T-Line box with a sealed side?

[Chris Hammer]

Has anyone ever made a T-line with a sealed side. Like how you build a 4th with a sealed and ported..Just doing a sealed box over the top of the sub thats already in a T-line?

In my mind it would increase power handling but probably decrease output at lower power levels....But the benefit I could think of(if my reasoning is correct) is that it would prevent the sub from bottoming or unloading if you go below tuning on the transmission line and MAYBE extend the frequency range down a little...Kinda how 4th can be tuned higher but still hit lows.

I have a newbish understanding of 4ths and other enclosure designs and feel I get the concept of a T-line and am running one in my truck right now.

The output surprised the hell out of me as I spent about 20$ total on amp and woofer lol. Parts Express&eBay. getting about 15w worth of power HAHAHA. This will be replaced soon enough and was more so just for shits and giggles and playing iwth scrap wood and enclosures.

I was just daydreaming at work like normal and looking at the box thinking why not.

I might just give it a go and see what happens if no one can chime in...I already have the mdf lying around.

[littlehitter]

I was wondering the same thing the other day.

[Chris Hammer]

I think Imma do it and see if i can't borrow an amp from a friend that puts out more than 15w at 8ohms lol. Just to satisfy my curiosity. The only tool I have is the good ol Earometer so I can't really say definitely if there is a improvement or loss in response output etc except just in how it sounds.

[CortezDTV]

Foreverbumpin made one its nin the tline thread.....

It makes it possiable to tune below thefs of the driver, and you can also throw more power to the sub because you can control the drivers suspention which is not normally possiable with a high power tline

[STEvil]

I never saw the sealed-side he posted in that thread?

But yes, it works. This is how folded horns work in general.

[Chris Hammer]

Imma look through it and try and find it. Does anyone ahve any advice on how big the sealed side should be? Im thinking of trying what the driver recommends sealed anyways and going from there. This is just to play around and if it sucks Im going back to regular t line

[the_garynator]

it actually defeats the purpose of a T-line. the whole reason to do a T-line is to invert the rear wave of the sub so that it provides constructive interference with the front wave (i.e. does not cancel it out). putting one side in a sealed box eliminates one of the sound waves. the only benefit over a sealed box that this may have is an extra resonance at the resonant frequency of the T-Line.

[Chris Hammer]

it actually defeats the purpose of a T-line. the whole reason to do a T-line is to invert the rear wave of the sub so that it provides constructive interference with the front wave (i.e. does not cancel it out). putting one side in a sealed box eliminates one of the sound waves. the only benefit over a sealed box that this may have is an extra resonance at the resonant frequency of the T-Line.

Theres a good answer that I was waiting for.

So you're saying its a waste of time?

How does port placement affect a tline than? Mine exits right next to the subwoofer..both firing the same direction.

[the_garynator]

it actually defeats the purpose of a T-line. the whole reason to do a T-line is to invert the rear wave of the sub so that it provides constructive interference with the front wave (i.e. does not cancel it out). putting one side in a sealed box eliminates one of the sound waves. the only benefit over a sealed box that this may have is an extra resonance at the resonant frequency of the T-Line.

Theres a good answer that I was waiting for.

So you're saying its a waste of time?

How does port placement affect a tline than? Mine exits right next to the subwoofer..both firing the same direction.

I'm not 100% but the only thing I've seen out there (haven't been able to find the info again) was in a paper on TLine theory, it stated that the mouth (exit) of the Tline should be as far away from the front of the sub as possible. I don't remember specifics but as I recall it has to do with cancellations when the front and rear wave react together.

The purpose of a t-line is to invert the rear wave at a specific frequency 1/4 of a wave length. Anything off of this tuning frequency within the passband of a typical sub is either more than a 1/4 wave off, or less. I think the reason it happens is that if the wave isn't inverted at a 1/4 wave, it does more harm as far as cancellation is concerned when it interacts with the front wave, seperating the two by distance helps prevent the waves from interacting with each other. Based on this assumption, theoretically having the opening close to the woofer shouldn't have any negative effect, possibly even having a positive effect (directionality) at the tuning frequency, but would hurt it on other frequencies at differing amounts.

Again, this is based on something I read a while ago and havent been able to find, so take it for what it's worth.

Hope it helps.

[CortezDTV]

From what I read you wanted the port opening as close to the sub as possiable, so they worth together....

Hmmmm... I might have to go reading some more again