T-line Questions

[Guest]

i was pondering about a t-line for a RF Punch 2 (old model) which has 79sqin of cone area. FS of the sub is 27hz, i plugged that into http://www.mcsquared.com/wavelength.htm and got 41.8 feet. 41.8/4 yielded 10.45ft.

so i have the amount of port area i need (from cone area), and how long i need the box to be.

my questions are, well 1 if my math was right. two, how do i go about figuring out the dimensions of the box and how big it will be. and three, how would i go about mounting the subwoofer inside the box when the port area is narrower than the sub's width.

Edited January 23, 2009 by Krannyman92

[Guest]

heres a quick picture i made to see if its right or not

drawing is not intended to be accurate.

Edited January 20, 2009 by Krannyman92

[Guest]

ttt?

[Forevrbumpn]

I dont see why the sub cant fit in the t line? Isnt that a somewhat shallow sub? I mean 79sq inches if 12" tall should be about 6.5" plus that 3/4" or 1.5" (if double baffled) IIRC that is just a small stamped steel frame woofer.

As far as the box dimensions, that is where good imagination comes to play, fewer bends preferably

Dont worget to put in consideration you should be measuring down the middle of the line if you can imagine that

I personally would run with a line length that is a little shorter, just because. Anything under 30 hz for a tline is almost a waste in a vehicle

[Guest]

the sub's Fs is 27hz, and the guide on here for t-lines said to use the subs Fs as the tuning guide.

i didnt understand what you said about "if 12" tall should be about 6.5""...what did you mean by that.

Edited January 20, 2009 by Krannyman92

[Forevrbumpn]

the sub's Fs is 27hz, and the guide on here for t-lines said to use the subs Fs as the tuning guide.

i didnt understand what you said about "if 12" tall should be about 6.5""...what did you mean by that.

for the length of the box, i can pretty much do whatever box i want except it has to be 79sqin throughout the whole length right?

I know what the tutorial says, I wrote it.

You dont need to tune to exact Fs, there are other variables, such as in car resonance, etc. Thats why I said why not tune a little higher? You will still see that 27hz and lower

Think of it like this, the Fs is just the mechanical and electrical peak of the subwoofer, but not all music is playing at 27hz, what does most rap these days play? mid 30's, and up to the 40s. Only time 27hz will be seen will be doing sine sweeps, or rare bass songs. You can still tune to 30- 35hz, and have good gains below 30hz, its called Transfer function. The larger the interior of the vehicle, the lower the natural vehicle resonance will be

You can throw that same sub in a 40hz bandpass t-line, and see 25hz playing better than it would if tuned to 27-30 hz, did you know that?

I prefer to tune a little higher when doing tlines, just because the loss in length of the quarter wave in the box will always be made up due to transfer function.

Have to remember, a 30hz tline, and a 30hz ported box may seem like they will play the same, but the characteristics of the tline allow the box to play a lot lower- Usually, dependent on the subwoofer parameters, and how the line is designed.- And watt for watt the tline will almost always get louder

[Forevrbumpn]

the sub's Fs is 27hz, and the guide on here for t-lines said to use the subs Fs as the tuning guide.

i didnt understand what you said about "if 12" tall should be about 6.5""...what did you mean by that.

79sq inches of line, an example would be about 12" tall inside, by 6.5" deep

Thats what I meant

Its a 12" right?

So... 79/ 12"= 6.5##- just round it off

[Guest]

that helped alot thanks. so making a change to 35hz changes the 1/4 wavelength to 8ft which will help alot when trying to save a little space.

but the only thing i dont get is how will i fit the sub in the opening? outer dimension is 12 11/16", inner dimension is 11 1/8", and the height is 6 1/8".

[Guest]

79sq inches of line, an example would be about 12" tall inside, by 6.5" deep

Thats what I meant

Its a 12" right?

So... 79/ 12"= 6.5##- just round it off

by 12" tall and 6.5" deep inside i assume you mean for the port area to be 12" in height and 6.5" wide and 8ft deep (with the bends)?

[Forevrbumpn]

yes