Duke

Keep any negative comments out please, unless they are constructive negative comments that might help me improve in future projects. I'd really appreciate that, thanks guys. Its a variation of a transmission line enclosure, designed to have alot better low end response than the big huge, low tuned ported box I had before. Don't bother trying to model it as a ported enclosure, because that is not what it is, and asking for Term Lab dash numbers is also pointless since this is a musical (TO THE EAR) box, and not designed to play loud on a PRESSURE sensor on the dashboard. I'll post response graphs once the other half is built and everything is installed. This is one half of the box and the gallon jug of green tea is in there so you can get an idea of the size of this thing. I still need to cut the sub hole, and fill/sand any screw holes. Haven't even started on the second half yet. Once again, its for a pair of these subs. Hope you like. Between this, building my amp rack/battery holder, building an ABC home theater tower, and designing an 8 foot grand piano skid, and also working two jobs... I've been quite busy... and sleepy. Enjoy. Lots of holes.

Almost done. Its going in a Durango. The first TLine I've designed and built myself.

I really don't want to divulge any of my methods as they may or may not work for someone else/another woofer. I'm really at noob status when it comes to designing enclosures, although this particular design worked as I had hoped, and then some. Audibel Customs, anything else you can tell me about the chamber would be greatly appreciated as woofer cone control is high on my list but information is very scarce on this subject. No worries about thread jacking here... I posted pictures of the enclosure, so that about completes my reason for this thread anyways... however, if we can get a bunch of useful info going in here about T-Lines and what not, thats cool.

Hey dude, thats an awesome box and some nice information! You got more pics? These two sentences are confusing me however. "The line itself is 1/4 of (the speed of sound divided by the desired tuning frequency). Not 1/4 the wavelength of the desired tuning frequency itself." Here is the second box since the first one was a success. Second box. The other piece of the port is also drying, just didn't take a fudgeing picture of it. The first box in teh Assrango. Notice the imaginary line in pic 2... a glare off something? Right at the window line. Perkins.

You're misunderstanding what I'm saying here. Yes, round T-Lines made with say, the sonotube stuff, are the direct definition of a T-Line. This box I have made is a variation of a T-Line using the same principles as a non chambered straight T-Line. This is not a bass reflex box, so I'm not going to call it one. Its a variation of a transmission line. Car audio T-Lines exist and they generally are designed to get the rear wave closer in phase with the front wave. I didn't just throw in a random volume of air for the chamber, random port area, and low tuned length... which is what most people tend to do. This box does not behave like a ported at all either. The woofer does not unload like crazy like it would if I threw it in say, 4 cubes/30hz. The output stays high down to the lowest common musical content and the excursion doesn't get out of hand. This box is designed around average wavelengths, the length from the port to the headrest, and a few T/S parameters. I'll refer to it as a wave box from now on...

the pic i posted above, with the RF sub.. will you consider that a line?? the builder kept the volume of the 'line' the same throughout its length.. he even accounted for the displacement of the driver in his design.. No he wouldn't consider that a line. Mine is very similar. Yours has a longer line length it appears and thats about it. They both have chambers. I don't understand the logic behind how they're thinking here. Its not hard to accept that there are different variations of DIFFERENT enclosures in existence. My box, and yours too probably, does not use a set volume of air, or a set surface area of port per cubic foot, or a standard "ported" tuning frequency. Mine was designed using various specs from the sub, and wavelength considerations/transmission line theories.

Yeah, thats true. There are alot of variations of T-Lines though... the chambered T-Line being one of them. Yeah Adrian, it looks like a ported box as said many times before. Its not a "ported" box though.

We're talking just regular chambered or straight T Lines here... how do these not resemble a T-Line? I think you're exaggerating your statement a bit. Word.

Neat. I'm assuming you don't mean the full wave... that doesn't look 30+ feet long.

Physical line tuning is somewhere between 47 and 55. The resonant frequency of the Durango is somewhere around 52 by my experience. I also factored in a small amount of "port" throat length to driver's head rest as well as the rough amount of height and width of the vehicle. This box is a total success though!!!!!!!

I don't know how much power its actually getting. It claims 1500 on 14.4v and 2 ohm, but that is overrated. The amp has fusing of 80 amps, and there aren't a whole lot of internals. Its also a class A/B. As for the "line tuning", I'll have to reverse crunch some of my numbers as I can't give a straight answer on that one. Give me a bit... I'm working out and screwing around on here in between sets.

Yeah, its particle board. This box sounds awesome and gets quite loud between 35 and 50 hz. It needs a better EQ to boost the low end of things. The excursion gets less and less the farther down in frequency we go, yet the output is still extremely loud. Box is a total success. I'm going to hook it up to my 40.1 in my truck sometime to see if a power upgrade would be worth it. I can't really video it right now... with sound that is. I'll also get an installed pic soon. The box isn't going to be painted or anything for a while. As for how this compares to a low tuned ported enclosure... I'm sure they would have comparable output, but I don't think a ported enclosure would exhibit the bandwidth that this box can do... especially since ported enclosures love to start unloading like crazy below the tuning frequency, whereas, this one has insanely awesome excursion control at the lowest of lows in most music.

Bringing this back from the dead... I finally got ONE sub installed a week or two ago. I'll have a pic or two up later today. The one sub does hair tricks on various music! Low end wise, this completely blows all my previous systems away!

Kind of looks like a dog... Its really not though. Point being: Yes, this is not going to be a true TL. I still have alot of learning to do, but this enclosure was not designed as a ported enclosure. I calculated the parameters (chamber volume, line length and "port" surface area") myself and decided on the off axis loading because that is what seems to work best in a Durango from my experience. Those TLs you show above are for a home. They are probably TQWPs. Yes, my box has a port, but it is not a ported box. You could probably model it up as a ported box in many different box modeling programs that simply show a cheap velocity profile in an anechoic environment, and you'd probably end up with a very different graph than what is actually going to happen... even in the room of a home. Here is what WinIsd says about it as a ported box. Transmission lines and horns come in many different shapes and forms, one of which can be a perfectly straight line/port with a square compression chamber, which would make it look just like a ported box. I have no idea what this box is going to do once hooked up, but I do have high hopes for it, especially below 35 hz. Also, 1/4 wave designs probably don't work too well in vehicles... although I'm sure it can be done. The taper in box designing is something I'm not comfortable with exploring just yet until I have a better understanding of how certain air masses interact in various environments. Pics now. I think he approves.

I have an el cheapo Creative Zen. It has a 5 band +-12db EQ, a built in mic (which records stuff really good) and 5 gb of space. Cost $50 FTW. I plan on getting a different/bigger one, but I'm worried about losing the adjustable EQ.

Yeah lawl. For just hooking up everything without tweaking the EQ(which was set to "flat") it didn't even sound bad... I think I posted it earlier, but this is what it resembles now. Going to be doing more tests/tweaks as soon as people aren't sleeping and I'm not at work.

I finally got them BOTH done and hooked up. I'm not putting a finish on them. They look fine to me. They're made out of 3/4" MDF with oak laminated onto them. On the edges you can see the MDF, but at this point, not a big deal to me. These needed to stay rather cheap so I didn't buy very nice wood. Each tower houses 2 Dayton DC160s (8ohm versions), one HiVi TN28 (6 ohms) and an 8 ohm 3khz passive crossover(from Partsexpress). Both towers are powered by a Dayton APA150 in stereo mode, running at just under 4 ohms. The source of audio is my computer. These things sound awesome. They respond very audibly into the low 40s, and audibly into the 30s. The best word I can think of to describe the sound is "Thunderous!". I still need to tweak the EQ on the computer, but I can't imagine them sounding much better than they already do. Some pics are slightly blurry as my hands are gargantuan, unsteady and I didn't feel like hunting down teh tripod. Yeah, I know... my room sucks too. Countersunk terminals.

I have failed at finding the edit button, so here is what those were. These were unEQed responses at the head of my chair... no sealed up on the desk.

Which ones are broken? They're all loading up for me.

If you've never used True RTA before, each darker horizontal line represents 5 db, while each lighter colored line represents 1 db. The biggest variance in most of the range is 2 dbs, until you get to 9 khz where you can see it drops off hard. For the lower, it drops off hard around 29. I get to see how this "flat" sounds with music today after a few more tweaks.

After some tweaking.

Use a Line Out Converter. Just involves splicing the pos and neg wires from your AV sub output to the pos and neg wires on the LOC (Line Out Converter). After that, you just run RCAs from the LOC to your subwoofer's input. You can probably get away with just hooking up one of the RCAs from the LOC to the sub input, and not having to use converting adapters to get both hooked to the sub.

Possibly. You could just build a random cubic foot box tuned to a low frequency and see what happens... or you could read up on placement, mass ratios, wavelengths, etc. There are alot of variables that go into a box and how it will do in a room. If you were to build a low tuned box, you could probably get away with it, and just use a good bass eq to fine tune it as much as you can.

Here we go. I haven't done any EQing. First one is without me in the seat, second one is with me in the seat. Not really that big of a difference... *WPSHHHH!* The lowest DB reading is -55 at 20 hz, and the highest is +1db at around 4 khz. I did tons of testing with the mic in different positions and there weren't a whole lot of variances. These are with the mic pointing almost horizontal at the monitor(which is in the middle of the towers roughly 3 1/2 feet from each tower.). The towers are angled towards my seat.

Well, ABC stands for Aperiodic Bi Chamber. The speakers's rear wave fires into a chamber which port itself into two areas: The upper port fires directly into the room surrounding the speaker. The other port goes to a second chamber which also has a tuning frequency, then fires out to the environment also. The box achieves two tuning frequencies, giving it a nice long frequency response. Some compare it to a 6th order bandpass box which also has two tuning frequencies. These are much easier to design and usually sound better from what I've read, due to the fact that the woofer isn't fully enclosed. The second chamber acts sort of like a filter and a small room It takes the sound in the "small room"(second chamber) and EQs it a bit to sound different, then, what you hear in the actual room is the result. I think I'm right on track here, anyone feel free to chime in.