I was wondering if anyone has experimented with the difference between round or tube ports and slotted ports, and are they calculated the same?
Replies (5)
Swez on 11/29/2003 22:37:09
Not sure I can really give you a good answer here. To my understanding, ported is a vent, slotted or a round tube. Shape is not the main issue.... a tuned air passage is.
The area inside the tube is the key to it all... not the shape per-se. The port/slot is designed to a give a specified level of air flow (velocity) through a conduit of bass waves. The interior size of the port/vent is dictated by the sub parameters, box design and tuning freqauency desired.
There are some good general parameters we can get from most of the better sub makers... but computer modeling tools like Win ISD Pro do a good job at helping to predict performance of a give sub, in a given box, tuned to a specified frequency.
I too wish to learn more on this aspect of enclosure design, but have been hard pressed for time of late to do so.
Swez
cplkittle on 11/30/2003 04:46:33
I answered my own question last night. I have done alot of research over the Thanksgiving holiday, and wrote 2 articles in the DIY section.. one on sealed boxes and one on tuning ported boxes. The information is out there, just hard to find and translate.
I hope these will make for an easy reference. Next time I will include all of the websites I used to compile the article for anyone wanting to do further research.
accusedmonk on 11/30/2003 09:10:13
What about a slotted maze port? Where the sub is in a chamber half the size of the box, and the rest of it is just a port. If any of you have heard of the snail shell box, it's like that, only outta wood, and the boards making up the port aren't slanted, parallel with the sides of the box. I'd draw it on here what it looks like but that's kinda hard.
It's like that so when the sub is moving outward, the air from the port is doing the same making it constanly in phase with the sub. From what I've seen this easily makes it at least twice as loud.
I'm gonna get a dual 12" made like this for my 2, cause the one I have now is all wrong. Never go to Custom Auto Sound in Roanoke, VA. They treat you like you shouldn't be there, get outta my store... That's one reason I want to open up my own shop not to long from now, so I can actually help people, unlike them. Which reminds me, are there any car audio installation schools closer to Virginia then the one in Florida I've heard about? If not it's all good I'll just go there.
Thanks
cplkittle on 11/30/2003 09:38:14
There is a link on the top left of this page for car audio schools. I believe I read about one in that area, where you can obtain MECP certification.
The box you are refering to is also called a transmission line. I plan to write a diy article covering this and all other setups in the near future. I have not yet done much research on this, but I will try to get that one finished this weekend.
Swez on 11/30/2003 12:54:03
Yep, that is a very cool sub enclosure design... transmission line (bass wave guide) configuration.
If I remember what I have read on them, they are not only tuned, but delay the bass wave output to the slot so that the bass is in phase and addititive to the cones' output. Not sure... but I think this design will net upwards of 5-6dB more SPL than a sealed box and maybe +3dB over a tuned port enclosure.
Swez
PS Not a new concept... but some high end Audiophile speakers employ this design for HT and Hi-Fi systems.
Replies (5)
Swez on 11/29/2003 22:37:09
Not sure I can really give you a good answer here. To my understanding, ported is a vent, slotted or a round tube. Shape is not the main issue.... a tuned air passage is.
The area inside the tube is the key to it all... not the shape per-se. The port/slot is designed to a give a specified level of air flow (velocity) through a conduit of bass waves. The interior size of the port/vent is dictated by the sub parameters, box design and tuning freqauency desired.
There are some good general parameters we can get from most of the better sub makers... but computer modeling tools like Win ISD Pro do a good job at helping to predict performance of a give sub, in a given box, tuned to a specified frequency.
I too wish to learn more on this aspect of enclosure design, but have been hard pressed for time of late to do so.
Swez
cplkittle on 11/30/2003 04:46:33
I answered my own question last night. I have done alot of research over the Thanksgiving holiday, and wrote 2 articles in the DIY section.. one on sealed boxes and one on tuning ported boxes. The information is out there, just hard to find and translate.
I hope these will make for an easy reference. Next time I will include all of the websites I used to compile the article for anyone wanting to do further research.
accusedmonk on 11/30/2003 09:10:13
What about a slotted maze port? Where the sub is in a chamber half the size of the box, and the rest of it is just a port. If any of you have heard of the snail shell box, it's like that, only outta wood, and the boards making up the port aren't slanted, parallel with the sides of the box. I'd draw it on here what it looks like but that's kinda hard.
It's like that so when the sub is moving outward, the air from the port is doing the same making it constanly in phase with the sub. From what I've seen this easily makes it at least twice as loud.
I'm gonna get a dual 12" made like this for my 2, cause the one I have now is all wrong. Never go to Custom Auto Sound in Roanoke, VA. They treat you like you shouldn't be there, get outta my store... That's one reason I want to open up my own shop not to long from now, so I can actually help people, unlike them. Which reminds me, are there any car audio installation schools closer to Virginia then the one in Florida I've heard about? If not it's all good I'll just go there.
Thanks
cplkittle on 11/30/2003 09:38:14
There is a link on the top left of this page for car audio schools. I believe I read about one in that area, where you can obtain MECP certification.
The box you are refering to is also called a transmission line. I plan to write a diy article covering this and all other setups in the near future. I have not yet done much research on this, but I will try to get that one finished this weekend.
Swez on 11/30/2003 12:54:03
Yep, that is a very cool sub enclosure design... transmission line (bass wave guide) configuration.
If I remember what I have read on them, they are not only tuned, but delay the bass wave output to the slot so that the bass is in phase and addititive to the cones' output. Not sure... but I think this design will net upwards of 5-6dB more SPL than a sealed box and maybe +3dB over a tuned port enclosure.
Swez
PS Not a new concept... but some high end Audiophile speakers employ this design for HT and Hi-Fi systems.
Copyright ClubKnowledge 2009 * All Rights Reserved
