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dontbeaprix
09-16-2011, 04:53 PM
Can anyone explain in english the advantage of a t-line box? I tried searching around the internet and most info about them is above my head. I saw the video with the 6.5 imagine in a t-line box. Are thes good for sq or just to make subs sound louder or what?

supermaxx123
09-16-2011, 04:55 PM
maybe this will help.
for me they tend to get lower, need less power and sound great.
what i dont like is how big they need to be and im talking 1/4 wave.

dontbeaprix
09-16-2011, 04:59 PM
1/4 wave? Can all subs run in one of these?

Kangaroux
09-16-2011, 05:02 PM
Quarter Wavelength Loudspeaker Design (http://www.quarter-wave.com/)

ace_800
09-16-2011, 05:03 PM
I had RAM design me one for my 8" Trubass. Sounds just as loud as what I had.

I went from a 10" Massive Audio powered by a Kicker 400.1(rated at ~430RMS) to the Trubass 8" powered by a Xtant 3150x(specs were 200x1, underpowered by about 15-20% from what I have been told so ~240RMS)

Its just as loud as my 10" was, but as stated above the box is f'n huge for an 8"

dontbeaprix
09-16-2011, 05:08 PM
Quarter Wavelength Loudspeaker Design (http://www.quarter-wave.com/)
Found that when i was searching around, but its like blah blah blah,lol.
So are they hard to build? From what I understand so far is they get lower and louder , but they take up alot of space. What about sq?

Kangaroux
09-16-2011, 05:15 PM
The hardest part in designing a TLine is figuring out the port length, which isn't that hard anyways lol. Just a fancy equation

dontbeaprix
09-16-2011, 05:16 PM
So is the size the only downfall of these? Why isn't more people using these.

Kangaroux
09-16-2011, 05:20 PM
They are designed more for a flat response and overall SQ. They will get loud but after the price of all the wood and the space it takes up you can get close to the same performance with just a well designed ported box

subzero
09-16-2011, 06:09 PM
I hit a 138 with one 12 on 1k in a tline box in the trunk. that I have for sale. they drop lows with ease. You add the polyfil to the sub chamber to make it sound deeper ect.

supermaxx123
09-16-2011, 06:23 PM
It is so much easier to kill a speaker in a tline and it also doesn't seem like an spl type enclosure, at least from the experience i've had with them. They are a good choice for home. I don't know much about designing them but this is how big i had to make a tline for my idmax, its a 12.
http://i115.photobucket.com/albums/n291/beetle123/DSC02066.jpg

sacsking916
09-16-2011, 06:33 PM
it is so much easier to kill a speaker in a tline and it also doesn't seem like an spl type enclosure, at least from the experience i've had with them. They are a good choice for home. I don't know much about designing them but this is how big i had to make a tline for my idmax, its a 12.
http://i115.photobucket.com/albums/n291/beetle123/dsc02066.jpg

thats fuckin huge

subzero
09-16-2011, 06:37 PM
mine is a folded tline, That is totally different than mine.

http://i703.photobucket.com/albums/ww35/brianncns/zsjz9j.gif

supermaxx123
09-16-2011, 06:41 PM
mine is a folded tline, That is totally different than mine.

Mine is also folded, the line is about 17ft long if i rememeber correctly, tuned to 24hz, or 23.5hz?

subzero
09-16-2011, 06:42 PM
added pic

RAM_Designs
09-16-2011, 07:35 PM
This is the one I did for ace_800

http://i45.photobucket.com/albums/f92/RyanM923/Sample%20Boxes/Single8-TB8-35hz-tline.png

Joseph7195
09-16-2011, 07:52 PM
I just built this T-Line this past weekend. I am hoping to get it covered and put in my truck soon.

http://i142.photobucket.com/albums/r105/joseph7195/insideview.jpg

surreal
09-17-2011, 03:30 AM
At that point its really just a vented enclosure. You could call is a chambered t-line but itd just be a fancy (and not too accurate IMO) name.
T-lines can be large or small, long or short. Tapered, consistent, or expanding. It all depends on the drivers used and their application.
There is no simply equation for them, or rules of thumb.

Moble Enclosurs
09-17-2011, 04:16 AM
Incorrect. A chambered transmission line is not the same as a vented enclosure with a fancy name. It is actually designed quite differently. In reality, the design of a tline has no similarities to a ported enclosure(basic) at all, even with a compression chamber. Also, it is not based on a simple quarter wave theory, though, back in the 1940s, this was all they had to go from. Now, other factors have been considered that control much more than just a "tuning". In fact, tuning is not even related to a tline, if done properly, nor does quarter wave technology. It is best to rely on half wave resonance if anything. Expansion or tapering the line also gives it much different characteristics than a "ported" box. It does not have to be used for a specific response curve, but can be controlled in most cases to replicate the anechoic response of a driver, which in turn causes a very controlled SQ response, but if that driver is designed for mainly SPL, such as the SA drivers, it can be used efficiently for that as well. Most believe that using a standard quarter wave along with a line area of the square area of the driver, that this will give best results. This cannot be further from the truth, as it is relative to the design goal, but if you were to design one without any knowledge of it at all, using those basics will give you a decent output for SQL. I would never recommend it though.

surreal
09-18-2011, 05:10 PM
Half of what you posted agreed with me, the other half seemed a bit misconstrued. A bit like a word problem in math, theres a lot in there that just doesnt pertain to the topic.

You can model a chambered t-line just as you can a vented box, and vice-versa. In the end, they all come down to ducts of a given size or mounting point. Giving them names such as t-line, vented, or what have you is only a vague label to a general sequence of ducts/radiators/etc for human interpretation.
You could model the above enclosure as either (and draw it as either..same specs produce same enclosure, regardless of human alias). They will perform the same, because they are the same box! Just because it was modeled one way doesnt make it something else - its only a means of understanding or simplification.

Especially in situations like this where the difference, if any, is so close and vague the differences are really negligible. If not, Im going to start modeling my ported boxes as tapped/OD horns and charge people as such.

RAM_Designs
09-18-2011, 05:50 PM
If not, Im going to start modeling my ported boxes as tapped/OD horns and charge people as such.

lol

Moble Enclosurs
09-18-2011, 06:00 PM
Half of what you posted agreed with me, the other half seemed a bit misconstrued. A bit like a word problem in math, theres a lot in there that just doesnt pertain to the topic.

You can model a chambered t-line just as you can a vented box, and vice-versa. In the end, they all come down to ducts of a given size or mounting point. Giving them names such as t-line, vented, or what have you is only a vague label to a general sequence of ducts/radiators/etc for human interpretation.
You could model the above enclosure as either (and draw it as either..same specs produce same enclosure, regardless of human alias). They will perform the same, because they are the same box! Just because it was modeled one way doesnt make it something else - its only a means of understanding or simplification.

Especially in situations like this where the difference, if any, is so close and vague the differences are really negligible. If not, Im going to start modeling my ported boxes as tapped/OD horns and charge people as such.

Negative. It does not all come down to just that. Also, in the audio world, in particular to the engineering side of it, they are not called "ducts". That is more related to the HVAC portion of a related field to area of pressure, such as installing an AC unit that is big enough to supply sufficient pressure for a given room area. Two completely different terms. SO, now that that is out of the way, I have to now mention that since you question my ability to explain such designs, it has to now at this point, as I have figured it to be inevitable anyhow, that when I first came here to this forum, you were asking me about how they work! Not sure you are yet in a position to question my knowledge.
The names given to each design is unique. The basis of a general transmission line was based from the electrical term in a sense that a coupling has to be designed for efficient operation. Now, a similar way to construct each enclosure is obvious do to the limitations we have in such a small environment(trunk, cabin, etc.) that most of them will start to be construed as identical in some fashion, when trying to maintain a proper acoustical reproduction of the original source.

Human interpretation is not a correct term either. More so, a human "perception". And yes, it does slightly change for each individual, though very similar. Differences can be heard, not so much with increased pressure as with decreased intensity. The above enclosure, yes, will give similar responses, but does not mean they are similar all together. You have to consider the other factors such as the load on the amplifier, and excursion possibilities, etc and many many other factors you have likely stumbled upon on your "google" research of such designs. I never wanted to attack your reasoning nor being another one who is a designer and supporter of the forum, but now it is going far enough for me to have to defend myself in a professional sense so those "competitors" do not give the community a sense of confusion.

Now, since you design as well, it must be mentioned that if you are saying the enclosures are so similar, that no one will notice any differences, first you must understand that the design goal can make one of the biggest differences in this, along with making it seem that what we do, is not any different than designing for a simple "box" persay. So, that will make others question our purpose for being "special" in the field. For this, I would not recommend giving the assumption that what we do is no different than a "standard" design. Even the sealed enclosures, can be modeled and designed much different than a concentration on spec volumes. It's like saying your boxes are more efficient, but designed the same. If that is true, the efficiency is one thing I would investigate. Do not protray that what you do is "simple" enough to be the same as another design, because the construction of a Tline against a BR is much different, even a compressed Tline. They will give similar responses, but some other factors will be different, in some cases much different, between the two, AS LONG AS THEY WERE DESIGNED CORRECTLY(huge key).

So, if differences are negligible, then you are saying paying attention to detail is useless and even your designs are simplified. Differences are not negligible, but some are more important than others. It's like noticing the difference in an HT setup by sitting in different locations...a lot of it has to do with phase, which is not the same as a frequency response curve(the one you mention looks similar). Each factor in the propagation of sound, whether reflected or direct, has their own individual contributions to the overall response. There are different responses to consider, not just a frequency response....such as phase and impulse. which control the quality of sound in most cases. SO, though I do appreciate your reasoning, and do COMPLETELY see where you are coming from, and agree that yes, frequency responses can look very very similar, but the designing of each enclosure SHOULD be different, as each one IS different in its own aspect. It's the limitations that make everything seem so alike.

As far as modeling bass reflexs as horns, there are similarities, but again are done very differently. DO NOT let a "program" make you think otherwise. And its tough to prove as hearing perception also has a factor, along with sensitivity. If you want to stay simple, sure, it works...but I would like to continue making designs that actually are different in their own sense of physical and acoustical construction. The problem is, you can argue this....what I have said! It can be aruged with a lot of sense! But that is because if you do not understand the differences, than ignorance is bliss.

T.I.K.
09-18-2011, 06:08 PM
nerd RAGE!

Moble Enclosurs
09-18-2011, 06:08 PM
I want to mention, to everyone that sees this, that it was inevitable. I am not saying surreal is a bad designer at all. I have actually given him business in the beginning by telling others that he is good at what he does (and have the "likes" from him to prove it). SO, do not think that I am trying to "expose" anyone, but saying that what I "rant" about or explain is misconstrued, and explain to me that all boxes that are physically the same, will perform the same, and stick to a concentration of a single response curve, likely using a program(do not trust programs so much with enclosure design), then I have to send the message. I am a very nice guy, and my purpose here is to help. But if you question my knowledge, or say it is incorrect(indirectly, or directly), or say something that is not fully true, i will be there to fix it. I do not know everything, I am not any different than anyone else here. But I do know audio very extensively, and arguing the points within a forum thread, is very inefficient as the information I use for my designs are not something that can be explained in words, or anything I would like to explain fully, as one, it would take forever, and two, that would be against the purpose of my existence here. if everyone understood the correct information, all the time, what would be the point of me making a living for my family doing what others can do just as well? That is my reasoning, and I have to defend it, even if it involves exposing the truth.

Again, surreal, you are great at what you do from what I have seen! I still feel that way.

Moble Enclosurs
09-18-2011, 06:11 PM
nerd RAGE!

nerd as in knowledge? That is wrong on so many levels, lol. Nah, no nerd **** here. I was on HS football team for 4 years and married a cheerleader (going over 8 years now), :). Also, military spec ops. So, pretty far from nerd. LMAO.

brodeisel
09-18-2011, 06:11 PM
OMFG will you explain in english and not in no one else will understand.

T.I.K.
09-18-2011, 06:19 PM
nerd as in knowledge? That is wrong on so many levels, lol. Nah, no nerd **** here. I was on HS football team for 4 years and married a cheerleader (going over 8 years now), :). Also, military spec ops. So, pretty far from nerd. LMAO.
I'm surprised, that's your first post in a while that was less than 500 words.

Moble Enclosurs
09-18-2011, 06:24 PM
I'm surprised, that's your first post in a while that was less than 500 words.

Yea, it likely was. Seriously, don't be mean for no reason though. I am here to help man. I'm not here to get into the kid talk or arguments of no purpose. So please, stay on topic if you can. Thanks man.

wenn_du_weinst
09-18-2011, 06:25 PM
nerd as in knowledge? That is wrong on so many levels, lol. Nah, no nerd **** here. I was on HS football team for 4 years and married a cheerleader (going over 8 years now), :). Also, military spec ops. So, pretty far from nerd. LMAO.

The ignorant constantly try to discourage the knowledgeable. It ends up poorly for the people trying to learn. That is a huge reason why I won't discuss enclosure design. I will say chambered t-lines are not modeled as ported enclosures. Tapered t-lines are not the same as a horn either. just because something looks similar doesn't make it so.

T.I.K.
09-18-2011, 06:28 PM
Yea, it likely was. Seriously, don't be mean for no reason though. I am here to help man. I'm not here to get into the kid talk or arguments of no purpose. So please, stay on topic if you can. Thanks man.
my first post wasn't even directly at you specifically, it was really more about the whole conversation you and surreal were having.



The ignorant constantly try to discourage the knowledgeable. It ends up poorly for the people trying to learn. That is a huge reason why I won't discuss enclosure design. I will say chambered t-lines are not modeled as ported enclosures. Tapered t-lines are not the same as a horn either. just because something looks similar doesn't make it so.
The worst part is when people who think they're knowledgeable try to act accordingly.

Moble Enclosurs
09-18-2011, 06:31 PM
my first post wasn't even directly at you specifically, it was really more about the whole conversation you and surreal were having.



The worst part is when people who think they're knowledgeable try to act accordingly.
Yea, it does seems a little confusing if you try to generalize it. I understand man.

This is very true also! Great point! But there is some innocence in it as well as ignorance. Some just want more than what they are willing to work for. I'm glad you made this statement.

wenn_du_weinst
09-18-2011, 06:34 PM
lol trying reverse psychology to get some one to teach you something that others have to pay to learn will not work with me.
I love how you said that but you consistently use larger words when responding to me.

wenn_du_weinst
09-18-2011, 06:44 PM
just to add on to this whole conversation.
I have been playing around with t line variants with subwoofers that would fail horribly in a regular t line. It takes a little more work on the design aspect but if you listen to no one type of music I think the t line and 1/4 wave horn are in the top 3 for musicality and when designed correctly play flat as well. I'm running a 1/8th wave horn in my durango and it will reach down to the low 20's with out much problems at all. It does sort of lack on the higher notes like 65 and up so I need to play my mids lower than I would like to. I will be swapping out for a longer horn and a tapered line here soon to see if I can fix that problem.
the biggest problem with these boxes is the huge space they take up compared to even a ported enclosure, my horn is still bigger than a 4th order for the same subwoofers. The biggest misconception with t lines is that your sub will lose half of it's power rating. It's not that simple, many drivers will be fine with rated rms or more. I know my shocker sigs were taking a 5k amp each in a box designed to unload the cone, the stronger the motor the more chance it has to stay where it is supposed to be. The motor doesn't just push the coil out of the gap, it will push, pull, hold, center, ect ect. A lot of high strength motor subs do better in Infinite baffle and t lines because of this. I have always had a problem getting the correct speed and punch out of a ported enclosure compared to a horn or t-line. I always recommend one of the 2 when I hear the person listens to rock or metal. You would never tell how much faster and punchier your sub can be just from swapping enclosures. With my ported enclosure I had to use my time alignment, with this horn it is all in line with the mids.

T.I.K.
09-18-2011, 06:44 PM
lol trying reverse psychology to get some one to teach you something that others have to pay to learn will not work with me.
I love how you said that but you consistently use larger words when responding to me.

The only thing i could ever learn from you is how to become largely unpopular on virtually every car audio forum on the internet, and you do that for free every time you post.

'Accordingly' isn't a big word :fyi:

wenn_du_weinst
09-18-2011, 06:46 PM
The only thing i could ever learn from you is how to become largely unpopular on virtually every car audio forum on the internet, and you do that for free every time you post.

'Accordingly' isn't a big word :fyi:
For you it is, I guess I need to go listen to some rap to get popular then I can fit in as well. I wasn't aware I needed to be popular on the internet. I do see one positive thing in your post though. You have finally taken the time to use correct punctuation and spelling, or at least gotten spell check.

brodeisel
09-18-2011, 06:51 PM
For you it is, I guess I need to go listen to some rap to get popular then I can fit in as well. I wasn't aware I needed to be popular on the internet. I do see one positive thing in your post though. You have finally taken the time to use correct punctuation and spelling, or at least gotten spell check.

http://images.cheezburger.com/completestore/2010/1/1/129068431461124749.jpg

RAM_Designs
09-18-2011, 06:51 PM
Mobile, how long is the line on that design that Joseph posted up?

wenn_du_weinst
09-18-2011, 06:55 PM
Mobile, how long is the line on that design that Joseph posted up?

Looks like about 30'' or so, It's not a t-line, it's just a ported enclosure with a folded port.
t lines do not have to be ''tuned'' to driver fs though. They can be much shorter if your car's cabin wants it to be so. I think pete's box is tuned in the 50's for his suv. My horn is 25hz higher than driver fs as well.

RAM_Designs
09-18-2011, 06:55 PM
I guess I need to go listen to some rap to get popular then I can fit in as well.

???

RAM_Designs
09-18-2011, 06:56 PM
Looks like about 30'' or so, It's not a t-line, it's just a ported enclosure with a folded port.

Be careful, I believe Mobile got quite upset when surreal said that. :laugh:

wenn_du_weinst
09-18-2011, 06:57 PM
???

It's just a generalization of his way of thinking. I do see now he is going to follow me around and groan everything I say. Just another point that people can not handle add on's like that on forums. Abusing the system because he didn't get his way or some one doesn't agree with him.

T.I.K.
09-18-2011, 06:58 PM
For you it is, I guess I need to go listen to some rap to get popular then I can fit in as well. I wasn't aware I needed to be popular on the internet. I do see one positive thing in your post though. You have finally taken the time to use correct punctuation and spelling, or at least gotten spell check.

Again with the assumptions regarding my taste in music, I wasn't speaking in terms of high school popular, I was talking mostly about how you're banned on CACO and you were run off of SMD for being a douche, which is kinda hard considering who owns the site. I haven't misspelled or made any huge grammar errors in any of my posts... I might forget to capitalize 'I' or the first word every now and then, but nothing that any normal person who wasn't reaching for anything to nitpick would notice or care about.

Moble Enclosurs
09-18-2011, 06:59 PM
Mobile, how long is the line on that design that Joseph posted up?

I would have to check if you like. I do not have it up right now. But yes, wenn, it is actually a constant area compression Tline, not a bass reflex.

wenn_du_weinst
09-18-2011, 06:59 PM
Be careful, I believe Mobile got quite upset when surreal said that. :laugh:

it's ok, that is one of the best ways to get a discussion going. That is of course when the 2 people talking can actually understand each other and no one ends up talking to a brick wall. I will see if I can find the paper I had on t lines. One of the few not based around home theater.

wenn_du_weinst
09-18-2011, 07:04 PM
I'm confused how it is acting as a tline with a chamber larger than the line width and length. Are you certain it is acting as a line? the whole point of a tline is to unload the driver and a chamber that large should be loading it quite a bit

Moble Enclosurs
09-18-2011, 07:04 PM
it's ok, that is one of the best ways to get a discussion going. That is of course when the 2 people talking can actually understand each other and no one ends up talking to a brick wall. I will see if I can find the paper I had on t lines. One of the few not based around home theater.

It is a good way to get a discussion going, but more on how to get an argument going, which is less efficient. :) As far as papers on designs, these actually have a lot to do with generalization in some cases and tests that are not repetitive. In scientific theory, it is best to get a trial and error going that consists on at least 3 consecutive similar results. A lot of papers do not do that. They model, then say, "oh, this must be a constant". Which is why so many papers exist, and the technological advances in audio have been slowed down from the beginning. It's not bias, but not enough for one paper to conclude in some cases. So, I would like to see which one that is, myself.

RAM_Designs
09-18-2011, 07:07 PM
I would have to check if you like. I do not have it up right now. But yes, wenn, it is actually a constant area compression Tline, not a bass reflex.

I was just curious, as it seemed kinda short. No need to look it up.

wenn_du_weinst
09-18-2011, 07:10 PM
I don't agree with many ways people argue ''is the way to do it''
Really it all has to be learned on your own. You never know what variables have been changed from one build to another. I know pete even went and designed his one modeling software to meat his designing requirements. I would like to see how it compares to real world but unfortunately it is unavailable.

Moble Enclosurs
09-18-2011, 07:17 PM
I'm confused how it is acting as a tline with a chamber larger than the line width and length. Are you certain it is acting as a line? the whole point of a tline is to unload the driver and a chamber that large should be loading it quite a bit

That is actually one of the reasons why the post from surreal existed, lol. It does have a similar response to a bass-reflex, if one were to calculate the design as such. But tlines do not have to have a small compression chamber compared to the line. The concept of the design is constant, but the requested response is what gives it similar characteristics of the bass-reflex, but the designing of the compression area with the line was done of that from my tline calculations. This is why I mentioned in my rebuttle post that it would be easy to argue the fact that they are similar. Because, without showing you the actual and exact way that I design them, it would be tough to form an arugment against others known knowledge of them.
The unloading of the driver is not a characteristic of the tline-but the coupling of it to the environment is, but so happens that it becomes popular with larger area lines. It is still loaded, but yes in this design, much more than what is "popular" and noticed around the world. So, to bunk this, yes, this design alone, has many visual characteristics of a bass-reflex and gives similar frequency response curves, but the other factors are different, as far as mechanical and thermal control of the driver. When dealing with physics and acoustics, as mentioned in the rebuttle post, limitations will cause this to occur(the similarities).
Now, since coupling is important in tlines, it also depends on the vehicle characteristics, which in this case, in order to give a lower response from the center of the vehicle, where losses are evident, than a smaller area is requested by the driver. But again, the calculations are the same. There is not direct rule of the relation to the area with the compression area or surface area of the driver, other than the ones needed to figure for the entire designs characteristics. In other words, unlike quarterwave, and simple ports, the line is based from all other characteristics as well as the others are around it. So, the line area will always vary, and there is no minimal area, other than that considered for "port mach" calculations. That is the main similarity of the designs, is the need for minimizing noise. Other than that, they are in fact quite different-to a point. And again, tough to argue without showing you "how" I do it. That, I will not do, as it took me a long time and a lot of work and money to get where I am.

Moble Enclosurs
09-18-2011, 07:21 PM
I was just curious, as it seemed kinda short. No need to look it up.

No problem, it seems short because it is not based on quarter-wave like most general ones are. :)
it will always be a tough argument for us to explain the reasons for our discussions and differences without evidence. But, this is not something that any of us are usually willing to give out. Mainly for me, because my business is legal and operating actively. It's not a patent or anything, but jsut a lot of information put together that make it work, and give each design the ability for flexibility in its own response for full control of the design output, other than exact spl, which relates more towards environmental factors. That is the one thing that is still tough to design for, unless you have the environment available to test as well, would be SPL output, so for that, I usually use the standard 2.83V output response. :)

wenn_du_weinst
09-18-2011, 07:21 PM
You mean you don't use the, cone area and fs rule? lmao
I always get irritated when a ''box designer'' simply uses max dimensions to design some one an enclosure. I mean I have moved my box 5'' to the side in my car and it changed the response greatly. Now you have some one taking a wild guess on what works best in your car with out any measurements or freq response data.

Moble Enclosurs
09-18-2011, 07:29 PM
You mean you don't use the, cone area and fs rule? lmao
I always get irritated when a ''box designer'' simply uses max dimensions to design some one an enclosure. I mean I have moved my box 5'' to the side in my car and it changed the response greatly. Now you have some one taking a wild guess on what works best in your car with out any measurements or freq response data.

Far from the truth. i use EVERY factor. I do not use it the way others normally do though. Some of what I have put together is of my own, and some is of constants that have to be used. In the case of all my designs, cone area does help figure for line area, moreso the length of the drivers surface area, rather than cone area alone, but fs is not something to go from. This is a free-air measurement and changes when in a restrictive environment of any size, respectively. I assure you that no wild guesses are made on my part, which I am sure I have made clear in a few earlier posts, such as the response comparison post I did using my math, constants, and programs to show it to the public. Now, regarding max dimensions, this is sensitive. They are usually recommended as an entire enclosures area, but compression will obviously change within the enclosure along with the need for tapering and such. The interior of the design is only related to the exterior in the limitations required. i assure you that any max dimensions used in car audio are still acoustically smaller than what SHOULD be used, and even max dimensions are considered a limitation. And as far as moving the enclosure, this is a factor that is important to me and figured for as well, and within the actual design, can be controlled (to a point like any other factor-as best as possible) by the location of the driver and output of the rear wave. EVERYTHING is involved int he design, and thinking of one single limitation will obviously cause confusion.

surreal
09-18-2011, 07:37 PM
Im not saying youre bad either. Just discussion - and to be kept as such of course.

And duct is something of a general term. Akabak uses this most often.. The creator of LEAP even stated their chambers and all are computed as very complex 'ducts'. Im too lazy to find the post on their forums but I know its there somewhere.

My point was simply because something is modeled or can be labeled a certain way..doesnt mean it cant be another and be the same/very similar. Box names as understood are only words used to give us a basic idea of what were working with. A chambered t-line for example with a larger initial cross-sectional area could be modeled exactly as a vented enclosure.

Moble Enclosurs
09-18-2011, 07:38 PM
Rant---It is obvious that a discussion of design will ALWAYS be turned into a bunch of different ideas, and rules, etc. It is because of this, that what i do will always be misunderstood in some case. i find it very tough to get a point across to anyone who has their ideas biased, or stuck on specific characteristics that they know of, from some other source. This is why most designers begin to become distanced during the course of their hobby or career, and why some of them are forced to say some mean things and have forceful attitudes, because someone will always be around to question, based on other forms of design that are so well known that people believe them to be correct.
I can relate this to a very sensitive topic of what we all deal with subconsciously everyday.........the governments around the world and the theories around corruption, specifically involving cults and organizations. The people that are on the side of the wealthy and involved, will always be forced to explain something that they cannot without sensitive information being exposed, and corrupting the actual ideas of the purpose of each organization. In a way, designers are the same. All businesses that do not fully expose their secrets will be questioned in some ways. So, for this, the point is, as much as you will question our ability to design correctly, just believe that it is done the best we can with the limitations we have, and it will never be perfect, but we do the best we can. Why is that never good enough for some people, when we bust our asses to get this far, and people try to figure it all out the easy way?

Immacomputer
04-05-2012, 12:56 PM
I'm confused how it is acting as a tline with a chamber larger than the line width and length. Are you certain it is acting as a line? the whole point of a tline is to unload the driver and a chamber that large should be loading it quite a bit

The actual point of a tline isn't to unload the driver but to couple the driver's rear wave to the environment and reduce the mechanical impedance on the driver near Fs to allow the driver to become critically damped, reducing distortion while still retaining solid output and increasing transient response. The chamber of a tline will go from a high pressure area at one end and when it leaves the enclosure, it will be at a high velocity area with respect to the air molecules. So there will be pressure and loading onto the driver.

Something that I have learned after many years of playing with 1/4 wave enclosures is that EVERY box will be affected by 1/4 wave theory, even bandpass enclosures and SEALED enclosures. I've demoed a box that was made like a tapered tline with no open end creating a very large sealed enclosure. I demoed that box right next to the same driver in an enclosure that was the same cubic feet but was constructed differently. The difference in output was almost the same with the tline sealed box playing a tad deeper. The sound quality was definitely noticeable by a much more clear and crisp mid to upper range on the tline enclosure.

The same thing applies to other enclosure types. So that ported enclosure will have a Helmholtz resonance and a 1/4 wave resonance. How well they mingle with each other will determine the response of the system. Simply summing the two output responses won't give you actual FR you're going to get but both are going to affect it. Also, once the enclosure enters into a vehicle, the transmission line continues with the dimensions of the vehicle and this will affect FR. People call it "cabin gain" having no real idea of what it actually is and they then put random values on it and call them default for all cars. This isn't the case and it's just the car acting as a tline extension. I had a mathcad model setup where I could put any type of enclosure into the cabin of my car and predict the response within 1dB across a 10-100hz sweep. All I did was modify a few formulas from MJKing and added a separate section to enter a set of vehicle interior dimensions.

The enclosure pictured in this thread can be modeled as a tline with the "compression chamber" leading to the line actually being part of the line with a much larger line area than the rest. There will be some 1/4 wave effects as well as Helmholtz resonance. If you design an enclosure like this properly, you get what Pete called a "t-box". I found awesome results from these to get a 1/4 wave sound while actually keeping the enclosure size smaller than it would normally be for a tline enclosure. I had an old AE AV12 in an enclosure like this and got excellent FR results from it while sounding amazing, getting very loud, and handling 1.2kw rms with no problems. I could even get hair trick action out of my sunroof at 22hz with that enclosure. The key I found in designing them was to calculate the line area based on Sd, Re, BL, Vas, and a couple other parameters. Once I found the optimal area, I would sync the helmholtz resonance with the 1/4 wave resonance and try to get them to match with the driver (not Fs). I would use the size of the compression chamber size to tweak the Helmholtz resonance and the actual driver resonance (again, not Fs). Once all these came together, the results were pretty awesome. I made a few enclosures like these for friends and everybody was extremely happy. I also made an enclosure design for two Fi SSD 12s that looked like a standard ported box tuned to 42hz but I synced the 1/4 wave resonance with the sub resonance and with the vehicle resonance to make it peak at 157dB at 44hz while still at 155dB at 27hz and 156dB at 60hz at the dash sealed up with a TL.

So all I'm saying is that all enclosures will have a 1/4 aspects to them regardless of what we try say that our design is or what theory it uses. Moble definitely understands what he's talking about so I would take some time if I were the OP and try to understand it.

Moble Enclosurs
04-05-2012, 05:00 PM
Wow, I remember this thread. :D. Thank you for the explanation as well IAC and it was very well written. The basics of tlines are not that basic when you deal with the changes that occur within a given environment, but if you dont have some sort of nominal figure to base the changes from, which we both seem to have working, then the accuracies of this enclosure will always be an issue of discussion.....as we all know, the same enclosure in a different environment will perform differently when loaded at the listening position, but one thing that remains semi constant is the characteristics of the FR from the seperate/calculated enclosure physical construction of the interior.
And great point about the "cabin gain" assumption. If you do model this out cofrrectly, involving all 3 dimensions, you can effectively "load" the driver to the enclosure, and "load" the enclosure to the vehicle seperately and be able to figure for the changes each time a "loading" situation occurs. The idea of an extended tline is the reason why the discussion/argument of a smaller tline performing much like a BR. Because if the factors of cabin gain are not considered, you may have an incorrect, or should I say, incomplete response curve in any situation of car audio design.
Awesome