TL design needs review

[iamamp3pimp 5,000+ posts]

whats the purpose then?

are they strictly SQ?

 

[iamamp3pimp 5,000+ posts]

to be honest i have a xxx 12 i'd like to try this on...

 

[mobeious 10+ year member]

they are designed for acurate responce and flat output not for loudness....

 

[iamamp3pimp 5,000+ posts]

where can you learn about the various enclosures that can be made (besides bandpass/ported/sealed?

 

[mobeious 10+ year member]

i just search on google.... topics like 1/4 wave and folded horn and stuff

 

[iamamp3pimp 5,000+ posts]

cool.

thanks.

 

[iamamp3pimp 5,000+ posts]

so on this, there is no chamber, and the entore box = port?

 

[sinosic 10+ year member]

yes all port. i found my formal here:

http://www.stevemeadedesigns.com/forums/index.php?topic=1828.0

its kinda a b1tch to understand at first but i just read the thread like 4 or 5 times and started crunchin numbers.

so on this, there is no chamber, and the entore box = port?

 

[sinosic 10+ year member]

inverted wont make a difference w the sound, and this one doesnt have a pole vent so u can mount it as close to the wood as possible.
but

you need 10 + inches of depth....You dont have it there.

you have to invert it.

i wonder if i could just do like a 5x baffle.

 

[Fast1one 10+ year member]

To figure out the needed information for a transmission line:
1: The subwoofer needs to have a Qts of .40 or lower

2: Get the subwoofer’s Fs

3: (1130/Fs)/4 will give you the length of the 1/4 wave length needed in feet. This needs to be the length of the port. Don’t worry, it will be long.

4: Next you need to figure out the port area needed, which should be the same as the subwoofer’s Sd. If you don’t have the Sd, here’s how to figure it out: Measure the subwoofer from center of surround to center of surround and divide that by 2. Then take that measurement and apply it like this: (measurement/2) x (measurement/2) x 3.14, that will give you the Sd. This is also your port area. If you are using multiple woofers, just multiply that by the number of woofers you have.

Confused yet?

5: Now you know how much port area and port length you need, and there is no chamber, it’s all one port, so now all you have to do is figure out how to get that length in the area that you have to work with.

You can thank stratusrt01 on the realm fourms, that's who I got this info from, I have not tried it yet.

It's not as easy as that explanation seems. If you can pay for some software, head over to http://quarter-wave.com That will give you a good explanation about the quarter wave theory and he has software to model your boxes. MJK is a pioneer in the design and construction of quarter wave designs and I trust is software...
BTW a subwoofer with a QTS lower than .4 is actualy harder to control in a transmission line. Reason being is they tend to yield nasty ripples in the upper response that are hard to hide....

http://t-linespeakers.org/design/MJK-for-dummies/index.html Cliff notes for the first site. These enclosures are not wonder boxes. They are extremely efficient but run out of juice quickly. They tend to only be slightly louder than a ported enclosure at the peak, but are louder over a broader range. If your looking for sound quality that resembles that of IB and efficiency this is for you. If your looking for SPL, it wont satisfy your needs...

 

[iamamp3pimp 5,000+ posts]

im already designing one for the house for my stagnant kicker comp 12......also will work well with my 12 xxx since they both have a sinmilar FS (26 hz)

 

[Omarvelous 10+ year member]

off Topic!!

What font it that in ur first pic? The title font?

 

[profundus-sanus 10+ year member]

run it inverted and switch the polarity.

You shouldn't have any problems.

Other than 1000 watts giving you too much excursion, possibly.

 

[Immacomputer 10+ year member]

Tuning the line to the Fs of the driver is not completely accurate for all drivers. You really need to calculate the line length based on the amount of air in the line itself. The sub will still see the air in the line and its resonant frequency will be higher than it's Fs unless the total amount of air is very large (lower Q drivers will have this happen often which is why people often say to use low Q drivers).

To find the real resonant frequency of the driver, use the total amount of air in the line and model the sub in a sealed enclosure with the same amount of airspace and then find the resonant frequency. You can use Winisd Alpha to do this if you want to save some time and effort.

From that point, you probably want to make the line slightly shorter and add stuffing until you get the desired response and impedance curve. Stuffing the line will change the speed of sound which will also change the apparent line length.

These are all things to consider when creating transmission line enclosures.

 

[sinosic 10+ year member]

"you probably want to make the line slightly shorter and add stuffing until you get the desired response and impedance curve. Stuffing the line will change the speed of sound which will also change the apparent line length."^^^^

why make it shorter, then add stuffing to make the line seem long again?