Port questions....*EDIT* *WE'VE* got answers.
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Port questions....*EDIT* *WE'VE* got answers. Designing a ported a.k.a. vented enclosure will not only give you added output, but can give you more low-frequency extension. This means louder and lower! Since the speaker system is the least efficient part of the whole audio chain, would it not make sense to make it as efficient as possible? Of coarse it does.
This is why venting is basically free output, and free sound quality. Local shops tell you that a small sealed box is the best way to go? Hit up your local hi-end home audio store and find out how many of those $20,000.00 pairs of speakers are sealed designs. You won't find many. This is why i personally never go with a small sealed enclosure.
Think of a box port not as a vent in the terms of a venting path for air to travel into and out of a box, but rather as extra cone area that is propagating acoustic energy from the enclosure to the cabin. The air in a port is fixed; it is trapped within the confines of the port walls. When the cone moves there is a corresponding change to the pressure in the box, that pressure change then causes the trapped air in the port to move either forward or backward. It moves as a solid unit, just like a speaker cone does.
Passive radiator and a vented port work on the same theory. When a port mass moves back and forth, a pressure wave (sound wave) is sent into the cabin. The larger the port, the larger the radiating area is that creates the pressure. Tuning a port is tuning the mass of the trapped air in the port to the air mass in the box volume.
For all out no holds barred SPL efficiency, rule of thumb is the larger the box, the higher the output. The larger the box, the larger the ports can be for a given frequency tuning range. There is no substitute for cubic inches.
The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.
Lets say we have a 12 inch speaker in a box, roughly 100 sq inches of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sq inches of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port air must move 2.0". It can handle this, but when the cone is moving 1.0", the port air must move 8 inches! Now you've got a leaky sealed box.
You need more port area for a clean sounding, high output system. The best port formula is this: 16 sq inches of port area per cubic foot of box volume. The port should be 13 inches long. Remember, the port is tuned to the box volume, not the sub(s). This rule of thumb will tune your box if it were in an open area to 45hz but with the small size and air pressure load of the interior space of a vehicle effectively tuning your box down to 30-35hz which is lower than most all cd's (except for specifically made bass cd's) play down to.
This is why venting is basically free output, and free sound quality. Local shops tell you that a small sealed box is the best way to go? Hit up your local hi-end home audio store and find out how many of those $20,000.00 pairs of speakers are sealed designs. You won't find many. This is why i personally never go with a small sealed enclosure.
Think of a box port not as a vent in the terms of a venting path for air to travel into and out of a box, but rather as extra cone area that is propagating acoustic energy from the enclosure to the cabin. The air in a port is fixed; it is trapped within the confines of the port walls. When the cone moves there is a corresponding change to the pressure in the box, that pressure change then causes the trapped air in the port to move either forward or backward. It moves as a solid unit, just like a speaker cone does.
Passive radiator and a vented port work on the same theory. When a port mass moves back and forth, a pressure wave (sound wave) is sent into the cabin. The larger the port, the larger the radiating area is that creates the pressure. Tuning a port is tuning the mass of the trapped air in the port to the air mass in the box volume.
For all out no holds barred SPL efficiency, rule of thumb is the larger the box, the higher the output. The larger the box, the larger the ports can be for a given frequency tuning range. There is no substitute for cubic inches.
The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.
Lets say we have a 12 inch speaker in a box, roughly 100 sq inches of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sq inches of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port air must move 2.0". It can handle this, but when the cone is moving 1.0", the port air must move 8 inches! Now you've got a leaky sealed box.
You need more port area for a clean sounding, high output system. The best port formula is this: 16 sq inches of port area per cubic foot of box volume. The port should be 13 inches long. Remember, the port is tuned to the box volume, not the sub(s). This rule of thumb will tune your box if it were in an open area to 45hz but with the small size and air pressure load of the interior space of a vehicle effectively tuning your box down to 30-35hz which is lower than most all cd's (except for specifically made bass cd's) play down to.
Last edited by ohiojosh78; Oct 26, 2004 at 11:41 PM.
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Like I said in the other post I made, ports don't move back and forth, they remain stationary and air flows through them at a specific velocity to create the tuning.
It's not necessarily the larger the box the higher the output. Some of the highest output boxes I've seen use the tiniest boxes (like 1.0 cu ft for an 18"). You can only go so big to a point, I believe it is to 3x the Vas (or some other T/S param, can't remember the exact one).
Most people recommend different port sizes for SQ and SPL. Design specs that I have beside me list different ports sizes for SQ and SPL and are different for 10's and 12's. Every recommendation should be different depending on the application. For SPL, I know of people who recommend a single slot port on the edge of the box, 17" deep. The length would be from one plane of the box to the opposite, and that leaves you the width to adjust to properly tune the box.
You don't necessarily need more port for a clean high output system, I would say quite the opposite. In an SPL application I would use more port, also as I stated in another thread, it is another of my rules of thumb to match port surface area with speaker surface area. This will definitely make for a high output design, but the clean part is debatable. I tend to base port area based on the surface area of the drivers and then adjust the length of the port based on the desired tuning. Combined with my 17" rule I mentioned earlier, that would make an SPL port X sq inches by 17" deep. You may get better results with a smaller surface area, but thats what testing is for.
I think that about covers it... not trying to start an argument but perhaps a good debate where we can learn something
It's not necessarily the larger the box the higher the output. Some of the highest output boxes I've seen use the tiniest boxes (like 1.0 cu ft for an 18"). You can only go so big to a point, I believe it is to 3x the Vas (or some other T/S param, can't remember the exact one).
Most people recommend different port sizes for SQ and SPL. Design specs that I have beside me list different ports sizes for SQ and SPL and are different for 10's and 12's. Every recommendation should be different depending on the application. For SPL, I know of people who recommend a single slot port on the edge of the box, 17" deep. The length would be from one plane of the box to the opposite, and that leaves you the width to adjust to properly tune the box.
You don't necessarily need more port for a clean high output system, I would say quite the opposite. In an SPL application I would use more port, also as I stated in another thread, it is another of my rules of thumb to match port surface area with speaker surface area. This will definitely make for a high output design, but the clean part is debatable. I tend to base port area based on the surface area of the drivers and then adjust the length of the port based on the desired tuning. Combined with my 17" rule I mentioned earlier, that would make an SPL port X sq inches by 17" deep. You may get better results with a smaller surface area, but thats what testing is for.
I think that about covers it... not trying to start an argument but perhaps a good debate where we can learn something
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Rep Power: 0 I'm always up for a good debate...not argument but it seems you are also knowlegable and that we can have a intelligent conversation on this topic.
Yes, for SPL larger port area is necessary to move more air to hit higher #'s. And you can go too large with the port for most subs. But the port size and length and box size is what determines your tuning frequency. You cannot take a port that is XXX" long and XXX square inches of port area in a box with a volume of YYY Cubic inches and then put it in a box of ZZZ cubic inches and be tuned to the same frequency.
Smaller port opening = lower tuning frequency
Longer port = lower tuning frequency
Bigger box = lower tuning frequency
That is why the bigger the box the bigger you have to make the port to compensate and keep the frequency #45hz. Yes, once you reach a certain point must subs wont operate correctly with a huge port, so then you must compensate another way. Well, the only other varible is port length. And since the larger the box the lower the frequency you must shorten the port to balance.
It's just my experience that the 13" port is a good starting point for a quality system. It may not work out well with lower grade subwoofers but for most high output subs it works well. But it may be adjusted either way for specific speakers.
That is a good setup. Sub at one end vent/port at the other. highest output and easiest to make since 3 sides of your port are already made for you just from making the box. All one has to do is insert one piece of wood for the 4th side of the port.
I'll put up some pics of my box. Thats what i have now.
I dont believe i ever said the port moved. I may not be following what you're saying though
As far as matching the port area x 17" long, that is fine but the frequency that the enclosure is tuned to will change depending on the box size as well. So if you use that theory with an extremely small or large box it will be tuned to the high or low end of the range.
Also if you go too small with the port then port noise becomes a problem. As stated earlier no matter port size the same amount of air must flow through so if your port is 1/8 the size of your sub then the air must flow 8X faster and that speed of the air may give off unwanted noise.
I'm just trying to let everyone know you dont tune to the sub you tune to the box to get the desired frequency FOR the sub. Most people dont know that box size effects the tuning frequency. You can stick many different subs in the same box and it will still be tuned to the same frequency.
Yes, for SPL larger port area is necessary to move more air to hit higher #'s. And you can go too large with the port for most subs. But the port size and length and box size is what determines your tuning frequency. You cannot take a port that is XXX" long and XXX square inches of port area in a box with a volume of YYY Cubic inches and then put it in a box of ZZZ cubic inches and be tuned to the same frequency.
Smaller port opening = lower tuning frequency
Longer port = lower tuning frequency
Bigger box = lower tuning frequency
That is why the bigger the box the bigger you have to make the port to compensate and keep the frequency #45hz. Yes, once you reach a certain point must subs wont operate correctly with a huge port, so then you must compensate another way. Well, the only other varible is port length. And since the larger the box the lower the frequency you must shorten the port to balance.
It's just my experience that the 13" port is a good starting point for a quality system. It may not work out well with lower grade subwoofers but for most high output subs it works well. But it may be adjusted either way for specific speakers.
Originally Posted by MegaHurtz
For SPL, I know of people who recommend a single slot port on the edge of the box, 17" deep. The length would be from one plane of the box to the opposite, and that leaves you the width to adjust to properly tune the box.
That is a good setup. Sub at one end vent/port at the other. highest output and easiest to make since 3 sides of your port are already made for you just from making the box. All one has to do is insert one piece of wood for the 4th side of the port.
I'll put up some pics of my box. Thats what i have now.
Originally Posted by MegaHurtz
Like I said in the other post I made, ports don't move back and forth, they remain stationary and air flows through them at a specific velocity to create the tuning.
As far as matching the port area x 17" long, that is fine but the frequency that the enclosure is tuned to will change depending on the box size as well. So if you use that theory with an extremely small or large box it will be tuned to the high or low end of the range.
Also if you go too small with the port then port noise becomes a problem. As stated earlier no matter port size the same amount of air must flow through so if your port is 1/8 the size of your sub then the air must flow 8X faster and that speed of the air may give off unwanted noise.
I'm just trying to let everyone know you dont tune to the sub you tune to the box to get the desired frequency FOR the sub. Most people dont know that box size effects the tuning frequency. You can stick many different subs in the same box and it will still be tuned to the same frequency.
Last edited by ohiojosh78; Oct 26, 2004 at 11:33 PM.
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Rep Power: 787 Awesome post, we need to see more like this on here
aaaaaand for the record:
like I said, since when do ports move 
aaaaaand for the record:
Originally Posted by ohiojosh78
When a port mass moves back and forth, a pressure wave (sound wave) is sent into the cabin
Originally Posted by ohiojosh78
If the 12 inch cone moves 0.25", the port must move 2.0". It can handle this, but when the cone is moving 1.0", the port must move 8 inches!
Last edited by MegaHurtz; Oct 26, 2004 at 11:44 PM.
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Rep Power: 0 If someone is going for straight SPL thats a whole different story. Then you have to tune your port/box to your vehicle. This will make it so that a specific box/woofer setup that yields 155DB in one vehicle and you take that box out and put it into another vehicle, it may vield 153DB even if you throw in more power.
Last edited by ohiojosh78; Oct 26, 2004 at 11:43 PM.
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Originally Posted by MegaHurtz
like I said, since when do posts move
thanks for pointing that out.GREAT DEBATE MHZ!!!
anyone else can jump in or ask away.
Last edited by ohiojosh78; Oct 26, 2004 at 11:44 PM.
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Rep Power: 787 I've seen boxes drop between identical vehicles. Case in point a competitor I know of wrote off his car and bought the same car, put his system in the SAME as it was before... and went down.
There's a million ways to tune a box, IMO the best way is to manually plot your driver's impedance chart so that you can REALLY properly tune a box. But AFAIK this is a seldom practiced technique but would produce stellar results.
There's a million ways to tune a box, IMO the best way is to manually plot your driver's impedance chart so that you can REALLY properly tune a box. But AFAIK this is a seldom practiced technique but would produce stellar results.
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Rep Power: 0 I believe that the Bass Mekanik cd's have the formula to figure the proper frequency of your car. I have it some place but i forget the formula. Have to measure from the speaker to the front windshield then use the lengthe of the waves of different frequencies to tune to. Once you find that then build and test, build, test, build, test... Have to try different Box/port configurations tuned to that frequency to see what works best. May end up with a 17"long port with a surface area of 50 sq inches or 13" long port with 65 sq inches or anything in between but it all needs to add up to the vehicles specific frequency for best results. It all just depends on the sub and vehicle for what works better.
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Rep Power: 0 ill throw in a few fun facts for you guys to argue amongst yourselves with, because i dont feel like arguing tonight, im tired...
and im lazy, so im using acronyms
Vb = box volume
Fb = port frequency
LFE = low frequency extension
1 - ported box with Fb below 5-6 hz, will act almost identically, and even identically when you get to the lowest possible, as a sealed box
2 - there is a point of diminishing returns with both port size and Vb. I believe that the figure is at 4x VAS, you begin to see the enclosure acting IB, especially in a sealed one, in a ported one, it just begins to sound like *** because the front and back wave are interacting while the suspension of the woofer isnt being aided properly as an enclosure does., hence, leaky sealed box sound. i forgot the exact figure with port size, but the problem with too big of a port anyways, is that you start requiring more length to attain a certain Fb, and it starts eating up your Vb with a longer port.
3 -
ah **** it, i have nothing to do
from the top:
yes and no, although efficiency is increased, a lot of transient response is lost, and massive amounts of group delay is encountered, in addition, you have to deal with MUCH more airspace, need added bracing, and have more chances of blowing a woofer with everyday usage unless you tune super low, which, removes total efficiency. Go play a 20 hz tone on a box tuned to 30-35 without a subsonic filter and see what i mean. theres a reason you dont see many ported enclosures in sq vehicles.
there are PLENTY of speakers in 20k+ sets that are sealed.
again, explain how group delay, loss in transient response, and peakyness equates to free sound quality?
and as to the lfe, a proper woofer in the proper sealed enclosure can do any lfe youd ever need
eh... kinda, a better analogy is blowing over the end of a bottle. the port acts the same way, the air in the port resonates but only at a certain frequency. below that youre screwed though.
remember, a port only really acts to its full potential at or around tuning frequency. put your hand by your port and play a sweep, youll feel a rush of air at or around tuning frequency, but not much of anything at other frequencies. then, impedance skyrockets, cone motion goes to almost zero, this is when parameters like QES start to matter over xmax and such.
passive radiator, again, doesnt work on the principle of the cone moving back and forth and the air moving back and forth, it works on the principle of the resonant frequency of a certain mass/area ratio. notice the PR only starts moving like mad at certain frequencies, again, this is when this certain area/mass ratio resonates. you cant just slap a pr in a box, you have to add weights to the back of the cone of the pr to modify the tuning of it. you have to change it's Fs.
again, we have a point of diminishing returns, and, that much port area is just silly to use.
also, the port air doesnt move back and forth as a solid chunk, the individual molecules resonate
ok, this is my favorite one:
a - you dont need to port for a clean sounding high output system. ive seen people do 160's or higher with sealed enclosures
now it gets fun
provide me one piece of REAL evidence that states that 16 sq inches per cubic foot is the best.
also, what the hell kind of arbitrary number is 13 inches for port length?
but my personal favorite of all:
explain how, and please, provide me the math or ask the person who told you this to provide the math, on how the interior of a car will drop the Fb of your box. this is seriously concerning me, because if its true, then everything i know is wrong.
If you want, I can provide textbook proof for every single thing I've said in my response to you, I just want to see if everything I know is wrong: all my professional training, years of installing, and my college years of being a physics major could all be disproved by you!
and im lazy, so im using acronyms
Vb = box volume
Fb = port frequency
LFE = low frequency extension
1 - ported box with Fb below 5-6 hz, will act almost identically, and even identically when you get to the lowest possible, as a sealed box
2 - there is a point of diminishing returns with both port size and Vb. I believe that the figure is at 4x VAS, you begin to see the enclosure acting IB, especially in a sealed one, in a ported one, it just begins to sound like *** because the front and back wave are interacting while the suspension of the woofer isnt being aided properly as an enclosure does., hence, leaky sealed box sound. i forgot the exact figure with port size, but the problem with too big of a port anyways, is that you start requiring more length to attain a certain Fb, and it starts eating up your Vb with a longer port.
3 -
ah **** it, i have nothing to do
from the top:
Originally Posted by ohiojosh78
Designing a ported a.k.a. vented enclosure will not only give you added output, but can give you more low-frequency extension. This means louder and lower! Since the speaker system is the least efficient part of the whole audio chain, would it not make sense to make it as efficient as possible? Of coarse it does.
Originally Posted by ohiojosh78
This is why venting is basically free output, and free sound quality. Local shops tell you that a small sealed box is the best way to go? Hit up your local hi-end home audio store and find out how many of those $20,000.00 pairs of speakers are sealed designs. You won't find many. This is why i personally never go with a small sealed enclosure.
again, explain how group delay, loss in transient response, and peakyness equates to free sound quality?
and as to the lfe, a proper woofer in the proper sealed enclosure can do any lfe youd ever need
Originally Posted by ohiojosh78
Think of a box port not as a vent in the terms of a venting path for air to travel into and out of a box, but rather as extra cone area that is propagating acoustic energy from the enclosure to the cabin. The air in a port is fixed; it is trapped within the confines of the port walls. When the cone moves there is a corresponding change to the pressure in the box, that pressure change then causes the trapped air in the port to move either forward or backward. It moves as a solid unit, just like a speaker cone does.
remember, a port only really acts to its full potential at or around tuning frequency. put your hand by your port and play a sweep, youll feel a rush of air at or around tuning frequency, but not much of anything at other frequencies. then, impedance skyrockets, cone motion goes to almost zero, this is when parameters like QES start to matter over xmax and such.
Originally Posted by ohiojosh78
Passive radiator and a vented port work on the same theory. When a port mass moves back and forth, a pressure wave (sound wave) is sent into the cabin. The larger the port, the larger the radiating area is that creates the pressure. Tuning a port is tuning the mass of the trapped air in the port to the air mass in the box volume.
Originally Posted by ohiojosh78
For all out no holds barred SPL efficiency, rule of thumb is the larger the box, the higher the output. The larger the box, the larger the ports can be for a given frequency tuning range. There is no substitute for cubic inches.
The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.
Lets say we have a 12 inch speaker in a box, roughly 100 sq inches of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sq inches of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port air must move 2.0". It can handle this, but when the cone is moving 1.0", the port air must move 8 inches! Now you've got a leaky sealed box.
The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.
Lets say we have a 12 inch speaker in a box, roughly 100 sq inches of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sq inches of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port air must move 2.0". It can handle this, but when the cone is moving 1.0", the port air must move 8 inches! Now you've got a leaky sealed box.
also, the port air doesnt move back and forth as a solid chunk, the individual molecules resonate
Originally Posted by ohiojosh78
You need more port area for a clean sounding, high output system. The best port formula is this: 16 sq inches of port area per cubic foot of box volume. The port should be 13 inches long. Remember, the port is tuned to the box volume, not the sub(s). This rule of thumb will tune your box if it were in an open area to 45hz but with the small size and air pressure load of the interior space of a vehicle effectively tuning your box down to 30-35hz which is lower than most all cd's (except for specifically made bass cd's) play down to.
a - you dont need to port for a clean sounding high output system. ive seen people do 160's or higher with sealed enclosures
now it gets fun
provide me one piece of REAL evidence that states that 16 sq inches per cubic foot is the best.
also, what the hell kind of arbitrary number is 13 inches for port length?
but my personal favorite of all:
explain how, and please, provide me the math or ask the person who told you this to provide the math, on how the interior of a car will drop the Fb of your box. this is seriously concerning me, because if its true, then everything i know is wrong.
If you want, I can provide textbook proof for every single thing I've said in my response to you, I just want to see if everything I know is wrong: all my professional training, years of installing, and my college years of being a physics major could all be disproved by you!
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Rep Power: 338 man lud, seems a bit harsh to me. he's not attacking you, right? Id edit some of your stuff out man. I'm not gonna question any of your stuff, but it seems like your points arent exactly addressing some of the incorrect issues in teh posts, but really, theres so much unneccesary meanness! I hope ohiojosh doesnt think you are a jerk for the rest of his time here, cause thatd be a real bummer....I know you are a nice guy, nick!
that much port area is rediculous? 100 square inches? I bet I cant count on two hands the number of 7th genners with more than 100 square inches of port.... (shhhh! nevermind they are all spl competitors
)
that much port area is rediculous? 100 square inches? I bet I cant count on two hands the number of 7th genners with more than 100 square inches of port.... (shhhh! nevermind they are all spl competitors
) Last edited by WhiteRabbit; Oct 27, 2004 at 01:06 AM.
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Rep Power: 0 damn steve... you ARE getting soft. I remember years ago you were a **** as well... I can recall one time with battery terminals exploding and leaving two dents in teh hood.
Look, I'm not attacking him directly, I'm only trying to be direct because this is why false rumors get started.
example -
capacitors make your alternator troubles go away
or
13" long ports are the best.
this is why salespeople can get away with making things up and having people believe it, while the shop profits on a persons ignorance.
Look, I'm not attacking him directly, I'm only trying to be direct because this is why false rumors get started.
example -
capacitors make your alternator troubles go away
or
13" long ports are the best.
this is why salespeople can get away with making things up and having people believe it, while the shop profits on a persons ignorance.
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Rep Power: 0 13" port is a good "starting point" like i stated earlier not the END ALL OF PORT DESIGNS.
Smaller area of the interior of the car porvides resistance to the movement of the speaker unlike inside of a large room.
READ...This works in conjunction with the 13" port to tune the box to 45hz.
Sigh...Majority are NOT sealed.
No, this is MY favorite one. Porting is free output. There is almost no way a sealed box can outperform a ported box. Give me an speaker in a sealed box and then i'll show you the same speaker in a ported box with higher output. And i thought you knew SOMETHING. That one really got me. You were doing such a good job of trying to be all high and mighty too.
As i stated earlier, if you can and did read, unless you're playing a "bass cd" you will almost never see this range of sound played. So, i was throwing that out. Those were in 2 different paragraphs, thus 2 different areas of my discussion. If you were going for sound Q you could tune lower. Dont be an idiot and come attack me with senseless replies.
1 i was trying to simplify and 2 it is not individual molecules resonating. The entire mass of the air is moving back and forth. Put a piece of paper in front of the port! While there is some mixing of the "chunk" while it is being pushed forward and backward but, depending on port size compared to the speaker size and xmax, the entire port air can be evacuated from the port which could not be caused by molecular ressonance.
Originally Posted by LudlamTheory
explain how, and please, provide me the math or ask the person who told you this to provide the math, on how the interior of a car will drop the Fb of your box.
Originally Posted by LudlamTheory
provide me one piece of REAL evidence that states that 16 sq inches per cubic foot is the best.
Originally Posted by LudlamTheory
there are PLENTY of speakers in 20k+ sets that are sealed.
again, explain how group delay, loss in transient response, and peakyness equates to free sound quality?
and as to the lfe, a proper woofer in the proper sealed enclosure can do any lfe youd ever need
again, explain how group delay, loss in transient response, and peakyness equates to free sound quality?
and as to the lfe, a proper woofer in the proper sealed enclosure can do any lfe youd ever need
Originally Posted by LudlamTheory
ok, this is my favorite one:
a - you dont need to port for a clean sounding high output system. ive seen people do 160's or higher with sealed enclosures
a - you dont need to port for a clean sounding high output system. ive seen people do 160's or higher with sealed enclosures
Originally Posted by LudlamTheory
Go play a 20 hz tone on a box tuned to 30-35 without a subsonic filter and see what i mean
Originally Posted by LudlamTheory
again, we have a point of diminishing returns, and, that much port area is just silly to use.
also, the port air doesnt move back and forth as a solid chunk, the individual molecules resonate
also, the port air doesnt move back and forth as a solid chunk, the individual molecules resonate
Last edited by ohiojosh78; Oct 27, 2004 at 02:00 AM.
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Originally Posted by WhiteRabbit
that much port area is rediculous? 100 square inches? I bet I cant count on two hands the number of 7th genners with more than 100 square inches of port.... (shhhh! nevermind they are all spl competitors )
)
For being a moderator Ludlam sure is a *****. I'm all up for a good discussion or debate but dont attack me personally like that
Last edited by ohiojosh78; Oct 27, 2004 at 01:48 AM.
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Rep Power: 338 not to be a ***** myself, but theres no reason to talk about yourself, when the discussion is at hand. We learned in 5th grade to talk about ourselves, but here its aggrivating. I disagree with much of what lud said, but I disagree with just about everything you said. (dont get me wrong, im not calling anyone here incorrect, just that I disagree with you both)
lud is only a ***** after a long night of drinking and going home to a computer rather than to a bedwarmer hes not a bad guy, definitely dont take it personal. By thanksgiving he will have forgotten this thread existed, as will I
lud is only a ***** after a long night of drinking and going home to a computer rather than to a bedwarmer
hes not a bad guy, definitely dont take it personal. By thanksgiving he will have forgotten this thread existed, as will I i boogie for the raindrops
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From: Jackson, Mississippi
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Originally Posted by WhiteRabbit
lud is only a ***** after a long night of drinking and going home to a computer rather than to a bedwarmer hes not a bad guy, definitely dont take it personal. By thanksgiving he will have forgotten this thread existed, as will I
hes not a bad guy, definitely dont take it personal. By thanksgiving he will have forgotten this thread existed, as will Ialthough this time its only after coming home from work, not drinking. heh...
and id say before thanksgiving. if this thread were to die right now, id forget by the end of the week to be honest with you
unless youre DIZZLE
who here remembers our great friend dizzle
i boogie for the raindrops
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Originally Posted by ohiojosh78
13" port is a good "starting point" like i stated earlier not the END ALL OF PORT DESIGNS.
Smaller area of the interior of the car porvides resistance to the movement of the speaker unlike inside of a large room.
READ...This works in conjunction with the 13" port to tune the box to 45hz.
Sigh...Majority are NOT sealed.
No, this is MY favorite one. Porting is free output. There is almost no way a sealed box can outperform a ported box. Give me an speaker in a sealed box and then i'll show you the same speaker in a ported box with higher output. And i thought you knew SOMETHING. That one really got me. You were doing such a good job of trying to be all high and mighty too.
As i stated earlier, if you can and did read, unless you're playing a "bass cd" you will almost never see this range of sound played. So, i was throwing that out. Those were in 2 different paragraphs, thus 2 different areas of my discussion. If you were going for sound Q you could tune lower. Dont be an idiot and come attack me with senseless replies.
1 i was trying to simplify and 2 it is not individual molecules resonating. The entire mass of the air is moving back and forth. Put a piece of paper in front of the port! While there is some mixing of the "chunk" while it is being pushed forward and backward but, depending on port size compared to the speaker size and xmax, the entire port air can be evacuated from the port which could not be caused by molecular ressonance.
Smaller area of the interior of the car porvides resistance to the movement of the speaker unlike inside of a large room.
READ...This works in conjunction with the 13" port to tune the box to 45hz.
Sigh...Majority are NOT sealed.
No, this is MY favorite one. Porting is free output. There is almost no way a sealed box can outperform a ported box. Give me an speaker in a sealed box and then i'll show you the same speaker in a ported box with higher output. And i thought you knew SOMETHING. That one really got me. You were doing such a good job of trying to be all high and mighty too.
As i stated earlier, if you can and did read, unless you're playing a "bass cd" you will almost never see this range of sound played. So, i was throwing that out. Those were in 2 different paragraphs, thus 2 different areas of my discussion. If you were going for sound Q you could tune lower. Dont be an idiot and come attack me with senseless replies.
1 i was trying to simplify and 2 it is not individual molecules resonating. The entire mass of the air is moving back and forth. Put a piece of paper in front of the port! While there is some mixing of the "chunk" while it is being pushed forward and backward but, depending on port size compared to the speaker size and xmax, the entire port air can be evacuated from the port which could not be caused by molecular ressonance.
2 - theres absolutely no evidence to prove that a box in car changes its Fb. There is cabin gain, which changes frequency response, but it at all doesnt change anything in the actual enclosure, this is all due to the acoustics of the car.
3 - according to your formula, 16 sq inches per cube, 13" long, at 1 cubic foot, 16 sq inches, at 13 inches long, thats 51.509 Hz. A good starting point is what the manufacturer reccomends.
4 - your defenition of outperform is strictly on a loudness scale. Again, tell me how group delay and loss of transient response make things sound more accurate? You might like the ported sound because its what you like, but that doesnt discredit the fact that you WILL lose sound quality, regardless of how high end the woofer is.
5 - I have plenty of music that does sub 30 Hz. YOU just can't hear it because youre tuned too high...
again, i wasnt attacking you, and i'll probably forget this all happened by next week, I just dont agree with a single thing from your post
Last edited by LudlamTheory; Oct 27, 2004 at 05:08 AM.
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Rep Power: 311 You know Lud, when I first met you, for lack of a better word, I kinda thought you were a **** too. But after a got to see your posts for a while and read your stuff, I was able to take you for what you are, a wicked ****! Just kidding. You are extremely passionate about your audio and I think that sometimes that transcends your friendly side. It may come off as a personal attack but its really more like an assault on what you feel is misinformation regardless of the source. You are on the upper knowledge bank of an industry where misguided fools consistantly flaunt their stuff and recycle their bullshit information wherever you turn and it's frustrating, this I know. For what its worth I'm sure most of the guys here look for you to shed your light on anything ambiguous in these discussions. I'm not trying to sound weird I think I'm just trying to say I know what its like to take you the wrong way at first and then to appreciate what you do here. I think its important for everyone to remember that there is a world of difference between me asking Lud, hey where'd you get those Utopias, and him saying, why do you care, you can't afford them. . . and him replying to a post that someone else starts that is meant to serve as an imformation source for all, where he feels the information isn't correct. That IS his job here afterall.
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Rep Power: 0 I'm glad Ludlam addressed group delay and such as well as box volume. Thats exactly why I have my subs sealed in my truck. I tried a slot ported box and hated it (custom made for my subs exactly). Granted it was much louder, but it just wasn't the same as the sealed. The bass wasn't nearly as tight anymore.
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Rep Power: 0 I think you're incorrect about having music that plays that low. At least as far as most mainstream music goes. Even most of all rap music, the lower bass frequencies dont even go that low. They know there is no need to since for 1 most peoples stereos lose efficency that low and 2 the sweet spot for most subs is around the 45hz range. Most people would be suprised how low 30hz is in music, not on Bass CDs.
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Rep Power: 0 actually Lud, with 13" long port with 16 square inches of port per cubic foot of box it turns out to be around 43hz. try it here with their calculator.
enter:
Port = square
Enclusure Vol = 5cubic feet
Tuning Frequency = 43
Slot port = yes
Square Vent:
Height = 25 \________my dimensions currently
Width = 3 . /
enter:
Port = square
Enclusure Vol = 5cubic feet
Tuning Frequency = 43
Slot port = yes
Square Vent:
Height = 25 \________my dimensions currently
Width = 3 . /
i boogie for the raindrops
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From: Jackson, Mississippi
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Originally Posted by ohiojosh78
actually Lud, with 13" long port with 16 square inches of port per cubic foot of box it turns out to be around 43hz. try it here with their calculator.
enter:
Port = square
Enclusure Vol = 5cubic feet
Tuning Frequency = 43
Slot port = yes
Square Vent:
Height = 25 \________my dimensions currently
Width = 3 . /
enter:
Port = square
Enclusure Vol = 5cubic feet
Tuning Frequency = 43
Slot port = yes
Square Vent:
Height = 25 \________my dimensions currently
Width = 3 . /
you put your enclosure volume at 5 cubic feet
you said to use 16 sq inches per cubic foot, so i did mine at 1 cube, 16 sq inches, 13 inches long
your formula only works at 5 cubic feet and 75 sq inches,
1 cube, 16 sq inches, 13 inches long, 51.51 hz
2 cubes, 32 sq inches, 13 inches long, 49.3 hz
3 cubes, 48 sq inches, 13 inches long, 48.3 hz
4 cubes, 64 sq inches, 13 inches long, 47.35 hz
5 cubes, 80 sq inches, 13 inches long, 46.45 hz
i boogie for the raindrops
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look familiar?
if youre gonna argue, be original...
look familiar?
if youre gonna argue, be original...
Last edited by LudlamTheory; Nov 1, 2004 at 02:46 PM.
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Rep Power: 0 yea, like many other people on this site i was just passing on information. There are plenty of other people that have done the same thing. I never said it was my ideas. I've just been convinced that these are correct so i passed them on and argued for them.
As far as the car lowering tuning frequency i am correct that it does. I've talked to the engineer at DD and he again confirmed it. The small volume of the car loads the speaker, which in turn lowers the fs.
As far as the car lowering tuning frequency i am correct that it does. I've talked to the engineer at DD and he again confirmed it. The small volume of the car loads the speaker, which in turn lowers the fs.
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Rep Power: 0 damn, i just that article. too confusing for me. but i really thought that was all original thoughts. i didn't realize that so many people here did that, i thought that usually people might put a link with the information to get back to the original article. thats how i always saw it. thanks for the info but i hope when most people put information out that they give alink to the article. it was great to be able to read that original article.
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Rep Power: 0 sir, my last and final argument, after this, you believe what you want, i'll believe what im saying now.
a box's tuning is affected by no factors that are at all subwoofer related. a 1 cubic foot box, with a 3" round port, 13 inches long, is tuned to 35 hz. this doesnt matter if the box holds a 6" jl w0 woofer, or a 9917. the function of the port is not at all changed by the sub. try this test at home. get a beer bottle, drink half of it, blow over it, remember the note. now get in your car (but dont start the car or youll get a DUI), blow over the bottle. guess what, its the same note! this means your box is tuned to the same note. regardless of where your box is, your woofer will unload below tuning.
what you speak of is Cabin Gain. cabin gain does not change the box, the tuning, or the woofer. different rooms have different peaks and valleys in their frequency response. luckily, cars have a huge increase in sub frequencies due to the room's shape and natural frequency response. this being said, this only adds to what the box curently delivers, it does not change what comes out of the box. the box itself produces the same band of frequencies, at the same loudness. the waves bouncing throughout the car is what creates the illusion of a "change in tuning".
I'm done
a box's tuning is affected by no factors that are at all subwoofer related. a 1 cubic foot box, with a 3" round port, 13 inches long, is tuned to 35 hz. this doesnt matter if the box holds a 6" jl w0 woofer, or a 9917. the function of the port is not at all changed by the sub. try this test at home. get a beer bottle, drink half of it, blow over it, remember the note. now get in your car (but dont start the car or youll get a DUI), blow over the bottle. guess what, its the same note! this means your box is tuned to the same note. regardless of where your box is, your woofer will unload below tuning.
what you speak of is Cabin Gain. cabin gain does not change the box, the tuning, or the woofer. different rooms have different peaks and valleys in their frequency response. luckily, cars have a huge increase in sub frequencies due to the room's shape and natural frequency response. this being said, this only adds to what the box curently delivers, it does not change what comes out of the box. the box itself produces the same band of frequencies, at the same loudness. the waves bouncing throughout the car is what creates the illusion of a "change in tuning".
I'm done
