Huge Kerfs with T-line building fun!! lots of pics

[revoracing247]

personally I would have went with the 2 folded design for two reasons. First reason being is that a perfect transmission line would be straight and round (i.e. a cylinder). folding the t-line is a compromise to save space, so the less you have to fold it, the better it will function. Second reason being is that you want the mouth/opening of the t-line as far away from the front of the sub as possible (as far as I know from my research), I guess it helps with less cancellation.

Interesting...I built two tlines for some cheapy 10" driver..it was louder in my room and vehicle with the port on the same face as the sub instead of coming out the side.

Also I htink earlier in his psts he said he wished he could do a 2bend...but didnt have the room.

well i actually did have enough room to do the 2 bend design (not enough for a single bend though) but honestly i was really worried about the port being in the bottom corner of the back of my truck. it would have restricted the air flow from it a lot more then the design i've already cut the wood for.

and i know a perfect t-line would be a tube with the same cross sectional area at the sd of the sub but i've decided that on all the bends on this box im gonna try making them as round as possible using bondo or filler or something. it should come out nice. (like where i have the 45's and stuff)

as for the cancellation, i get the idea behind it but haven't hear anything about that for the t-line. do you have any sources i can read up garynator? and if it is a big problem then how come tons of people have the port facing same side on many ported boxes? i know a t-line pushes a lot more air cause it's basically free airing the sub but if im understanding the concept then shouldn't it also effect ported boxes or walled vehicles?

[RooTxBeeR]

Hey revo, a suggestion on curving the bends. I have seen people get really big PVC pipe, that is thin. Cut in 1/4 pieces, and cut out parts that match the width, and put one in each of the spots where you are putting a 45 cut. Throw some bondo on it, and make sure it's smooth, the 45's you are adding, take a lot out of the bend, which will have an effect on the performance. Other than that, Bad ass man, would love to make a T-Line some day.

[the_garynator]

personally I would have went with the 2 folded design for two reasons. First reason being is that a perfect transmission line would be straight and round (i.e. a cylinder). folding the t-line is a compromise to save space, so the less you have to fold it, the better it will function. Second reason being is that you want the mouth/opening of the t-line as far away from the front of the sub as possible (as far as I know from my research), I guess it helps with less cancellation.

Interesting...I built two tlines for some cheapy 10" driver..it was louder in my room and vehicle with the port on the same face as the sub instead of coming out the side.

Also I htink earlier in his psts he said he wished he could do a 2bend...but didnt have the room.

well i actually did have enough room to do the 2 bend design (not enough for a single bend though) but honestly i was really worried about the port being in the bottom corner of the back of my truck. it would have restricted the air flow from it a lot more then the design i've already cut the wood for.

and i know a perfect t-line would be a tube with the same cross sectional area at the sd of the sub but i've decided that on all the bends on this box im gonna try making them as round as possible using bondo or filler or something. it should come out nice. (like where i have the 45's and stuff)

as for the cancellation, i get the idea behind it but haven't hear anything about that for the t-line. do you have any sources i can read up garynator? and if it is a big problem then how come tons of people have the port facing same side on many ported boxes? i know a t-line pushes a lot more air cause it's basically free airing the sub but if im understanding the concept then shouldn't it also effect ported boxes or walled vehicles?

I can post some sources at some point later tonight or tomorrow. As far as the line opening on the same plane as the driver face, I will have to continue digging. I came across it on one of the T-line papers I was reading, but last time I looked for it for confirmation I could not find it. I know I was unable to find any information on placement other than that, so that's why I said afaik. From what I remember, it was a fairly good source. My theory about why this would be better is that the waves coming out of the line are only inverted for the tuning frequency, so you don't want the waves interacting with each other at that point, hence seperating them minimizes cancellation. I beleive it also helps dispersion in a room, i.e. bass is less directional. A difficult thing when dealing with t-lines is that much of the information out there is for the home environment, which can have different goals in mind.

As far as the sub being free-air, from what I remember, technically it is not. The amount of air in the line should act as a cusion at and around tuning frequency, as to how much, that I don't recall enough to feel comfortable making a statement at this time.

have you considered tapering the t-line? Tapering the line helps get rid of standing waves. it also has the benefit of making the enclosure smaller for a given line length. I'll post some links when I have a chance.

On another note, I have a subscription/account on martin king's site but haven't had time to get into it (paid for it like 6 months back lol). I've kinda been getting the itch to get back into t-line design theory again, so I'll probably get into that in the near future.

Edit: Also, you're better off with the vent on the same face as the sub if doing so the other way would have issues with not enough space around it. If there are benefits to having it far away from the driver, my guess is that it wouldn't be much of a difference, where as having the opening "choked" off would hurt output significantly.

[the_garynator]

BTW I don't claim to be a T-Line expert. Sadly, the more I learn, the less I seem to know lol. It seems like a simple concept, but it's much more complicated than it seems once you start getting into any folded lines.

[revoracing247]

personally I would have went with the 2 folded design for two reasons. First reason being is that a perfect transmission line would be straight and round (i.e. a cylinder). folding the t-line is a compromise to save space, so the less you have to fold it, the better it will function. Second reason being is that you want the mouth/opening of the t-line as far away from the front of the sub as possible (as far as I know from my research), I guess it helps with less cancellation.

Interesting...I built two tlines for some cheapy 10" driver..it was louder in my room and vehicle with the port on the same face as the sub instead of coming out the side.

Also I htink earlier in his psts he said he wished he could do a 2bend...but didnt have the room.

well i actually did have enough room to do the 2 bend design (not enough for a single bend though) but honestly i was really worried about the port being in the bottom corner of the back of my truck. it would have restricted the air flow from it a lot more then the design i've already cut the wood for.

and i know a perfect t-line would be a tube with the same cross sectional area at the sd of the sub but i've decided that on all the bends on this box im gonna try making them as round as possible using bondo or filler or something. it should come out nice. (like where i have the 45's and stuff)

as for the cancellation, i get the idea behind it but haven't hear anything about that for the t-line. do you have any sources i can read up garynator? and if it is a big problem then how come tons of people have the port facing same side on many ported boxes? i know a t-line pushes a lot more air cause it's basically free airing the sub but if im understanding the concept then shouldn't it also effect ported boxes or walled vehicles?

I can post some sources at some point later tonight or tomorrow. As far as the line opening on the same plane as the driver face, I will have to continue digging. I came across it on one of the T-line papers I was reading, but last time I looked for it for confirmation I could not find it. I know I was unable to find any information on placement other than that, so that's why I said afaik. From what I remember, it was a fairly good source. My theory about why this would be better is that the waves coming out of the line are only inverted for the tuning frequency, so you don't want the waves interacting with each other at that point, hence seperating them minimizes cancellation. I beleive it also helps dispersion in a room, i.e. bass is less directional. A difficult thing when dealing with t-lines is that much of the information out there is for the home environment, which can have different goals in mind.

As far as the sub being free-air, from what I remember, technically it is not. The amount of air in the line should act as a cusion at and around tuning frequency, as to how much, that I don't recall enough to feel comfortable making a statement at this time.

have you considered tapering the t-line? Tapering the line helps get rid of standing waves. it also has the benefit of making the enclosure smaller for a given line length. I'll post some links when I have a chance.

On another note, I have a subscription/account on martin king's site but haven't had time to get into it (paid for it like 6 months back lol). I've kinda been getting the itch to get back into t-line design theory again, so I'll probably get into that in the near future.

Edit: Also, you're better off with the vent on the same face as the sub if doing so the other way would have issues with not enough space around it. If there are benefits to having it far away from the driver, my guess is that it wouldn't be much of a difference, where as having the opening "choked" off would hurt output significantly.

yeah i got the same itch a bit ago and was reading some guys papers on tests he did with t-lines. i don't feel like going back and looking it up at the moment but i remember seeing how much he calculated for apparent cone mass was added to the sub from the air inside the t-line.

also i could taper it but it'd make the box more difficult to make and plus i'm honestly not looking for pure SQ with this box. im just looking to see what 300rms sounds like in a good ol' t-line lol

i actually was tempted to maybe make it into a horn but i decided i would rather just leave it and have the good balance between SQ and SPL. plus i'd be better for when i sell it down the road a little if i just did a normal t-line.

also it'd be great if you could give me any resources i'd love to learn me some more t-line stuff!

oh (sorry i make long posts) also about the 45's. i've already got them cut and i have like no money and now i have to look for a new amp to push this 12 so idk if im gonna go for the pvc idea. i've seen people on here use that before but i think i can get it pretty close to that using a ton of bondo and a lot of sand paper. and plus i wouldn't have to spend money with the bondo as the guy i live with has some already.

BTW I don't claim to be a T-Line expert. Sadly, the more I learn, the less I seem to know lol. It seems like a simple concept, but it's much more complicated than it seems once you start getting into any folded lines.

lol im deffinetely not either! though like i said above i'd love to learn more! and im hoping that if i just read through all the alien garble at least once, then maybe if i come back through again in a couple day's it'll make more sense

p.s. just looked again and the guys said it added around 40g to the cone with the lowest possible resonant frequency (20Hz) if im reading it right

[StreetMetalBen]

I love all of the inof up here, and i just LOT playing with T-Lines... So what would this be called?

It is fora 12, tuned to 25.5 Hz.... depending how you measure...

I would build thing right now, but i have nothing that it would fit in!

[david in germany]

I have been thinking about a T-line for a little JL 6w0 I have, anyone have a design that I could try?

[revoracing247]

I love all of the inof up here, and i just LOT playing with T-Lines... So what would this be called?

It is fora 12, tuned to 25.5 Hz.... depending how you measure...

I would build thing right now, but i have nothing that it would fit in!

honestly idk what exactly this would be called. it does like a kind of t-line but not exactly sure what having the port come all the way to the sub does. and someone who's maybe a little more experienced can come along but doesn't having that design go exactly opposite to the whole keep the port as far away from the sub as possible? lol

I have been thinking about a T-line for a little JL 6w0 I have, anyone have a design that I could try?

does it have a low qts and qms? and it'd have to depend on your max dim you have available and stuff. if you can make it with the least number of bends as possible. if you want more specific help feel free to pm me or make another thread asking that.

[revoracing247]

alright sorry not much has happened for a bit. being getting other stuff done with my build. anyways!

got progress on the box today!

got the lines drawn

my ghetto circle jig for first hole

and my crappy results

my ghetto jig for my second hole

and my better results.

flush mount!!

and gluing the double baffle

anyways if you want more detailed then visit my build log!

and also im hoping to get more done soon! sorry it's going so slow!

[revoracing247]

more box progress!

this is where i got last night