PDA

View Full Version : sub box design help



jaegerbombs
01-26-2012, 01:53 AM
So this is my personal debate between myself. idk if i should go ported or sealed? I have a pair of the 03 cvrs i am stuck with. Only pair i can use right now. im looking to get alot of low end truck shaking base. i am wondering if i should build a ported or sealed enclosure. i know sealed is better sound quality, blah blah... these are the measurements i was looking to use for a sealed angled box. 24"tall, 50" wide, 5" top' 10" bottom which gave me like a 3.78 cu/ft box. If a ported box is better, what demensions (in those balpark area) should i use. thanks for the advice ahead time. Oh and also if I was to do a ported box eahhh all i am basically loosing in my single cab f-150 is some leg room but ill live! will that same box demensions still wor
k? and i was thinking a 4 in round PVC tube port? could i go from the top near the edge and go down? was thinking of tuning it to 33hz making the tube 14.35" long? should i do lower or higher hz?

Moble Enclosurs
01-26-2012, 03:23 AM
If those are the maximum dimensions you have to work with, and you want to see if a ported design will work, then use all of the area you can utilize. But, if the requirements ask for less space, then use less. I can give you an idea of what chamber volume they will work best in if you like. But the thing is, to get the right answers, you really need a complete design done for these.
Sure, someone could jump on here and tell you what they think they work best in, or what has worked for them, etc, but all in all, if the concern for the design is enough for you to post a question or two to get the right answer, the right answer would be a full design from scratch.
This will ensure you get all of the specification correct and have a better, more accurate idea of what will and will not work for you.

Moble Enclosurs
01-26-2012, 03:25 AM
And for the port.....if you want to use a round port, then with those dimensions, something from the side into the box may be a better idea for placement. Just make sure the design likes the port there.

jaegerbombs
01-26-2012, 11:44 AM
Could you help me build a design? Or do I need to seek a better place for this or what? And I wanna get the best bass with this subs so if they are better in a sealed box the I can do a sealed. But those a pretty close to maximum I would go. Maybe 6 inches longer. But I'm building a complete behind seat box with these subs and mounting amp under seat. I'm sort of a newguy to this box building thing, only built one nice box but switched to 12s so much help on the design would elp. Thanks

kushy_dreams
01-26-2012, 12:01 PM
Whoever told you that sealed has better sq than ported is a dirty stinking liar. A properly designed and built port box can sound every bit as good or better than a sealed box.

jaegerbombs
01-26-2012, 12:08 PM
Thanks for your help kusy_dreams. That helped me a lot :)

Moble Enclosurs
01-26-2012, 06:42 PM
Could you help me build a design? Or do I need to seek a better place for this or what? And I wanna get the best bass with this subs so if they are better in a sealed box the I can do a sealed. But those a pretty close to maximum I would go. Maybe 6 inches longer. But I'm building a complete behind seat box with these subs and mounting amp under seat. I'm sort of a newguy to this box building thing, only built one nice box but switched to 12s so much help on the design would elp. Thanks

I can, most definitely! My designs do come for a purchase, just to let you know up front. I put much more detail in the designs (during the design process) than most you will find, to give a better sense of accuracy. So, if you would like to purchase the blueprints for a design, please let me know.

If not, that is completely understandable. Not many people want to buy designs anymore, and that is ok. There are people on the forum that will get you acceptable information for free, and hopefully they will chime in for you at any time.

As far as what Kushy said about sealed vs ported SQ, that could not be any more correct. With a proper enclosure and response (in all aspects), a ported design can give just as good sq than a sealed. And, depending on your preference of low end, can be more beneficial than a sealed enclosure. Great post Kushy!

jaegerbombs
01-26-2012, 09:55 PM
Nahhh I'm sorry man thanks for all ur help though.

RAM_Designs
01-26-2012, 10:26 PM
Whoever told you that sealed has better sq than ported is a dirty stinking liar. A properly designed and built port box can sound every bit as good or better than a sealed box.

I think the main reason why people insist sealed has better SQ is because the groups delay is lower so quick bass-lines/double kicks/etc do sound cleaner or more accurate due to the better transient response of the sealed enclosure. It's one thing that a ported box will never have over a sealed one. The group delay associated with a ported box is one of the reasons why I like tuning so low. The delay is going to be greater the closer you get to tuning, and it slowly declines the further you get away. So, it makes sense that a person who likes actual music should tune low in order to keep group delay at a minimum where the kick-drum and bass guitar will be playing.

Moble Enclosurs
01-26-2012, 11:43 PM
I think the main reason why people insist sealed has better SQ is because the groups delay is lower so quick bass-lines/double kicks/etc do sound cleaner or more accurate due to the better transient response of the sealed enclosure. It's one thing that a ported box will never have over a sealed one. The group delay associated with a ported box is one of the reasons why I like tuning so low. The delay is going to be greater the closer you get to tuning, and it slowly declines the further you get away. So, it makes sense that a person who likes actual music should tune low in order to keep group delay at a minimum where the kick-drum and bass guitar will be playing.

True, but only for most conventional style designs. The group delay does increase around tuning, but this is only for designs with a tuning factor. Those that are "loaded" correctly will have a very small group delay.not as smooth as a sealed, but still the peak will be greatly reduced when coupling is greater. In sealed designs, coupling is not a factor of environmental concern more than compression area, so group delay will peak based on mechanical parameters alone. There is another factor that helps group delay, in which the output will be more accurate when those are smooth as well.

But yes, in a conventional design, the GD is very tough to control if the design is based on a specified tuning alone, and sealed enclosures do not work on tuning more so than compression compliance.
You cannot tune low and expect the issues to be resolved, because you create a loss in other factors in the design, UNLESS, the tuning creates higher efficiency, but again, that relates to coupling environmentally. You can unfortunately get an averaged delay of over 100ms at tuning in some designs, but if you look at what type of sound it produces, you can even visually see the improvements needed in quite a few of them.

In non-conventional designs (those not based on tuning), you can control the delay quite a bit. And when you do, everything else falls into place with the exception of a few things that tweaks can control. Optimism is not perfection, but when they all work together, man what sound that can be produced! The thing is, even with higher tuning, such as that in a sealed design, GD can be controlled. A great design concept of this example would be a tapped 4th order. if you know how they work, you will understand the control they can have....even over a conventional 4th order.

Take for instance, this:
http://img80.imageshack.us/img80/7153/sealedto4thresponses.png (http://imageshack.us/photo/my-images/80/sealedto4thresponses.png/)

This first pic is a conventional sealed response against a conventional 4th and a non-conventional tapped 4th. The tuning is different from the three because each required a different tuning to control the group delay and phase to what will be shown.

http://img11.imageshack.us/img11/4481/sealedgd.png (http://imageshack.us/photo/my-images/11/sealedgd.png/)

This second pic is the group delay from the sealed design. Notice that as mechanical parameters are matched, or challenged, the delay gets higher. This is a different effect than that of a ported design because coupling is designed different.

http://img853.imageshack.us/img853/6088/sealedphase.png (http://imageshack.us/photo/my-images/853/sealedphase.png/)

This is the phase response of the sealed design. At 0 degrees indicated the same effect as a tuning frequency, but based on compression only. This is around 73Hz, which would denote the "tuning" of the sealed enclosure, if it were to have one.

NEXT, is the 4th order comparisons to this...........The purpose will be to show that tuning in not a major factor in group delay, and that higher tuning can create a smaller delay if coupling is better than that of the other.

http://img706.imageshack.us/img706/3262/4thorderresponses.png (http://imageshack.us/photo/my-images/706/4thorderresponses.png/)

Again, tuning is different because the non-conventional design is not based on tuning. But this also notes that if it were, then tuning would be higher, not lower. Next, compare the GD and phase of the non-conventional to the conventional. You will see that it is more controlled even though tuning is higher. This is all because of how it is designed.

http://img11.imageshack.us/img11/7789/4thgd.png (http://imageshack.us/photo/my-images/11/4thgd.png/)

This is the conventional GD of the 4th. Notice the peak at 41-42Hz? That is the tuning GD peak that RAM discussed. Very good point for other designers to note!

Next.....
http://img830.imageshack.us/img830/4108/4thphase.png (http://imageshack.us/photo/my-images/830/4thphase.png/)

This is the phase of the conventional 4th. Note the response between 90/-90, This is where the design will sound best.

Next is the tapped 4th non conventional design........
http://img836.imageshack.us/img836/3127/tapd4thgd.png (http://imageshack.us/photo/my-images/836/tapd4thgd.png/)

That was the GD from the tapped 4th. MUCH better than conventional even though parameters are changed. This is with the same driver and specs used to create each design, by the way.

Now, the phase.......
http://img846.imageshack.us/img846/6259/tapd4thphase.png (http://imageshack.us/photo/my-images/846/tapd4thphase.png/)

. So, the phase of the non-conventional is still very good compared to the sealed as well.

So, if you noticed the differences of GD from the conventional and non, to the compared sealed design. The non conventional design has a better delay factor, which will, like RAM mentioned, sound better.
This was only to show that different designs of ported ones, can, in fact keep a steady balance compared to that of a sealed design, if done correctly. Not to prove anything to anyone. This is for educational purposes only.

This is ALSO, the main reason why non conventional designs, such as horns and tlines and such become popular, because if they are done right, they can generally give better response accuracy than a conventional design.
And this was to show the comparison of those to a sealed enclosure, so that this concept of GD is understood to the point where it, as RAM mentioned, can make or break a design and how the peaks are related to tuning, BUT more importantly, that tuning does not have to have such an effect on GD if all other parameters are designed right.

Hope that helps!

Great post RAM, this is completely the reason why sealed and ported have been confused for a lot of us! Very glad you posted that. :D

RAM_Designs
01-26-2012, 11:48 PM
This is ALSO, the main reason why non conventional designs, such as horns and tlines and such become popular, because if they are done right, they can generally give better response accuracy than a conventional design.

Very true.

jaegerbombs
01-26-2012, 11:59 PM
Wow alrighty