T-Line Experts get in here!! ~Please (big pic inside)

[SojiaRaggs9000]

anyways as for this design the tapering does effect the length of the line. i have a calculator someone made to calculate that and i can find it if you want sojiaraggs

Yeah for sure. Hook me up haha.

Here is the negative taper (on the right) I made next to the postive taper. they both se the same ratio.. 6.9735" to 4.625"

[revoracing247]

alright give me a minute lol and btw a taper usually is referred to as shrinking and then when the port area grows as it goes along it's usually refereed to as a horn. or folded horn.

[revoracing247]

alright here ya go.

http://www.quarter-wave.com/TLs/TL_Theory.html

get the "Alignment tables spreadsheet" down near the bottom and that should give ya what ya need.

[SojiaRaggs9000]

Ok taking eveything said here into account (negative taper vs a positive taper, making the line a little longer etc....) The line is longer by about 6 inchs which is needed according to the calculator above. The taper starts at 6.98245" behind the sub and ends at 4.63523" at the mouth. Which is 1 : 1.5 ratio. It takes away the flared port look but whats your thoughts on this one.

[revoracing247]

i like the look of that one a lot better. though one thing i'd change is where the sub it mounted ish. move it as close to the right side as possible and make that half pipe end that is just to the right of the magnet into only a quarter pipe. and sorry, i know that makes you remodel the whole thing again lol

[SojiaRaggs9000]

i like the look of that one a lot better. though one thing i'd change is where the sub it mounted ish. move it as close to the right side as possible and make that half pipe end that is just to the right of the magnet into only a quarter pipe. and sorry, i know that makes you remodel the whole thing again lol

Nah didn't have to remodel the whole thing just redraw a couple line. (took like 3 mins if that) I was actually thinking about the same thing for the start of the line. Only thing Im not sure of now is the right side port wall that needs to be flush with the kerfd angle. I guess making it a little smaller say 1/16" and then glassing it would be the best route?

[HunterJohnson]

I built a t line out of concrete tubing for a 12" sub rmsed at 300 watts. It would only take 80rms in a 1/4 length T line. The 12 fs'd at 27 and wow it sounded like sex. Even off 5 watts it shook the room

[SojiaRaggs9000]

This is why Im leaning towards a taper (mass loaded quaterwave)

Check out these qutoes I got from a t-line form...

A mltl with expanding taper will be larger than a straight or reverse taper mltl to maintain the same tuning and response curve (assuming the port details don't change). The horn shape places the impedance peaks higher and closer together, this is why it needs to be larger. The larger size will result in more spl for a given power level.

Horn shapes have the same effect whether the entire enclosure is a horn, or if any single part of the enclosure (the box or port) is horn shaped.

But to be clear, mltl's do not have to have an expanding taper, it can be any shape you choose.

Taper implies a change in cross sectional area. The taper can be either positive (expanding cross sectional area) or negative (decreasing).

Your example, where the line starts out big and fat and gets narrow as it approaches the exit, describes a negative taper. If it's not a smooth taper, it can be described as "stepped".

Positive tapers will have more excursion related potential max spl, but they have to be larger to maintain the same tuning and response curve.

[revoracing247]

i like the look of that one a lot better. though one thing i'd change is where the sub it mounted ish. move it as close to the right side as possible and make that half pipe end that is just to the right of the magnet into only a quarter pipe. and sorry, i know that makes you remodel the whole thing again lol

Nah didn't have to remodel the whole thing just redraw a couple line. (took like 3 mins if that) I was actually thinking about the same thing for the start of the line. Only thing Im not sure of now is the right side port wall that needs to be flush with the kerfd angle. I guess making it a little smaller say 1/16" and then glassing it would be the best route?

yeah that looks better. and i was just saying you might have to change the whole thing because i usually measure my line starting from the middle of the magnet. therefor if you move the sub it changes the length of the whole line. and what piece exactly are you talking about on the right side port wall?

oh and also anything on that forum of how the horns react in a car's cabin space? cause i saw on a forum somewhere that they might be bad in cars. but i wouldn't trust only one source.

[SojiaRaggs9000]

i like the look of that one a lot better. though one thing i'd change is where the sub it mounted ish. move it as close to the right side as possible and make that half pipe end that is just to the right of the magnet into only a quarter pipe. and sorry, i know that makes you remodel the whole thing again lol

Nah didn't have to remodel the whole thing just redraw a couple line. (took like 3 mins if that) I was actually thinking about the same thing for the start of the line. Only thing Im not sure of now is the right side port wall that needs to be flush with the kerfd angle. I guess making it a little smaller say 1/16" and then glassing it would be the best route?

yeah that looks better. and i was just saying you might have to change the whole thing because i usually measure my line starting from the middle of the magnet. therefor if you move the sub it changes the length of the whole line. and what piece exactly are you talking about on the right side port wall?

oh and also anything on that forum of how the horns react in a car's cabin space? cause i saw on a forum somewhere that they might be bad in cars. but i wouldn't trust only one source.

From all the articles I've read, they suggest that you start measuring the line length at the wall not the magnet. As far as the placement of the sub on the line. Only thing that effects is which of the harmonics get canceled out. House speaker wise they say you should put the driver at about 30-40% down the line. Although in our applications that would be impractical. Due to the fact that, that would place the sub inside the box. Also the reason I thought a positive taper would be better is the same reason flared ports on a slotted box. Iirc it changes port output by -/+15db.

Edit: right side wall of the mouth, connected to the baffle.