Octagon shaped Transmission Line for SA8v2

[Miles 128]

I recently aquired a brand new Sundown SA8v2. I talked with Thumper about a variation of an enclosure he built years ago for this sub, but after a lot of thinking, I wanted to do something original. Even though I have way more power than the 8 was designed to handle, I wanted to build a T-Line box. I built one years ago, and it sounded amazing. However, I didn't want to build just another boring rectangle t-line box that just looks like a ported box from the outside...

 

 

So... I present to you my variation of a t-line box I threw together this evening. It took a couple of days to design it, and I thought it was going to be a nightmare to build, but it actually went together in under an hour. All I have is the one picture, but the glue on the top and bottom are drying as I type this, so, if all goes well, I'll be finishing the box tomorrow morning, and have it playing by tomorrow afternoon...

 

 

Tell me what y'all think...

 

 

 

 

 

[jonbearsmt 919]

nice work.. bet that fucker is heavy!

[jonbearsmt 919]

oh what do you figure it to be tuned to?

[Miles 128]

It's not as big as it looks. It's only 26" in diameter. About 3/4 of a sheet of worth of wood. And It's "tuned" to the Fs of the sub, which is 34.7 hz. The line is 8.05 feet long.

[Tirefryr 1,742]

Great craftsmanship!

 

 

But fuck that!

[Miles 128]

Really wasn't as bad as it looks. Only took about an hour to assemble. About halfway through I shot a nail into my finger. Luckily, it bounced off the bone and came right out...

[Jay-C76 333]

Snail shell!

[edouble101 314]

Very cool man. That should make a nice coffee table, especially if it had a plexi top.

[95Honda 486]

No "tuning" with a T-line. 

 

What are you going to stuff with?

[95Honda 486]

 Looks cool, btw...

[Miles 128]

Stuff with? Im putting just one SA8v2 in it. No polyfil. No need. I have the correct line length.

[95Honda 486]

Stuffing it is the only way to adjust for flat impedance and decent response.  Unstuffed is the worst way to run a T-line, you loose all the non-resonant behavior a T-line provides, and that is the only advantage they have.

 

I have been building 1/4 wave T-lines since the early 90s...

 

Read Martin Kings white paper.

[Miles 128]

I'll have to put a pound of stuffing in the box before i.put the sub in.

[95Honda 486]

Read the white paper, it will help you decide on the stuffing and how to properly install it.

[95Honda 486]

And yes, don't finish the box until you finalize stuffing...

[95Honda 486]

If you don't stuff, you are going to get 100% better performance out of a standard 4th order...  In all aspects...

[Miles 128]

Have a link to the white paper?

[Miles 128]

Was planning on building a 4th order next anyway. Haha.

[///M5 2,833]

If you don't stuff, you are going to get 100% better performance out of a standard 4th order...  In all aspects...

You just disrupted the fabric of truth that holds the internet together. The car audio world will never be the same.

[Quentin Jarrell 671]

I like different stuff and I like to see new people try stuff they've never attempted.

I've built plenty if just about everything. Doesn't mean I know much. Just because you do something for a while doesn't mean your doing it right. I'm sure this thread will turn into another pissing match but maybe it won't and maybe a few will help. I'll do my part others can add their helpful info too if they wish.

Per Vance Dickason (the way I interpreted it) states acoustic stuffing is to be used only in a transmission line after testing and to adjust system clue. Although not really sure how much that joker really knows. Or maybe I read wrong.

If your interested in a bit more of his teachings I recommend purchasing a copy of his "Loudspeaker Cookbook".

[Impious 1,476]

Was planning on building a 4th order next anyway. Haha.

By 4th order he meant a ported enclosure, not a 4th order bandpass

[Miles 128]

Ive always heard about the "woofer cookbook"... might pick up a copy. I'll probably just throw this box in, test, add some polyfil, test, and so on. But, this is going in a softtop jeep... Not like im striving for SQ here... almost all T-Lines i see have no form of filler. So does that mean everyone is doing it wrong?

[Impious 1,476]

Most of the t-lines you see on car audio forums aren't truly t-lines and most of those people also have no idea why they would even want a t-line compared to a more standard enclosure.

So the short answer is yes, most people in this hobby do it wrong.

[Sencheezy 689]

The box looks great!

[Sencheezy 689]

The white paper, I think? It's just what I found while using Google.

 

http://www.quarter-wave.com/OBs/OB_Design.pdf