the line that acts on the cone, that's more tuning, but the mass in the port that's resonating that's affecting the cone.

 

This is my understanding.

 

 

wow, well thank you very much for your input. I really appreciate your sight on the matter. 

 

So, overall, the response I'm getting seems to be a battle of real world experience vs laws and physics. Not really sure of which route to take at this point.

 

 

I think the others are also changing the net volume as well as the port and this is why they're seeing the results they are or missing the tuning and unloading the driver.

 

Quentin is posting from "loud speaker design cookbook"  by Vance Dickason, Which is a great book.

He's telling you the others are not correct and he's designing speakers, I think I'd take his word for it.

 

The larger the port the lower the velocity the air resonates in the port and the less noisey the port becomes.

The idea is to keep port velocity down/slower.

 

 

[OuTLaWeD 110]

I personally think you have too much port area now. Maybe even too much box and port. But this is my opinion. I would have done about 7.5cu with 100sqin of port.

You need to make your mind up if your goal is SPL or something that sounds good. If you want both you need alot more cone area and power. One sub isn't gonna do it all.

Yeah, for me personally I like to run with less port area. If I were building my own enclosure for that sub I would be around 7.5 cubes also, but I would still stick with around 120ish sq. In for the port

[cobra93 47]

What I am also noticing, is that, many people will place a driver in

any paticular enclosure, some will have great results, and others won't

know any better either way. But my misunderstanding of this, is that

most will never build again to tell whether or not they are reaching

full potential or not. My point to this is, for the people who are using

less than optimal enclosure size, enclosure tuning and port area, how

can they say that what worked for them, is the better option vs

more traditional enclosure designs based upon the works of helmholtz and

Small/Thiele?

 

Well, I'd say because you need to build/experiment to find what you like in the enviroment you're in.

There's no best, but only best for you AND the driver you're using.

 

As far as enclosures go, you need to have goals to be met and and those would require a certain type of enclosure/system to achieve them.

I don't think allot of people consider what the driver is telling them it needs to perform a certain way and throw it in whatever box they feel like.

They probably don't know what they want besides loud anyway.

I say that excluding allot of members on this forum, many of them know allot more than I do and I'll admit that.

 

Sencheezy, have you modeled you system to see what the port velocity is?

Edited August 4, 2013 by cobra93

[95Honda 486]

If it behaving like a Hemolitz resonator, area and size don't really matter, neglecting compression. Q  Jerrel has tried showing you this.  It is physics.  If you find otherwise in your testing, it is biased in some way.

 

I have had a 7" subwoofer properly load a 10" diameter Sonotube vent...  It didn't behave any different than the 2" PVC pipe I did small signal testing with IMP earlier...

[Sencheezy 689]

If it behaving like a Hemolitz resonator, area and size don't really matter, neglecting compression. Q  Jerrel has tried showing you this.  It is physics.  If you find otherwise in your testing, it is biased in some way.

 

I have had a 7" subwoofer properly load a 10" diameter Sonotube vent...  It didn't behave any different than the 2" PVC pipe I did small signal testing with IMP earlier...

 

 

So what characteristically behaviors were changed when going from the 2" PVC to the 10" sonotube? Smaller bandwith, Peaker sound, smoother response, etc?

[Rail 0]

Interesting info here, so according to the loud speaker design cookbook having large port area won't effect your excursion until you get below tuning frequency of the enclosure. It seems like if you don't play much below tuning then more port is the way to go, but what I am left wondering is if your port can be too large. Larger port reduces air velocity, so can too large of a port be bad if you are trying to move some air for hairtricks? Or would a larger port area be good for hairtricks because the port will be wider as well as longer to maintain your tuning frequency, so there will be more air in the port that is being moved even though it is at a lower speed?

[95Honda 486]

So what characteristically behaviors were changed when going from the 2" PVC to the 10" sonotube? Smaller bandwith, Peaker sound, smoother response, etc?

 

No change.  The 7" driver didn't have enough stroke to cause much compression with the 2" vent with the power I was using.  I was trying the bigger 10" because I had a ton of Sonotube and was trying to see if a 1ft3 would still work as predicted with a vent that big.

 

Everything in the Loudspeaker Design Cookbook is proven fact.  It is decades of engineering and predicted results.  Everything can be modeled. There is no "magic" in loudspeaker design. 

 

The problem with most "tests" that are done is that they are subjective, especially in car audio.  There are too many uncontrolled parameters to be objective.  You see all these "results" that people post, but they are meaningless because they never remove all the uncontrolled variables when they conduct their "test".

 

As far a subjective sound quality in relation to vent size, if you hear differences other than compression issues, you screwed with something else and caused an un-intended change...

 

Again, if it is acting like a Helmholtz resonator, and you aren't running into compression issues, there is no sound quality difference.  Also, a tiny ass woofer will load a huge ass vent, everything will work like it is supposed to if you designed it right. 

 

These goofy opinions come from not understanding the physics behind Helmholtz resonation...

[Sencheezy 689]

So what characteristically behaviors were changed when going from the 2" PVC to the 10" sonotube? Smaller bandwith, Peaker sound, smoother response, etc?

No change. The 7" driver didn't have enough stroke to cause much compression with the 2" vent with the power I was using. I was trying the bigger 10" because I had a ton of Sonotube and was trying to see if a 1ft3 would still work as predicted with a vent that big.

Everything in the Loudspeaker Design Cookbook is proven fact. It is decades of engineering and predicted results. Everything can be modeled. There is no "magic" in loudspeaker design.

The problem with most "tests" that are done is that they are subjective, especially in car audio. There are too many uncontrolled parameters to be objective. You see all these "results" that people post, but they are meaningless because they never remove all the uncontrolled variables when they conduct their "test".

As far a subjective sound quality in relation to vent size, if you hear differences other than compression issues, you screwed with something else and caused an un-intended change...

Again, if it is acting like a Helmholtz resonator, and you aren't running into compression issues, there is no sound quality difference. Also, a tiny ass woofer will load a huge ass vent, everything will work like it is supposed to if you designed it right.

These goofy opinions come from not understanding the physics behind Helmholtz resonation...

But sound quality is not measurable is it? I'm only asking to learn and to educate myself. When you say there will be no sound quality difference between 2" port and 10" port, that goes against what some other people would say when increasing port size. Giving it a "muddy" or "sloppy" sound. And using smaller sized port would give a more "tighter" sound. What are your thoughts?

[frogcase2002 393]

So what characteristically behaviors were changed when going from the 2" PVC to the 10" sonotube? Smaller bandwith, Peaker sound, smoother response, etc?

No change. The 7" driver didn't have enough stroke to cause much compression with the 2" vent with the power I was using. I was trying the bigger 10" because I had a ton of Sonotube and was trying to see if a 1ft3 would still work as predicted with a vent that big.

Everything in the Loudspeaker Design Cookbook is proven fact. It is decades of engineering and predicted results. Everything can be modeled. There is no "magic" in loudspeaker design.

The problem with most "tests" that are done is that they are subjective, especially in car audio. There are too many uncontrolled parameters to be objective. You see all these "results" that people post, but they are meaningless because they never remove all the uncontrolled variables when they conduct their "test".

As far a subjective sound quality in relation to vent size, if you hear differences other than compression issues, you screwed with something else and caused an un-intended change...

Again, if it is acting like a Helmholtz resonator, and you aren't running into compression issues, there is no sound quality difference. Also, a tiny ass woofer will load a huge ass vent, everything will work like it is supposed to if you designed it right.

These goofy opinions come from not understanding the physics behind Helmholtz resonation...

But sound quality is not measurable is it? I'm only asking to learn and to educate myself. When you say there will be no sound quality difference between 2" port and 10" port, that goes against what some other people would say when increasing port size. Giving it a "muddy" or "sloppy" sound. And using smaller sized port would give a more "tighter" sound. What are your thoughts?

Buy the materials and ill make you some different enclosures you can try on the evil lol

[95Honda 486]

I agree with you 100%.  Because the people who told you about these results were giving you subjective results.  They were manipulating variables they were unaware of.

 

Everything is measurable.  Sound Quality, or what we perceive as Sound Quality, is measurable.  You just have to know what you are looking at/for.

[95Honda 486]

Vance built controlled test boxes and measured the results.  Nobody on here who has said otherwise has done this.