Help with Transmission Line design for Tumult (1 Viewer)

[DavidFun]

Is it even possible to build a TL Box for a tumult. I currently have it in a 2.5 cubic foot box. It is nice, but I want to try something different and don't want to dump money into PR's. What about a TL? Any thoughts experts.

David

 

[Travis Cain]

OOOooooo.. I know it is possible, but I don't have a clue how to design a properly tuned line but I sure hope someone can help you. TL's are a beautiful thing and are much too often overlooked.

And if you want to impress your friends, you can tell them you've discovered Bose's secrets and designed your own "acoustic waveguide technology" subwoofer.

 

[ThomasW]

What are you trying to accomplish? Louder? Lower?

T-lines IMO are a pain design, and a bigger pain to build and certainly not for noobies.....

Just do a google search for "quarter wave loudspeakers", "T-line loudspeakers" and you find enough links to get lost forever.....

The easy part is the line length. It's simply 1/4th of the wavelength you want to use for the tuning frequency.

 

[Allen Ross]

i was asking around if i could do this with my tempest for shits and giggles and i believe you need to look for a driver that has a relatively high EBP in order to have a box that isn't the size of your room.

I am just going off of my memory, so it might not be 100% true, i just remember a guy did a quick box volume and it was going to turn out the size of my dorm room. I contemplated doing it (turning my dorm room into a 1/4 wave 20hz LT) for about a day or two, i have some rough plans

 

[DavidFun]

My goals are to build a sub that sounds fantastic, and plays as low as possible. I would like to get more out of the Tumult than the sealed box can provide. I am a skilled woodworker, and was looking for another project that wouldn't cost much. It sounds like a TL tuned to 18 hz would be freakin huge. Maybe it's not really feasible.

 

[Mark gas]

why not go ported?

 

[DavidFun]

I probably will. I guess it will have to be a slot ported box. I just wanted to ask about a TL design before I built a ported box.

 

[Jack Gilvey]

What advantage are you looking for with a TL over other options?

 

[Allen Ross]

my interest would be to get that SPL up above 87, i can't stand inefficient driver.

 

[ThomasW]

Then I guess you shouldn't have purchased one, it's that Hoffman's Iron law thing.....

You'll gain a little efficiency going with a bigger box. And going ported will add some additional low frequency output. But nothing aside horn loading, is going to actually increase the efficiency of a Tumult.

 

[TimForman]

A true TL design would make the line length equal to 1/4 wavelength of your tuning frequency. If you want to tune to 18hz you'd need a line length of 188 inches. I've made a "cheater" TL with a Shiva that's 72" long. Anyway, a Tumult TL, even folded, would be longer than your couch.

 

[Pete Mazz]

Yea, they get big! I did this with a Tempest tuned to ~28Hz, IIRC. Line length was like 122".




Stood 78" high with the base on it.

Pete

 

[TimForman]

There's no avoiding it.

 

[Seth_L]

Sure there is just ask all the people with Sunfire subs.

 

[Allen Ross]

Pete what did you use to model how that tempest enclosure? how does it sound? are you happy with it?

AND DAMN THAT SOME STUFFING!!!

 

[TimForman]

So they have small enclosures without high power and EQ?


Hoffman's Iron Law

 

[TimForman]

I used 1 lb per cubic foot in my Shiva.

 

[Brett DiMichele]

Ohh Seth is just babbling again..

The Sunfire does not circumvent Mr.Hoffman's law in any way.
It's a driver with tons of excursion, fed tons of power in
a very small box... It works... It may have too much distorsion
for some listeners but damn that Iron Law thing again.. And
yes it's heavily EQ'd as well

Doesn't seem much different than putting any driver in a
smaller than required enclosure and needing an LT Circuit to
get any useable output way down low eh?

 

[Elza]

Pete,

I'm thinking about building a subwoofer to use for about 50% Music/50% HT. How did your TL sub turn out? Would you use the same design again?

Thanks,
Elza

 

[Seth_L]

Apparently you missed my sarcasm. Some Sunfire owners on AVS think that the Sunfire bends Hoffman's law through technical advances. Hence my remark.

Apparently they think their Sunfire is every bit the equal of something like a big driver, in a big box, with lots of power. After all it plays at 111dB and goes down to 20Hz.