Quarter Wave / T-Line tutorial-UPDATED

[Triticum Agricolam]

You will get more even response if you put the sub 1/3 of the way down the line.

Check out hornresp, its a really handy tool for this kind of stuff.

[jayman72]

Looks good. I assume it's an LFE sub?

It's an original Dayton Audio Titanic 1200 Subwoofer

http://www.parts-express.com/dayton-audio-12-titanic-subwoofer-4-ohm--295-400

You will get more even response if you put the sub 1/3 of the way down the line.

Check out hornresp, its a really handy tool for this kind of stuff.

When you say 1/3 of the way down the line do you mean on the front of the woofer or the actual line. If so I'm not sure how that would fit.

Thanks

Jay

[Triticum Agricolam]

When you say 1/3 of the way down the line do you mean on the front of the woofer or the actual line. If so I'm not sure how that would fit.

Thanks

Jay

So right now your TL has the mouth at one end and the beginning end with the sub at the other. I'm suggesting you place the sub about 1/3 of the way between the mouth and and the beginning end. You will have to rearrange the path a bit inside the box, but it shouldn't be too tough. If you post a link to your sketchup file can show what I have in mind.

Here is why you may want to do this, here is the simulated output from how you have your TL now:

And here is what you get just from moving the sub 1/3 of the way down the line:

You give up a little bit of efficiency, but you get extended output and smoother rolloff on the low end and you loose that giant suck out a ~62 Hz. Instead of having smooth output only up to about 50 Hz, you will be good up to around 75 Hz so it should blend better with your main speakers.

[jayman72]

When you say 1/3 of the way down the line do you mean on the front of the woofer or the actual line. If so I'm not sure how that would fit.

Thanks

Jay

So right now your TL has the mouth at one end and the beginning end with the sub at the other. I'm suggesting you place the sub about 1/3 of the way between the mouth and and the beginning end. You will have to rearrange the path a bit inside the box, but it shouldn't be too tough. If you post a link to your sketchup file can show what I have in mind.

*****

Thanks for the input Triticum,

So since my last post a few changes have happened.

I had to shorten the over all height of the cabinet to just under 48" so I could the 2 sides pieces from one 4x8 sheet of MDF.

This decreased the over all line by 40 inches which in turns changes the tuning to about 19.7HZ.

The other issue is that I went ahead and built it. (Weekend project)

So knowing that its basically built and I will not be able to move it the sub to were you suggested other than using an EQ to shape the sound is there anything I can do to "fix" it? (Lining the cab with egg crate? stuffing it with some acoustic fiber?)

I appreciate the advice, I just wish I had not been in such a hurry to build it but once I get the bug to build something it usually gets done pretty quick.

Thanks again

Jay

Tampa, FL

[bbeljefe]

Looks good. I assume it's an LFE sub?

It's an original Dayton Audio Titanic 1200 Subwoofer

http://www.parts-express.com/dayton-audio-12-titanic-subwoofer-4-ohm--295-400

You will get more even response if you put the sub 1/3 of the way down the line.

Check out hornresp, its a really handy tool for this kind of stuff.

When you say 1/3 of the way down the line do you mean on the front of the woofer or the actual line. If so I'm not sure how that would fit.

Thanks

Jay

LFE stands for Low Frequency Effects, as in home theater sub rather than two channel stereo sub.

[jayman72]

LFE stands for Low Frequency Effects, as in home theater sub rather than two channel stereo sub.

Yeah it will primarily be used for HT but should also be able to reproduce music.

[Triticum Agricolam]

Thanks for the input Triticum,

So since my last post a few changes have happened.

I had to shorten the over all height of the cabinet to just under 48" so I could the 2 sides pieces from one 4x8 sheet of MDF.

This decreased the over all line by 40 inches which in turns changes the tuning to about 19.7HZ.

The other issue is that I went ahead and built it. (Weekend project)

So knowing that its basically built and I will not be able to move it the sub to were you suggested other than using an EQ to shape the sound is there anything I can do to "fix" it? (Lining the cab with egg crate? stuffing it with some acoustic fiber?)

I appreciate the advice, I just wish I had not been in such a hurry to build it but once I get the bug to build something it usually gets done pretty quick.

Thanks again

Jay

Tampa, FL

Unfortunately at this point your are not going to be able to completely "fix" it. The biggest issue is that 60 Hz suck-out. The good news is big dips is output are less noticeable to the ear than big peaks. The bad news is peaks are a lot easier to fix with stuffing/EQ than dips. Its just about impossible to EQ out a dip like that. You could play around with stuffing to see if that helps or not. You want to use polyfill/acoustical stuffing, I get mine at Walmart, egg crate foam isn't going to do anything for you. I would start will putting some stuffing behind the sub and try to stuff about the first 1/4 of the line. If you get too much you will kill your output, its going to take some trial and error. If you have a way to measure the output so you aren't just using the ear-o-meter it will be a lot easier.

[Yellow1000]

Can anyone help me with a design for an hx2 10?

[bumpinTL364]

t-lines are really easy. Take 1130, divide by 4, and then divide by the resonant frequency (Fs) of your woofer. That's how long your "port" is going to be, in feet. Your "port" area should be equivalent to the cone area of your driver. From there it's just figuring out a design that works in your desired space, good luck!

[Yellow1000]

Exact come area ?