T line design?

[d-REW]

Is there a degree cut on the port and line

[Triticum Agricolam]

Is there a degree cut on the port and line

Yes, 1.7 degrees. Its close enough to 90 that you could probably just cut the pieces square the glue would take care of the rest. Though if you can make the angled cuts it would be better.

[CortezDTV]

Why is the sub halfway down the line? It should be as close to the start of the line and the output of the port as possible; partly how a T line works

So move the fucking speaker hole

This is turning into my new pet peeve watching people put the sub in the worst possible spots....

[Triticum Agricolam]

Why is the sub halfway down the line? It should be as close to the start of the line and the output of the port as possible; partly how a T line works

So move the fucking speaker hole

This is turning into my new pet peeve watching people put the sub in the worst possible spots....

Its put there intentionally and for a very good reason. When you put the sub at the closed end of the line you get a giant spike in output at around 3x times the tuning frequency followed by a giant dip at around 4x. Putting the sub 1/3 of the way down the line eliminates this and smoothes the response.

So why do you think its the worst possible spot?

[RooTxBeeR]

Interesting. Triticum, doors that method apply with t lines or does that apply to any ported enclosure.

[Triticum Agricolam]

Interesting. Triticum, doors that method apply with t lines or does that apply to any ported enclosure.

Just t-lines.

ETA: In theory it could happen with a ported box if it was long and skinny enough to start acting a little like a T-line, but the frequencies it would effect would be so high they wouldn't matter and would get filtered out by the port anyway.

[Sergeant_Skyrim]

Googled the sub, it's a 10 inch correct? Sd was ~399 sq centimeters, converted to inches is ~62 sq inches. That'll be the opening of the tline. To find out the length all you do is take the speed of sound 1130ft/sec, divide by the resonant frequency (25.528 hz), and then divide again to get the quarter wave length. So the tline will be 62 sq inches by 11.07 feet long (~132.8 inches long).

The trickiest part is just contouring it and bending it around in your maximum dimensions.

The problem with this method is it tries to be a one-size-fits-all solution. Its more like a one-size-fits-almost-none. You have no idea what the final result is going to sound like, it could give smooth even response with good low end output, or it could be a peaky one-note wonder. Chances are its going to be closer to the latter of the two.

d-REW, what kind of music do you listen to?

One thing to keep in mind with T-lines is they basically do the same thing as a ported box, they just do it in a different way. Because of this their performance is going to be very similar to what a ported box would be of similar size.

Then how would you go about designing a tline for a specific setup then? Any tlines I've ever seen/heard have had subs at the closed end done up exactly like this. What sort of benefits do you get from putting the sub ~1/3 of the way down the line vs. at the closed end, and how would you go about designing a tline aside from the method pinned at the top of this forum? It seems like a pretty standard cookie cutter type of design based around the resonant frequency of the sub and displacement, however I'd be interested in learning more about it from you if possible

[Triticum Agricolam]

Then how would you go about designing a tline for a specific setup then? Any tlines I've ever seen/heard have had subs at the closed end done up exactly like this. What sort of benefits do you get from putting the sub ~1/3 of the way down the line vs. at the closed end, and how would you go about designing a tline aside from the method pinned at the top of this forum? It seems like a pretty standard cookie cutter type of design based around the resonant frequency of the sub and displacement, however I'd be interested in learning more about it from you if possible

First off, I'm not saying that designing a t-line using the method pinned in the enclosure section is always wrong. I'm just saying its an oversimplification, so its not always the right thing to do, and you don't know what the result is going to be until you build it.

How I design t-lines is using modeling software so I have a pretty good idea of the results are going to be before making any sawdust. The software I use is called Hornresp, its free and very powerful though not the most intuitive to use. T-lines are a LOT like ported boxes where as you can control how they are going to sound by adjusting the size, shape, and length of the line just like with ported boxes you can adjust the net volume and tuning to get the sound you want.

Put the sub 1/3 down the line eliminates some funky resonant issues you get when you put it at the closed end. Here are some pictures that show what's going on pretty well. First we have a t-line with the sub at the closed end:

Here is the exact same t-line with the sub put 1/3 up the line:

See how it moves all the erratic response further up the frequency range?

[Joe X]

^ Do you mind posting input parameters for that?

[Triticum Agricolam]

^ Do you mind posting input parameters for that?

No prob:

Thats for the offset driver version, if you change the Driver Arrangement to Normal that will give you the "sub at closed end" version.