T-Line enclosures
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2255 Registered: May-07 | Lately I've been reading up allot on transmission line enclosures. I think I have the room to do a very basic 1/4 wave t-line in my trunk. If I am wrong on something, please correct me as I am wanting input. The sub I would be using is a 12" LA storm x1, which has a QTS of .36 and an FS of 29hz (from what I've read). I should match the ports cross section to the subs SD and could possibly get away with a slightly smaller port due to a low QTS correct? The enclosure I'm wanting to do is basic, just same size port from beginning of the line to the exit. Now by tuning the enclosure higher than the subs FS, it would also make the roll off steeper on frequencies higher than wherever the enclosure would peak at. And a lower tuned enclosure would have a higher roll off, opposite of a low tuned bass-reflex style enclosure, correct? If I'm looking for superb freqency response would I tune right at the subs FS that the manufactures rate it at, or possibly go a few hz lower to compensate for the subs break in? Last, if my math is correct, I would need an enclosure with a port length of 9.74ft long to tune to 29hz. Going back to the subs SD, do I measure just the cone, or half of the surround as well? Are T-lines my best bet for that SQ sound with that SPL feel? I apologize for the long read, but it's not like I forced you to read it lol. Any input is appreciated.  |
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2257 Registered: May-07 | Bump! C'mon has E really gone this far down hill? I know there is still a good dozen of smart regulars out there left that can help me. |
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Gold Member Username: Nd4spd18Philadelphia, PA Post Number: 9411 Registered: Jul-06 | Usually they are not any better than a good old fashioned ported box, just a hell of a lot bigger. Part of the reason you don't see many of them. That and they're a bittch to design. |
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Gold Member Username: Nd4spd18Philadelphia, PA Post Number: 9413 Registered: Jul-06 | PM canaan for a better answer |
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Gold Member Username: Hittin1TEAM REVOLUTIONLake Charles... Post Number: 2139 Registered: May-07 | I've never got into them because I heard they were more trouble than they were worth. Again, this is only word-of-mouth. |
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2263 Registered: May-07 | I emailed Canaan, hopefully he can be of some assistance. I've been lightly modeling a few boxes (in my head lol) and I just realized that the only way the sub would work in this type of enclosure is if I reverse mount it, due to that the mounting depth is too big. And that might not work since I'm crunched for space as it is! Unless I do like a triple baffle or something crazy. |
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Platinum Member Username: GlasswolfRaccoon City, MI USA Post Number: 12206 Registered: Dec-03 | What's the vehicle? I typically would not do a TL box for a 12" sub in a car. Far too big of a box where TL s usually done for an 8" at the largest. That said, for a 12" you can get approximately the same results and accuracy from an AP enclosure instead, and still get the "wow neat" factor from it. I've run two RE XXX 12" in an AP box in my car with 3Kw of power to them and it did beautifully. TL is better suited to home speaker cabinets for floor standing mains. |
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Platinum Member Username: InsearchofbassPost Number: 11124 Registered: Jun-04 | AP = aperiodic for those that are wondering. |
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Platinum Member Username: GlasswolfRaccoon City, MI USA Post Number: 12212 Registered: Dec-03 | indeed it does. google can give more info on an aperiodic membrane or I can probably dig out a few links. |
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Silver Member Username: CozceSt. Louis ILLside, Pronounced: ... U.S.A. Post Number: 459 Registered: Mar-08 | I'm a nub but I'm glad GlassWolf is back. Few links for AP? |
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2265 Registered: May-07 | Thanks Glass. It would be going in the trunk of a 98 Grand Prix 4 door. Just how difficult would a AP enclosure be to design? What type of design would recommend for my application and for a first time experience? Back to T-Lines...the 12" LA storm has a cone diameter of only ~7.5" (due to a huge surround), So could I get away with a ~44sq inch port? If I did incorporate another 2" to make up for roughly half the surround would I be looking at ~71sq inch port or am I way off? |
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Platinum Member Username: GlasswolfRaccoon City, MI USA Post Number: 12219 Registered: Dec-03 | the typical problem with a TL enclosure is the length of it, not so much the opening for the port. you need considerable length to mature that quarter wave. AP: http://www.audiogearreviews.com/tech/theory/enclosure_design/aperiodic_membrane. asp had other links but the sites seem to have died.. sorry most of the rest I have is all on paper around here somewhere. |
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2266 Registered: May-07 | Thanks for the info...but I don't think I'm going to go the AP route, don't want to seal my trunk off from my cabin or anything like that, this is my winter car. But...would doing an AP setup work in something like a camaro hatch? They have the area in the back where the T-tops go into, could I seal off the membrane in there? |
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Platinum Member Username: GlasswolfRaccoon City, MI USA Post Number: 12228 Registered: Dec-03 | you don't really need to seal off the trun. you can just make a dual chambered enclosure to serve the same purpose. |
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2271 Registered: May-07 | How big would the chamber for the sub need to be, same as sealed? What about the chamber for the membrane to breath in? Do you know any other links by chance that would be more detailed on the design? |
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Platinum Member Username: GlasswolfRaccoon City, MI USA Post Number: 12235 Registered: Dec-03 | have you tried google for formulas for an AP enclosure? If you have I can dig mine out. Otherwise, try that and see if that helps first. Mine are packed up for a move this coming Spring already. |
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Gold Member Username: BernymacPhnom PenhCambodia Post Number: 4543 Registered: Sep-04 | http://www.usdaudio.com/aptutorial.htm Looks interesting. I would probaly want to try something like this for my civic possibly. |
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Gold Member Username: SomedonniedudeIllinois Braaap MX Post Number: 2275 Registered: May-07 | I couldn't find any formulas. But I have done a bit more reading about AP's. I think I'm going to wait till later this spring and try an AP build in my Camaro, since I plan on going almost all SQ with that vehicle (don't want to rattle it apart). Maybe in the spring I'll contact you and see if you have those formulas unpacked. I'm probably just going to stick a standard bass-reflex box for now, I have some chopping to do on my current box to keep me entertained. I really wanted to do a T-line just to experiment, but that might also come later since my buddy just got a suburban and plenty of room  |
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Platinum Member Username: GlasswolfRaccoon City, MI USA Post Number: 12266 Registered: Dec-03 | No problem. I've been here for years, and I'm not planning to vanish any time soon. TL enclosures are really nice, don't get me wrong. I just feel personally that tey are better suited to a home environment for acoustic response and typical enclosure size. They make outstanding floor standing main speakers in a home, with a TL loaded small bass driver and a mid or two with a tweeter front firing in the cabinet. It's not too unlike the KEF 104/2 Refernce mains I use currently in design. AP works very well in a vehicle with a trunk or isolated space you can seal off, or if you have room to build a dual chambered enclosure.. otherwise for SQ, just go sealed with a good sub. Fi has good subs designed for smaller sealed enclosures which may suit your needs as well. I wound up using an Fi Q15 in the spare tire well of my old Charger, and it works splendidly as small sealed enclosure completely concealed. |
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