Building a Transmission line

[SpeakerBoy 64]

I have saved a little money for some wood, and still have glue, clamps and screws from my other box. I wanted to give building a T-line a try since i have heard fairly good things about them. It's just a for fun box, for my 12" visonik i got a while back. Amp and power and all that is covered, it's going in the house for now (no car til who knows when >.<). it's for music, primarily low notes in rap music. i was gonna try for a tuning of ~27-29hz. Now on to the hard part.

I havent had alot of computer time recently, but in the time i have had, i couldnt find a calculator for a 1/4th wave transmission line. The specs i can give you for my sub: 250rms rated (takes double fine for a couple hours) 8mm xmax between 6"-8" mounting depth, and overall, in every box i've had it performs extremely well for a $20 sub, brand new.

How do i calculate length for the line? Box will be 3/4" mdf. Size Is Not an issue.

Thanks for your answers, looking forward to this project.

Gotta get this done, severe boredom and grounding has landed my poor sub in a cardboard box (took the time to reinforce and deaden the cardboard too ). Sadly it still sounds better than my radio

[///M5 2,833]

Other way around. Figure out what you think you should do and then ask, otherwise don't build a t-line. No spoon feeding, you've lost your capability for that here.

[///M5 2,833]

Make sure you add exactly why you are choosing a T-line over another style enclosure and its actual use.

[SpeakerBoy 64]

Make sure you add exactly why you are choosing a T-line over another style enclosure and its actual use.

I have read that T-lines can be more efficient (sound produced vs power used), as well as beneficial to drivers with less motor strength. I have had ported boxes, several actually, and i like them overall, but the low low end is stil a bit lacking, and though it might be corrected with a bigger box, or little more power, that isn't really an option. Basically, i am after efficiency.

[///M5 2,833]

That didn't include anything about the plans you propose...

[95Honda 486]

My god, who is spreading all this crap about T-lines and high efficiency....? It seems like every time I drop in here there is some new subwoofer urban legend BS, lol...

[SpeakerBoy 64]

That didn't include anything about the plans you propose...

I don't think i'm understanding you. What plans specifically?

[///M5 2,833]

My god, who is spreading all this crap about T-lines and high efficiency....? It seems like every time I drop in here there is some new subwoofer urban legend BS, lol...

Some idiot. Driving me nuts as well. Must be some fucktard on ROE or some other dipshit site.

[95Honda 486]

Actually, you need to read Martin King's entire primer on T-lines before you ask any more questions.

I have been using his guidlines for T-lines for almost 10 years and find them invaluable.

Seriously, read this befor eyou ask any more questions.

Edited February 9, 2010 by 95Honda

[///M5 2,833]

That didn't include anything about the plans you propose...

I don't think i'm understanding you. What plans specifically?

The plans for your box specifically. No one here is going to make a design for you. You've worn out any spoonfeeding potential you have on this site. Either post your plans and goals the next time you post in this thread or don't post in this thread again.

[///M5 2,833]

Actually, you need to read Martin King's entire primer on T-lines before you ask any more questions.

I have been using his guidlines for T-lines for over the last 15 years and find them invaluable.

Seriously, read this befor eyou ask any more questions.

I think you should have said UNDERSTAND and not read. It will probably take him a good 30-40 reads to get that far though; however, I 10000% agree. And will add if you don't comprehend King's work then you should NOT ever even think about building a T-Line.

[SpeakerBoy 64]

That didn't include anything about the plans you propose...

I don't think i'm understanding you. What plans specifically?

The plans for your box specifically. No one here is going to make a design for you. You've worn out any spoonfeeding potential you have on this site. Either post your plans and goals the next time you post in this thread or don't post in this thread again.

Oh. Dimensions and specifications and such? i need to learn more about T-lines in general to decide that. I'm gonna stop now, and hit the library today. I'll post again after hitting a few sites. Links to good sources are also appreciated.

-Chris

[Duran 387]

You realize that the enclosure will be HUGE to obtain 27 Hz tuning right?

[ryan s 12]

You realize that the enclosure will be HUGE to obtain 27 Hz tuning right?

With a 12" sub...might as well put it in a straight truck. Rent one if ya don't own one...cause it's gonna be massive

Plus it would take mad carpentry skillz

Edited February 10, 2010 by ryan s

[///M5 2,833]

And if you make it too easy for him he is just going to go and make another stupid thread about a different kind of box

[porkchop 304]

Actually, you need to read Martin King's entire primer on T-lines before you ask any more questions.

I have been using his guidlines for T-lines for almost 10 years and find them invaluable.

Seriously, read this befor eyou ask any more questions.

thanks for posting this one up again.... i read at it, and like ///M5 mentioned, i am one of those folks that could read it a few times over and still struggle on some of it.

i am posting it in my audio folder, just so i got it, so thanks again.

chop

yes i have a audio folder, my head seems to leak shit back out of it, lol

[///M5 2,833]

Actually, you need to read Martin King's entire primer on T-lines before you ask any more questions.

I have been using his guidlines for T-lines for almost 10 years and find them invaluable.

Seriously, read this befor eyou ask any more questions.

thanks for posting this one up again.... i read at it, and like ///M5 mentioned, i am one of those folks that could read it a few times over and still struggle on some of it.

i am posting it in my audio folder, just so i got it, so thanks again.

chop

yes i have a audio folder, my head seems to leak shit back out of it, lol

Funny thing is you and EVERYONE who is promoting T-lines for cars could read it a few times and struggle over most of it. Actually it isn't so funny.

[Duran 387]

Actually, you need to read Martin King's entire primer on T-lines before you ask any more questions.

I have been using his guidlines for T-lines for almost 10 years and find them invaluable.

Seriously, read this befor eyou ask any more questions.

thanks for posting this one up again.... i read at it, and like ///M5 mentioned, i am one of those folks that could read it a few times over and still struggle on some of it.

i am posting it in my audio folder, just so i got it, so thanks again.

chop

yes i have a audio folder, my head seems to leak shit back out of it, lol

I have an audio folder as well, there is too much info to not compile it into one source.

[porkchop 304]

Actually, you need to read Martin King's entire primer on T-lines before you ask any more questions.

I have been using his guidlines for T-lines for almost 10 years and find them invaluable.

Seriously, read this befor eyou ask any more questions.

thanks for posting this one up again.... i read at it, and like ///M5 mentioned, i am one of those folks that could read it a few times over and still struggle on some of it.

i am posting it in my audio folder, just so i got it, so thanks again.

chop

yes i have a audio folder, my head seems to leak shit back out of it, lol

Funny thing is you and EVERYONE who is promoting T-lines for cars could read it a few times and struggle over most of it. Actually it isn't so funny.

five, you got me all wrong bro, i am not on that train now, nor have i been for a while....

i did as you suggested....

as well as 95honda.......

i commented on this for the informational part, saying it was an important read....

perhaps my post in the other thread similar to this one will state my stance better....

i took your advice, read, attempted to apply, walked away to something that was closer to my goals and have not truly looked back.

well other than to advise my findings to others who ask. just like where alot of reading got me to.

chop

[///M5 2,833]

five, you got me all wrong bro, i am not on that train now, nor have i been for a while....

i did as you suggested....

A comma may have made my statement read better for you (after you). Either way, it wasn't about you other than agreeing that I understand it is a non-straight forward read it was the "everyone promoting" that the point of the sentence was geared to.

Glad you took the advice

[porkchop 304]

right on.

[SpeakerBoy 64]

Transmission line is basically a driver in a port, with as little actual chamber volume as possible; correct?

[kirill007 52]

Transmission line is basically a driver in a port, with as little actual chamber volume as possible; correct?

No, It doesn't has a chamber at all, just a port.

You can calculate port lenght by using this formula. 1125(=speed of sound) divided by the desired tuning and then divided by 4.

Example: 1125/27=41,67ft

41.67ft /4 =10,417ft

This is how long the port needs to be.(10.417ft or 125.00400 inches)

Then you need to figure out port area, measure the cone from the surround(inside of it) to surround, then divide by two and take the square of that number and multiply by Pi(3,1415926535897932384626433832795)

example(12 inch sub,with a 10inch radius cone): 10/2=5

5²=25

25xPi=25x3,1415926535897932384626433832795=78sq inches of port area.

So for a 12 inch sub you need 78sq inches of port area and a lenght of 125 inches.

You can also add some stuffing to make the Tline sound less peakier, but this is trail and error.

You can fold the Line, so the enclosure looks smaller and thicker.

A raw Tline with no dampening added is more efficient then a normal ported box tuned to the same frequency.(i have tested it myself)

@Duran, yes a enclosure tuned to 27hz is huge even for a Ten inch sub.

[SpeakerBoy 64]

Transmission line is basically a driver in a port, with as little actual chamber volume as possible; correct?

No, It doesn't has a chamber at all, just a port.

You can calculate port lenght by using this formula. 1125(=speed of sound) divided by the desired tuning and then divided by 4.

Example: 1125/27=41,67ft

41.67ft /4 =10,417ft

This is how long the port needs to be.(10.417ft or 125.00400 inches)

Then you need to figure out port area, measure the cone from the surround(inside of it) to surround, then divide by two and take the square of that number and multiply by Pi(3,1415926535897932384626433832795)

example(12 inch sub,with a 10inch radius cone): 10/2=5

5²=25

25xPi=25x3,1415926535897932384626433832795=78sq inches of port area.

So for a 12 inch sub you need 78sq inches of port area and a lenght of 125 inches.

You can also add some stuffing to make the Tline sound less peakier, but this is trail and error.

You can fold the Line, so the enclosure looks smaller and thicker.

A raw Tline with no dampening added is more efficient then a normal ported box tuned to the same frequency.(i have tested it myself)

@Duran, yes a enclosure tuned to 27hz is huge even for a Ten inch sub.

How huge? give me a mental picture to work with

[Duran 387]

Transmission line is basically a driver in a port, with as little actual chamber volume as possible; correct?

No, It doesn't has a chamber at all, just a port.

You can calculate port lenght by using this formula. 1125(=speed of sound) divided by the desired tuning and then divided by 4.

Example: 1125/27=41,67ft

41.67ft /4 =10,417ft

This is how long the port needs to be.(10.417ft or 125.00400 inches)

Then you need to figure out port area, measure the cone from the surround(inside of it) to surround, then divide by two and take the square of that number and multiply by Pi(3,1415926535897932384626433832795)

example(12 inch sub,with a 10inch radius cone): 10/2=5

5²=25

25xPi=25x3,1415926535897932384626433832795=78sq inches of port area.

So for a 12 inch sub you need 78sq inches of port area and a lenght of 125 inches.

You can also add some stuffing to make the Tline sound less peakier, but this is trail and error.

You can fold the Line, so the enclosure looks smaller and thicker.

A raw Tline with no dampening added is more efficient then a normal ported box tuned to the same frequency.(i have tested it myself)

@Duran, yes a enclosure tuned to 27hz is huge even for a Ten inch sub.

How huge? give me a mental picture to work with

Look at his formula a little closer, he calculated 10.417 feet long to achieve 27 Hz. tuning.