How to Design Transmission Line Subwoofer Enclosure
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- เผยแพร่เมื่อ 10 ก.ค. 2024
- Ever wonder How to Design a Transmission Line or " T-Line " Subwoofer Box Enclosure ? A transmission line is known for it low bass frequency response and flat accurate response, but is it ideal for custom car audio? After all there are many other choices like ported, sealed, fourth order bandpass, sixth order bandpass and more....
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Who's ready to see the build video? Let's see if we can get this video to 1,000 likes for the next video to be released! Thanks for watching! - Mark
heck yeah!! i'd also love to see the other side of the spectrum. like maybe an aperiodic bi-chamber, or a 4th order, or something!!
You know it Mark, I've made a 8th order or Triple Reflex Bandpass.
Very difficult indeed.
Any chance of putting the T Line in the jeep for a test bump when it's finished?
CarAudioF
abrication
T/L subs are awesome!! Thanks for the quick tutorial on the math. Had them with my ESL's in my home rig.
CarAudioFabrication Of course why not!
My passion for building enclosures using mathematics is the only reason why I graduated college. My classmates always griped about how “boring” math is, but when they came to me to build an enclosure, they finally understood a real-world application that affected them directly.
I'm currently a mechanical engineering student and my car audio hobby makes most of what I'm learning pertinent.
Great video! As a ham radio operator, the concept of a transmission line box for audio really resonates with me. Thank you for making it easy to understand!
Genuinely one of, if not the most useful video I have ever seen on TH-cam. How did I not find this channel earlier! Always wanted to know how Bose get so much bass from a small speaker and this pretty much sums it up. Top man! 👍🏼
This is a very simple TL box. The woofer is at one end meaning the peaks and dips are pretty big. Moving the sub down the line can help smooth the response quite a bit. You can also taper the line(bigger at one end) and also play with damping at various points in the line.
This is a good explanation but there are many more variables that can be tuned in a TL.
Car Audio, bagging a dozen parameters … not a problem.
Mark, this is honestly one of the best explanations of the basics of enclosure design that I've ever seen. If you just add the qualities of different types of enclosures so people learn what the do to the frequency response (maybe more with the dogfood if Hz doesn't mind ;-) ) there would be a lot of people that would finally understand what's going on in their sub box. Heck, I think even some experienced people would gain by watching this, nailing down some basic concepts that are often overlooked.
The first time i ever saw the bose wave radio ad in a magazine showing the port layout inside ive been wondering how it would work in a vehicle. thank you so much for making this video and explaining the pros and cons. Much appreciated man!
Glad to see you explain the science behind it. When I was in the industry (Got out when Tweeter went belly up) I stayed away from ported as I thought they always sounded sloppy. It was also hard to explain to people how much more work it was.
An you just blew my mind how you took time to explain all of the math used in the builds, awesome! Please keep up the informative vids, I learn more every vid. Thank you.
This was a really good and informative video about T-line design, I understand the math so much more now that!
Thanks as always, looking forward to the build video! :D
Excellent video! I've been wanting to do something with T-Line myself and your explanation is much easier to follow than some of the other stuff online lol.
Great video Mark....never built one of these transmission line enclosures ...but I’ll now have a better grasp of the construction and math behind one...thanks again
T-Lines (or back wave variation) will always be my go to enclosure for SQ or in home and when I can get them to fit, the vehicle environment.
There are some good tricks you can employ using these.
I had already known much of this because I have been studying this subject since the 90's. But this was the best simplified explanation of TLine vs ported boxes I have heard to date. Well done.
Brother thank you soooo very much for this video. you explain everything so well. I just built a TLine for my American Bass VFL 8 and i wish this video was around a year ago when i first decided to build it simply because i wanted it for car and home due to my new baby Boy so he can love it just as much as Daddy!!!
Brilliant explanation. I saw one once back in 1996 that was a single 18” in the bed of a p/u truck. Took up the entire bed.
My buddy had 2 10" DC Audio xl's in a t line box, that box was huge and heavy, sounded really good tho, love these boxes
Great video!! I understand the making of these much more than reading about them!!!
I've built two T-Lines designed by a guy on the East Coast. One for two 12's (Pretty basic layout) and another for a single 15 (Tapered with a 180 degree kerfed wall). There is nothing like a properly designed T-Line! Also, both of these enclosures were very compact and broke a lot of the "rules" around T-Lines. I got out of car audio for awhile, but I'm hoping to build one again soon! Nice video!
Justin Vetter
Ehm, when you brake a lot of the "rules" for a TM build, is it still a TM? And how about frequency curves, doesn't that hurt?
As always, a clear and concise explanation to a subject with lots of technical depth. I've been watching for years and just wanted to say thank you and if you offered online classes or even in person classes I'd be (one of the) first in line. Maybe even selling ~hour long instructive videos on parameters for various applications and the various theories for sound quality etc. Just a thought, I don't mean to be that guy who tells you how to run your business lol. Anyways, superb video just like all your others. Your dog is one adorable lil fella too btw.
I have worked with Mark in making a custom box for my 12's and everything went great.
Right now I'm having him build another for some DDX-12's
Daniel Lanning can you let me know what you come up with for yr ddxs I'd really appreciate it thanks
Interesting followup, the differences between quarter wave, half wave, full wave, ect.
Really good visual explanation using the dog food. Good stuff!
I wanted to have a way to visually represent it, I hope it helped! Thanks for watching.
CarAudioFabrication it did the trick
Stuart Wood I find the wet dog food yields a smoother response.
@@CarAudioFabrication Agree! What if you horn-load the sub? Does that add to the number of dog foods, due to higher efficiency?
Best explanation I have ever seen. Good Job.
AMAZING WORK, ive been looking into trying a T line but just didnt know enough and have mainly built low tuned ported boxes, definitely going to try a build for a single or a single 10. thanks mark
I actually really enjoyed the way you presented and explained that.
I really wanted to design a tline but didn't know where to start. Thanks for the info bro!!
Thanks for watching!
Awesome video with user-friendly explanations on the technical stuff. Well done. Subscribed.
Love the dog food/total available energy description. I would really enjoy an informational video on aperiodic loaded subwoofer.
Excellent video, every time I was thinking, "but what about....(tappered, guys who think they add SPL, stuffed, multiple complex mathematical theory formulas, )" man, you had it covered. I think you really covered the basics of a T-line enclosure, with a simple formula to get someone started. 👌
Just like sealed, ported, and passive radiators, you can make full-range T-lines for home speakers. The ones I have seen are usually 6"-8" full-range drivers in a T-line.
Hey Mark, Great intro to T-lines. Please consider doing an advanced math video for T-Lines as well.
Cheers
I was very entertained by this video, and I learned some good info from it! Keep it up! I like these types of videos, as I'm sure many others do.
Wow I learned something today! Kudos! Very well explained, Excellent job!
Very interesting, I always thought of t-line as sort of a mystery I could probably figure out if I was really interested, but I 'get it' now, and it's not exceptionally difficult. I'm not sure about _tapered_ t-lines, but this is a good starting point. Thanks!
Great video! Very informative, very easy to understand and to apply!
Thank you for being so clear.
Man... I loved this video, lots of juicy information, keep going :) I am going to try the math in Excel mode and passing it to european units.
Thanks a lot for this T- line building idea.
Thank you. That’s was a very easy explanation and informative
Saw this video before work...instant like!👍
Dog food demo was so on point, couldn’t explain any better great video
The Fab Kitchen is looking good and clean. Good video on t line boxes also.
coincidentally this was exactly the video I needed right now xD also I now know a T-line is not for me. regular ported it is :D thanks for another great video!
Thank you that answered a lot of questions.
You should do videos explaining the difference between ported, 4th order, and 6th order bandpass enclosures and also show how the work and how to build them for people trying to get into spl builds.
Really like these super technical videos. You do such a good job at explains complex concepts and techniques.
Could you possibly do a video or even a demo comparing 3 boxes of equal size and volume but one is t line, 1 ported, 1 sealed and measure the response with the same woofer and amp?
That would be so interesting to see and would reinforce how much difference a good enclosure can make.
Car Audio.etc i
This isn't super technical, its basic.....
You are the best on the line!
Great explaination and great workmanship
In some more advanced TL theory is stated that the speed of sound is slowed when passing through fibrous material such as poly-fill. This reduction in speed is dependant upon the sound frequency in question. It involves some extra math. However with proper stuffing it is possible to build a much smaller (read shorter line) TL subwoofer cabinet.
Fantastic explanation. Thanks so much. 😉
I love the line box
The dog food explanation ! ...perfect 😎
I made a tapering T-line with stuffing. Some tapering enclosures expand, the one I made contracts from equal surface area to about one third. It's half wave with a 12", and my god does it pound at 20Hz. I'd be interested to see what it's like in a car though it's 8' long, this one is just for the home theatre. The idea of the stuffing is also to reduce any port type resonances as the chamber behind the sub is larger, before the stuffing it had a 50Hz resonance and had cancellation at 60-70, the stuffing absorbs the higher frequency waves to reduce cancellation and reduces the type of airflow that a port produces to eliminate that resonance. I also used thin sheet metal behind the driver and at the curve (the design is up and back) with expanding foam behind it to make a perfect curve.
UniCrafter In the South, we don't use Stuffing... We make dressing on the side... Will that work? 😂
I love the dog food graphics! Amazing :D
this channel is awesome. im addict to it.
Man i love your reveiws man
This is your best video!
So glad you covered a t line. I love this part of audio
thanks for sharing Mark!
This was a bit helpful, will be building one for an 8" infinity sub, thanks...
Great explanation!
FINE! subb'd bcuz U did a really good job essplainin' the maths behind a T-line.
Thank you so much for this. I used your math to build a regenerative transmission line subwoofer like I saw from wisdom audio. I used 2-3ohm 8" Tymphany woofers with a QTS of .58 and it sounds incredible. The bass hits lower then I could have ever hoped for. I do have a question though as I want to build a giant cabinet to go under the couch.
My question is: Would a woofer with a lower QTS yield better results? or are there particular specs you look for when choosing a woofer?
OH man I so miss my T line box in my old wagon... The car was painted flat black, with a coffin shaped outer layer on the box. Figured since it was so big might as well play to the "coffin" thing everyone refers these as :P
Great videos man.remind me of some of the quantum mechanics videos I watch.so many things to think about.its probably so hard for someone like you to settle on and install a personal system in your vehicle.so much to think about...port length ,frequencies,even eventually have to factor on dimensions of your car.....keep ya up at night thinking for months.lol.thanx for the lessons
Cheers buddy, I'm learning about subs here 👍
Great video mark!!!
i have a double rockford t2 12 in a transmission and it wins alot in db and sound great
Nice explantion!!!!!!!!!!!! Thanks so much!!!
KibbleRTA(tm)! Hahaha, I like it. A well-built T-Line sounds really good, but they can be grossly inefficient, especially for Car Audio. At least with a ported box, you can adjust your tuning frequency to work with cabin gain for SPL or SQ!
I have built those for a few years. Hertz is hella cute.
hi there, thanks for share your knowledge! very nice videos. you have a beautiful workshop, i wish mine was like that ; greeting from colombia.
I just designed a T-line enclosure for a DC m3 8" and it was not that hard.
Thanks for the vid.
did you get a chance to measure the response curve?
Perfect!
Great video!
WOW Mark , great Video! I will share the heck out of this.
+adam watkins appreciate that! Thank you
You the best mark love your videos !!! You the man tnx for sharing
I appreciate that, thank you for watching!
I'm keen on this build for a number of reasons, not least because the 6.5" Skar subwoofer I got for a specific application, and planned on a bass reflex enclosure based on an email in which they claimed a "tuning frequency" of 40Hz (which I thought meant resonant frequency) turned out to have a resonant frequency of 64Hz. I am definitely looking for FLAT frequency response (I'm 62 years old and have never been a fan of BOOM BOOM!), and if this takes me down to 32Hz (using you half-below-twice-above-Fs rule of thumb) before things fall off, I think I can live with that.
If you're wondering why I'm using a 6.5" sub, the space I'm working with (package shelf of a first series Miata) is very limited in height. While there's not much total volume either, given the SD of 17.52in2, and the relatively high Fs (which, if my calculations are correct, makes for a port length of less than 4.5 feet), I think it's doable.
What scares me is the "...once we build the box, we're going to need to do some [testing and] fine tuning". Besides adding stuffing, it's hard to imagine how to fine tune something that is a glued together wooden box. And apart from using my ear, I don't know about testing (I'll be searching this site for videos about that, but if you wanted to shoot me some links, that would be most helpful).
Alan Johansson did you ever do this? I too have some spare 6.5 woofers around
Bry Ytab Not yet. Considerable life has happened since.
Alan Johansson understandable..it will be cool to see, if you ever attempt it
Usually tuning is adding wood in the "chamber" or creating a narrow "throat" to distinguish where the chamber ends and the port begins
Hi there, Mark. I liked your video for explaining things in very easy terms to understand for a newbie like myself. Got a question - let's say you target frequency was 60 hz using a driver with a response of 48Hz - 22000Hz. So, 60 hz is higher than 48hz. But what would happen if your target were 35hz? Would the accordingly calculated enclosure work with the same driver?
LOVE This video dude. I was truly expecting to be correcting you in my head on how/why/etc. I can say my only gripe of the whole video was your handwriting. LOL :)
Question for you Mark:
I noticed in your calculations as well as a few of my own T-Lines trying with different speakers, the mounting depth is larger than the 'W' calculation. Now correct me if I'm wrong, but wouldn't this put the speaker through the first wall? Or did i misunderstand the orientation of the 'width'? I also noticed you didn't touch too much on Md in your Thiele Parameters video, which i could also have misunderstood.
Thanks
-From, a fellow engineer.
So if it's not built 100% mathematically correct, the nice flat frequency will be off. Good stuff. I thought a tline was just a fancy name for a extra long port. I learned something. Thanks
I was looking at the box and thinking that it would make a great home theater enclosure. I might have to build one for my home system.
Mark's onscreen voice is maturing.
Great information here
Thank you, appreciate it.
World's cutest pooch!
Good morning, thank you for so much in-depth info.
Was curious on where line starts....
Your drawing looks like past speaker,and I've read from speaker
Center line and above speaker to port wall?????? Help!!🤯
Thanks again for your time making
us educated😁
I will say also I built a 2way ,inspired from this video
Not being sure of starting point
Of line so I guessed........
I used a Dayton designer series 5" and hivi tweeter (parts express stuff)
I hid crossover in the bottom of box in a pedestal.
Results were amazing!!
My son thought other larger speakers where playing when I showed him them😃
Thanks again man.
This is a chalenge I want to build for a JL 8Wo I have laying around.. Gonna give it a run
1) there will be a 180° phase change when the sound wave reflects off a hard surface.
2) there should also be a 180° phase change when it transitions from the box to the cabin of the vehicle.
3) this box design tunes the system at the Fs of the driver, what happens when you tune the system for the resonant frequency of the vehicle, say 60hz? What gap does it fill in or does it provide a boosted response at that frequency, assuming the driver Fs is much lower?
Nice box!!! Imma call this one "The Tay-lay dog food box" 😋
...I told Rafa's mom
Be nice af to have some of that mobile solutions equipment lol
Question, I’m working with a 12 inch speaker that’s 6 inch’s in depth, do I have to make my air passage way more than 6 inch’s or can I stay at 6 inch’s where the speaker would touch the back of the board for the t line build. Looking at dimensions 15” x 38” x20”
Do a 6th order build log
Omg thanks for this vid...there isnt much info about t line enclosures
You could absolutely get more output with 2 ported 10’s/12’s. But I’ve always been intrigued with how efficient a box can be with little power. I wonder how a band pass compares to a t-line like this.
People. If you have not experienced a 1/4 wave T-line. It is so worth the time to design and build. This isn't a throw together box. You want all cuts tight and precise. Mine was first used in a 2010 ford Taurus SHO. I loved it. it is now doing work no in a 30x50 pole barn. Still the loudest and cleanest single 10" sub I've ever heard. Put my buddies twin 12 Sony Xplodes in a Sony pre fab to total shame. In his own Explorer.
I've been waiting for this video for a while! I want to build one for two 8" Sundown X-8s. I want to build it for the experience. I've built ported and sealed boxes but I've been curious about the actual build for T-Line boxes.
You ever end up building that box?
I have been missing the Dog food! thats why my Violent Bass Air is not so Violent... Great video man
If I were to design my t-line with two 8" drivers, would I just double my SD and base my port dimensions off that new larger number or are my other parameters like port length now going to vary because of how the additional woofer impacts performance when in an enclosure? This is not intended for a vehicle so air space is quite flexible.
can you build a box with the port having staggered humps creating 40 to 50 hertz frequency along the whole port and would it be louder?
does 2x/3x the amount of speakers change the cross-sectional area only, the length only or do both need to be multiplied accordingly?