Printer Friendly Forum Posts - Transmission Line Enclosure

Hey guys whats up...Just wanted to post up a build I finished tonight.

I'm sure Haemphyst will like this one.

Took a few hours. It's not perfect but its pretty good and solid. The only thing I would have done different is add the 45s in the corners but my saw was being a f'in spaz and wouldn't cut no more than 4 inches on the 45 degree angle.

Its 1/4 wave tuning is right around 31Hz. The sub in there right now is a Elemental Designs EHQS 12. The enclosure is originally designed for an old school JL 12W6.

I haven't gotten a chance to test it out yet besides 20 seconds with 40 watts going towards it. From that listening test the lows are pretty good and seems like the lows have much more authority than the previous 2.5 cu ft @ 30Hz box the sub was in.

I'll come back tomorrow after a thorough listening test.

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aznboi3644 wrote:

Hey guys whats up...Just wanted to post up a build I finished tonight.

ALWAYS like the pics! posted_image

aznboi3644 wrote:

I'm sure Haemphyst will like this one.

I'm honored! Seriously, thanks for thinking of me!

aznboi3644 wrote:

Took a few hours. It's not perfect but its pretty good and solid. The only thing I would have done different is add the 45s in the corners but my saw was being a f'in spaz and wouldn't cut no more than 4 inches on the 45 degree angle.

At subwoofer frequencies, a 45 won't add anything, acoustically... You can add them for structure, but if you are otherwise doing pretty well "solidity-wise", then you are probably OK...

aznboi3644 wrote:

Its 1/4 wave tuning is right around 31Hz. The sub in there right now is a Elemental Designs EHQS 12. The enclosure is originally designed for an old school JL 12W6.

How did you figure the wavelength? That looks a little bit short for 31Hz. Post up a few specs (the ones you used in your calculations) lemme plug 'em in! posted_image

Just as a cross check!

aznboi3644 wrote:

I haven't gotten a chance to test it out yet besides 20 seconds with 40 watts going towards it. From that listening test the lows are pretty good and seems like the lows have much more authority than the previous 2.5 cu ft @ 30Hz box the sub was in.

That looks like... what... about 3 cubes, or maybe a little more? That's a BIG box! TLs will always sound deeper than a roughly equivalently sized vented enclosure...

aznboi3644 wrote:

I'll come back tomorrow after a thorough listening test.

Cool! Let us know!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Whats up guys...I took a small vid today. my sister's camera has barely any memory on it so 29 seconds is all I got.

As for how it sounds..._IN AWESOME. The tonality is a lot different from the 2.5 cu ft @ 30Hz box it the EHQS was in. This thing digs deep and has usable response down to 25Hz testing with sine waves...below that it unloads and doesn't have much output. It has a pretty flat response from 28 - 60Hz. I really love how it sounds. It's easy to tell when the EHQS is reaching its mechanical limits as I can hear it bottoming out but that is only on certain beats but overall it slams hard and gets really low but still retains its punchiness and transients.

30-35Hz tones are fun. Compared to the 2.5 cu ft ported...this T-Line rapes it hands down. Only thing is that the box is 38.5" wide and 21.75" deep lol. But I don't need cargo space.

I think everyone should get to listen to a transmission line enclosure...it does really have a different sound to it.

Anyways...heres a little vid

Also Haem...the box is 38.5" wide and 21.75" deep and 16.5 inches tall...external dimensions that is. Port width is 6.25" throughout. Just a little bit over 3 cu ft lol.

Heres a pic of the sketch up

posted_image

If my trunk wasn't so tiny I'd try one. That thing is really cool.

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"I'm finished!" - Daniel Plainview

Today I put in the 12W6 and WOW...it is even BETTER. It's a lot louder than the EHQS 12. Slams the lows really really well.

I went to a couple shops here and asked some people what they thought was in the back...test track was of course Euphoric Midnight Bass - Track 11

The first shop theres a guy with four 12's sealed off 2000 watts in his dodge avenger....he guessed I had two 15's and 1000 watts.

Owner of the first shop is more experienced....he guessed one 12 and 800-1000 watts.

Next shop a guy there guessed three 10's and 1000 watts.

second guy at the next shop guessed a single 12 and 1000 watts.

Sounds really good to me for a single 12 and 200-250 watts without impedance rise. Surprised the hell out of me.

Tomorrow I'll take some more videos. This is one efficient enclosure.

Enclosure is 38.5" wide, 21.75" deep, and 16.5" tall

Haem could you recheck the line tuning for me??

I get an EFFECTIVE line length of about 100 inches. 100*4=400

400 inches is right at about 32Hz, which is why you have so much fun with the 32-35Hz signals... posted_image

This is a high Q line, meaning it's peaky. With a taper, it smooths the Q a bit, and makes the terminus's output a bit smoother.

I would have modified it a bit to include a taper in the length, that'll help prevent standing waves - that's just me. Also, my personal opinion is that the terminus is a little too big. 15*6.25=93.75 square inches... too big for a 12 inch woofer. (The ideal unstuffed line aims for 25 to 50 percent of the driver's Sd - this terminus is close to 1.1 times posted_image

)With that much terminus you are relying EXCULSIVELY on the air mass in the line to damp the woofer, which means minimal extension below resonance, and FAST unloading below resonance... I hope you have a subsonic!

If it works for you, though, KEEP it... I'm just saying what I would have done with it! posted_image

sedate wrote:

If my trunk wasn't so tiny I'd try one. That thing is really cool.

Hell, man! I did it in MY trunk - a two door Civic!! ANYBODY can do it!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Haem...this was my first T-line build. I only want to learn from it.

If I were to design another T-Line but a tapered line. What should the starting area be if the terminus is 25-50% Sd???

aznboi3644 wrote:

Haem...this was my first T-line build. I only want to learn from it.

No, dude... I totally respect that. I didn't mean to sound like I was tearing anything apart...

aznboi3644 wrote:

If I were to design another T-Line but a tapered line. What should the starting area be if the terminus is 25-50% Sd???

If stuffing, I generally use 100 to 150% of the Sd, and it is wherever you start the line... If you are adding a box to house the woofer, then wherever you attach the line to that box would be 100 to 150% Sd... (I'm reading that back to myself, and it makes NO sense at all... I hope you know what I mean...)

The difficulty comes in trying to decide whether to add a true taper, or a stepped taper. Acoustically, I prefer a true taper, even though it is SIGNIFICANLY harder to design and build. Then you have to decide whether you want to stuff or not... LOL Fun, fun, fun...

Stuffing shortens the line, so your taper becomes tighter. Heavier stuffing shortens the line further, so your taper becomes even tighter! See where this leads?

I sent a bunch of stuff to DYohn about a year or a year and a half ago... DYohn, you still got those files? Can you put 'em up on the downloads side? I'd like to get a copy of them back if possible, I had a HD crash, and I've lost 'em all...

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

A HD crash with no backup? Tsk tsk, maybe you should get some help from somone who works in, oh I don't know, IT? posted_image

I still have the printouts. I'll get them scanned.

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I wasn't taking your post as offensive...I just fell in love with the sound of a transmission line and want to improve the sound.

I'll try to design a tapered line and post it up to see if it is correct.

aznboi3644 wrote:

I wasn't taking your post as offensive...I just fell in love with the sound of a transmission line and want to improve the sound.

Cool... Like I said, wasn't trying to tear anything apart. posted_image

But it's pretty easy to do, huh? I've been in love with TL's since the first time I ever heard one! Then I built one! WOW!! Fun to play with and tweak, too!

aznboi3644 wrote:

I'll try to design a tapered line and post it up to see if it is correct.

Happy to do what I can to help!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

heamph wrote:

sedate wrote:
If my trunk wasn't so tiny I'd try one. That thing is really cool.
Hell, man! I did it in MY trunk - a two door Civic!! ANYBODY can do it!

Allright heamph, I'll bite. aznboi's got me dyin to try one - and my stereo is about to come out to make room for a case of Dynamat anyway. I never could find woofers to replace those CDT's I've been complaining about anyway - I haven't liked a woofer I've purchased since my Kappa Perfects got stolen a few years ago. I might as well try a whole new deal eh....

Any links you could recommend to start researching the build? Googling seems to turn up alot of stuff about electrical cables - and the topic doesn't seem to get much coverage here on the12volt. Does WinISD Alpha do transmission lines? How does this alignment influence total power handling?

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"I'm finished!" - Daniel Plainview

www.quarter-wave.com

aznboi3644 wrote:

www.quarter-wave.com

I've got some others, as well... I'll get em tomorrow for ya!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

haemphyst wrote:

aznboi3644 wrote:

www.quarter-wave.com

I've got some others, as well... I'll get em tomorrow for ya!

Another good one!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Copies of the how-to files are HERE. Have fun. (BTW I've built systems using the hybrid TL theory described in these docs and they sound fantastic. Extension to 28Hz with a 7" woofer, for example.)

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Thanks, DYohn! MUCHLY appreciated!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Ok well Haem could you check the line length here?? I tried and came up with around 100 inches...shouldn't that be around 34Hz??

posted_image

Bump Haem??

BTW

OMG...today I took one of my friends 12 Type R's and put it in my T-line.

He has the Best Buy 4 year replacement plan so he wanted to blow his two and get new ones...I said I could help with that

Well I just got back from a HEAVY BEATING SESSION. I mean I threw the full fury of the Elemental Designs Nine.1 at it at 1 ohm and it only gave out some burnt coil smell but still pounds.

I mean first I gave it the usual full blast of "White Girl" and "Hypnotize"...the WHOLE SONG.

Still nothing...so I said aight well lets see if we can bottom it out. Played a 10Hz tone for a FULL MINUTE. No sweat the sub just laughed at us.

Played 20Hz tone for a FULL MINUTE. Ehhh some vc smell but nothing major. Hey how about another minute of some 30Hz tone. Still nothing. The smell came and went. Maybe it was some excess glue.

BUT GOD DAMN...this Type R will NOT DIE. My ears are KILLING. I even played a bunch of Bass songs...the usual stuff you download from limewire when putting in "bass tester" and stuff like that.

I mean 30 minutes of full blast 1200 watts and tones...the sub is still alive and kicking.

wth?? lol

I'll take some vids sunday..I'll be gone for the weekend for a wedding.

WTH... I thought I HAD posted... Jeez, I'm WAY too busy lately.

Anyway, yes, you should be right around 34Hz with that one, too... Again, pretty high Q, though.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Since the walls aren't tapered is this a transmission line?

Yes, it is still a TL. The tapering, stuffing, wall treatment, corners, etc., all add to the response characteristics and/or the overall size of the resultant TL, but the line does not have to taper for the enclosure to be called a transmission line.

BTW, azn, that looks like an enclosure for a 15... Is that what you have in mind? I get 11 to 13 cubic feet! (give or take) GAH!!! A bit... ummmmm.... BIG for the car, wouldn't you say!?!?!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

DYon said: Yes, a "speaker at the end of a long tube" can be stuffed and tuned like a transmission line. A true TL uses a tapered line, with the TQWT approach being most common.

I'm a bit confused since the box aznboi has built is identicle to the picture in the post "Bass reflex design" dealing with the qualification of being a T-line enclosure.

Dyohn also said:

"It's not a transmission line if the size of the port remains constant. If it is the same size from start to finish, it is a bass reflex enclosure."

its a transmission line for an 18 inch subwoofer lol

going to take up pretty much all of my cargo area in my explorer

I'm basically going to huge output between 30-60Hz Hopefully.

Its quite big...externally the box should be right around 14.85 cubic feet. haha

damn...i remeasured my cargo area..the enclosure has to be smaller.

Max dimensions are 31 deep, 41.5 wide, and 20 tall.

So back to the drawing board...I am going to try to make a stepped tapered line going from 100% Sd down to 30-50% Sd

Haem...what do you mean from that line having a high Q???

aznboi > embarking on project that has no light at end of tunnel ( Confucius )

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

stevdart wrote:

aznboi > embarking on project that has no light at end of tunnel ( Confucius )

lol...its just an experiment...if it doesn't work out than I'll have learned from it. I'm not expecting anything crazy. If it turns out good than awesome.

I'm planing on building a normal ported enclosure for it also as a backup.

The Q of the line will be relatively high, without tapering... A high Q line will tend to have a fairly peaky response, and tend to unload faster below resonance.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

so a tapered line will have a smoother flatter response??

Generally speaking, yes. It is also what I have discovered in practice as well.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Haem, I finally read two of those articles DYhon posted up. VERY informative. I also dug up some articles my A.R. Baily that were very helpful also as well as a couple others I haven't read yet.

I think I am starting to learn more about transmission lines. There are a some details about them that I am catching onto. Thank you again for those articles. I am starting to realize what stuffing the line does and how it affects the line as well as the correlation between the line length, cross sectional area, and volume.

There is still MUCH to learn as I have only hit the top of the iceberg but I am still learning and have some redesigning to do.

are tl boxes effective if you reverse mount the sub?

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theetimurban wrote:

are tl boxes effective if you reverse mount the sub?

Sure. Reverse mounting a subwoofer means very little to its performance.

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Weird thing I came across...I reversed the phase of the subwoofer and BAM...the bass was a lot tighter and louder. The sub is hitting "in" now but the bass sounds a lot better...reversing the phase also brought the bass up front more.

That means that at the crossover point of you mid-bass in the doors, your sub was out of phase, and now you have fixed it.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I always demand a reverse phase test with the subwoofer in the initial days of the setup. Car audio, home audio, it doesn't matter. Variable phase adjustment...well, that could take a little longer. Once you get phase right, you know it.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

its weird because with the same 12W6 in a 2.5 cu ft ported the sub sounds better with the phase reversed...lol

Also I remember when I had my old rf punchZ 10s in a SEALED box they sounded better with the phase reversed

The woofer will "sound" the same, always. What I mean, is this: If the sub were the ONLY speaker in the system, the human ear would never be able to hear an "in" phase or "out" of phase woofer, I guarantee it. Integration with the front stage is what you are hearing.

If your woofer is out of phase from the fronts, the highest registers from the sub will cancel the lowest registers from the fronts, causing a suck-out in the frequency response. That is what you are experiencing. One polarity just prevents it better than the other.

Since TLs and vented enclosures will have different phase characteristics in the highest harmonics, it is possible that you are hearing those differences as well, but overall, what you are hearing is an improvement in phase integration.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

yeah...I've learned to mess with the phase setting to bring the bass up front and improve the transients. Before without reversing the phase the bass got muddy on quick double kick drums...now with the same exact setup the midbass and bass is as fast as it should be.

I guess there was a lot more cancellation with the sub in phase with the fronts.