I have scoured the web and watch watched all the idiots on youtube that slap together a box with a lot of angles and call it T-line and this 2 part explanation is the only one so far that has any real explanation or scientific merit behind it. Thank you for the very detailed explanation and how one can figure this on his own without magic dust. Best line ever: Problem is when you put the speaker in the box, the box has volume and its going to change the free air resonance and that changes the line length but when you change the line length, you change the volume which changes the free air resonance which changes the line which changes the volume which...... I'm going to print that and hang it in my shop as a reminder to quit trying to build t-line speakers :)
felix991 lmao! My thoughts exactly!!!!Shit I have a damn headache after listening to that and for damn sure feel less intelligent than I thought I was!
The pulsating area of a woofer is NOT measured from cone edge to cone edge. It is measured from half a roll of suspension to half a roll of suspension.
Yeah, problem is, the new method is totally reliant on specialized software and most of that is no longer available because this is such a niche application. So unless you can whip up a bunch of calculus and matrix models in math cad, this the approximation that was used for decades prior to "non obsolete" and now obscure to access methods.
I built a 1/4 wave length transmission line back in 1979 using the math for tuning and an 8 inch woofer , because the design is so non precise you can be plus and minus 30% on the line length and it will still sound great , mine sounded amazing esp on bass guitar notes the definition was amazing , the TL sounded better than any other alignment I have ever listened to , they have been my choice of design since then , nothing else sounds as good !!!!
Don't know if I'll build it, but had some fun breaking out my TI-83 calculator programming skills for the formulas. Huge thank you from years later!!!!
Your video is great, I just would like to point out one thing. When you are measuring for cone area you need to take into account the movement of the surround, and how you do this is by measuring from the out side of the surround on one side of the driver to the inside of the surround on the other. From there it is math time.
i dont know if he mentioned it, but the 280 is one quarter of the speed of sound in the first equation. Also, if you use the program's equation solver and set it to solve a system of 2 equations, it will give you the exact length and frequency
I usually work with equation until it well-done finished. Then I entry the numbers to get final result. This video force me to learn more. Cheers from Indonesia
Fine tuning can also be tweaked with volume and density of poly fill . Not to replace correct 1/4 wave length but just for fine tuning to reach a reasonable RTA . Good video on where to start .
SD² - Speed of sound ÷ frequency ÷ 4 x 12(inches) and you have the line length. Personally I've have better audible results with tapered enclosures. Personally I find t-lines to be the most easy to design. Building them depends on the complexity of the enclosure, but its not a problem really if you have even the most basic of woodwork skills.
When I started my quest on knowledge of transmission line theory and design, I was stuck reading math by Martin King and others on the algebraic equations. That scared me off since I was a much better hands on person than dealing with math. I always used simple equations to find my answers. After 150 box designs and builds over a few years, I simplified the formulas to a 6-8th grade standard. No need for all that. But it makes it look legit, I'll give you that. Best bet is to have a good box program like Bassbox6.0 or Termpro box design. Also a wt3 or know called a DAT tester. Knowing the t/s of the sub, inputting them in to the program to find sealed box resonance (still trying to figure out why that's important and usually a lot higher than any number you would want to see anyways ) Also sea level is 1130ft per second not 1120ft. Anyways the simplistic formula ( as on the SMD forum, my Quarter wave tutorial states) Fs example 30hz (1130/30=37.66/4= 9.41) you can also find your 8th wave which is a secondary peak your box will create by (1130/30=37.66/8= 4.7) So if you built a quarter wave for 30hz you will also have a 8th wave gain at 60hz And here is the kicker, depending on your car these numbers barely matter. You will most likely build a line slightly shorter to save space and allow transfer function to take effect. Unless you want a 8" box in a box as big as a box for a 15". Either way, this is still my favorite box design, next to 6th order designs - very fun to build and experiment with.
This is so fascinating! Yet, I cannot find these designs in any of the $10,000 thru $200,000 speaker systems on the market, namely, the Steinway Lyngdorf Model D
Excellent tutorial, was exactly what I needed. I managed to go one step further which may be of use to some people, if you transpose your formula you can end up with an equation in the form length=a*b*c*d etc which tells you the exact length of the line, ie you don't need to rely visually on where the graphs cross. It ends up a nasty formula but works great. Using the same program, make a transpose equation where "equation1 - equation2 = 0" (blue line - green line = 0 ie when they are equal), and then solve it for x. Put the resulting formula in a spreadsheet and you can just enter fs,vas and sd and it spits out the required line length.
it is the speed of sound 1123 feet per secant divided by the speakers Fs and then divide that by 4 gives you the TL length and this formula works really well my horns have only one fold and vent out of the back of the speaker ! instead of the front , instead of stuffing the TL I use acoustic foam on the back wall of the TL , since there are no hard design rules I experimented to see what worked and sounded best ! I found that is the best way to approach a TL design and built there is a lot of wiggle room !!!
Interesting video... I would point out that the surface of the cone area also includes the characteristics of the surround. That value depends highly on the design of the driver and has its own set of equations to determine. To be safe, just use the manufacturer's spec. Also, the free-air resonance of the driver is constant because it is the resonant frequency of the driver system (because the driver is a system composed of many components) while NOT installed in an enclosure. Once the driver has been installed in an enclosure, the system changes and the "Fs" is now the resonant frequency of the driver PLUS the enclosure. In short, worrying about how the resonant frequency of a driver changes after installing it into an enclosure is an exercise in futility because the driver is only one part of the system.
Are you sure you really understood TL? Speaker driver has FREE AIR RESONANT FREQUENCY. Fs. This is frequency where all mechanical parts of driver start to resonate, giving the excessive membrane excursion and impedance peak. This is bad for the sound at that point. Physics explains that any air volume of closed or ported box has it's own resonance (of enclosed air), which actually has much greater force/impact than pure Fs of speaker. So it's canceling Fs to it's own value. Does it really matter where you have your box tuned to resonate? Not much. But usually you tune the TL box to have Fs between resonance peaks of the transmission line cabinet, in order to cancel the natural resonance of driver. If you take a closer look and put your amp meter to speaker, you'll notice there are actually two resonant peaks in TL, side by side in low spectrum, and many more as frequency rise, but you damp that with taper, or pure line damping. I'm afraid your enthusiastic effort is not much worth in real life application, unfortunately. Stay well.
paddle hard hey man, iappreciate your comment. iam a enthousiastic Young speaker builder and i am Building a T-line speaker system. 2 Towers with 8" drivers tuned to 60Hz and a subwoofer with 2 8" drivers tuned to 40 Hz. is it okay for me to Just get the 1/4 wavelength of those frequenties and make that my line length and the line size the cone area, and Double the cone area of my sub. i also would like to decrease the line size going Down to reduce resonance. is this a good idee. would Love some advice. cheers a mutual fanatic
Excellent explanation. I have some TL speakers I designed with a friend, but I’ve had to replace the drivers. It would be nice to see if they are still within parameters.
Does the resonant frequency math change for multiple drivers in the same enclosure? Obviously the port area does, but as far as tuning, should I treat it as one speaker?
You did well and I was following each stage perfectly until you "threw in " that extra 1000 sq inches !! I thought you wanted to determine line length , volume and the quarter wave resonance ? If you have a large volume immediately after the driver the enclosure behaves more like a reflex enclosure with a very long port ... Have a good look at the construction of the original B&W Nautilus enclose ... you'll see what I mean 😀
I got a line length that was 30% shorter than the quarter wave length? According the Martin Kings method, the line length doesn't change, only the cross section area. Great video, I'm just making sure I am following this correctly. Made a test, my first transmission line enclosureusing this method and it doesn't sound bad. However, am I loosing output/bass extension using this method?
If I use multiple woofers does that mean I will need to add up all of the radiating surfaces and make that number my tube area? Example: if I use two 8 inch woofer I would need to have a tube with 16 inches of area?
Very good and interesting video. Even today I watched another misinformed video about the topic, which is sad. One last thing though. Why does the port tuning have to be at the system resonance? The answer is it doesn't. I needs to be close to it, but it also can be slightly below. You can use a simple sim such as Leonard Audio and see the resulting response.
What if i'm trying to design one for a speaker that I pulled out of a junk pile (still in good condition obliviously) that I don't know the specifications of?
HASH VELANI I'm also interested to know where the 12 came from... did you eventually find out? Perhaps it's representing the number of inches in a foot? I'm building a box using metric figures, so need to make sure I get these figures correct! Thanks
How did the sound quality turn out? I am experimenting with TL and am curious about the 1000 in^2 chamber followed by the 96 inch transmission line. How has your box turned out for you?
1120 ÷ 40 ÷ 4 x 12 = 84" - 40 Hz - For a straight t-line 1120 ÷ 35 ÷ 4 x 12 = 96" - 35Hz 1120 ÷ 30 ÷ 4 x 12 = 112" - 30Hz Take the SD² number (T/S parameters) and then adapt it to build the enclosure. Take my latest project of the JL Audio 13TW5v2 subwoofer. ruclips.net/video/ayFFXxoIqXc/видео.html - Getting Naughty with the JL Audio 13TW5v2 Subwoofer Effective Piston Area (Sd) 98.26 sq in / 0.0634 sq m JL Audio 13TW5v2 subwoofer Lets just round it up to 100 sq in. Square root of 100 is 10, so you need the internal enclosure size to be 10" x 10". Ah! ... The problem is that the subwoofer is 13.5" wide. So then you have to adapt the enclosure a little; 10 x 10 11 x 9 12 x 8 13 x 7 14 x 6 - Bingo!! Now you have a 14" Baffle, wide enough to house the subwoofer, and the depth of 6" Then you use the formula (above) to determine how low you want to go. Its really simple!
This is a great video. But it would help if you stopped referring to the drive units resonance as "free air" when it's being placed in a defined volume.
The idea behind TL is to extend the bass performance down to free air resonance. The boost from the tuned tl gives a greater boost to the speakers output as free air resonance is approached and less output the farther away from free air resonce. TL can become tricky since the TL becomes resonant at 1/2, 1, etc so a port tuned to 30 hz would also be resonant at 60, 120 etc. For subs this is not an issue but for tower speakers this may create overly entusiastic bass response.
9.21feet is 110ínches. this whole thing would be nicer if you didn't make the wacky front chamber of 1000cubic inches because without it, i would be the output of your formula would be pretty close to 1/4 the wave length of Fs. and if the dimensions are a bit off the exiting wave would is not just be a bit quieter, because the output would not be he peak of the wave but slightly less. but then a slightly higher frequency would be amplified. a phase change would only happen at 3/4 wavelength of Fs. Do you even need to use Fs really? could you tune the box to spit out different frequencies.
When you added the "1,000" to Volx, you stated that it was in units of in^2, but if that is the case, then the formula does not account for how long the larger portion of the box is in relation to the calculated Line Area derived from the Driver Area. If instead the "1,000" is in units of in^3, then that factors in a larger Line Area of box (let's say 10"x10"x10"). The formula then graphs the total length of the Line Area where the Calculated Line Area Length is simply what remains after the known Larger Line Area. Is this correct?
I agree. That "1,000" in the equation is incorrect in that it is olny defining the "larger sections" cross-sectional area and needs the 3rd dimension to define the actual "volume" of said larger area.
What happens if you tune lower of higher than the drivers fs? it will still increase the output at the tuned frequency correct? or will it cause some problem?
Won't the Fs of the speaker change if you put it in a closed box with equivalent T-line volume? Fs is usually measured with no box, that's why it is "Free air".
+Rennie Ash heck the FS lowers as the sub is used. I do not tune a t-line to the FS, i tune to the desired bandwidth. I tend to tune to 31-32hz (around 97-109" of line). This gives me a useable bandwidth of around 16hz-48hz which is.. perfect for me. A lot of this seems like bad advice.
Eian Wahgener I'm a newbie at this tline box building. I have a rf power hx12 sub with an Fs of 26. so what you are saying is that in order for me to get tline length and portsize for the hrtz I want which is like 35hz. use the frequency instead of the fs? I'm confused
Hey are you confusing the drivers membran area and drivers diameter?. on this video, you talk like the diameter you show as the cone area.Since the membran is not flat the effektive area is bigger then just the diameter inside the rubber suspention.
this is a great video. i mean i been looking for info like this for days now. thanks man. but i would like to know one thing. the Fs of my speaker is 53hz, but i want the box to give nice lows like 30hz. if i use 30hz instead of 53hz in the calculation would it work fine or not, or can it even damage the speaker? PLease someone answer this. I need to know
this is a great video. i mean i been looking for info like this for days now. thanks man. but i would like to know one thing. the Fs of my speaker is 53hz, but i want the box to give nice lows like 30hz. if i use 30hz instead of 53hz in the calculation would it work fine or not, or can it even damage the speaker?
yeah and what about the 12? I just would like to know, because I don't get that. I mean yeah, f= speed of sound/wavelength but how does the portlenght exactly play into that (with that 12)? In the end I think it worked out perfectly but I just also would like to know what exactly I calculated :P
1:54 Are you taking into account that it is a cone and not a flat surface? Also I think you might have over-complicated this a bit. The CarAudioFab channel has a much more simple explanation of this method.
You can use WiniSD, Hornresp - here - www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software-88.html#post5669795 Personally, I've always had issue correlating a graph, with my enjoyment of the said speaker/sub, and most of the time I came up wanting. So I developed my own formula.
Is it me or does something goes wrong here ? The area of the cone ( SD ) is not the diameter because that is a circle . To calculate the SD you also have to include the height of the cone . So ii think it should be something like this : RxRxPixHeight ... Or do a speak all bleh bleh blah ...?? Please correct me if I'm wrong here :-)
I have been trying to do this for about 2 hrs now and for some reason your equation changes when it jumps to the box above the graph. Ive done the step by step about 3 times and my lines don't cross on the graph. Please anyone help.
@@408SPLKINGS So i'm thinking a rectangular box. 8 foot tall or so (Ceiling) with a simple angled piece of wood in the center so it separates it into ~16 feet length.
Need help with a T-Line design Kicker L7 15" sub on left - port on right finish length 58 1/2" finish height - 18 1/2" finish width - 20" using 3/4" mdf tuned to 35-40 hrtz?
port area 180^2 inches. port length at 34 hz is 34 ft peak to peak, so port length is 8.5 ft. Your port needs to be 8.5 feet long with an area of 180 square inches.
can you help me out with some port measurements I want to double up the inside port---outside box of finish measurements given above will also be doubled up i am putting a lot of time in other work on my van and want this to be correct!
+andy wiley your finished box with double wall 3/4 inch had a usable space of 55.5x15.5x17... that makes you port 17x10.5. there is no way to fit 1/4 wave t line into those space requirements.
+andy wiley required port volume for a 15 is 18360^3 inches, your usable space has a volume of only 14624^3... plus you need room for a driver. Drop to a good 12, and you can make it happen.
+Sigma Octantis T-line enclosures direct the rear wave of the speaker to be captured, then channeled to the front (or listening area) in a manner that prevents the rear wave from being out of phase with the frontal radiation. Usually the only part of the wave length that can be repurposed is 1/4 or 3/4 of the wave, the balance of the wave being out of phase. Isn't that your understanding, Backyard Amusement?
Sigma Octantis Because the length and cross section are calculated using constants like the free air resonance of the driver, and the lowest frequency wavelength they are trying to achieve. Sigma no one is saying that they walk on water but if you ever get to hear a properly tuned TL enclosure with wide band program material for a good source...it is often memorable enough to make a life long impression...THAT IS....if you are into fidelity and not just "bump".
Take the SD² number (T/S parameters) and then adapt it to build the enclosure. Take my latest project of the JL Audio 13TW5v2 subwoofer. ruclips.net/video/ayFFXxoIqXc/видео.html - Getting Naughty with the JL Audio 13TW5v2 Subwoofer Effective Piston Area (Sd) 98.26 sq in / 0.0634 sq m JL Audio 13TW5v2 subwoofer Lets just round it up to 100 sq in. Square root of 100 is 10, so you need the internal enclosure size to be 10" x 10". Ah! ... The problem is that the subwoofer is 13.5" wide. So then you have to adapt the enclosure a little 10 x 10 11 x 9 12 x 8 13 x 7 14 x 6 - Bingo!! Now you have a 14" Baffle, wide enough to house the subwoofer, and the depth of 6"
1120 ÷ 40 ÷ 4 x 12 = 84" - 40 Hz - For a straight t-line 1 120 ÷ 35 ÷ 4 x 12 = 96" - 35Hz 1 120 ÷ 30 ÷ 4 x 12 = 112" - 30Hz Take the SD² number (T/S parameters) and then adapt it to build the enclosure. Take my latest project of the JL Audio 13TW5v2 subwoofer. ruclips.net/video/ayFFXxoIqXc/видео.html - Getting Naughty with the JL Audio 13TW5v2 Subwoofer Effective Piston Area (Sd) 98.26 sq in / 0.0634 sq m JL Audio 13TW5v2 subwoofer Lets just round it up to 100 sq in. Square root of 100 is 10, so you need the internal enclosure size to be 10" x 10". Ah! ... The problem is that the subwoofer is 13.5" wide. So then you have to adapt the enclosure a little 10 x 10 11 x 9 12 x 8 13 x 7 14 x 6 - Bingo!! Now you have a 14" Baffle, wide enough to house the subwoofer, and the depth of 6" Then you use the formula (above) to determine how low you want to go. Its really simple!
America; please learn metric! It's not the end of capitalism. It's not a Chinese plot and it's not agin' the constitution. It's just much easier to work with, especially when you're using physics calculations.
+Michael Trainor a rockford fosgate punch will do really well in a small closed box. Rockford fosgate has free plans to build around your t1. (good choice, btw, rockford ;))
![BAK Jay - Find Out (For Your Love) [Official Music Video]](http://i.ytimg.com/vi/10FJO_XBCvY/mqdefault.jpg)
Looks like its going to be a ported enclosure for me. Very good video though. Thanks
I have scoured the web and watch watched all the idiots on youtube that slap together a box with a lot of angles and call it T-line and this 2 part explanation is the only one so far that has any real explanation or scientific merit behind it.
Thank you for the very detailed explanation and how one can figure this on his own without magic dust.
Best line ever: Problem is when you put the speaker in the box, the box has volume and its going to change the free air resonance and that changes the line length but when you change the line length, you change the volume which changes the free air resonance which changes the line which changes the volume which......
I'm going to print that and hang it in my shop as a reminder to quit trying to build t-line speakers :)
felix991 lmao
felix991 lmao! My thoughts exactly!!!!Shit I have a damn headache after listening to that and for damn sure feel less intelligent than I thought I was!
The pulsating area of a woofer is NOT measured from cone edge to cone edge. It is measured from half a roll of suspension to half a roll of suspension.
"This methodology is obsolete"... it's right there, written in RED at the top of the article you chose to follow...
Yeah, problem is, the new method is totally reliant on specialized software and most of that is no longer available because this is such a niche application. So unless you can whip up a bunch of calculus and matrix models in math cad, this the approximation that was used for decades prior to "non obsolete" and now obscure to access methods.
I built a 1/4 wave length transmission line back in 1979 using the math for tuning and an 8 inch woofer , because the design is so non precise you can be plus and minus 30% on the line length and it will still sound great , mine sounded amazing esp on bass guitar notes the definition was amazing , the TL sounded better than any other alignment I have ever listened to , they have been my choice of design since then , nothing else sounds as good !!!!
Don't know if I'll build it, but had some fun breaking out my TI-83 calculator programming skills for the formulas.
Huge thank you from years later!!!!
Ppl should note if they don't have the manufacturer spec you need to include part of the area of the surround as well
Your video is great, I just would like to point out one thing. When you are measuring for cone area you need to take into account the movement of the surround, and how you do this is by measuring from the out side of the surround on one side of the driver to the inside of the surround on the other. From there it is math time.
i dont know if he mentioned it, but the 280 is one quarter of the speed of sound in the first equation. Also, if you use the program's equation solver and set it to solve a system of 2 equations, it will give you the exact length and frequency
I know it's 2 years ago, but thank you for this!
I usually work with equation until it well-done finished. Then I entry the numbers to get final result.
This video force me to learn more.
Cheers from Indonesia
The slope of the lines is so close, it reveals high sensitivity. If you sneeze while cutting the last piece, the TL tune is off. LOL.
"Made easy" - doesn't use metric for caculations
Fine tuning can also be tweaked with volume and density of poly fill . Not to replace correct 1/4 wave length but just for fine tuning to reach a reasonable RTA . Good video on where to start .
SD² - Speed of sound ÷ frequency ÷ 4 x 12(inches) and you have the line length. Personally I've have better audible results with tapered enclosures. Personally I find t-lines to be the most easy to design. Building them depends on the complexity of the enclosure, but its not a problem really if you have even the most basic of woodwork skills.
When I started my quest on knowledge of transmission line theory and design, I was stuck reading math by Martin King and others on the algebraic equations. That scared me off since I was a much better hands on person than dealing with math. I always used simple equations to find my answers.
After 150 box designs and builds over a few years, I simplified the formulas to a 6-8th grade standard. No need for all that. But it makes it look legit, I'll give you that.
Best bet is to have a good box program like Bassbox6.0 or Termpro box design. Also a wt3 or know called a DAT tester.
Knowing the t/s of the sub, inputting them in to the program to find sealed box resonance (still trying to figure out why that's important and usually a lot higher than any number you would want to see anyways )
Also sea level is 1130ft per second not 1120ft.
Anyways the simplistic formula ( as on the SMD forum, my Quarter wave tutorial states)
Fs example 30hz (1130/30=37.66/4= 9.41) you can also find your 8th wave which is a secondary peak your box will create by (1130/30=37.66/8= 4.7)
So if you built a quarter wave for 30hz you will also have a 8th wave gain at 60hz
And here is the kicker, depending on your car these numbers barely matter.
You will most likely build a line slightly shorter to save space and allow transfer function to take effect. Unless you want a 8" box in a box as big as a box for a 15".
Either way, this is still my favorite box design, next to 6th order designs - very fun to build and experiment with.
your theory came out as 9.41 feet (113 inches) of line length for 30hz, and his is saying 8 feet (96 inches) of line length. what do I do?
There are ways to get that number down!
This is so fascinating! Yet, I cannot find these designs in any of the $10,000 thru $200,000 speaker systems on the market, namely, the Steinway Lyngdorf Model D
Excellent tutorial, was exactly what I needed.
I managed to go one step further which may be of use to some people, if you transpose your formula you can end up with an equation in the form length=a*b*c*d etc which tells you the exact length of the line, ie you don't need to rely visually on where the graphs cross. It ends up a nasty formula but works great.
Using the same program, make a transpose equation where "equation1 - equation2 = 0" (blue line - green line = 0 ie when they are equal), and then solve it for x.
Put the resulting formula in a spreadsheet and you can just enter fs,vas and sd and it spits out the required line length.
Me Athome Could you give an example formula? Interested to give this a try!
it is the speed of sound 1123 feet per secant divided by the speakers Fs and then divide that by 4 gives you the TL length and this formula works really well my horns have only one fold and vent out of the back of the speaker ! instead of the front , instead of stuffing the TL I use acoustic foam on the back wall of the TL , since there are no hard design rules I experimented to see what worked and sounded best ! I found that is the best way to approach a TL design and built there is a lot of wiggle room !!!
Interesting video...
I would point out that the surface of the cone area also includes the characteristics of the surround. That value depends highly on the design of the driver and has its own set of equations to determine. To be safe, just use the manufacturer's spec.
Also, the free-air resonance of the driver is constant because it is the resonant frequency of the driver system (because the driver is a system composed of many components) while NOT installed in an enclosure. Once the driver has been installed in an enclosure, the system changes and the "Fs" is now the resonant frequency of the driver PLUS the enclosure. In short, worrying about how the resonant frequency of a driver changes after installing it into an enclosure is an exercise in futility because the driver is only one part of the system.
Are you sure you really understood TL?
Speaker driver has FREE AIR RESONANT FREQUENCY.
Fs.
This is frequency where all mechanical parts of driver start to resonate, giving the excessive membrane excursion and impedance peak. This is bad for the sound at that point. Physics explains that any air volume of closed or ported box has it's own resonance (of enclosed air), which actually has much greater force/impact than pure Fs of speaker. So it's canceling Fs to it's own value. Does it really matter where you have your box tuned to resonate? Not much. But usually you tune the TL box to have Fs between resonance peaks of the transmission line cabinet, in order to cancel the natural resonance of driver. If you take a closer look and put your amp meter to speaker, you'll notice there are actually two resonant peaks in TL, side by side in low spectrum, and many more as frequency rise, but you damp that with taper, or pure line damping.
I'm afraid your enthusiastic effort is not much worth in real life application, unfortunately.
Stay well.
paddle hard
hey man,
iappreciate your comment. iam a enthousiastic Young speaker builder and i am Building a T-line speaker system.
2 Towers with 8" drivers tuned to 60Hz and a subwoofer with 2 8" drivers tuned to 40 Hz. is it okay for me to Just get the 1/4 wavelength of those frequenties and make that my line length and the line size the cone area, and Double the cone area of my sub.
i also would like to decrease the line size going Down to reduce resonance. is this a good idee.
would Love some advice.
cheers a mutual fanatic
Excellent explanation. I have some TL speakers I designed with a friend, but I’ve had to replace the drivers. It would be nice to see if they are still within parameters.
If I use more than one woofer does that mean I will need to add up all of the radiating surfaces to determine the "line area"?
Great video. Great visual examples. I didn't understand a lot of it, but good job. Wish there wasn't so much mic rattle though.
Uhm, I am going to have to watch this a few times lol.
THis is mean to be easy explanation right??? Wow... My head hz... Get it hz haha
great video my friend.
Also ppl do measure from cone side to rubber end. Need to check the difference in sound.
Does the resonant frequency math change for multiple drivers in the same enclosure? Obviously the port area does, but as far as tuning, should I treat it as one speaker?
You did well and I was following each stage perfectly until you "threw in " that extra 1000 sq inches !! I thought you wanted to determine line length , volume and the quarter wave resonance ?
If you have a large volume immediately after the driver the enclosure behaves more like a reflex enclosure with a very long port ...
Have a good look at the construction of the original B&W Nautilus enclose ... you'll see what I mean 😀
MI PREGUNTA LAS TABLAS O MADERA DEL PORT OCUPAN ESPACIO ADENTRO USTED NO LE DESCONTÓ ESO AL LITRAJE NI TAMPOCO LA PARTE TRASERA DEL ALTAVOZ
Great Video. Is there somewhere i can se these numbers and diagrams in metric instead?
I got a line length that was 30% shorter than the quarter wave length? According the Martin Kings method, the line length doesn't change, only the cross section area. Great video, I'm just making sure I am following this correctly. Made a test, my first transmission line enclosureusing this method and it doesn't sound bad. However, am I loosing output/bass extension using this method?
One of the best TL for Dummies out there. Excellent video.
Does your equations account for insulation in the TL port?
If I use multiple woofers does that mean I will need to add up all of the radiating surfaces and make that number my tube area?
Example: if I use two 8 inch woofer I would need to have a tube with 16 inches of area?
Very good and interesting video. Even today I watched another misinformed video about the topic, which is sad. One last thing though. Why does the port tuning have to be at the system resonance?
The answer is it doesn't. I needs to be close to it, but it also can be slightly below. You can use a simple sim such as Leonard Audio and see the resulting response.
Formerly I had to calculate this on paper and the only known values were the size of the woofer and the fs.
What if i'm trying to design one for a speaker that I pulled out of a junk pile (still in good condition obliviously) that I don't know the specifications of?
Just use the basic quarter wave formula, and measure the results.
Great video. In the first function y= 280/x/12, could you explain where the 280 value came from?
just worked out the 280=1120(speed of sound)/4... did u work out what the 12 in that equation was about?
HASH VELANI I'm also interested to know where the 12 came from... did you eventually find out? Perhaps it's representing the number of inches in a foot? I'm building a box using metric figures, so need to make sure I get these figures correct! Thanks
+Jes Kerr, Hey 12 is a unit conversion from ft to inches
What if instead you hust filled it up with lots of tiny polystyrene peices and then sealed the outside in tons of concrete ?
But l want to use a 12 inch woofer. Can l use it ? Will it reverse phase?
Do you add up the radiating area of multiple woofers to create a larger port tube?
I want to use 8 four inch drivers so would that work?
How did the sound quality turn out? I am experimenting with TL and am curious about the 1000 in^2 chamber followed by the 96 inch transmission line. How has your box turned out for you?
Where did you get that 280 from???
Would it be possible to build tline for 3 8s
Superb video! just awesome!
Hello, I am not very capable of doing this calculation, can you do this for me?
It will give you all the electro-acoustic speaker parameters.
1120 ÷ 40 ÷ 4 x 12 = 84" - 40 Hz - For a straight t-line
1120 ÷ 35 ÷ 4 x 12 = 96" - 35Hz
1120 ÷ 30 ÷ 4 x 12 = 112" - 30Hz
Take the SD² number (T/S parameters) and then adapt it to build the enclosure. Take my latest project of the JL Audio 13TW5v2 subwoofer. ruclips.net/video/ayFFXxoIqXc/видео.html - Getting Naughty with the JL Audio 13TW5v2 Subwoofer
Effective Piston Area (Sd) 98.26 sq in / 0.0634 sq m JL Audio 13TW5v2 subwoofer Lets just round it up to 100 sq in.
Square root of 100 is 10, so you need the internal enclosure size to be 10" x 10". Ah! ... The problem is that the subwoofer is 13.5" wide. So then you have to adapt the enclosure a little;
10 x 10
11 x 9
12 x 8
13 x 7
14 x 6 - Bingo!! Now you have a 14" Baffle, wide enough to house the subwoofer, and the depth of 6" Then you use the formula (above) to determine how low you want to go. Its really simple!
This is a great video. But it would help if you stopped referring to the drive units resonance as "free air" when it's being placed in a defined volume.
It is the free air resonance that is being tuned to the TL port.
well that would be pointless as the drive unit wont have a free air resonance in box thats the same as the free air resonance
The idea behind TL is to extend the bass performance down to free air resonance. The boost from the tuned tl gives a greater boost to the speakers output as free air resonance is approached and less output the farther away from free air resonce. TL can become tricky since the TL becomes resonant at 1/2, 1, etc so a port tuned to 30 hz would also be resonant at 60, 120 etc. For subs this is not an issue but for tower speakers this may create overly entusiastic bass response.
No its not. Its to make the rear energy from the drive unit in phase with the front giving a 3 db increase roughly in the area the system is tuned to.
I've never design down to or around FS. I've always done what I want to do with the driver. - ruclips.net/video/hIwZjJanXag/видео.html
9.21feet is 110ínches. this whole thing would be nicer if you didn't make the wacky front chamber of 1000cubic inches because without it, i would be the output of your formula would be pretty close to 1/4 the wave length of Fs.
and if the dimensions are a bit off the exiting wave would is not just be a bit quieter, because the output would not be he peak of the wave but slightly less. but then a slightly higher frequency would be amplified.
a phase change would only happen at 3/4 wavelength of Fs.
Do you even need to use Fs really? could you tune the box to spit out different frequencies.
When you added the "1,000" to Volx, you stated that it was in units of in^2, but if that is the case, then the formula does not account for how long the larger portion of the box is in relation to the calculated Line Area derived from the Driver Area. If instead the "1,000" is in units of in^3, then that factors in a larger Line Area of box (let's say 10"x10"x10"). The formula then graphs the total length of the Line Area where the Calculated Line Area Length is simply what remains after the known Larger Line Area. Is this correct?
I agree. That "1,000" in the equation is incorrect in that it is olny defining the "larger sections" cross-sectional area and needs the 3rd dimension to define the actual "volume" of said larger area.
What happens if you tune lower of higher than the drivers fs? it will still increase the output at the tuned frequency correct? or will it cause some problem?
What if I want to do mmt speakers? Do I just double the length of double the channel width??
Won't the Fs of the speaker change if you put it in a closed box with equivalent T-line volume? Fs is usually measured with no box, that's why it is "Free air".
+Rennie Ash heck the FS lowers as the sub is used. I do not tune a t-line to the FS, i tune to the desired bandwidth. I tend to tune to 31-32hz (around 97-109" of line). This gives me a useable bandwidth of around 16hz-48hz which is.. perfect for me. A lot of this seems like bad advice.
Eian Wahgener I'm a newbie at this tline box building. I have a rf power hx12 sub with an Fs of 26. so what you are saying is that in order for me to get tline length and portsize for the hrtz I want which is like 35hz. use the frequency instead of the fs? I'm confused
Fantastic
Hey are you confusing the drivers membran area and drivers diameter?. on this video, you talk like the diameter you show as the cone area.Since the membran is not flat the effektive area is bigger then just the diameter inside the rubber suspention.
this is a great video. i mean i been looking for info like this for days now. thanks man. but i would like to know one thing. the Fs of my speaker is 53hz, but i want the box to give nice lows like 30hz. if i use 30hz instead of 53hz in the calculation would it work fine or not, or can it even damage the speaker? PLease someone answer this. I need to know
A 53 hz tline may get down to 30hz if you use stuffing inside the box
Very good video, thank you!
You're getting diameter and radius mixed up so it's hard to understand what you mean
1:35 the red line that you draw is actually the diameter
this is a great video. i mean i been looking for info like this for days now. thanks man. but i would like to know one thing. the Fs of my speaker is 53hz, but i want the box to give nice lows like 30hz. if i use 30hz instead of 53hz in the calculation would it work fine or not, or can it even damage the speaker?
If it's 53, you need a larger subwoofer..
Where do the numbers of the first function come from ? Otherwise awesome Explanation ! :D
Yea, so the 280? wtf?
yeah and what about the 12? I just would like to know, because I don't get that. I mean yeah, f= speed of sound/wavelength but how does the portlenght exactly play into that (with that 12)?
In the end I think it worked out perfectly but I just also would like to know what exactly I calculated :P
1120 feet per second ÷4 = 280 for the quarter wave, ×12 inches per foot because he wants to get his TL length in inches.
1:54 Are you taking into account that it is a cone and not a flat surface? Also I think you might have over-complicated this a bit. The CarAudioFab channel has a much more simple explanation of this method.
What if instead i kicked out my naredowell son who wont get a job and filled his room with cottan peices and then ported the tubes i to that?
Where did you get the 1000 squ in from?
Wich software are you using ??
You can use WiniSD, Hornresp - here - www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software-88.html#post5669795
Personally, I've always had issue correlating a graph, with my enjoyment of the said speaker/sub, and most of the time I came up wanting. So I developed my own formula.
If using two speakers, do you make the port the surface area of both the speakers added together?
No, I read something a couple of days ago saying that you shouldn't do that.
hey just wondering if you could do a vid explaining how much accoustic wadding i could put and how it affects the box design
the accoustic wadding slowes the speed of wave and allows the sub to go lower fs ... how much .... must try.
Is it me or does something goes wrong here ? The area of the cone ( SD ) is not the diameter because that is a circle . To calculate the SD you also have to include the height of the cone . So ii think it should be something like this : RxRxPixHeight ... Or do a speak all bleh bleh blah ...?? Please correct me if I'm wrong here :-)
I wrote it down wrong i ment
PI. R. r... So you basicly calculate the cone without the base...
Oops i ment
Pi. R. r
So you basicly calculate the cone without the base...
Do you use the the width from left side of the suspension to the right or left side of the cone to the right?
i use suspension peak to peak. it gives you that little bit of extra space you need to accommodate for especially in non angled ports.
if i wanna make t line enclosure for 2 subs do i measure both cones and calculate the port by that?
I wanna know that too
Do these fight climate change?
I have been trying to do this for about 2 hrs now and for some reason your equation changes when it jumps to the box above the graph. Ive done the step by step about 3 times and my lines don't cross on the graph. Please anyone help.
I was trying to add the 1000cm to the equation and kept getting messed up.
what was that?
Why not make the box a 1/2 Wave length? Why go 1/4 or even 1/3?
1/2 wave length would end up being a huge enclosure
@@408SPLKINGS So i'm thinking a rectangular box. 8 foot tall or so (Ceiling) with a simple angled piece of wood in the center so it separates it into ~16 feet length.
where do I go to get a tline box made for my two 12' quantum audio subs 5000w each
Need help with a T-Line design
Kicker L7 15"
sub on left - port on right
finish length 58 1/2"
finish height - 18 1/2"
finish width - 20"
using 3/4" mdf
tuned to 35-40 hrtz?
port area 180^2 inches. port length at 34 hz is 34 ft peak to peak, so port length is 8.5 ft. Your port needs to be 8.5 feet long with an area of 180 square inches.
can you help me out with some port measurements
I want to double up the inside port---outside box of finish measurements given above will also be doubled up
i am putting a lot of time in other work on my van and want this to be correct!
+andy wiley your finished box with double wall 3/4 inch had a usable space of 55.5x15.5x17... that makes you port 17x10.5. there is no way to fit 1/4 wave t line into those space requirements.
+andy wiley required port volume for a 15 is 18360^3 inches, your usable space has a volume of only 14624^3... plus you need room for a driver. Drop to a good 12, and you can make it happen.
So it's basically a ported box with a huge port?
+Sigma Octantis no
amananca no
+Sigma Octantis T-line enclosures direct the rear wave of the speaker to be captured, then channeled to the front (or listening area) in a manner that prevents the rear wave from being out of phase with the frontal radiation. Usually the only part of the wave length that can be repurposed is 1/4 or 3/4 of the wave, the balance of the wave being out of phase. Isn't that your understanding, Backyard Amusement?
martianshoes Just saying, my ported box looks almost identical to a T-Line box so I don't get why they are so special.
Sigma Octantis Because the length and cross section are calculated using constants like the free air resonance of the driver, and the lowest frequency wavelength they are trying to achieve. Sigma no one is saying that they walk on water but if you ever get to hear a properly tuned TL enclosure with wide band program material for a good source...it is often memorable enough to make a life long impression...THAT IS....if you are into fidelity and not just "bump".
Ill buy a design gladly
If I can help .... drop me a line -no punn intended
I have a planet audio 10 39 Hz qes 0.976 sms 4.47 vas 0.988 Xmas one way 10mm sensitivity 86db I really need some help building a t-line box
Area of a line?
Take the SD² number (T/S parameters) and then adapt it to build the enclosure.
Take my latest project of the JL Audio 13TW5v2 subwoofer. ruclips.net/video/ayFFXxoIqXc/видео.html - Getting Naughty with the JL Audio 13TW5v2 Subwoofer
Effective Piston Area (Sd) 98.26 sq in / 0.0634 sq m JL Audio 13TW5v2 subwoofer Lets just round it up to 100 sq in.
Square root of 100 is 10, so you need the internal enclosure size to be 10" x 10". Ah! ... The problem is that the subwoofer is 13.5" wide. So then you have to adapt the enclosure a little
10 x 10
11 x 9
12 x 8
13 x 7
14 x 6 - Bingo!! Now you have a 14" Baffle, wide enough to house the subwoofer, and the depth of 6"
"cubic feet" "square inches" makes me cringe!
me to... why are we so archaic here as to use a non base 10 system of measurement?
my gf has cubic feet also, so adorable.
You do not want to put in any "wadding" in a transmission line box.
"The little rubber thing that attaches the cone to the outside".... annnnddd i'm gonna go find another video
America, time to go metric, make life easier on yourself.
Dumb it down even more bc I'm lost
1120 ÷ 40 ÷ 4 x 12 = 84" - 40 Hz - For a straight t-line 1
120 ÷ 35 ÷ 4 x 12 = 96" - 35Hz 1
120 ÷ 30 ÷ 4 x 12 = 112" - 30Hz
Take the SD² number (T/S parameters) and then adapt it to build the enclosure. Take my latest project of the JL Audio 13TW5v2 subwoofer. ruclips.net/video/ayFFXxoIqXc/видео.html - Getting Naughty with the JL Audio 13TW5v2 Subwoofer
Effective Piston Area (Sd) 98.26 sq in / 0.0634 sq m JL Audio 13TW5v2 subwoofer Lets just round it up to 100 sq in. Square root of 100 is 10, so you need the internal enclosure size to be 10" x 10". Ah! ... The problem is that the subwoofer is 13.5" wide. So then you have to adapt the enclosure a little
10 x 10
11 x 9
12 x 8
13 x 7
14 x 6 - Bingo!! Now you have a 14" Baffle, wide enough to house the subwoofer, and the depth of 6" Then you use the formula (above) to determine how low you want to go. Its really simple!
America; please learn metric! It's not the end of capitalism. It's not a Chinese plot and it's not agin' the constitution. It's just much easier to work with, especially when you're using physics calculations.
Gwat
I am new to audio can you just email me what I need to do for a rockford t1 12 inch I'll pay you via PayPal for the blue print lol
+Michael Trainor a rockford fosgate punch will do really well in a small closed box. Rockford fosgate has free plans to build around your t1. (good choice, btw, rockford ;))
Help me brother re se x 10d4 in LT
What d'you wanna know?
Too much math for me... oh well
This voice compressor is very fatiguing.
whatever. You lost me at hello. You said easy?! TMI
Worst tline vid ever lol
where do I go to get a tline box made for my two 12' quantum audio subs 5000w each
www.caraudiofabrication.com/